Gravitricity – Fast, long-life energy storage(gravitricity.com)
gravitricity.com
Gravitricity – Fast, long-life energy storage
https://gravitricity.com/
287 comments
I'm not sure if you are joking or not, but regenerative elevators exist, and have existed for over 100 years:
> DC-driven winding-drum elevators—the leading design until the 1930s—use a DC motor in the basement that winds and unwinds the elevator’s steel cable on a steel drum, thus lifting and lowering the car from pulleys atop the elevator shaft. DC drive was the only way to go at the time for a speedy elevator, because only DC could deliver variable-speed operation for smooth starts and stops. The DC motors were also energy efficient, capable of something that has only recently become possible with modern elevator designs: regenerating power when the elevator descends.
https://spectrum.ieee.org/tech-history/dawn-of-electronics/s...
> DC-driven winding-drum elevators—the leading design until the 1930s—use a DC motor in the basement that winds and unwinds the elevator’s steel cable on a steel drum, thus lifting and lowering the car from pulleys atop the elevator shaft. DC drive was the only way to go at the time for a speedy elevator, because only DC could deliver variable-speed operation for smooth starts and stops. The DC motors were also energy efficient, capable of something that has only recently become possible with modern elevator designs: regenerating power when the elevator descends.
https://spectrum.ieee.org/tech-history/dawn-of-electronics/s...
> Idea: Could elevators be retrofitted with something like this?
I think it would not work so well because they have counterweights to make the up-down operation much easier. If you remove the counterweight, it would store energy, but be prohibitively slow when going up and probably frighteningly fast going down.
Regarding the uhaul, this is not too far off from other people mentioning driving a train uphill and letting it fall downhill to generate electricity. Interesting ideas.
I think it would not work so well because they have counterweights to make the up-down operation much easier. If you remove the counterweight, it would store energy, but be prohibitively slow when going up and probably frighteningly fast going down.
Regarding the uhaul, this is not too far off from other people mentioning driving a train uphill and letting it fall downhill to generate electricity. Interesting ideas.
Am I the only one to expect the goatse on the bottom of the site?
Can we stop with these convoluted systems and just do nuclear already?
You'd compare the relative simplicity and complexity of a nuclear reactor to this "dig a hole in the ground and drop a weight" scheme ?
Regardless of your thoughts on Nuclear, this is clearly a much simpler device. Also, I suspect the failure modes in this are pretty boring ...
Regardless of your thoughts on Nuclear, this is clearly a much simpler device. Also, I suspect the failure modes in this are pretty boring ...
With nuclear you still need storage to flatten the peaks and troughs though right?
Also this does not seem very convoluted, it's using an electric engine pretty directly. If you are actually boring straight down it seems like the failure modes are pretty okay.
Also this does not seem very convoluted, it's using an electric engine pretty directly. If you are actually boring straight down it seems like the failure modes are pretty okay.
> With nuclear you still need storage to flatten the peaks and troughs though right?
Why? Just build more. Keep expanding capacity so the base load covers the peaks and thensome. Push the price of electricity down while keeping it carbon-neutral and crush competition. Get everyone 2c/kwh power. Wouldn't that be more fun?
Why? Just build more. Keep expanding capacity so the base load covers the peaks and thensome. Push the price of electricity down while keeping it carbon-neutral and crush competition. Get everyone 2c/kwh power. Wouldn't that be more fun?
Are you joking? Building nuclear power to cover peaks is insanely uneconomical. More expensive than building a nuclear power plant in a flexible grid.
If you don't know anything about how a grid functions then maybe you should stop shoehorning a single solution to solve every problem when everyone is already aware that a large array of different technologies is necessary for a modern grid.
If you don't know anything about how a grid functions then maybe you should stop shoehorning a single solution to solve every problem when everyone is already aware that a large array of different technologies is necessary for a modern grid.
The problem is the speed at which the reactors can be ramped up and down, this is very limited. Also, if you have enough capacity to cover all peaks, most of the time the reactors are not running at full power. That increases the cost of operating the reactors, which is far higher than you claim. Currently, projects building new nuclear reactors are challenged by their costs. Never mention the safety concerns and of course the waste problem.
Current versions of the traditional LWR design can ramp at about 5% of full power per minute, which is about the same ramping rate as a CCGT plant. With steam bypass it's possible to ramp even faster.
Demand response, frequently promoted as a way to increase penetration of intermittent renewables, can also be used to reduce the cost of a system composed on high capital cost, low marginal cost dispatchable generators like nuclear. Charge the EV's and run heat pumps to warm thermal storages during the night when demand is lower, say.
Demand response, frequently promoted as a way to increase penetration of intermittent renewables, can also be used to reduce the cost of a system composed on high capital cost, low marginal cost dispatchable generators like nuclear. Charge the EV's and run heat pumps to warm thermal storages during the night when demand is lower, say.
Yes, demand response will play a huge role in the grids of the future. But when you say "current versions", which current operating nuclear plant achieves this ramp speed?
Also, it means you have to run your reactors regularly at below 100%, so you still can react on additional demand, which increases further the cost of a very expensive technology.
Also, it means you have to run your reactors regularly at below 100%, so you still can react on additional demand, which increases further the cost of a very expensive technology.
> But when you say "current versions", which current operating nuclear plant achieves this ramp speed?
IIRC that 5% figure I read was wrt EPR and AP1000, presumably older generation LWR's are slower, by how much I'm not sure. France has run older generation PWR's in load-following mode for decades, but I'm not sure which ramp speeds they achieve; fast enough in practice in any case it seems. CANDU reactors in Canada have steam bypass and can apparently ramp at >10%/min.
In any case, my point is that ramp speed is in practice not a technical limitation. Of course you want to run a generator with high capital cost but very low marginal cost at 100% as much as possible, but if you now and then need to ramp (say, if the wholesale price goes negative) you can do it.
> Also, it means you have to run your reactors regularly at below 100%, so you still can react on additional demand, which increases further the cost of a very expensive technology.
To be clear, I'm not advocating a 100% nuclear grid. I'm just pointing out that the "nuclear can't ramp and is thus unsuited for the grid of the future" isn't correct. In particular, I think solar and a moderate amount of storage is very well suited to cover the daily variation in many parts of the world. I also think that dispatchable low-carbon sources (which could be hydro, or nuclear, or something else like geothermal where available, CCS where geological formations for storing CO2 are available, etc.) have a role to play in least-cost deep decarbonized grids. See e.g. https://doi.org/10.1016/j.joule.2018.08.006
IIRC that 5% figure I read was wrt EPR and AP1000, presumably older generation LWR's are slower, by how much I'm not sure. France has run older generation PWR's in load-following mode for decades, but I'm not sure which ramp speeds they achieve; fast enough in practice in any case it seems. CANDU reactors in Canada have steam bypass and can apparently ramp at >10%/min.
In any case, my point is that ramp speed is in practice not a technical limitation. Of course you want to run a generator with high capital cost but very low marginal cost at 100% as much as possible, but if you now and then need to ramp (say, if the wholesale price goes negative) you can do it.
> Also, it means you have to run your reactors regularly at below 100%, so you still can react on additional demand, which increases further the cost of a very expensive technology.
To be clear, I'm not advocating a 100% nuclear grid. I'm just pointing out that the "nuclear can't ramp and is thus unsuited for the grid of the future" isn't correct. In particular, I think solar and a moderate amount of storage is very well suited to cover the daily variation in many parts of the world. I also think that dispatchable low-carbon sources (which could be hydro, or nuclear, or something else like geothermal where available, CCS where geological formations for storing CO2 are available, etc.) have a role to play in least-cost deep decarbonized grids. See e.g. https://doi.org/10.1016/j.joule.2018.08.006
From my understanding some of the "delay" in ramping up is related to enrichment level of the nuclear fuel and thus how fast the speed of the reaction can change.
Kind of. When reducing power there's a buildup of a particular Xenon isotope, which is a powerful neutron adsorber. So until that isotope decays away sufficiently you might have problems starting the reactor back up again. Unless you have enough excess reactivity, such as by having fresher fuel loaded.
AFAIU France primarily uses reactors which are earlier in their fuel cycle for load balancing, and ones which are near the end run with a flatter profile.
AFAIU France primarily uses reactors which are earlier in their fuel cycle for load balancing, and ones which are near the end run with a flatter profile.
Makes sense!
Didn't know about specific as it's not really my area, but would running a PWR with very high enrichment level (AFAIK some designs use 93% U-235) allow quick spin down and spin up?
Didn't know about specific as it's not really my area, but would running a PWR with very high enrichment level (AFAIK some designs use 93% U-235) allow quick spin down and spin up?
> would running a PWR with very high enrichment level (AFAIK some designs use 93% U-235) allow quick spin down and spin up?
Well.. there are a lot of factors in a reactor design affecting the ability to increase or decrease power quickly. Geometry, fuel/moderator ratio, fuel density, burnable poisons (for flattening the reactivity swing over the fuel cycle), amount of control rods etc etc. Fuel enrichment being only one thing, which in turn affects other things as well (e.g. reactors using highly enriched uranium tend to use different fuel designs than low enriched fuels).
But yes, military reactors for navy ships obviously have very different demands on them than civilian power reactors, and are designed accordingly.
And yes, while US navy reactors use 93% enriched fuel, it's not necessary, e.g. French and apparently Chinese submarines use low enriched fuel (7% for French).
Well.. there are a lot of factors in a reactor design affecting the ability to increase or decrease power quickly. Geometry, fuel/moderator ratio, fuel density, burnable poisons (for flattening the reactivity swing over the fuel cycle), amount of control rods etc etc. Fuel enrichment being only one thing, which in turn affects other things as well (e.g. reactors using highly enriched uranium tend to use different fuel designs than low enriched fuels).
But yes, military reactors for navy ships obviously have very different demands on them than civilian power reactors, and are designed accordingly.
And yes, while US navy reactors use 93% enriched fuel, it's not necessary, e.g. French and apparently Chinese submarines use low enriched fuel (7% for French).
A lot of the costs is politics, and second-order effects from lack of production lines making everything a one-off.
Which "funnily" enough makes it so that the more dangerous reactors remain in use for longer, as the new designs aren't built, despite huge safety improvements (even if you go just for late 1970's self-sealing molten lead/bismuth reactors).
Overcapacity is a problem, especially for low-enriched reactors, but that's why it shouldn't be the only answer.
Which "funnily" enough makes it so that the more dangerous reactors remain in use for longer, as the new designs aren't built, despite huge safety improvements (even if you go just for late 1970's self-sealing molten lead/bismuth reactors).
Overcapacity is a problem, especially for low-enriched reactors, but that's why it shouldn't be the only answer.
So print more money, what does it even matter anymore in the land of MMT?
> the waste problem.
Ehh, it's well managed in Canada and France, I don't see why Americans can't handle it. Just keep it away from fault lines, right? I bet some of those old missile silos would be perfect.
> the waste problem.
Ehh, it's well managed in Canada and France, I don't see why Americans can't handle it. Just keep it away from fault lines, right? I bet some of those old missile silos would be perfect.
You would only have to print half as much money, if you use solar+wind+storage.
And please enlighten me, how does France manage their nuclear waste problem?
And please enlighten me, how does France manage their nuclear waste problem?
Like every sane country, they reuse it - only the final, hard-to-use fractions are stored, which takes a relatively small hall (pretty sure typical US football stadium is bigger).
And those hard-to-use fractions aren't going to be a problem for long, pretty sure they are considerably shorter-time risk than the timeframe for cleanup of WW1 battlefields in France (which currently stands at around 700 years).
And those hard-to-use fractions aren't going to be a problem for long, pretty sure they are considerably shorter-time risk than the timeframe for cleanup of WW1 battlefields in France (which currently stands at around 700 years).
If you have more production than demand you need to store it somewhere, which is exactly the point of such projects, if only to prevent network desynchronisation that causes brown/blackouts due to power flowing in different way than you want in the grid.
Energy storage has also been planned for nuclear power plants as starter and emergency power.
Energy storage has also been planned for nuclear power plants as starter and emergency power.
Exactly.
Most people just don't want to accept the fact that when it comes to energy density, nothing compares to nuclear. Nothing even comes close.
https://dothemath.ucsd.edu/2011/11/pump-up-the-storage/
Most people just don't want to accept the fact that when it comes to energy density, nothing compares to nuclear. Nothing even comes close.
https://dothemath.ucsd.edu/2011/11/pump-up-the-storage/
even if nuclear had no contamination horrors, this is no longer true. Hydrino energy is much more energy dense and will be the ubiquitous portable power source for the 21st century and beyond.
https://brilliantlightpower.com/news/
https://brilliantlightpower.com/news/
My comment might be read as 'Nothing will EVER compare to nuclear'.
While in fact what I meant was 'CURRENTLY nothing scientifically viable compares to nuclear.'
I do have high hopes about fusion and molten salt thorium is also up there as something I'd like to be further explored.
But currently nothing up and coming seems to compare to nuclear.
I just did a quick skim of the wikipedia page of that 'hydrino' stuff: https://en.wikipedia.org/wiki/Brilliant_Light_Power#Criticis....
I'm not an expert, but reading those criticisms makes me think this is nothing more than a money grab scheme without delivering anything usable for the past 30 years.
Also, this thread: https://news.ycombinator.com/item?id=24423103
I do have high hopes about fusion and molten salt thorium is also up there as something I'd like to be further explored.
But currently nothing up and coming seems to compare to nuclear.
I just did a quick skim of the wikipedia page of that 'hydrino' stuff: https://en.wikipedia.org/wiki/Brilliant_Light_Power#Criticis....
I'm not an expert, but reading those criticisms makes me think this is nothing more than a money grab scheme without delivering anything usable for the past 30 years.
Also, this thread: https://news.ycombinator.com/item?id=24423103
Is it really worth it to dig a hole? I seem to recall some other initiative that was stacking large blocks with some kind of tested COTS construction cranes. The stack-of-blocks way seems to intuitively scale better. You can increase capacity without digging another super deep hole, or ever upgrading your cabling.
[deleted]
There are a bunch of these seemingly questionable ideas out there trying to score funding. A few years ago there was one to run a train up a mountain or create a giant compressed gas reservoir underground.
It may seem strange to use energy density in this context but in many ways those are even worse than batteries due to the massive amount of work they require and poor scalability because of all the physical infrastructure and space.
In fact, this exact scheme looks to have been posted to HN in 2014. From my understanding they are looking to re-purpose holes that have already been dug, for the most part, which is a good idea, but if the planned prototypes are only doing 250 kW nameplate with maybe 100 KWH of stored power, there is almost no way it's going to beat a battery plant you can have more or less just built to order already commercially. And said battery plants aren't even remotely good enough at purpose for meaningful energy storage, they're mostly used for what are considered "ancillary services" in the US power markets, like eating or producing reactive power, voltage support, etc, because the modern grid scale inverters can react to grid conditions faster than grid frequencies (50-60 Hz). More rarely they might be scaled big enough to shave the peak off a demand curve for 5-10 minutes to save transmission capacity or congestion.
Keep in mind all this in happening when LNG is basically free except for the cost of moving it, so you can also put in 1-60 MW combined cycle gas plants in short amounts of time with very well understood technology and proven manufacturers.
It may seem strange to use energy density in this context but in many ways those are even worse than batteries due to the massive amount of work they require and poor scalability because of all the physical infrastructure and space.
In fact, this exact scheme looks to have been posted to HN in 2014. From my understanding they are looking to re-purpose holes that have already been dug, for the most part, which is a good idea, but if the planned prototypes are only doing 250 kW nameplate with maybe 100 KWH of stored power, there is almost no way it's going to beat a battery plant you can have more or less just built to order already commercially. And said battery plants aren't even remotely good enough at purpose for meaningful energy storage, they're mostly used for what are considered "ancillary services" in the US power markets, like eating or producing reactive power, voltage support, etc, because the modern grid scale inverters can react to grid conditions faster than grid frequencies (50-60 Hz). More rarely they might be scaled big enough to shave the peak off a demand curve for 5-10 minutes to save transmission capacity or congestion.
Keep in mind all this in happening when LNG is basically free except for the cost of moving it, so you can also put in 1-60 MW combined cycle gas plants in short amounts of time with very well understood technology and proven manufacturers.
> create a giant compressed gas reservoir underground.
The McIntosh CAES plant began in 1991 and from my understanding, has been widely viewed as successful. https://www.smithsonianmag.com/innovation/salt-power-plant-m...
That's 110 MWs for 26 hours. Probably not 2.8 GW-hrs of energy storage (they can't sustain 110MWs for all 26 hours), but this plant is probably GW-hr range. I'm pretty sure all of Li-Ion right now is less than 2GW-hrs for the entirety of the USA.
---------
The 290 MW plant in Huntorf Germany (1978) also is successful.
--------
There's a 2nd, 300MW+ plant (that's 300MW power for multiple hours. So near GW-hr scale as well). This is the more recent Apex Bethel Energy Center you were badmouthing earlier. Its not fully built yet, but given the history of CAES, I'm optimistic.
--------
There aren't many CAES plants in the world. But from what I can tell, they are all safe and successful. The one issue is that you need to reheat the air as it leaves the caverns: compressing it underground reduces its temperature. A bit of natural gas is used in this heating process, but not nearly as much as an actual natural-gas plant.
------------
The "Rail up a hill" project is 50MWs with 12.5 MWhr storage capacity: https://s3.amazonaws.com/siteninja/multitenant/assets/21126/...
50MWs is somewhat small, but there's something to be said about the simplicity and ease-of-deployment of rail energy storage. Those 50MWs were spec'd out with only 7 trains. It isn't too hard to imagine scaling the system up to support more than 7 trains.
The McIntosh CAES plant began in 1991 and from my understanding, has been widely viewed as successful. https://www.smithsonianmag.com/innovation/salt-power-plant-m...
That's 110 MWs for 26 hours. Probably not 2.8 GW-hrs of energy storage (they can't sustain 110MWs for all 26 hours), but this plant is probably GW-hr range. I'm pretty sure all of Li-Ion right now is less than 2GW-hrs for the entirety of the USA.
---------
The 290 MW plant in Huntorf Germany (1978) also is successful.
--------
There's a 2nd, 300MW+ plant (that's 300MW power for multiple hours. So near GW-hr scale as well). This is the more recent Apex Bethel Energy Center you were badmouthing earlier. Its not fully built yet, but given the history of CAES, I'm optimistic.
--------
There aren't many CAES plants in the world. But from what I can tell, they are all safe and successful. The one issue is that you need to reheat the air as it leaves the caverns: compressing it underground reduces its temperature. A bit of natural gas is used in this heating process, but not nearly as much as an actual natural-gas plant.
------------
The "Rail up a hill" project is 50MWs with 12.5 MWhr storage capacity: https://s3.amazonaws.com/siteninja/multitenant/assets/21126/...
50MWs is somewhat small, but there's something to be said about the simplicity and ease-of-deployment of rail energy storage. Those 50MWs were spec'd out with only 7 trains. It isn't too hard to imagine scaling the system up to support more than 7 trains.
Yeah, I have to say I'm actually pretty impressed with the "rail up a hill" thing. Sure, 50MW isn't a ton, but it takes up nearly no space, infrastructure is very simple (5 miles of plain electrified track and that's it!), doesn't even need a crazy grade (7%), and most importantly: locomotives are cheap. IIRC, less than a million bucks for a good DC electric one, used. So you can be up and running pretty cheap and simple.
I'd love to see people running more of these setups. Especially in places where DC locomotives are cheap (former CIS countries), this could be even more cost effective.
I'd love to see people running more of these setups. Especially in places where DC locomotives are cheap (former CIS countries), this could be even more cost effective.
Indeed; I'm not sure why exactly so few of the CAES plants have been built, it's well understood, has minimal safety problems, and doesn't seem unreasonably expensive. If I had to wager an uneducated guess, workable salt mines may not be located anywhere the power pricing makes sense for long term storage offsetting like that.
Compressed air storage has very bad efficiency, due to the adiabatic heating and cooling when the pressure changes.
Brief reminder that the predominate means of energy storage is literally pumping water up a mountain to flood a valley. On the surface, it's equally zany sounding, but of course the massive storage potential there is the big selling point.
Do you mean actual mechanical pumping or are you confounding the water cycle in this which is what most people would call hydro power?
https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta...
Pumped Hydro energy storage is the #1 energy storage in America, and probably the world. A single plant provides 24GW-hrs of energy storage, dozens of more energy storage than all American utility scale Li-Ion batteries combined.
Bath County is the biggest pumped-hydro battery in the USA (and probably the world), but there are dozens of pumped-hydro plants across the country.
------------
Turns out that all the water in a lake can hold a huge amount of potential energy through gravity: just pump it up a mountain.
Pumped Hydro energy storage is the #1 energy storage in America, and probably the world. A single plant provides 24GW-hrs of energy storage, dozens of more energy storage than all American utility scale Li-Ion batteries combined.
Bath County is the biggest pumped-hydro battery in the USA (and probably the world), but there are dozens of pumped-hydro plants across the country.
------------
Turns out that all the water in a lake can hold a huge amount of potential energy through gravity: just pump it up a mountain.
Thanks for the link and apologies for the skepticism. I didn't know we had systems that basically slosh water from upper to lower during high demand and lower to upper during low demand to even out capacity.
https://youtu.be/6Jx_bJgIFhI
https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
Actual mechanical pumping.
Actual mechanical pumping.
That's two separate issues. In many existing hydro systems, the turbines are operated in reverse in order to store power.
Sure, if it's all in pipes and if it's pumping into a large volume rather than just river outflow. Sounds good.
> LNG is basically free
Free as in money, costly in consequences. The whole point of energy storage schemes is to allow us to migrate away from fossil fueled energy.
Free as in money, costly in consequences. The whole point of energy storage schemes is to allow us to migrate away from fossil fueled energy.
I'm wondering why we don't use hydrolysis -> store hydrogen -> burn hydrogen -> run a steam turbine for energy storage.
Efficiency would be low, at about 70% * 60% ~= 40% but capacity would be huge. 1 kg of hydrogen has specific energy of over 140 MW.
We could even capture CO2 as well with that energy and make methan and use normal gas powerplants for retrieving the power :)
Just build double the number of solar panels to account for efficiency loses. Should be cheaper than grid-scale energy storage with 90%+ efficiency.
Efficiency would be low, at about 70% * 60% ~= 40% but capacity would be huge. 1 kg of hydrogen has specific energy of over 140 MW.
We could even capture CO2 as well with that energy and make methan and use normal gas powerplants for retrieving the power :)
Just build double the number of solar panels to account for efficiency loses. Should be cheaper than grid-scale energy storage with 90%+ efficiency.
That was part of the old nuclear age dream back when a fleet of reactors would make power too cheap to meter, although using methane or propane instead may be easier to work with from an engineering perspective. Moving energy around as liquefied gas is also significantly more efficient in most circumstances.
IIRC there was some study on doing something like that in Germany in the 2000s but I'm not finding references to it now. If you don't have to build the dam (since it already exists), pumping water back up into the reservoir is going to be better in the limited locations you can do that, and given the relatively tiny amount of energy storage vs power production I suspect the economies of scale on that won't change without a preceding sea change in global commitment to fossil fuel retirement.
There is also a better transition path to that as we already are building amazingly good gas turbines that could just as well be burning synthesized or biogas on demand from solar or nuclear over-generation. I sort of suspect that may end up being politically poisonous to the people that would normally be pushing for carbon-neutral storage options.
It would be way more than double the solar panels though. Solar generation is generally maxing at around 25% capacity factor, so replacing an existing fossil fuel generator requires 4x or more the nominal capacity in solar plus whatever efficiency loss in storage, so going with a pure solar + storage replacement of a 1500 MW combustion plant could easily require 12,0000 MW of equivalent generation.
IIRC there was some study on doing something like that in Germany in the 2000s but I'm not finding references to it now. If you don't have to build the dam (since it already exists), pumping water back up into the reservoir is going to be better in the limited locations you can do that, and given the relatively tiny amount of energy storage vs power production I suspect the economies of scale on that won't change without a preceding sea change in global commitment to fossil fuel retirement.
There is also a better transition path to that as we already are building amazingly good gas turbines that could just as well be burning synthesized or biogas on demand from solar or nuclear over-generation. I sort of suspect that may end up being politically poisonous to the people that would normally be pushing for carbon-neutral storage options.
It would be way more than double the solar panels though. Solar generation is generally maxing at around 25% capacity factor, so replacing an existing fossil fuel generator requires 4x or more the nominal capacity in solar plus whatever efficiency loss in storage, so going with a pure solar + storage replacement of a 1500 MW combustion plant could easily require 12,0000 MW of equivalent generation.
> It would be way more than double the solar panels though.
We're comparing energy storage so no matter how much fossil fuel powerplants we replace - it would be x solar panels for energy storage with 80-90% efficiency (for example this gravicity stuff or hydro or batteries) and 2x for methane synthesis.
We're comparing energy storage so no matter how much fossil fuel powerplants we replace - it would be x solar panels for energy storage with 80-90% efficiency (for example this gravicity stuff or hydro or batteries) and 2x for methane synthesis.
Hydrogen is difficult and consequently expensive to store. Also, the low efficiency is a problem. Pumped storage hydroelectricity is way more efficient.
At small scale, this is correct. At very large scale, hydrogen is incredibly easy to store. You can just fill up and old depleted gas well and store terawatt-hours of energy easily.
Germany has enough gas well storage to survive several months. This infrastructure is currently used for natural gas, but it can be repurposed for hydrogen.
I still think that commoditized battery storage will win in the end, but storage cost is not an argument against hydrogen.
Germany has enough gas well storage to survive several months. This infrastructure is currently used for natural gas, but it can be repurposed for hydrogen.
I still think that commoditized battery storage will win in the end, but storage cost is not an argument against hydrogen.
Besides it is not trivial to repurpose natural gas storage for hydrogen - you need an entirely different level of tightness, you would be disappointed about the amount of energy you can store this way, as hydrogen is way less dense than natural gas, so the capacity of the storage would be poor.
For very large scale storage we are not talking about steel pressure vessels that are subject to hydrogen embrittlement, but depleted natural gas reservoirs which are just gas-tight geological formations and have no issues whatsoever with hydrogen embrittlement.
For small and medium scale storage you are right. Which is why hydrogen for cars and even trucks is a bad idea.
For small and medium scale storage you are right. Which is why hydrogen for cars and even trucks is a bad idea.
And you would get much less hydrogen stored at the same pressure than methane. To store reasonable amounts of hydrogen, you need very high pressures. Gas powered cars use like 60 bars of pressure, hydrogen 700.
Yes, that is correct. But the end to end efficiency of Electricity -> H2 -> Electricity is much better than Electricity -> H2 -> CH4 -> Electricity.
Hydrogen at 0°C and 100 Bar (~10MPa) has a density of 8.3447 kg/m^3. It has an energy density of 120 MJ/kg. So about 33 kWh/kg. So you end up with 278 kWh/m^3.
Now of course you have to multiply this by the H2->Electricity efficiency. Let's be very pessimistic and take 0.6 or 60%, which is what a gas turbine plant can achieve today.
You end up with 166 kWh/m^3 of usable electricity per cubic meter.
One of many german gas storage facilities https://www.nafta-speicher.de/en/company has a volume of 1.8e9 m^3. That translates into 300 Terawatt-Hours of storage capacity for just this one facility.
Hydrogen at 0°C and 100 Bar (~10MPa) has a density of 8.3447 kg/m^3. It has an energy density of 120 MJ/kg. So about 33 kWh/kg. So you end up with 278 kWh/m^3.
Now of course you have to multiply this by the H2->Electricity efficiency. Let's be very pessimistic and take 0.6 or 60%, which is what a gas turbine plant can achieve today.
You end up with 166 kWh/m^3 of usable electricity per cubic meter.
One of many german gas storage facilities https://www.nafta-speicher.de/en/company has a volume of 1.8e9 m^3. That translates into 300 Terawatt-Hours of storage capacity for just this one facility.
Right now the German gas infrastructure can only handle a hydrogen content of around 10% or 20% with modest infrastructure upgrades. This is why there are projects where that hydrogen is further processed into methane at which point all of it is compatible with the existing gas infrastructure.
That is a limitation of the pipeline infrastructure, because of hydrogen embrittlement of steel pipes.
It is not a limitation of the large storage facilities, which are just exhausted natural gas wells and work just fine with hydrogen.
The cost of outfitting one such facility with steel pipes that are not subject to hydrogen embrittlement is trivial compared to the cost for the electrolysis units etc.
Note that I am not a big fan of hydrogen at all. But large scale storage is one of its few redeeming qualities.
It is not a limitation of the large storage facilities, which are just exhausted natural gas wells and work just fine with hydrogen.
The cost of outfitting one such facility with steel pipes that are not subject to hydrogen embrittlement is trivial compared to the cost for the electrolysis units etc.
Note that I am not a big fan of hydrogen at all. But large scale storage is one of its few redeeming qualities.
Then combine with carbon from air and store methane.
Pumped is great when you have the geography for it but most countries don't. And building dams is pretty harsh on the environment too, just in different ways than CO2 emmisions.
Pumped is great when you have the geography for it but most countries don't. And building dams is pretty harsh on the environment too, just in different ways than CO2 emmisions.
Right, I think we will convert any hydrogen produced via electrolysis to methane for better storage. That methane would be completely compatible with the storage/distribution/usage infrastructure which many countries already have in place. I was commenting on the statement, that hydrogen by itself is easily stored.
There is a lot of push into hydrogen because of that. I know Germany is doing that.
Germany is already investing into power to gas infrastructure for both hydrogen and methane. What you are talking about is already reality albeit at a small scale.
hydrogen as storage is not efficient. This problem is reduced if hydrogen is used for transport.
I think the stacked approach has people concerned about the towers falling. This approach might be safer, but I think the other thing is it may aesthetically pleasing since the working bits are hidden below ground. This increases its viability.
Yeah, and as I mention above, the key thing is height. You can build 10x taller underground than above ground. And that gives you 10x more potential energy for the same amount of weight.
This proposal would likely be a lot more economic if they could reuse existing holes, like abandoned mines. However, mines tend not to dig down vertically and the cost of retrofitting and maintenance would be non-trivial.
The vertical train approach of terrament (linked above) could theoretically work with that. But we'll probably have to wait for the first prototype to see if it can really work with existing infrastructure.
It is worth it to dig a hole! Because building one tall tower is ~exponentially~ (edit: quadratically) better than building multiple shorter ones side by side with the same combined height. You can dig a mile deep which is about 10 times taller than the practical height of a tower. My startup, Terrament, is working on a similar technology, and there is a slide in our deck that illustrates this.
https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh...
Reusing abandoned mine shafts could have an advantage. But there is also ample researching showing that the cost of digging from scratch is still worth it. The US Dept of energy even studied it back in the 1980s when they were evaluating underground pumped hydro energy storage. I wrote a white paper on it that's linked from here. see here https://www.terramenthq.com/uphs/
Reusing abandoned mine shafts could have an advantage. But there is also ample researching showing that the cost of digging from scratch is still worth it. The US Dept of energy even studied it back in the 1980s when they were evaluating underground pumped hydro energy storage. I wrote a white paper on it that's linked from here. see here https://www.terramenthq.com/uphs/
It is not exponentially better. Energy stored in a stacked mass scales as n^2 whereas horizontal stacks scales as n. That’s quadratic scaling, not exponential.
There is no stacked mass however. Just a single piece of mass moving up/down that results in linear scaling from height.
Edit: reviewed the Terraent slides they indeed plan to literally drive a mile long train vertically into the ground. In which case the quadratic argument stands.
At the cost of significant added complexity. It comes down to drilling cost vs installation/ maintenance cost.
Edit: reviewed the Terraent slides they indeed plan to literally drive a mile long train vertically into the ground. In which case the quadratic argument stands.
At the cost of significant added complexity. It comes down to drilling cost vs installation/ maintenance cost.
Damn, you're right - thanks spot5010. I thought that I could use "exponential" colloquially and it would still be accurate enough (because quadratic scaling is even more esoteric to most people). But thanks for the callout, you're right that saying exponential is technically just wrong. I'll figure out how to re-word.
Could you explain how it is quadratic? I would have thought it to be linear, by the formula for potential energy
Take a look at Terrament slides. They are driving a train vertically into the ground.
With increased depth more cars can be added, increasing total weight, so m = Ch and ep =~ Ch*h/2
Yeah, I clearly need to change the wording here as it's just adding confusion.
The key thing here is that adding 10x height gives you 10x more PE per weight without extra digging costs (or tower costs assuming the cost per unit of height is constant)
Here's how to think of it: by digging one deep hole instead of many shallow holes (with the same amount of digging) you get (n^2 / 2) instead of (n/2) Potential energy. The average height of all the modules is half the height of the shaft. With one deep shaft, the modules pass through the same excavated volume so they can all go deeper on average.
The key thing here is that adding 10x height gives you 10x more PE per weight without extra digging costs (or tower costs assuming the cost per unit of height is constant)
Here's how to think of it: by digging one deep hole instead of many shallow holes (with the same amount of digging) you get (n^2 / 2) instead of (n/2) Potential energy. The average height of all the modules is half the height of the shaft. With one deep shaft, the modules pass through the same excavated volume so they can all go deeper on average.
Bro, your pitch deck is 100 slides!
But also, getting your quadratic gain on a mile deep hole requires a mile of weights to lower into it. That's a lot more above ground infrastructure than just the single shaft!
But also, getting your quadratic gain on a mile deep hole requires a mile of weights to lower into it. That's a lot more above ground infrastructure than just the single shaft!
Haha well, 70 of those slides are appendix slides.
The way our design works, the modular weights are autonomous on a track. So we don't have huge cranes above ground. We just have a track above ground that also runs a mile. That track can be partly or fully buried if desired. It will be enclosed protecting it from weather, and solar can be installed on top to save real-estate.
But yes, these installations are enormous. They might cost around $150M and could provide about 200MW.
The way our design works, the modular weights are autonomous on a track. So we don't have huge cranes above ground. We just have a track above ground that also runs a mile. That track can be partly or fully buried if desired. It will be enclosed protecting it from weather, and solar can be installed on top to save real-estate.
But yes, these installations are enormous. They might cost around $150M and could provide about 200MW.
You're not making any sense. mgh is mgh. If you lift the blocks above or below the ground makes no difference. But you absolutely save a ton of money by not digging the expensive hole that will fill up with water.
- You can't build a mile tall tower though.
- Keeping water out of a hole is a solved problem.
- as discussed in other comments here, adding more height gives you more PE for the same amount of weight so it's a very valuable investment that pays profits over 20-100 years for your one time investment.
https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh...
- Keeping water out of a hole is a solved problem.
- as discussed in other comments here, adding more height gives you more PE for the same amount of weight so it's a very valuable investment that pays profits over 20-100 years for your one time investment.
https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh...
Energy Vault:
https://www.youtube.com/watch?v=NIhCuzxNvv0
From the News section:
"We plan to roll out our technology in disused mine shafts worldwide."
"We plan to roll out our technology in disused mine shafts worldwide."
Energy storage by lifting or releasing a weight, in their case, in a well underground. Nothing new; I am wondering what's special about them, compared to tens of other companies trying to offer the same type of energy storage.
AFAIK, the most common is done around hydro dams, by pumping water upstream as a form of energy storage. The infra is already there, but it's not as efficient as systems like Gravitricity. But it costs a negligible amount of money to "activate" energy storage in a pre-existing dam.
AFAIK, the most common is done around hydro dams, by pumping water upstream as a form of energy storage. The infra is already there, but it's not as efficient as systems like Gravitricity. But it costs a negligible amount of money to "activate" energy storage in a pre-existing dam.
I believe the argument for new storage concepts is that renewables will drive a need for large amounts of new energy storage capacity, batteries are expensive, and that not everyone is situated near a suitable geography for pumped hydro.
Interesting concept but digging a big hole sounds expensive and prone to flooding. I can see how this would have better efficiency than pumped-storage hydro but I wonder if you couldn't raise and lower weight near cliffs rather than drilling wells.
If it does work, I would imagine the Boring company would be all over this.
If it does work, I would imagine the Boring company would be all over this.
> and prone to flooding.
and prone to Earth quakes, I would assume.
and prone to Earth quakes, I would assume.
I can see why you'd suspect that. But it turns out that the oil and gas industry has 100 years of precedent demonstrating how to build such shafts into bedrock. Flooding and earthquakes are all real concerns, but we have well-proven solutions.
Oil rigs only need to drill a hole with the diameter of a pipe. With gravity storage you would want the hole to be as large as possible.
Maybe not as large as possible, but we're looking at about 10m diameter and about 1 mile deep. Here's an example of existing mining tech that meets this capacity.
https://www.youtube.com/watch?v=z5vAWR7rpco
Isn't this the exact same concept as a dam which pumps water back up when you have excess power? Also how heavy does that weight have to be to be able to store enough energy worth digging a hole that large? Can you even get a weight heavy enough to store a significant amount of energy?
Same concept, but the tl;dr is that no, you can't, unless you're talking hydro from a dam in a good location. It's not just a not-so good idea, it's an orders-of-magnitude-awful idea when you compare it to just about any other form of energy storage per dollar.
Anything involving dams typically also has to involve water release schedules, which at least in some parts of the western US will produce some of the most vicious political battles you can imagine.
You can in fact! Pumped hydro is already the cheapest form of energy storage - about 95% of all energy storage is pumped hydro. We can't build more pumped hydro because it's not feasible to build enough dams. (We've used up the best locations)
The US Gov has studied plenty of research showing that underground pumped hydro is cost effective and obviates the need for dams. (See my white paper here: https://github.com/syllable-hq/uphs-feasibility-study)
So startups like Gravitricity (and Terrament, my startup) are innovating on what is already well-researched territory.
The US Gov has studied plenty of research showing that underground pumped hydro is cost effective and obviates the need for dams. (See my white paper here: https://github.com/syllable-hq/uphs-feasibility-study)
So startups like Gravitricity (and Terrament, my startup) are innovating on what is already well-researched territory.
The video has some numbers in it about performance. They say dig a shaft of 150-1500m and hang a weight of 500-5000 tonnes. This translates to energy storage of between 204-20400 KWh storage.
Obviously, this seems very technically challenging. 500 tonnes is 64 m^3 of iron. We will see if their engineering is good enough to pull off their claimed 171 US$/MWh.
Obviously, this seems very technically challenging. 500 tonnes is 64 m^3 of iron. We will see if their engineering is good enough to pull off their claimed 171 US$/MWh.
26 m^3 of tungsten is what, less than a 3x3x3m cube? If they stack 10 cubes at the bottom they get mostly the full storage (-3m at least) for each weight. Seems feasible.
There is 280x difference in price between iron and tungsten.
https://www.metalary.com/tungsten-price/
2000 tonnes of tungsten is 60 million USD, of iron is 200k USD.
https://www.metalary.com/tungsten-price/
2000 tonnes of tungsten is 60 million USD, of iron is 200k USD.
Tungsten costs around $30k/ton, so you'd be looking at a cool $15M for that 500T cube.
Lead goes for around $2k/ton, so this might be a more feasible compromise.
Lead goes for around $2k/ton, so this might be a more feasible compromise.
Depleted uranium prices are very hard to find, but should come as cheaper than tungsten.
Civilian sales look at least possible, I heard of at least one sailboat with a DU keel.
Civilian sales look at least possible, I heard of at least one sailboat with a DU keel.
[deleted]
[deleted]
This is a technology where energy density doesn't matter at all because the amount of energy stored per ton is the same. So you want as many tons as cheap as possible. Therefore we either use water or concrete.
I assume the weight would be at least partially some of the dirt they dug out of the hole. Cost is the name of the game.
Quite a few similar companies are looking at compacted earth mixed with concrete to reuse some dirt and rock that is excavated. See also https://energyvault.com/
I always thought it'd be interesting to do the gravity storage inside the column of a wind turbine. After all you've already built a tall steel tower. Individually it's tiny storage, but in aggregate it's not meaningless, especially as we keep building more towers.
But I assume there's structural issues with suspending a few extra tons on your structure.
But I assume there's structural issues with suspending a few extra tons on your structure.
This actually exists using water. There's a pilot installation in southern Germany which has been running for a few years:
https://www.naturspeicher.de/de/pilotprojekt/pilotprojekt.ph...
I feel like "gravity storage" should take advantage of natural landscapes better.
ARES (rail energy storage) builds a rail-line uphill, for example. Rail cannot handle a very steep slope, but a gentle hill climb will build up potential energy fine.
In the case of vertical-based gravity storage, I'd imagine that lifting blocks to the top of a cliff (or down a valley) would be most efficient.
I mean, Pumped Hydro is gravity storage, and does just that. Pumping water up a mountain and generating energy by dropping it back down. But presumably, we don't want to use water in the Western states (where water is scarce). So Gravity-energy storage WITHOUT water is the goal.
ARES (rail energy storage) builds a rail-line uphill, for example. Rail cannot handle a very steep slope, but a gentle hill climb will build up potential energy fine.
In the case of vertical-based gravity storage, I'd imagine that lifting blocks to the top of a cliff (or down a valley) would be most efficient.
I mean, Pumped Hydro is gravity storage, and does just that. Pumping water up a mountain and generating energy by dropping it back down. But presumably, we don't want to use water in the Western states (where water is scarce). So Gravity-energy storage WITHOUT water is the goal.
Lifting things creates hazards for what's below them in the event of catastrophic failure.
For example, all the dam failures that have obliterated entire towns.
I'd rather a failure obliterated a bunch of earthworms and voles.
I expect that the voles disagree with me.
For example, all the dam failures that have obliterated entire towns.
I'd rather a failure obliterated a bunch of earthworms and voles.
I expect that the voles disagree with me.
The issue with using natural landscapes is that it limits your height. And adding more height is ~exponentially~ (edit: quadratically) better than just adding more installations with an equivalent total height. (You can dig about a mile deep). You can see more details in my comments below - search for the text "It is worth it to dig a hole!"
I was thinking of combining techniques. Best case scenario in USA is something like Owens Valley: 14,000 at its peak, but 4000 feet at the bottom of the valley.
Leading to ~10,000 feet (or nearly 2-miles) of elevation change. From there, you can dig another mile underground, leading to 1-mile (under ground), or -1000 feet elevation, to a peak elevation of 14,000.
If a tower were built on the top of the mountain: you could gain another 2000 feet or so on top: so maybe 16,000 (a 2000 foot tower on top of the mountain peak) to -1000ft (1-mile deep from the bottom of the 4000-ft elevation valley), for a total differential of 17,000 feet.
Ignoring earthquakes and other issues, of course. :-) Just purely from a hypothetical perspective: working with nature and the natural landscape seems like it'd be better than "just" digging a hole.
EDIT: Repurposing abandoned mine shafts might be worthwhile, depending how deep they are.
Leading to ~10,000 feet (or nearly 2-miles) of elevation change. From there, you can dig another mile underground, leading to 1-mile (under ground), or -1000 feet elevation, to a peak elevation of 14,000.
If a tower were built on the top of the mountain: you could gain another 2000 feet or so on top: so maybe 16,000 (a 2000 foot tower on top of the mountain peak) to -1000ft (1-mile deep from the bottom of the 4000-ft elevation valley), for a total differential of 17,000 feet.
Ignoring earthquakes and other issues, of course. :-) Just purely from a hypothetical perspective: working with nature and the natural landscape seems like it'd be better than "just" digging a hole.
EDIT: Repurposing abandoned mine shafts might be worthwhile, depending how deep they are.
Wrong, wrong, wrong, so wrong!
Gravitational potential energy is (approximately) linear in height. I say approximately because this assumes constant g (which is a good assumption when h is small compared to the radius of the earth, which it is).
And in fact, a consequence of gravity's 1/r^2 nature is that one is only subject to gravitational acceleration from what is beneath them (shells above cancel out), so mine shafts are less efficient than towers (the effect size is small to the depths we can mine).
So adding more height doesn't help, and if that height is underground it could actually hurt net efficiency.
Efficiency in this context refers potential energy stored per unit height. The field is conservative no matter what you build.
Gravitational potential energy is (approximately) linear in height. I say approximately because this assumes constant g (which is a good assumption when h is small compared to the radius of the earth, which it is).
And in fact, a consequence of gravity's 1/r^2 nature is that one is only subject to gravitational acceleration from what is beneath them (shells above cancel out), so mine shafts are less efficient than towers (the effect size is small to the depths we can mine).
So adding more height doesn't help, and if that height is underground it could actually hurt net efficiency.
Efficiency in this context refers potential energy stored per unit height. The field is conservative no matter what you build.
I'm assuming that the quadratic parent refers to comes from the increased potential energy per kg of material multiplied by the ability to store more material due to the additional volume.
If you picture a dense weight like a cannon ball on the end of a string you're right, but if you're digging down n meters, encasing n/2 meters worth of dirt and moving it up and down the free n/2 meters of shaft, the energy storage would indeed be proportional to n^2.
I don't know anything about the field and had the same reaction you did, but considering parent is running a startup in it they're either a lunatic that doesn't know the equivalent of FizzBuzz or there's something we missed on first inspection, and we should charitably assume the latter...
If you picture a dense weight like a cannon ball on the end of a string you're right, but if you're digging down n meters, encasing n/2 meters worth of dirt and moving it up and down the free n/2 meters of shaft, the energy storage would indeed be proportional to n^2.
I don't know anything about the field and had the same reaction you did, but considering parent is running a startup in it they're either a lunatic that doesn't know the equivalent of FizzBuzz or there's something we missed on first inspection, and we should charitably assume the latter...
Haha, thanks. It's a little of both of course. You have to be a bit of a lunatic to think you can do these things. But someone's got to get it done.
I read the whole pitch deck and it seems like you've thought it through well. I'm curious about the potential for failure; if one of the last links freezes up somehow (i.e. the disengagement you mention elsewhere fails), is there a process for clearing it?
The single shaft vs multiple parallel approach does seem a bit risky in the early days. If there's a 10% failure rate, and you built one shaft, that's a 10% chance of an existential threat to the company. 10 shorter shafts mean one will likely be inoperable.
Of course over the long term worrying about this doesn't make sense. Once you've scaled, 1k large vs 10k small shafts would not matter from this perspective.
Best of luck mate!
The single shaft vs multiple parallel approach does seem a bit risky in the early days. If there's a 10% failure rate, and you built one shaft, that's a 10% chance of an existential threat to the company. 10 shorter shafts mean one will likely be inoperable.
Of course over the long term worrying about this doesn't make sense. Once you've scaled, 1k large vs 10k small shafts would not matter from this perspective.
Best of luck mate!
Hey andbberger,
Yeah, we're _definitely_ assuming that g is constant for all elevations :)
There's another thread on this comment page talking about why height is important. Please see this slide in our presentation illustrating it. https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh...
There's another thread on this comment page talking about why height is important. Please see this slide in our presentation illustrating it. https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh...
I don't think it's fair to call that "scales quadratic". Certainly the energy stored in the total number of blocks is growing quadratic by digging deeper, but it also ignores that costs and effort grow when digging deeper. In effect, adding a block at the bottom comes with substantially higher effort than adding a block right next to it on the same level.
The issue here is that not everyone has that landscape (and as we know, doesn't want to destroy the view). I grew up in the US midwest--no hills for miles on which to build railcars, pump hydro etc.
But high-voltage power lines can run power for hundreds of miles with minuscule losses. Look at the MISO grid: https://upload.wikimedia.org/wikipedia/commons/4/40/2015_MIS...
There's hills somewhere in there, and those hills can form energy-storage solutions that can be transmitted across the entire MISO grid.
There's hills somewhere in there, and those hills can form energy-storage solutions that can be transmitted across the entire MISO grid.
High voltage lines are not free. You have to compete with different energy storage that doesn't need special landscapes, e.g. batteries.
High voltage power lines already exist. They are part of the landscape, and connect large parts of the country together. Case in point: a solar panel is Missouri could be providing power to Iowa.
Bonus points: if you want to build a big battery in Iowa, you can take advantage of excess power in Iowa or Missouri. Building tiny batteries here and there will only lower your efficiency.
There's a reason why a lot of discussion here is on large 100s of MW proposals: because anything smaller won't really be a big win economically. And it shouldn't be too hard to fill up 100s of MW capacity because of the nature of our large and reliable power grids here in the USA.
Bonus points: if you want to build a big battery in Iowa, you can take advantage of excess power in Iowa or Missouri. Building tiny batteries here and there will only lower your efficiency.
There's a reason why a lot of discussion here is on large 100s of MW proposals: because anything smaller won't really be a big win economically. And it shouldn't be too hard to fill up 100s of MW capacity because of the nature of our large and reliable power grids here in the USA.
In general more connectivity means you need less storage as it's always windy/sunny somewhere in the world.
> (100 ton) * (80 meter) * (9.81 (m / (s^2))) = 21.8 kilowatt hours
Nah.
In exchange for nearly doubling the weight of the average 3MW tower, adding enormous complexity, you'd be able to boost power output to 3.02 MW for one hour.
That gets us back to the fundamental problem with gravity storage - it's all mgh. You want to store a lot of energy, you better have a shit-ton of either m, g, or h, and one of those numbers is already tough to change :)
Nah.
In exchange for nearly doubling the weight of the average 3MW tower, adding enormous complexity, you'd be able to boost power output to 3.02 MW for one hour.
That gets us back to the fundamental problem with gravity storage - it's all mgh. You want to store a lot of energy, you better have a shit-ton of either m, g, or h, and one of those numbers is already tough to change :)
Yeah, this would be similar to what energyvault.com is doing. I love that energy vault got funding ($110M) and is pushing the industry forward. But IMHO, I ultimately don't think they will be able to compete with underground gravity storage because of the massive 10x advantage you get from digging underground and getting 10x more height (see my other comments below why that is.)
It wouldn't work - the towers would need to be heavier to handle the extra weight of the gravity storage, denying all benefits.
This idea assumes that the interior of the tower is empty space that could be used by the moving weight. Towers have an elevator for maintenance personnel that would reduce the available space. I'm guessing that the towers aren't high enough to store enough energy to justify the cost of the extra equipment.
I doubt that suspending the weight is the main structural issue. It's the high center of mass when the weight is at the top.
I doubt that suspending the weight is the main structural issue. It's the high center of mass when the weight is at the top.
Yup, internal space is a very valid issue, given that cheap weights are probably big. I'd worry about oscillations for a high-up, suspended weight too.
Regarding justifying the cost--obviously depends what the cost is. If it's really just the generator, cabling etc, it might work as a short term load balancer. I saw somewhere about GE investing $X millions to smooth turbine output over 5min intervals.
Regarding justifying the cost--obviously depends what the cost is. If it's really just the generator, cabling etc, it might work as a short term load balancer. I saw somewhere about GE investing $X millions to smooth turbine output over 5min intervals.
That's pretty clever! I would guess that wind turbine towers are mainly loaded in bending, and an extra compression load wouldn't hurt much as long as it doesn't cause buckling.
I love Gravitricity. I'm the founder of a similar startup called Terrament. We are also building gravity storage underground, but our patents are extending this idea to use autonomous, modular weights. This enables us to maximize both height and weight, which is the simple recipe for cheap gravitational energy storage.
We are also working on a seed-round of investment. It's an exciting field with plenty of room for competition. And it's so important for fighting climate change! We need to build this asap. https://www.terramenthq.com/
We are also working on a seed-round of investment. It's an exciting field with plenty of room for competition. And it's so important for fighting climate change! We need to build this asap. https://www.terramenthq.com/
How do you and Gravitricity deal with ground water? Wouldn't you require constant pumping to keep water out, using additional energy? Or can they be sealed that well to work for decades without maintenance?
Great question.
I suspect that if the water table is high enough to cause problems, you'd do pumped hydro storage instead.
A lot of solar power is out in the desert where the water table is hundreds or even thousands of feet below surface.
I suspect that if the water table is high enough to cause problems, you'd do pumped hydro storage instead.
A lot of solar power is out in the desert where the water table is hundreds or even thousands of feet below surface.
But we're talking about energy storage close to consumers, not in remote locations I thought? For deployment in Europe, I don't think it'd be possible to find areas where ground water is that deep (luckily).
And pumped storage still doesn't work as you'd need surface area for new lakes. Also, not sure if you'd want to pump out huge amounts of ground water for pumped storage, lowering the water table for everyone.
And pumped storage still doesn't work as you'd need surface area for new lakes. Also, not sure if you'd want to pump out huge amounts of ground water for pumped storage, lowering the water table for everyone.
My civil engineer partner could speak to this in more detail, but it's a well-understood solvable problem. You seal the shaft wall as you dig past the water table. And some small amount of pumping is used as needed.
Hmmm.
1. So the units are actually modular, i.e., not connected. Aha. If a unit jams, it's annoying but not fatal, as all the units above it continue to be usable.
2. Since the weight units are separate, then the force on the gearing (both wall and unit) is constant and thus the wear and tear is manageable.
3. The max energy stored is when all the weights are horizontal, of course. So there needs to be a transmission line built into the shaft, along with a motor/generator per weight unit. Some cleverness needed so the transmitted power is passed to (and received from) the correct units. The sliding contact where power is transmitted would also be a major possible point of failure.
4. Yeah, that's the downside of separate modular units. Each unit now needs to transmit/receive power.
5. It would seem prudent to build two or more shafts adjacent to each other. So if there is a problem in one shaft, you can go down the other and fix it. Increases reliability significantly.
6. If the units and power transmission are waterproof, water in the shaft isn't too much of an issue. You might lose ~20% of energy storage due to the buoyancy of the water, but that's it. Might save energy not having to constantly pump out the shaft.
7. Right. Definitely need a failsafe mechanism so a unit doesn't plunge down (say, when the motor/generator clutch fails) and take out the units at the bottom.
Cool idea. Good luck with power transmission.
1. So the units are actually modular, i.e., not connected. Aha. If a unit jams, it's annoying but not fatal, as all the units above it continue to be usable.
2. Since the weight units are separate, then the force on the gearing (both wall and unit) is constant and thus the wear and tear is manageable.
3. The max energy stored is when all the weights are horizontal, of course. So there needs to be a transmission line built into the shaft, along with a motor/generator per weight unit. Some cleverness needed so the transmitted power is passed to (and received from) the correct units. The sliding contact where power is transmitted would also be a major possible point of failure.
4. Yeah, that's the downside of separate modular units. Each unit now needs to transmit/receive power.
5. It would seem prudent to build two or more shafts adjacent to each other. So if there is a problem in one shaft, you can go down the other and fix it. Increases reliability significantly.
6. If the units and power transmission are waterproof, water in the shaft isn't too much of an issue. You might lose ~20% of energy storage due to the buoyancy of the water, but that's it. Might save energy not having to constantly pump out the shaft.
7. Right. Definitely need a failsafe mechanism so a unit doesn't plunge down (say, when the motor/generator clutch fails) and take out the units at the bottom.
Cool idea. Good luck with power transmission.
Thanks!
- Regarding jams, failures, etc. These should be extremely rare, but in the event, each unit is designed to "disengage" if needed so it's just dumb weight, and modules adjacent to it will be designed to lift it. Then when the train is above ground, the unit can be swapped out for another one and repaired while the system keeps operating. - Yup failsafe mechanisms will be built in as well. - Yeah each unit has its own motor/generator. A power line will enter through the module's axle.
- Regarding jams, failures, etc. These should be extremely rare, but in the event, each unit is designed to "disengage" if needed so it's just dumb weight, and modules adjacent to it will be designed to lift it. Then when the train is above ground, the unit can be swapped out for another one and repaired while the system keeps operating. - Yup failsafe mechanisms will be built in as well. - Yeah each unit has its own motor/generator. A power line will enter through the module's axle.
Yure credebility as en xpert is somwat deminished if you cannot spell weight or axle. Yup, yeah.
corrected, thank you :)
What are they patenting ?
I note from the website: "Our patented technology is based on a simple principle ..."
I think it's a great idea but I don't see what there is to patent or what IP they could defend ...
I note from the website: "Our patented technology is based on a simple principle ..."
I think it's a great idea but I don't see what there is to patent or what IP they could defend ...
Terrament is patenting a number of different designs which enable us to maximize both height and weight to nearly 100% of a mine shaft. When you think about the physics of suspending thousands of tons inside a mile deep hole, the devil is in the details. To paraphrase Boromir, One does not simply hang a mile of concrete and steel from a cable ;) There are already some videos on the website that give away some details. We're waiting to secure funding before sharing the rest.
edit: oh sorry, I think you meant gravitricity sorry. I'm not sure what they're patenting. Also I don't think their patents are in the US.
edit: oh sorry, I think you meant gravitricity sorry. I'm not sure what they're patenting. Also I don't think their patents are in the US.
Both solutions present heavy machinery, presumably aimed at big industrial installations.
How about home use? Could it be used small-scale, e.g. as an alternative to Tesla's PowerPack? I've long been curious about distributed energy solutions, from heating (e.g. cogeneration / CHP, heat pumps, geothermal energy, solar+battery for off-grid energy), could this be a low-cost, low-tech, low-maintenance, low-risk alternative to batteries?
How about home use? Could it be used small-scale, e.g. as an alternative to Tesla's PowerPack? I've long been curious about distributed energy solutions, from heating (e.g. cogeneration / CHP, heat pumps, geothermal energy, solar+battery for off-grid energy), could this be a low-cost, low-tech, low-maintenance, low-risk alternative to batteries?
At small scales, the setup costs world dwarf those of lithium by an order of magnitude. You can have a powerwall shipped to you and a local electrician install it. This, you’d have to have an engineering crew dig a shaft, unless of course you happen to own an old mine.
Can you explain why this is better/different than flywheels?
I know Pennsylvania and New York both have 20 MW storage systems that takes up a few acres and are relatively cheap per unit of storage.
I know Pennsylvania and New York both have 20 MW storage systems that takes up a few acres and are relatively cheap per unit of storage.
> 20 MW storage systems
Megawatts measure the peak discharge rate, not that amount of energy stored.
For a fixed number of dollars of investment, gravity will store far more joules of energy.
Megawatts measure the peak discharge rate, not that amount of energy stored.
For a fixed number of dollars of investment, gravity will store far more joules of energy.
Is it with or without an existing hole?
The problem with a flywheel is that you ha w to keep it moving. Bearing wear out, require lubrication...
A weight you can just hang there
A weight you can just hang there
A flywheel in a vacuum floating on a magnet also just hangs there. But indeed the weight solution seems more simple.
You would need to supply a lot of power just to maintain a vacuum and levitating your flywheel. Not sure this solution would be very effective. Maybe with superconductors, but then cooling is your problem instead.
Or use normal magnets (non-electro magnets) The vaccuum, sure, this may take some energy depending on the insulation.
This isn't really the same use case.
A basic thing to understand about electricity storage is that there are very different needs for different kinds of storage. Flywheels from what I understand are for very shortterm storage needs, i.e. balancing out shortterm fluctuations in electricity use vs. generation. But they're unsuitable for any kind of longterm storage, because they loose power over time.
In the long run with a high-solar-high-wind-scenario we'll need some seasonal storage to get us over a couple of weeks in some circumstances. This will need some storage that doesn't loose power over time.
(FWIW I have no idea if these gravitational storage techs will play any role in that, and one can be doubtful about it.)
A basic thing to understand about electricity storage is that there are very different needs for different kinds of storage. Flywheels from what I understand are for very shortterm storage needs, i.e. balancing out shortterm fluctuations in electricity use vs. generation. But they're unsuitable for any kind of longterm storage, because they loose power over time.
In the long run with a high-solar-high-wind-scenario we'll need some seasonal storage to get us over a couple of weeks in some circumstances. This will need some storage that doesn't loose power over time.
(FWIW I have no idea if these gravitational storage techs will play any role in that, and one can be doubtful about it.)
From Wikipedia: Flywheel energy storage systems using mechanical bearings can lose 20% to 50% of their energy in two hours.
Basically flywheel cannot store energy for a long time. It needs to be constantly used to be effective.
Basically flywheel cannot store energy for a long time. It needs to be constantly used to be effective.
If that weight were a fission reactor you wouldn't have to move it up and down. And it would be 100% efficient. And you wouldn't need an external power plant.
The nuclear debate is interesting, with valid talking points on both sides. But even if nuclear were safer and cheaper than wind+solar+storage (which it isn't), it would take decades to build. We might not have that much time.
Climate change is urgent and we need all hands on deck to build as fast and as cheap as possible. May the best designs win asap in this fight!
Climate change is urgent and we need all hands on deck to build as fast and as cheap as possible. May the best designs win asap in this fight!
Some of the known SMR designs are amenable for mass production, if someone would kickstart the line by putting money on the table. Very safe ones at that.
A lot of the cost goes down when the reactor isn't a practically one-off build, and when you can for example use prefabricated components to "assemble" a power plant quickly.
Some designs go even further, and have power blocks that are essentially something you slap on large railcar, including option that instead of refueling you send back the module while the vendor sends you a freshly-fueled one.
A lot of the cost goes down when the reactor isn't a practically one-off build, and when you can for example use prefabricated components to "assemble" a power plant quickly.
Some designs go even further, and have power blocks that are essentially something you slap on large railcar, including option that instead of refueling you send back the module while the vendor sends you a freshly-fueled one.
If you wanted to build one at the scale of a PowerWall (5kW/13.5kWh) what kind of height/weight combinations would be required?
By my calculations you would need to raise 40 tons up 3 meters to store 13.5kWh. Definitely not a home storage revolution!
Now, if the entire house was built on a lift....
By my calculations you would need to raise 40 tons up 3 meters to store 13.5kWh. Definitely not a home storage revolution!
Now, if the entire house was built on a lift....
If you dig a well with cross-sectional area A and depth D, the amount of energy you can store with compressed air at 10 MPa is 10AD MJ if A and D are expressed in m^2 and m respectively. [1]
If you drop a steel weight down the same well of cross-section A and height H in the same units the energy stored is 0.08HA(D-H) MJ[2]. Again, H is in meters, and AD > A(D-H), and in order to beat compressed air 0.08H > 10, so your steel weight needs to be 10/0.08 = 125 meters long! That's taller than most of the buildings in downtown San Francisco -- and in order to get any use out of this thing, your hole should be at least twice that deep.
Of course, compressed air has its inefficiencies and complexity, but the feasibility of a metal rod even close to that long seems pretty low to me. Compressed-air caverns use as much as 7.5 MPa, but a purpose-built well could potentially go much higher. Plus you don't have to deal with the damn thing vibrating from Coriolis forces and seismicity.
Now, I know what you're saying -- you're saying, if you're so smart, why don't you do it? -- but there are simply too many huge caverns out there to even think about constructing CAES chambers. There are several GW in service today. And even with that huge resource people wonder if batteries won't simply corner the market. Storage is getting here painfully slow, it seems like, but the competition is very fierce.
1: True isothermal decompression cycles are impossible, so of course I'm approximating by using the ideal gas law.
2: (8000 kg/m^3)(10 m/s^2)/(mega = 1000000) = 0.08
If you drop a steel weight down the same well of cross-section A and height H in the same units the energy stored is 0.08HA(D-H) MJ[2]. Again, H is in meters, and AD > A(D-H), and in order to beat compressed air 0.08H > 10, so your steel weight needs to be 10/0.08 = 125 meters long! That's taller than most of the buildings in downtown San Francisco -- and in order to get any use out of this thing, your hole should be at least twice that deep.
Of course, compressed air has its inefficiencies and complexity, but the feasibility of a metal rod even close to that long seems pretty low to me. Compressed-air caverns use as much as 7.5 MPa, but a purpose-built well could potentially go much higher. Plus you don't have to deal with the damn thing vibrating from Coriolis forces and seismicity.
Now, I know what you're saying -- you're saying, if you're so smart, why don't you do it? -- but there are simply too many huge caverns out there to even think about constructing CAES chambers. There are several GW in service today. And even with that huge resource people wonder if batteries won't simply corner the market. Storage is getting here painfully slow, it seems like, but the competition is very fierce.
1: True isothermal decompression cycles are impossible, so of course I'm approximating by using the ideal gas law.
2: (8000 kg/m^3)(10 m/s^2)/(mega = 1000000) = 0.08
Yeah, compressed air is a very viable and promising solution. It does have efficiency trade-offs as you mention though. And typical compressed air designs still use fossil fuels in the compression process. There are some new designs I've seen that get around using fossil fuels.
One of the most prominent new startups out there exploring advanced compressed air is hydrostor. Note that they also dig underground :) https://www.hydrostor.ca/technology/
One of the most prominent new startups out there exploring advanced compressed air is hydrostor. Note that they also dig underground :) https://www.hydrostor.ca/technology/
Sorry for repeating myself, but gravity is weak. If you hang a 500t weight in a 150m vertical tunnel, it only holds 500 * 1000 * 9.8 * 150 = 735000000 J, or 735 MJ, that is, 204 kWh.
A Tesla model 3, basic model (MSRP ~$38k) has battery capacity of 50 kWh, so we're talking about four Tesla 3's.
I don't think digging a 150m hole is cheaper than four Teslas - and Teslas come with the rest of the car you can use for driving.
A Tesla model 3, basic model (MSRP ~$38k) has battery capacity of 50 kWh, so we're talking about four Tesla 3's.
I don't think digging a 150m hole is cheaper than four Teslas - and Teslas come with the rest of the car you can use for driving.
Gravity is weak, but it's cheap. It is indeed surprising, but plenty of research shows that the levelized cost of gravity storage is cheaper than Li-ion batteries - even if you assume that Li-ion will get 4x cheaper in the next 20 years. There are other problems with Li-ion as well that will prevent it from scaling up to the amount of storage that our grid will need. I discuss all this with lots of citations in a white paper here https://github.com/syllable-hq/uphs-feasibility-study
> Gravity is weak, but it's cheap.
I'm sorry, I'm not trying to be pedantic, but what does "gravity is cheap" even mean?
I'm sorry, I'm not trying to be pedantic, but what does "gravity is cheap" even mean?
No worries. Here is a good resource that talks about the levelized costs of gravity storage. It's estimated to be much cheaper than Li-ion battery storage on large scales.
https://www.storage-lab.com/gravity-based-storage
https://www.storage-lab.com/gravity-based-storage
The primary benefit is reliability and lifetime. Your lifted rock isn't going to "malfunction" and suddenly weigh less.
I agree that gravity based energy technologies are mostly junk though. There are two important factors: cheap weights and unlimited scalability. Doing something "cute" such as using a mountain side or old mineshaft is reducing the scalability.
I agree that gravity based energy technologies are mostly junk though. There are two important factors: cheap weights and unlimited scalability. Doing something "cute" such as using a mountain side or old mineshaft is reducing the scalability.
Isn't pumped water storage the same thing but much easier to manage? Like think of a 10 ton weight suspended from cables 100m high vs a $300 above ground pool on a 300 foot hill. Isn't pumped water storage going to be hundreds of times cheaper for amount of energy stored?
I didn't do the math but this reeks scam to me
I didn't do the math but this reeks scam to me
$300 for an above ground pool? Where do I sign up?
All you need is walmart, a hose, and a parking lot!
Quite a few comments question the cost of digging -- which is understandable. But the context to remember is that these are huge infrastructure investments that will return revenue from that investment over 20-100 years with little maintenance costs. The excavated shaft is like a factory not a product. The product is each cycle of energy generation giving you a profit day after day. The shaft is a one time investment that will yield that product forever.
There's lots of research showing how the costs work out (see my other comments here)
There's lots of research showing how the costs work out (see my other comments here)
Also, hasn't digging become much cheaper in recent years with new technologies from the oil industry? I'm sure some of that efficiency gain can be used for those shafts (they're obviously bigger than a bore hole for oil).
[deleted]
Why not merge all the energy storage ideas?
Pump air into a giant pressure chamber...that's also a super-deep hole with a pulley system...and the weight for the pulley is a flywheel sealed in a vacuum chamber, magnetically levitating to avoid any friction losses. Oh, and the mass for the flywheel? A bunch of batteries.
Pump air into a giant pressure chamber...that's also a super-deep hole with a pulley system...and the weight for the pulley is a flywheel sealed in a vacuum chamber, magnetically levitating to avoid any friction losses. Oh, and the mass for the flywheel? A bunch of batteries.
This is probably a joke, but it's not so crazy. Many designs are combining one or more of these.
Not entirely joking. I just saw the big hole and immediately thought it'd be a great place to store pressurized air, and then I continued thinking of other energy storage mechanisms you could cram in there.
This will work, obviously. But I don't see how it can be competitive with batteries.
High energy density lithium batteries are currently being commoditized. They are also increasingly able to handle many thousands of cycles. E.g LiFePo4 cells.
The raw materials for batteries are not actually that expensive or rare, so that leaves the manufacturing.
You might think that making something as complex as a battery can never be as cheap as hanging a weight from a rope. But there are examples of very complex products (solar cells, LCD displays) that became incredibly cheap due to mass manufacturing.
A square meter of solar cells, requiring extremely pure silicon and nanometer scale engineering, is now not much more expensive than a square meter of good roofing shingles.
High energy density lithium batteries are currently being commoditized. They are also increasingly able to handle many thousands of cycles. E.g LiFePo4 cells.
The raw materials for batteries are not actually that expensive or rare, so that leaves the manufacturing.
You might think that making something as complex as a battery can never be as cheap as hanging a weight from a rope. But there are examples of very complex products (solar cells, LCD displays) that became incredibly cheap due to mass manufacturing.
A square meter of solar cells, requiring extremely pure silicon and nanometer scale engineering, is now not much more expensive than a square meter of good roofing shingles.
Interesting idea.
Why would this be better than a set of railway lines down a hill side into a forest pulling up standard goods carriages full of rocks?
You get a forest (which buffers runaway carriages and does all the other lovely forest things) and energy storage on the hill. All using largely commodity items and you can build it anywhere there's a spare slope.
Why would this be better than a set of railway lines down a hill side into a forest pulling up standard goods carriages full of rocks?
You get a forest (which buffers runaway carriages and does all the other lovely forest things) and energy storage on the hill. All using largely commodity items and you can build it anywhere there's a spare slope.
That's what ARES promised 4 years ago. But their website looks abandoned. [1]
[1] https://www.aresnorthamerica.com/
[1] https://www.aresnorthamerica.com/
I don't get how any of these gravitational energy storage startups get past the napkin phase. There is no competition with pumped hydro. Who cares if weights on winches are marginally more efficient when you have many orders of magnitude more mass to move.
This site claims a max weight of 4.5e6 kg. Lake Powell, for example, has a max capacity of 3e13 kg!
So, SEVEN orders of magnitude less mass to move. Sounds competitive.
This site claims a max weight of 4.5e6 kg. Lake Powell, for example, has a max capacity of 3e13 kg!
So, SEVEN orders of magnitude less mass to move. Sounds competitive.
You are looking at the wrong metrics. Capacities and efficiencies are interesting from a technical point of view. But the only metric that really matters is $/kwh of storage. And depending on where you are pumped hydro can be stupendously expensive and disruptive to the local environment or require expensive infrastructure to be put in place. Even just having access to water is a non trivial thing in a lot of places (e.g. deserts).
In some places pumped hydro does make sense of course but you have to compare basically on $/kwh what is the best solution taking into account the local environment. There are no silver bullets here. Which is why a lot of places seem to be ending up with lithium ion batteries, because they are there and can be put in place without a lot of fuss or rearranging of the local environment.
In some places pumped hydro does make sense of course but you have to compare basically on $/kwh what is the best solution taking into account the local environment. There are no silver bullets here. Which is why a lot of places seem to be ending up with lithium ion batteries, because they are there and can be put in place without a lot of fuss or rearranging of the local environment.
The power density for gravity storage such as this is directly proportional to the density of the storage medium.
Water is 1 tonne per cubic meter. Steel is 7.9 tonnes per cubic meter. Lead is 11.34 tonnes per cubic meter - which means that in the same amount of space, you can store vastly more energy if you use these metals instead of water.
The initial cost of set up will also vary depending on the metal you use but lead is cheap.
Also, water evaporates etc.
Water is 1 tonne per cubic meter. Steel is 7.9 tonnes per cubic meter. Lead is 11.34 tonnes per cubic meter - which means that in the same amount of space, you can store vastly more energy if you use these metals instead of water.
The initial cost of set up will also vary depending on the metal you use but lead is cheap.
Also, water evaporates etc.
Wow the density makes a lot of sense. But why stop at lead, depleted uranium is 19 tonnes per cubic meter (1.67 times as dense as lead)!
Cost / density. You quite literally want the cheapest dead weight.
Cost of lead/tonne : USD 1900 (approx) Cost of Uranium/tonne: At least USD 60000 (approx regular uranium) even if you are able to source it.. and then you still have to build containment for this, get permits etc..
For that price, you could get much higher efficiencies if you went for a cheaper metal - even something like Tungsten which is extremely dense will be much cheaper.
Cost of lead/tonne : USD 1900 (approx) Cost of Uranium/tonne: At least USD 60000 (approx regular uranium) even if you are able to source it.. and then you still have to build containment for this, get permits etc..
For that price, you could get much higher efficiencies if you went for a cheaper metal - even something like Tungsten which is extremely dense will be much cheaper.
Pumped hydro is great but unrealistic in many countries. You need hills or mountains with space for new lakes. All obvious places already have them, for the others the ecological impact often is quite significant.
All obvious places may have hydro plants already, but not all hydro plants are reversible.
The country point is interesting, so the market is countries lacking topography suited to hydro plants? How big is that market really?
And considering that pumped hydro is currently the only viable grid scale energy storage mechanism (inb4 but li-on), those countries currently either 1) share a grid with neighboring countries that do have pumped hydro, or 2) forego energy storage altogether and use peaker plants like everyone else. If you do 1 you better trust your neighbors to never go to war with you, otherwise you better have 2.
So the market is: countries lacking topography suited to hydro plants, who currently share energy storage with neighbors who they don't trust, and who for some reason aren't just building peaker plants (which are essentially just normal fossil fuel power plants) and are holding out for a non-extant technology to be developed.
I'm not much of a capitalist myself, but even I can tell that that's a bad investment.
The country point is interesting, so the market is countries lacking topography suited to hydro plants? How big is that market really?
And considering that pumped hydro is currently the only viable grid scale energy storage mechanism (inb4 but li-on), those countries currently either 1) share a grid with neighboring countries that do have pumped hydro, or 2) forego energy storage altogether and use peaker plants like everyone else. If you do 1 you better trust your neighbors to never go to war with you, otherwise you better have 2.
So the market is: countries lacking topography suited to hydro plants, who currently share energy storage with neighbors who they don't trust, and who for some reason aren't just building peaker plants (which are essentially just normal fossil fuel power plants) and are holding out for a non-extant technology to be developed.
I'm not much of a capitalist myself, but even I can tell that that's a bad investment.
Assuming that pretty much everyone is planning on eventually phasing out peaker plants for environmental reasons: I'd say that the market is pretty huge if you can develop viable technology to service it.
> All obvious places may have hydro plants already, but not all hydro plants are reversible.
Hydro plants are built reversible whenever possible. The ones that aren't ("run of river") are that way because it was impractical to impound storage.
Hydro plants are built reversible whenever possible. The ones that aren't ("run of river") are that way because it was impractical to impound storage.
> All obvious places may have hydro plants already, but not all hydro plants are reversible.
If a hydro site is convertible to reversible, chances are it’s been already. Most sites are not really suitable because regular hydro plants don’t need a lower reservoir or water source and so can be built in locations which don’t have one.
Meanwhile pumped hydro can be built in locations where normal hydro makes no sense because there is no natural downflow or upper reservoir e.g. Taum Sauk.
If a hydro site is convertible to reversible, chances are it’s been already. Most sites are not really suitable because regular hydro plants don’t need a lower reservoir or water source and so can be built in locations which don’t have one.
Meanwhile pumped hydro can be built in locations where normal hydro makes no sense because there is no natural downflow or upper reservoir e.g. Taum Sauk.
Power to gas is promising. Just generate hydrogen or methane and feed it into existing gas pipelines. Storage infrastructure for gas already exists and has several TWh of capacity.
How do you convert power to methane?
To answer my own question: https://en.m.wikipedia.org/wiki/Sabatier_reaction
I think the salient point is this:
> All obvious places already have them
That is, we’re already practically at max capacity for hydro.
> All obvious places already have them
That is, we’re already practically at max capacity for hydro.
A salient point for the wrong conversation? We're talking about energy storage, not energy production.
https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
I may be wrong, but there is a limited capability for doing pumped hydro - you may run out of elevated lakes in a region, and if you want to create new ones then you will affect the environment.
A hole in the ground can be dug up everywhere, e.g. next to each single PV plant.
A hole in the ground can be dug up everywhere, e.g. next to each single PV plant.
[deleted]
With seven orders of magnitude of difference, you'd have to dig a whole lotta holes before hydro has to start worrying about competition on the capacity level.
Many of these projects also falsely assume that there are enough abandoned mineshafts or other types of holes to convert into a battery storage system. They have to do this because you would see through the scam immediately. Digging a wide and deep hole is expensive and not economic unless there is something valuable at the bottom of the hole.
There is also the fact that weights are expensive relative to the energy they can store so you have to take them directly from nature (usually via dams or pumping water uphill).
There is also the fact that weights are expensive relative to the energy they can store so you have to take them directly from nature (usually via dams or pumping water uphill).
Right, the thing to worry about is power, not energy. Ideally the pumps would be sized to fill/drain lake Powell in 12 hours. Which is ludicrous. The turbines in the Glenn Canyon Dam have a max (output) capacity of 890m^3/s [0]. It would take just over a year to drain the reservoir through them.
[0] https://web.archive.org/web/2016*/http://www.gcrg.org/bqr/6-...
[0] https://web.archive.org/web/2016*/http://www.gcrg.org/bqr/6-...
Which is fine, as many regions have a strong seasonal availability of renewables. Storing energy for some months will be required to go fully renewable. There are also short term storage requirements, over the course of a day or a week.
Compared to energy loss over distance, which you don't really have if you dig your hole right next to you, it's more like 6 orders of magnitude, maybe less.
But maybe capacity is only part of the story. What about locality? Distributed energy storage may not be as efficient, but it has a lot of other benefits.
But maybe capacity is only part of the story. What about locality? Distributed energy storage may not be as efficient, but it has a lot of other benefits.
This an overly narrow view of the problem. The footprint of pumped hydro is enormous and you can't just put it anywhere where you actually need the power.
The footprint of anything that stores enormous amounts of energy is enormous. (If you think it isn't - batteries, say - it's because you've ignored the socking great mine needed to extract the materials, the factories needed to make them, etc.). And we don't need it to be that near - we have pylons.
This seems to be one of the key indicators of green pseudoengineering - an obsession with avoiding transporting power. Pylons work. Really. If you can get large amounts of RELIABLE renewable power/storage, with low labour and machine costs, from a large amount of cheap land, land far away from people or crops or even trees, you do not have to worry about the rest. Worry about how to get those labour and machine costs down.
This seems to be one of the key indicators of green pseudoengineering - an obsession with avoiding transporting power. Pylons work. Really. If you can get large amounts of RELIABLE renewable power/storage, with low labour and machine costs, from a large amount of cheap land, land far away from people or crops or even trees, you do not have to worry about the rest. Worry about how to get those labour and machine costs down.
Okay, let's just say the footprint of something that stores energy vertically is going to be enormously lower. For what it's worth, this "Graviticity" thing may be utter nonsense, that's besides the point.
Pylons may work, but you need to pay off everyone owning the land those lines go across. In many areas, they can't build pylons at all because of rampant NIMBYism.
Pylons may work, but you need to pay off everyone owning the land those lines go across. In many areas, they can't build pylons at all because of rampant NIMBYism.
Where is innovation and efficiency ?
To me it smells like https://www.youtube.com/watch?v=uzV_uzSTCTM and all about patents, marketing and money burning, but I don't know as much as these professors do so maybe I am wrong.
To me it smells like https://www.youtube.com/watch?v=uzV_uzSTCTM and all about patents, marketing and money burning, but I don't know as much as these professors do so maybe I am wrong.
Oh, there are definitely interesting problems to solve. See my post below for some issues.
The concept is quite obvious and has been proposed several times in the past. The key question is, what are the costs? Even if the costs for drilling the hole are written off over a very long time span, the wires that hold the weight and the machinery have constant operation costs.
It probably can't compete with pumped storage, but pumped storage isn't viable without at least some hills. This concept could be deployed in many regions, also wouldn't take much surface space, you could deploy it even in densely populated regions. The question is: how does it compete with e.g. batteries?
Does anyone know if something like this has been implemented in some way already? In old mine shafts maybe? The geology has been studied, and some shafts at least there already...
Yeah, I did a feasibility study on underground pumped hydro which you can find here: https://www.terramenthq.com/uphs/
UPHS has never been fully built to my knowledge, but it's been well studied and quite a few projects have tried to get funding for it.
U.S. DOE research from 1984: https://www.osti.gov/biblio/6517343.pdf
Projects trying to work on this: https://utilitymagazine.com.au/pumped-hydro-storage-the-futu...
Other proposed projects: - https://www.waterpowermagazine.com/features/featureinvestiga...
- http://www.eaglecrestenergy.com/project-description.html https://www.osti.gov/biblio/6517343.pdf
UPHS has never been fully built to my knowledge, but it's been well studied and quite a few projects have tried to get funding for it.
U.S. DOE research from 1984: https://www.osti.gov/biblio/6517343.pdf
Projects trying to work on this: https://utilitymagazine.com.au/pumped-hydro-storage-the-futu...
Other proposed projects: - https://www.waterpowermagazine.com/features/featureinvestiga...
- http://www.eaglecrestenergy.com/project-description.html https://www.osti.gov/biblio/6517343.pdf
My father has an idea to use sodium (Na) as fuel for fuel cells. This could easily replace batteries by having more or less instant reactions to demand, being much more energy dense and being simple to handle. Also, there is no CO_2 that would need to be captured compared to "bio" fuels. The resulting sodium hydroxide (NaOH) and hydrogen (H_2) can easily be used further e.g. in the chemical industry or recycled, electrolysis of NaOH is well known and also produces hydrogen as a byproduct. The resulting sodium metal can again be used as fuel. It creates a circular economy. Handling sodium securely at scale is also probably even easier than handling gasoline or diesel. Most of these reactions at industrial scale are more than 50 years old but nobody bothered to actually implement it (even though a hint about sodium cells for electricity generation is present in "Twenty Thousand Leagues Under the Seas: A World Tour Underwater" by Jules Verne already) instead of the more complex approaches like e.g. synthetic gasoline.
You can look at the orgpage about these ideas https://orgpad.com/s/energiewende my father also gave a talk last week about it, there is a recording, which will be posted during the next days.
Disclaimer: I work for the small startup OrgPad, which tries to create a tool for easier decomposition of linear ideas/ content into a network of ideas/ content. An ex-Googler, Pavel Klavík PhD. describes the technology (hint Clojure and ClojureScript) and approaches behind OrgPad in a recent talk https://www.youtube.com/watch?v=4UoIfeb31UU
You can look at the orgpage about these ideas https://orgpad.com/s/energiewende my father also gave a talk last week about it, there is a recording, which will be posted during the next days.
Disclaimer: I work for the small startup OrgPad, which tries to create a tool for easier decomposition of linear ideas/ content into a network of ideas/ content. An ex-Googler, Pavel Klavík PhD. describes the technology (hint Clojure and ClojureScript) and approaches behind OrgPad in a recent talk https://www.youtube.com/watch?v=4UoIfeb31UU
Many years ago I briefly had a thought experiment about converting a gasoline/oxygen combustion engine into a sodium/water combustion engine. Solid fuel mixing concerns aren’t the primary issue. The primary issue is the energy density is just so danged low compared to gasoline. However, compared to electric batteries, sodium is far more energy dense.
Well, there are patents for running diesel engines with sodium, at least I was told so much by my father who researched the problem thoroughly.
The density isn't that low considering using a fuel cell, you can convert the energy a lot more efficiently. Also you don't just burn up the fuel into the air as currently, there is no industrial process to collect the CO_2 and other gases produced from the exhaust.
You could theoretically store energy by winding springs and making use of it by letting them unwind (by spinning a generator or whatever). Toy-car style.
This doesn't involve digging a deep hole in the ground and hope that the earth keeps it level.
A drawback would be the hazards that heavy tension/forces bring with them.
This doesn't involve digging a deep hole in the ground and hope that the earth keeps it level.
A drawback would be the hazards that heavy tension/forces bring with them.
This was precisely the basis of the energy storage systems in Paolo Bacigalupi's novel, The Windup Girl.
This reminds of Energy Vault [1], which is based on the same principle, just above ground. Doing this above ground seems to make a lot more sense when you consider all of the additional costs associated with digging and maintain massive shafts. I am not clear why the underground approach is at all appealing. Can anyone explain?
[1] https://energyvault.com/
[1] https://energyvault.com/
Yeah, very similar. The main reason is that you can get about 10x more height underground. You can dig about a mile deep. An Energy Vault tower is about 500 feet tall. And as mentioned below in other comments, adding more height gives you more storage per weight, so it's super important. Adding more height and weight scales quadratically while just adding more weight (in side by side towers) only scales linearly.
https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh...
https://docs.google.com/presentation/d/17FI-jrI9RWS3q7Ng44Yh...
Wow, I see you have already thought about this exact question a great deal. This was a clear and compelling answer.
Your pitch deck is impressive. Good luck!
Your pitch deck is impressive. Good luck!
thx!
An underground facility is arguably less unsightly than a tower. You might also be able to repurpose an unused mine shaft, though I'm not sure how common that scenario is going to be.
is digging a shaft more expensive than building a tower taller than the sears tower that can hold 5,000 tons?
Why do so many of these gravity thingies show up lately?
An easy calculation shows how low the storage potential is.
Lets take a weight of 500 tones of steel, which would be 63.29 cubic meters.
Now sink those 500 tonnes into a hole a 100 meters deep that would make a rather lowly 0.1362 MWh of storage.
https://www.wolframalpha.com/input/?i=500+*+1000+kilograms+*...
Not sure what the cost of digging a 100 meter hole where you can sink 63 cubic meters of steel in would be, specially since water management is needed too.
I am not convinced that it is worth it.
An easy calculation shows how low the storage potential is.
Lets take a weight of 500 tones of steel, which would be 63.29 cubic meters.
Now sink those 500 tonnes into a hole a 100 meters deep that would make a rather lowly 0.1362 MWh of storage.
https://www.wolframalpha.com/input/?i=500+*+1000+kilograms+*...
Not sure what the cost of digging a 100 meter hole where you can sink 63 cubic meters of steel in would be, specially since water management is needed too.
I am not convinced that it is worth it.
You're thinking too small though ;). You can dig a mile deep. And you can lift enormous weights. As comments show below. Gravity is weak, but cheap. It can scale up to provide 1 GW of storage - enough to balance the load of an entire large city.
Lots of these ideas are popping up right now because it's a very compelling idea which is demonstrated to work. And because climate change is driving massive growth in renewable energy (woot) we will desperately need massive amounts of energy storage in the very new future. The energy storage market is expected to grow massively year over year.
Lots of these ideas are popping up right now because it's a very compelling idea which is demonstrated to work. And because climate change is driving massive growth in renewable energy (woot) we will desperately need massive amounts of energy storage in the very new future. The energy storage market is expected to grow massively year over year.
Sure you can always get the big option but that does not mean it is feasible.
What does it cost to dig and maintain a 1.5km deep shaft?
I found is something around 8000-10000$ per meter. I can buy a whole lot of batteries for that.
This technology just does not scale since mgh always holds true.
Unlike flywheels where you get w^2.
Just making the wheel out of carbon fiber and making them go fast, squares the amount of energy you can store.
What does it cost to dig and maintain a 1.5km deep shaft?
I found is something around 8000-10000$ per meter. I can buy a whole lot of batteries for that.
This technology just does not scale since mgh always holds true.
Unlike flywheels where you get w^2.
Just making the wheel out of carbon fiber and making them go fast, squares the amount of energy you can store.
$8000 to dig a 1m hole sounds very high - that's months of someone's salary. Surely the best drilling machines can beat the cost of paying someone with a shovel for a month?
But mostly they won't be digging the holes, they will be using shafts left over from earlier mining operations.
But mostly they won't be digging the holes, they will be using shafts left over from earlier mining operations.
That is what i found:
https://minewiki.engineering.queensu.ca/mediawiki/index.php/...
Honestly i would have thought it to be more expensive.
At higher depths the ground pressure is enormous and you need a lot of bracing.
Then there is water management, air, transportation of the dug out material...
When there is rock you usually need blasting or gargantuan drills which i am not sure even exists in the required diameter.
https://minewiki.engineering.queensu.ca/mediawiki/index.php/...
Honestly i would have thought it to be more expensive.
At higher depths the ground pressure is enormous and you need a lot of bracing.
Then there is water management, air, transportation of the dug out material...
When there is rock you usually need blasting or gargantuan drills which i am not sure even exists in the required diameter.
OH come on, I'm sure you can imagine the complexity of digging grows as the depth grows. the first meter would cost 100$ the second 150$, the 3rd 200$, the fourth 500$ the fifth 550$, the sixth 600$, etc.
Those prices are probably only true once you go deep enough to require permits, ground water management and all the other complications of very deep holes.
batteries don’t last as long as a hole. some holes already exist.
yup it's feasible. It does scale. Here are two links to research that support the feasibility and cost effectiveness of underground gravity storage.
https://www.storage-lab.com/gravity-based-storage https://www.osti.gov/biblio/6517343
https://www.storage-lab.com/gravity-based-storage https://www.osti.gov/biblio/6517343
>> the load of an entire large city.
Maybe if you are lifting the entire city. For perspective, take electric vehicles. Each moving EV is a mass being constantly accelerated at say 0.1G. So the weight in the graviticity system to power those EVs would have to be at least 10% of the mass of all the EVs active in a city.
Maybe if you are lifting the entire city. For perspective, take electric vehicles. Each moving EV is a mass being constantly accelerated at say 0.1G. So the weight in the graviticity system to power those EVs would have to be at least 10% of the mass of all the EVs active in a city.
> Maybe if you are lifting the entire city.
This would be a really cool element in a sci-fi world
This would be a really cool element in a sci-fi world
A long time ago I did the napkin math to check if it'd be worth it to lift a skyscraper up and down just slightly for energy storage. You know, you'd just use adjusting ramps as the height changed ever so slowly. Not surprisingly, it's surely not worth it. The empire state building could run some tea kettles, but, yeah, no.
Japanese TECOREP brand demolition system generates power as it lowers material down from skyscrapers
https://sipilpedia.com/tecorep-system-high-tech-demolition-s...
https://sipilpedia.com/tecorep-system-high-tech-demolition-s...
I calculate a rather better figure for the Empire State Building:
365000 tons × 9.81 m/s2 × 1 m = 1 MWh
which ought to at least be enough to provide short term backup power to the whole building.
365000 tons × 9.81 m/s2 × 1 m = 1 MWh
which ought to at least be enough to provide short term backup power to the whole building.
I just mean for load balancing a city running on wind and solar to optimize their costs.
This is only used to smooth out power generation with respect to demand. It doesn't have to power an entire city, just the shortfall between demand and current supply. Which, granted, could be substantial in a 100% solar and wind grid.
> You're thinking too small though ;). You can dig a mile deep. And you can lift enormous weights.
But at that point, why wouldn't you just do a classic pumped-storage reservoir?
But at that point, why wouldn't you just do a classic pumped-storage reservoir?
Because as noted in other comments here, all the best natural pumped-storage reservoirs are tapped. It's not feasible to build enough dams in enough places to get the job done.
Furthermore, my most optimistic estimates show that underground solid mass gravity storage could compete with pumped hydro on cost anyways. One reason is that solid mass is about 2.5x heavier than water. If excavation is one of your biggest costs, this density is important.
Furthermore, my most optimistic estimates show that underground solid mass gravity storage could compete with pumped hydro on cost anyways. One reason is that solid mass is about 2.5x heavier than water. If excavation is one of your biggest costs, this density is important.
The deeper you dig, the heavier your cable is, and the more energy you waste on accelerating that cable.
And the much bigger issue is, you have to constantly pump out water that will inevitably fill the hole. And that only costs you money.
And the much bigger issue is, you have to constantly pump out water that will inevitably fill the hole. And that only costs you money.
Yeah, my startup, Terrament solves the heavy cable problem by using modules which each contain a motor/generator and they each support their own weight. This allows us to truly maximize height and weight per shaft volume. You can see my other comments for context. (https://www.terramenthq.com/)
But the water leaking in is a feature, not a bug! You run pumps during surplus periods and generate hydroelectric in demand periods as the tunnel floods.
No, it's not a feature. It's a massive problem.
1) Pumps that can pump water 150 meters or a kilometer high are very expensive and require constant expensive maintenance.
2) Where will you pump the water to? Now you have to build huge storage tanks.
3) The water never stops flowing in. Sooner or later you will run out of storage space and your expensive hole will fill up with water.
1) Pumps that can pump water 150 meters or a kilometer high are very expensive and require constant expensive maintenance.
2) Where will you pump the water to? Now you have to build huge storage tanks.
3) The water never stops flowing in. Sooner or later you will run out of storage space and your expensive hole will fill up with water.
Maybe pump the water to the nearest river? As long as you aren’t digging from the lowest point in the landscape it won’t be a problem to get rid of the water.
seems the water could be a secondary energy source, and the cable energy wouldn’t be wasted, thats just more mass to lift and drop.
Do tell how you generate energy from water at the bottom of a gravity well.
Tidal Power? Though the ocean is not strictly at the bottom of the gravity well. And I assume that's not really what you're asking.
That's from an external system, and won't work in the bottom of a hole.
There is no way, short of fusion that I know of. And fusion is not a valid answer in this context anyway (even if we had the tech for it).
There is no way, short of fusion that I know of. And fusion is not a valid answer in this context anyway (even if we had the tech for it).
FTA
Each unit can be configured to produce between 1 and 20MW peak power, with output duration from 15 minutes to 8 hours.
For reference, 20MW is ~4 large aerogenerators. A single nuclear PWR is 500-1000MW.
It can scale up to provide 1 GW of storage - enough to balance the load of an entire large city.
You'd need 50 of these installations for a single city, for 15 minutes of power, 1000 for the 8 hours.
Each unit can be configured to produce between 1 and 20MW peak power, with output duration from 15 minutes to 8 hours.
For reference, 20MW is ~4 large aerogenerators. A single nuclear PWR is 500-1000MW.
It can scale up to provide 1 GW of storage - enough to balance the load of an entire large city.
You'd need 50 of these installations for a single city, for 15 minutes of power, 1000 for the 8 hours.
I do not know about Gravicity but Heindl Energy (bankrupt as of this year) planned to lift a granite block 500m in radius hydrolicly for an on paper storage capacity of 1614 GWh.
source: http://www.eduard-heindl.de/energy-storage/energy-storage-sy...
Wow, I didn't know they went bankrupt! Sad, thank you Heindl for paving the way forward. Innovation is truly a collaborative effort.
https://heindl-energy.com/about-us/
How about combining that with a landfill?
Dig a very deep hole with a radius of 500 m, with a 500 m granite block that you can raise and lower in it to store and retrieve energy.
When the block is raised, toss trash into the hole. Then when the block is lowered to retrieve energy it also becomes the world's largest trash compactor.
Eventually, you'll get enough trash in the hole that even massively compacted you won't have enough room to make the energy storage from raising the block worthwhile.
You then have to dig another hole and move the block, leaving behind a full landfill that has more trash in it than a normal landfill of that size would have.
Dig a very deep hole with a radius of 500 m, with a 500 m granite block that you can raise and lower in it to store and retrieve energy.
When the block is raised, toss trash into the hole. Then when the block is lowered to retrieve energy it also becomes the world's largest trash compactor.
Eventually, you'll get enough trash in the hole that even massively compacted you won't have enough room to make the energy storage from raising the block worthwhile.
You then have to dig another hole and move the block, leaving behind a full landfill that has more trash in it than a normal landfill of that size would have.
I think that neither is compacting trash that much a problem that you need a huge granite block for that (hydraulic press should be sufficient), nor do you want to move a block of granite 1km in diameter more than necessary. The idea by Heindl was to cut the granite cylinder in the place where the plant is build.
Here's the simplest quick answer I have regarding "is it worth it." This is just one example of independent research vetting that it is indeed promising. The math checks out.
https://www.storage-lab.com/gravity-based-storage
https://www.storage-lab.com/gravity-based-storage
That research is not independent but made by a bancrupt startup of gravity based energy storage.
And it still does not answer how the construction and running costs are calculated.
Only if those are as low as claimed (which I highly doubt) something like this might be feasible.
This tech just does not scale well.
Digging holes is stupid expensive. Moving giant masses is not trivial and to double the storage capacity you need twice the weight or twice the height.
The energy density is way too low.
The only thing run by weights have been those old grandfather clocks. And even there the weights got replaced by springs and in the end batteries.
And it still does not answer how the construction and running costs are calculated.
Only if those are as low as claimed (which I highly doubt) something like this might be feasible.
This tech just does not scale well.
Digging holes is stupid expensive. Moving giant masses is not trivial and to double the storage capacity you need twice the weight or twice the height.
The energy density is way too low.
The only thing run by weights have been those old grandfather clocks. And even there the weights got replaced by springs and in the end batteries.
My understanding is that Dr Oliver Schmidt was hired by Heindl to do this research independently. It explains everything on the link I sent, so I didn't mean to imply that he wasn't hired to do it, but he's a third party. There is other research like the 1984 U.S. PNNL that validates how underground storage is estimated to be cost effective.
https://www.osti.gov/biblio/6517343
https://www.osti.gov/biblio/6517343
Gravitricity is claiming weights as massive as 5,000 tons and shaft depths from 150m to 1,500m
That’s equivalent to ~83 tons of lithium ion battery: http://www.wolframalpha.com/input/?i=5000%20tons%20%2A%209.8...
Ah - so we can measure the specific capacity of a battery in kilometres of altitude. e = mgh, so h = e/mg.
Lead-acid = 0.14 MJ/kg = 14.3 km
LiFePO4 = 0.58 MJ/kg = 59.1 km
LiNiMnCoO2 = 0.74 MJ/kg = 75.5 km
Lead-acid = 0.14 MJ/kg = 14.3 km
LiFePO4 = 0.58 MJ/kg = 59.1 km
LiNiMnCoO2 = 0.74 MJ/kg = 75.5 km
And uranium = 80,620,000 MJ/kg = 8,226,530,612 km[1], or about 180% the distance to Neptune.
Sometimes I wish we lived in an alternative world with fully developed nuclear power. Think about the possibilities. And no global warming! :/
[1] Not accurate, obviously.
Sometimes I wish we lived in an alternative world with fully developed nuclear power. Think about the possibilities. And no global warming! :/
[1] Not accurate, obviously.
Yes; how high a fully charged battery could lift itself. I guess it’s similar to counting rocket fuel in seconds (lb_force-seconds per lb_weight).
What's the analogous interpretation of the 'seconds' of a rocket fuel? How long you can burn it for?
How long the rocket fuel could offset the force of gravity upon itself, thus suspending itself in-place.
In the real world, you'd need the rocket itself (which in turn contains the rocket fuel) which adds weight, and you'd have a difficult time controlling power output so the rocket doesn't drift and lengthen/reduce the burn time -- but that's not the point.
The idea is that we want a unit that relates the mass of the fuel with its total energy, and one way to approach that is to consider how long the fuel could offset the force of gravity on that fuel, which gives you a cute unit of measure in terms of time.
In the real world, you'd need the rocket itself (which in turn contains the rocket fuel) which adds weight, and you'd have a difficult time controlling power output so the rocket doesn't drift and lengthen/reduce the burn time -- but that's not the point.
The idea is that we want a unit that relates the mass of the fuel with its total energy, and one way to approach that is to consider how long the fuel could offset the force of gravity on that fuel, which gives you a cute unit of measure in terms of time.
this is the new solar panels on everything, 3d print everything, water from air, spectrophotometer is a tricorder... wave of kickstarter-esque ideas that already have relatively well optimized solutions that they will pick on the drawbacks of while admitting none of their own. In this case, it's the maintenance nightmare something like this would be as an underground project with a falling risk.
This might not work for economic reasons, but not because of falling risk.
[deleted]
Eduard Heindl's gravity storage: https://heindl-energy.com/
Potentially reaches a storage capacity between 1 and 10 GWh. Lifting a (huge) rock by pumping water underneath.
Interview: https://omegataupodcast.net/299-gravity-storage/
Potentially reaches a storage capacity between 1 and 10 GWh. Lifting a (huge) rock by pumping water underneath.
Interview: https://omegataupodcast.net/299-gravity-storage/
Pumping water comes with host of fluid-related inefficiencies. And you need pressure vessels. The big advantage of the OP is that there are no potential leak points. Worst case scenario, cables break and the rock drops.
Yeah, this is another promising one. The other disadvantage with that design is that the weight of the water is actually working against them. So if their rock/concrete is about 2.5x heavier than water, the weight of water is subtracted and you only get 1.5x the weight of water. Also their height is limited by the height of their piston. So I'm not yet convinced that their solution is better than just using underground pumped hydro.
Unfortunately, Heidl Energy is no more:
"Heindl Energy GmbH ran out of cash in 2020 and filed for insolvency. The patents and the engineering work has been sold to an interim investor, New Energy Let´s Go, who is now looking for a new strategic investor willing to continue the development with the goal of constructing a pilot project to prrof the concept."
from: https://heindl-energy.com/about-us/
from: https://heindl-energy.com/about-us/
How does it compare to liquified air storage? It might have a sweetspot somewhere but liquid air uses a lot of off-the-shelf technology.
https://www.rechargenews.com/transition/liquid-air-storage-o...
https://www.rechargenews.com/transition/liquid-air-storage-o...
5000 tons at 1500m is ~20MWh [1], assuming 100% efficiency (frictionless free fall).
That means that the theoretical maximum is 50x (!) less than 1 nuclear reactor can do in 1 hour (1000 MW for 18 months or 13 140 000 MWh). Put it differently, you'd need to dig 50 of these to output the equivalent of 1 nuclear reactor (and nuclear plants have 2 or more reactors) for one hour.
That's also assuming digging a hole this deep in a stable manner.
[1]. https://www.wolframalpha.com/input/?i=5000+tons+*+9.8m%2Fs%2...
That means that the theoretical maximum is 50x (!) less than 1 nuclear reactor can do in 1 hour (1000 MW for 18 months or 13 140 000 MWh). Put it differently, you'd need to dig 50 of these to output the equivalent of 1 nuclear reactor (and nuclear plants have 2 or more reactors) for one hour.
That's also assuming digging a hole this deep in a stable manner.
[1]. https://www.wolframalpha.com/input/?i=5000+tons+*+9.8m%2Fs%2...
Different categories/uses. This is storage and on-demand production.
Also, I would assume that 50x of these wells is cheaper than 1x nuclear (especially operational costs). But again, not in the same category.
Also, I would assume that 50x of these wells is cheaper than 1x nuclear (especially operational costs). But again, not in the same category.
All this is moot. Hydrino energy will make storage largely unnecessary except possibly for small handheld devices.
https://brilliantlightpower.com/news/
Is this a joke?
Did you check out their web site? - does it look like a joke?
Considering they've apparently been claiming for years to be able to convert the humidity in the air into the same mysterious dark matter that makes up much of the universe but whose composition and nature is currently unknown? Yes. It's about as believable as a product to convert belly button lint into plutonium.
It looks like crank nonsense.
Don't take my word for it - check out the experiments and prototypes yourself at https://brilliantlightpower.com/
Wow, this is surprisingly less-debunked than I expected. Though, of course my first reaction is extreme skepticism. But I guess we'll see!
https://www.quora.com/What-is-wrong-with-Dr-Mills-Hydrino-Th...
https://en.m.wikipedia.org/wiki/Brilliant_Light_Power
https://www.quora.com/What-is-wrong-with-Dr-Mills-Hydrino-Th...
https://en.m.wikipedia.org/wiki/Brilliant_Light_Power
Ahem.[1][2]
"We'll see?" This guy has been milking this since 1991. As Aaronson's article so sardonically points out, there's nothing there to debunk. Every claim that can be made about the "hydrino" can be made with equal weight about the "doofusino," so what's the point?
He's had three DECADES to set up any kind of publicity stunt or get the attention of any number of existing billionaires or just scrape together the resources he needs to build the no-shit this-changes-everything prototype. Or maybe Elon Musk and everyone who knows him is an idiot without vision who think they can make a buck on solar when this guy's world-changing technology is right around the corner this time for really real I promise.
[1] https://en.wikipedia.org/wiki/Brilliant_Light_Power#Criticis...
[2] https://www.scottaaronson.com/writings/doofusino.html
"We'll see?" This guy has been milking this since 1991. As Aaronson's article so sardonically points out, there's nothing there to debunk. Every claim that can be made about the "hydrino" can be made with equal weight about the "doofusino," so what's the point?
He's had three DECADES to set up any kind of publicity stunt or get the attention of any number of existing billionaires or just scrape together the resources he needs to build the no-shit this-changes-everything prototype. Or maybe Elon Musk and everyone who knows him is an idiot without vision who think they can make a buck on solar when this guy's world-changing technology is right around the corner this time for really real I promise.
[1] https://en.wikipedia.org/wiki/Brilliant_Light_Power#Criticis...
[2] https://www.scottaaronson.com/writings/doofusino.html
The Wikipedia article has been policed by skeptics and is not a fair assessment of Mills. Doofusino theory article is just satire and offers no serious rebuttal.
Mills has made considerable progress over the decades overcoming engineering challenges in harnessing hydrino energy release. Recent advances of electromagnetically pumped liquid metal electrodes (to solve the problem of tungsten electrodes instantly melting), and a ceramic cell liner (solves the problem of the hydrinos melting a hole in the side of the reaction vessel) have got Mills close to a field prototype and he has prototypes that produce hundreds of kW continuously (hundred hour run) with water bath calorimetry. The skeptics will soon have scoffed their last.
Policed by skeptics? That's the POINT of Wikipedia! Are you saying that a communal resource based on accurately documenting actual reality should be run by credulous people who will accept any statement without applying one second's worth of critical thinking?
As I said, Doofusino doesn't NEED to be a rebuttal. THERE IS NOTHING HERE TO REBUT. The proof is in the pudding and Mills has no pudding whatsoever. All he has are his claims about all the magical fairytale things his wonderful technology can do.
I don't care if he says it can braid my hair and create free cheerios on demand because he finally found the right alloy to use in his psychogravitic negamatrix. It's not real until there's proof and he hasn't offered any in thirty years. See you in another thirty, I guess.
As I said, Doofusino doesn't NEED to be a rebuttal. THERE IS NOTHING HERE TO REBUT. The proof is in the pudding and Mills has no pudding whatsoever. All he has are his claims about all the magical fairytale things his wonderful technology can do.
I don't care if he says it can braid my hair and create free cheerios on demand because he finally found the right alloy to use in his psychogravitic negamatrix. It's not real until there's proof and he hasn't offered any in thirty years. See you in another thirty, I guess.
Wikipedia doesn't support debate - only authoritative sources are allowed - which means novel theories yet to be fully accepted get locked out and ridiculed by the skeptically correct.
There are many experimental papers that show hydrinos exist and have the properties predicted by Mills classical model of the hydrogen atom. https://brilliantlightpower.com/ has many videos of working prototypes producing excess energy. Dark matter exists and interacts gravitationally like baryonic matter but is electromagnetically inert like hydrinos are predicted to be. The expansion of the universe accelerates (Mills predicted in the 1990s). Etc.
There are many experimental papers that show hydrinos exist and have the properties predicted by Mills classical model of the hydrogen atom. https://brilliantlightpower.com/ has many videos of working prototypes producing excess energy. Dark matter exists and interacts gravitationally like baryonic matter but is electromagnetically inert like hydrinos are predicted to be. The expansion of the universe accelerates (Mills predicted in the 1990s). Etc.
Also fusion energy research has been consuming billions for decades with little if any real progress. Of course everyone believes in this because there were plenty of believable demos in the bombing of Japan and the nuclear tests.
The difference is that nuclear fusion has happened before. In fact, if you go outside and look up on a clear day or night, you can see it happening right now.
Nobody has ever created hydrinos. They are not real. If they were, he would be selling barrels of hydrinos. He will never sell one single hydrino. Because they are not real.
Nobody has ever created hydrinos. They are not real. If they were, he would be selling barrels of hydrinos. He will never sell one single hydrino. Because they are not real.
Well he has bottles of hydrinos and multiple experimental results (e.g. gas chromatography with passage faster than any known substance) that prove hydrinos exist and have exactly the properties his theory predicts.
The fact that you continue to think this is true after this guy has been selling this snake oil for thirty years makes me think you've given money to him. If so, I'm truly sorry he took you in like that, and I suggest cutting your losses if you can.
I wish - I admit I did look into buying shares but it was too expensive. The reason I believe in it is that I have read all his papers and his hydrogen atom model makes a lot more sense than the Shroedinger electron probability distribution does. Then there are all the predictions of the model that come out in precise agreement with experimental values.
The fact that you continue to sneer tells me you have not seriously examined his claims and merely rely on biased secondary sources. Yelling rubbish more loudly does not an argument make.
The fact that you continue to sneer tells me you have not seriously examined his claims and merely rely on biased secondary sources. Yelling rubbish more loudly does not an argument make.
Why does every gravity storage startup claim they invented gravity storage?
It's not just not true, it's like, obviously not true. Anybody that took high-school level physics understands gravitation potential energy and it's not a huge leap from there.
It's not just not true, it's like, obviously not true. Anybody that took high-school level physics understands gravitation potential energy and it's not a huge leap from there.
Idea: Could elevators be retrofitted with something like this?
Then they could use/store energy only while going up, and regenerate some of it going down... and take passengers to various floors while doing that!
"The Regenerative Elevator"!
Stores energy going up, regenerates some of it while going down!
Invented here on Hacker News, by yours truly, 9/8/2020!
(Yes, I know, it's a stupid related idea! <g>. But my other related idea was more stupid, and that one was to fill up a U-Haul truck with trash, put a steel cable on it, find a hill, and use the steel cable (in conjunction with the overweighted U-Haul truck and hill!) to drive a motor/generator/winch assembly that uses electricity going up the hill, and regenerates some of it back, going down the hill... <g>)
On a serious note however (for non-passenger elevator energy storage), I think Gravitricity has a good idea, and I wish them much success with it!