Alternative energy can power the world in 20-40 years(news.stanford.edu)
news.stanford.edu
Alternative energy can power the world in 20-40 years
http://news.stanford.edu/news/2011/january/jacobson-world-energy-012611.html
15 comments
Intermittent renewables aren't a complete solution to our energy needs because they aren't available when we need them.
In a lot of places in the world, solar energy is more available generally when it's most needed.
That said, I'm all for non-intermittent renewables. Newer geothermal and tide-energy and wave-energy technologies could fit the bill. We could also develop infrastructure that would allow us to lob bulk cargoes cheaply into orbit, which would bypass the unfavorable economics of the rocket equation and enable orbital solar power.
I'm also for saving the earth with newer nuclear technology. (Thorium wouldn't carry the proliferation risk of current breeder reactors.)
In a lot of places in the world, solar energy is more available generally when it's most needed.
That said, I'm all for non-intermittent renewables. Newer geothermal and tide-energy and wave-energy technologies could fit the bill. We could also develop infrastructure that would allow us to lob bulk cargoes cheaply into orbit, which would bypass the unfavorable economics of the rocket equation and enable orbital solar power.
I'm also for saving the earth with newer nuclear technology. (Thorium wouldn't carry the proliferation risk of current breeder reactors.)
A modern FBR that uses commercial plutonium as a starting fuel and with no external blanket could breed with a ratio around 1.0 and, at all points in the fuel cycle, have the Pu be so contaminated with Pu-238, Pu-240 and Pu-241 that weapons use would be impossible.
In fact, sodium cooled cartridge reactors are considered so proliferation resistant that they could be deployed to places where they could fall into enemy hands. Not only is the material inside not usable for weapons, but people trying to get the fuel out would probably be killed by a sodium fire.
Now there's another risk that a government could use FBR technology to construct a system for creating weapons plutonium. For instance, a country like Iran could use an improved version of the EBR-II with integral reprocessing to produce 'supergrade' plutonium. On the other hand, any country that wants weapon grade plutonium can build a graphite or heavy water and use the well-understood PUREX process.
It's too early to compare the proliferation risk of a thorium vs plutonium cycle. Solid fuel thorium systems are highly resistant, but liquid fuel systems are too immature to characterize. If a highly effective system of protactinium removal were perfected, it might be possible to extract weapons grade U-233 from a liquid fuel reactor.
Another problem with liquid fueled reactors is that it isn't easy to verify the fuel cycle. In a solid fuel cycle, every fuel element has a serial number, and a random sample of them can be occasionally looked up to make sure that none have disappeared... Diversion outside of the reprocessing center can be easily detected with only intermittent surveillance. With liquid fuel systems, it's impossible to know exactly how much fissionable material was made and where it ended up.
In fact, sodium cooled cartridge reactors are considered so proliferation resistant that they could be deployed to places where they could fall into enemy hands. Not only is the material inside not usable for weapons, but people trying to get the fuel out would probably be killed by a sodium fire.
Now there's another risk that a government could use FBR technology to construct a system for creating weapons plutonium. For instance, a country like Iran could use an improved version of the EBR-II with integral reprocessing to produce 'supergrade' plutonium. On the other hand, any country that wants weapon grade plutonium can build a graphite or heavy water and use the well-understood PUREX process.
It's too early to compare the proliferation risk of a thorium vs plutonium cycle. Solid fuel thorium systems are highly resistant, but liquid fuel systems are too immature to characterize. If a highly effective system of protactinium removal were perfected, it might be possible to extract weapons grade U-233 from a liquid fuel reactor.
Another problem with liquid fueled reactors is that it isn't easy to verify the fuel cycle. In a solid fuel cycle, every fuel element has a serial number, and a random sample of them can be occasionally looked up to make sure that none have disappeared... Diversion outside of the reprocessing center can be easily detected with only intermittent surveillance. With liquid fuel systems, it's impossible to know exactly how much fissionable material was made and where it ended up.
What are the disadvantages of solid fuel Thorium reactors?
The advantage is that they really work. A Thorium-U233 core was tested in the Shippingport reactor and demonstrated slightly over-unity breeding without operational problems.
One disadvantage is that fuel cycle costs are higher, a lot higher. Some people estimate the cost of electricity from a Shippingport-style reactor could be 3-4 the cost of electricity from conventional LWRs. U-233 in a Thorium cycle gets contaminated with U-232, which has isotopes in its decay chain that emit nasty gamma rays.
Uranium Oxide or Plutonium-Uranium Oxide fuel can be handled manually, but U233-rich fuel is too radioactive for manual handling. The Japanese have managed to fabricate a few sample fuel elements remotely, but this is far from a mature technology.
Another issue with the Shippingport design is that the fuel assemblies are more more complicated and must be fabricated to more precise tolerances than a conventional LWR because reactivity is managed by moving some of the fuel elements relative to other fuel elements.
I think capital costs suffer too: I'd suspect you'd need a larger pressure vessel to contain the same volume of fuel, and power output won't be as good because heat production will happen predominantly in the U-233 'seed' elements, so power density won't be as good as a conventional LWR.
Now, the folks at Lightbridge
http://www.ltbridge.com/
have been doing some work on a seed and blanket core that puts U-233 into metal fuel elements (which would be easier to fabricate remotely) and puts the Th in oxide fuel elements. The metal fuel does better at transporting heat to the fluid, so power peaking may be less of a problem.
Reprocessing is also more expensive in a sold-fuel Th cycle. Th fuel can handled by the THOREX process, which is a modification of PUREX, but it's harder to dissolve Th fuel than U-based fuel.
One disadvantage is that fuel cycle costs are higher, a lot higher. Some people estimate the cost of electricity from a Shippingport-style reactor could be 3-4 the cost of electricity from conventional LWRs. U-233 in a Thorium cycle gets contaminated with U-232, which has isotopes in its decay chain that emit nasty gamma rays.
Uranium Oxide or Plutonium-Uranium Oxide fuel can be handled manually, but U233-rich fuel is too radioactive for manual handling. The Japanese have managed to fabricate a few sample fuel elements remotely, but this is far from a mature technology.
Another issue with the Shippingport design is that the fuel assemblies are more more complicated and must be fabricated to more precise tolerances than a conventional LWR because reactivity is managed by moving some of the fuel elements relative to other fuel elements.
I think capital costs suffer too: I'd suspect you'd need a larger pressure vessel to contain the same volume of fuel, and power output won't be as good because heat production will happen predominantly in the U-233 'seed' elements, so power density won't be as good as a conventional LWR.
Now, the folks at Lightbridge
http://www.ltbridge.com/
have been doing some work on a seed and blanket core that puts U-233 into metal fuel elements (which would be easier to fabricate remotely) and puts the Th in oxide fuel elements. The metal fuel does better at transporting heat to the fluid, so power peaking may be less of a problem.
Reprocessing is also more expensive in a sold-fuel Th cycle. Th fuel can handled by the THOREX process, which is a modification of PUREX, but it's harder to dissolve Th fuel than U-based fuel.
I'm also not enamored with the idea of planes flying around with tanks of liquid hydrogen.
From what the article says, it seems that the paper hasn't considered very much of the follow-on effects.
From what the article says, it seems that the paper hasn't considered very much of the follow-on effects.
It's not as if planes flying around with tanks of jet fuel are much better. I've read many folks' comments that hydrogen is better, since it tends to float up, out of the way of everything heavier than air.
So you think the solution to the intermittency issue outlined in the article isn't workable? Why?
Although hydroelectric power is cheap and carbon-free it causes serious habitat destruction. It's unlikely that significant new hydropower facilities are going to be built in the developed world, and in fact, the ability to produce hydropower is endangered by siltation and climate change.
The availability of hydropower might be enough to use as a buffer, given favorable assumptions, but note that this would cause violent fluctuations of water level downstream of the dams... And many dams are already facing criticism of the water-level fluctuations they cause today. The level of habitat disruption involved is in the "pave the earth" category.
The availability of hydropower might be enough to use as a buffer, given favorable assumptions, but note that this would cause violent fluctuations of water level downstream of the dams... And many dams are already facing criticism of the water-level fluctuations they cause today. The level of habitat disruption involved is in the "pave the earth" category.
I think his main argument was that the sun always shines somewhere and the wind always blows somewhere so if you build a good enough grid you can balance it all out. I don't know how much energy is lost in long distance transmission though.
Most of the issues with renewable can be solved using pumped storage hydroelectric which has minimal environmental impact.
http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
PS: If you simply covered every road in the world with mid range solar panels you meet the worlds current energy needs. EX: The 160,000 miles (260,000 km) of NHS include only 4% of the nation's roads so call it 4,000,000 miles with an average width of say 10 feet. 4,000,000miles * 10 feet (which is vary conservative) = 7,575 square miles or 19,621,122,048m^2. At 750w/m^2 * 15% efficient solar cell * 8 hours a day * 365 days a year * 19,621,122,048m^2 = ~6 * 10^12kwh vs 4 * 10^12kwh actually generated in the USA.
PS: If you simply covered every road in the world with mid range solar panels you meet the worlds current energy needs. EX: The 160,000 miles (260,000 km) of NHS include only 4% of the nation's roads so call it 4,000,000 miles with an average width of say 10 feet. 4,000,000miles * 10 feet (which is vary conservative) = 7,575 square miles or 19,621,122,048m^2. At 750w/m^2 * 15% efficient solar cell * 8 hours a day * 365 days a year * 19,621,122,048m^2 = ~6 * 10^12kwh vs 4 * 10^12kwh actually generated in the USA.
"If you simply covered every road in the world with mid range solar panels you meet the worlds current energy needs"
Ponder the immense amount of effort, cost, and trouble it took to build every road in the world. Even the massive Interstate Highway system only constitutes a fraction of US roads. Now, instead of laying down inert asphalt, blacktop, concrete, or gravel, what you suggest as an encouraging example involves laying down a much more complicated and expensive infrastructure.
There's no "simply" here, despite the breezy phrasing. (Which is of a piece of all grandiose plans that require only "political will" and umpteen trillions of dollars.)
Ponder the immense amount of effort, cost, and trouble it took to build every road in the world. Even the massive Interstate Highway system only constitutes a fraction of US roads. Now, instead of laying down inert asphalt, blacktop, concrete, or gravel, what you suggest as an encouraging example involves laying down a much more complicated and expensive infrastructure.
There's no "simply" here, despite the breezy phrasing. (Which is of a piece of all grandiose plans that require only "political will" and umpteen trillions of dollars.)
You know we have the ability to build structures above ground, with the added benefit of reducing the need for snow removal etc. Clearly it's not the cheapest solution, however roads already cover far more land than any reasonable collection of solar power plants so it's useful to add an idea of the scale we are talking about.
Pumped-storage hydro tends to be staggeringly expensive, because you've got all the capital costs of building the dam and then the pumps to pump water up, and then you've got to spend energy pumping water uphill.
Note that the reservoir for a pumped-storage hydro system will be environmentally degraded because water levels are going to fluctuate drastically.
Also, a pumped-storage system failed in the Ozarks, sending a wall of water downstream and nearly killing a family.
http://en.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_S...
Although fossil fuel pollution kills millions of people a year, hydroelecticity is the most dangerous form of power when one considers catastrophic fatalities:
Workers at the plant were killed in this case:
http://www.unspillable.com/oil-alternatives/hydro-power/russ...
but a dam failure near Rapid City, SD killed nearly 250 in 1972 and the failure of Vajont Dam killed about 2000 people:
http://en.wikipedia.org/wiki/Vajont_Dam
Some large dams are situated in places where 10,000-100,000 people could be killed in a failure.
Note that the reservoir for a pumped-storage hydro system will be environmentally degraded because water levels are going to fluctuate drastically.
Also, a pumped-storage system failed in the Ozarks, sending a wall of water downstream and nearly killing a family.
http://en.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_S...
Although fossil fuel pollution kills millions of people a year, hydroelecticity is the most dangerous form of power when one considers catastrophic fatalities:
Workers at the plant were killed in this case:
http://www.unspillable.com/oil-alternatives/hydro-power/russ...
but a dam failure near Rapid City, SD killed nearly 250 in 1972 and the failure of Vajont Dam killed about 2000 people:
http://en.wikipedia.org/wiki/Vajont_Dam
Some large dams are situated in places where 10,000-100,000 people could be killed in a failure.
Umm, I would rather risk x lives once every 100 years than know I am going to kill 10x that every year. (Or did I miss read what you just said.)
The whole point of their study was to determine what kind of mix would work. They made no claims that intermittent renewables could provide 100% of energy needs all the time.
Intermittent production is why they include hydro as one of the technologies: http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
If there is a strong shift to grid-charged electric vehicles (as opposed to hydrogen fuel cells), that also holds great potential as a buffering mechanism for intermittent energy production. Just because we don't do it now doesn't mean it can't be done.
Intermittent production is why they include hydro as one of the technologies: http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
If there is a strong shift to grid-charged electric vehicles (as opposed to hydrogen fuel cells), that also holds great potential as a buffering mechanism for intermittent energy production. Just because we don't do it now doesn't mean it can't be done.
Yet another iteration of the soundly discredited "hydrogen economy" model. I'm really surprised this came out of Stanford, of all places.
>They found that even materials such as platinum and the rare earth metals, the most obvious potential supply bottlenecks, are available in sufficient amounts. And >recycling could effectively extend the supply.
>For solar cells there are different materials, but there are so many choices that if one becomes short, you can switch,"
Cornucopian hand waving. It reminds me of Julian Simon and his assertion that if we ever run out of Copper, we'll find a way to just make it or substitute something else for it.
I'm really, really curious how they came up with their numbers on that. I'm also very interested to see if they accounted for the quantum limitations on solar cell efficiency.
I think i'm going to have to actually read the paper.
>They found that even materials such as platinum and the rare earth metals, the most obvious potential supply bottlenecks, are available in sufficient amounts. And >recycling could effectively extend the supply.
>For solar cells there are different materials, but there are so many choices that if one becomes short, you can switch,"
Cornucopian hand waving. It reminds me of Julian Simon and his assertion that if we ever run out of Copper, we'll find a way to just make it or substitute something else for it.
I'm really, really curious how they came up with their numbers on that. I'm also very interested to see if they accounted for the quantum limitations on solar cell efficiency.
I think i'm going to have to actually read the paper.
"If someone told you there was a way you could [do amazing things at a cost comparable to the Moon landings], why wouldn't you do it?"
Because such large and complex projects are bound to seriously overrun initial budget and time estimates, and sometimes fail altogether. I'm always suspicious when big and fancy promises are made, if only we're willing to pay an arm and a leg. Tell you what: pick the bluest of the blue states, where the political will definitely exists, and implement all this stuff there. (You did say it could be done with today's technology, and only political will was needed?) Then we'll talk about the world.
Because such large and complex projects are bound to seriously overrun initial budget and time estimates, and sometimes fail altogether. I'm always suspicious when big and fancy promises are made, if only we're willing to pay an arm and a leg. Tell you what: pick the bluest of the blue states, where the political will definitely exists, and implement all this stuff there. (You did say it could be done with today's technology, and only political will was needed?) Then we'll talk about the world.
I don't think this is a bad idea, and would vote for this to happen in my state.
The problem is that if only one state does this at significant expense, they won't see any appreciable benefit because the rest of the states and the rest of the world would still be emitting CO2.
So one state has huge expenses with an unlikely payback, AND they won't benefit from the economies of scale that everyone else will if they do get around to converting. It's a hard sell.
I think the best way to look at it is that non renewable energy does has huge hidden costs to society. Converting to renewables is the rational action, so if we use a cap or a carbon tax to price non renewables appropriately the price of each will reflect that.
*edited for typos
The problem is that if only one state does this at significant expense, they won't see any appreciable benefit because the rest of the states and the rest of the world would still be emitting CO2.
So one state has huge expenses with an unlikely payback, AND they won't benefit from the economies of scale that everyone else will if they do get around to converting. It's a hard sell.
I think the best way to look at it is that non renewable energy does has huge hidden costs to society. Converting to renewables is the rational action, so if we use a cap or a carbon tax to price non renewables appropriately the price of each will reflect that.
*edited for typos
> AND they won't benefit from the economies of scale that everyone else will
Most of the "economies of scale" happen at a fairly modest level. In fact, there are actually diseconomies at extreme scale. (The US Govt is a nice example.)
> The problem is that if only one state does this at significant expense, they won't see any appreciable benefit
The claim was that the expense wasn't significant, that it was mostly just "will".
> if we use a cap or a carbon tax to price non renewables appropriately
And what makes you think that the price will be "appropriate"?
The arguments for carbon taxes and the like are comparing an abstract ideal with what we got through the political process. That's a meaningless comparison because that processh pretty much guarantees that the nice properties of the ideal won't be realized if we try to implement it.
When a proposal contains basic errors like those mentioned above, what are the odds that the rest of it is sound?
Most of the "economies of scale" happen at a fairly modest level. In fact, there are actually diseconomies at extreme scale. (The US Govt is a nice example.)
> The problem is that if only one state does this at significant expense, they won't see any appreciable benefit
The claim was that the expense wasn't significant, that it was mostly just "will".
> if we use a cap or a carbon tax to price non renewables appropriately
And what makes you think that the price will be "appropriate"?
The arguments for carbon taxes and the like are comparing an abstract ideal with what we got through the political process. That's a meaningless comparison because that processh pretty much guarantees that the nice properties of the ideal won't be realized if we try to implement it.
When a proposal contains basic errors like those mentioned above, what are the odds that the rest of it is sound?
Do you think the price of energy now is appropriate? There are clearly negative externalities associated with CO2 emissions that aren't taken into account in the price today.
Wouldn't an artificially high price of carbon emissions be quite a bit better than an artificially low one?
Wouldn't an artificially high price of carbon emissions be quite a bit better than an artificially low one?
> There are clearly negative externalities associated with CO2 emissions that aren't taken into account in the price today.
I'd be more sympathetic to your externalities argument if there was some evidence that you weren't just using it as an excuse to do what you want to do for other reasons.
For example, you're ignoring the negative externalities of your proposal.
And then there's the small matter that the predicted cost of the externalities is significantly lower than cost of the "solution". Money has positive time value.
What? You don't like numerical arguments? Or, is it that you didn't know that the numbers existed?
> Wouldn't an artificially high price of carbon emissions be quite a bit better than an artificially low one?
No. Or rather, it depends on the magnitudes of "high" and "low".
Most folks who complain about subidized energy miscount. Feel free to demonstrate that you'r an exception.
I'd be more sympathetic to your externalities argument if there was some evidence that you weren't just using it as an excuse to do what you want to do for other reasons.
For example, you're ignoring the negative externalities of your proposal.
And then there's the small matter that the predicted cost of the externalities is significantly lower than cost of the "solution". Money has positive time value.
What? You don't like numerical arguments? Or, is it that you didn't know that the numbers existed?
> Wouldn't an artificially high price of carbon emissions be quite a bit better than an artificially low one?
No. Or rather, it depends on the magnitudes of "high" and "low".
Most folks who complain about subidized energy miscount. Feel free to demonstrate that you'r an exception.
Right, one state won't make a big difference in global CO2 emissions, but the point is to lead by example. There are a lot of people / political entities sitting on the fence right now, because it is unknown what the cost would be for these projects, or even if they're feasible and would work as intended. If they are shown to work in one place, and at an affordable cost, they would be a much easier sell to everyone else.
This is one of the best ideas I have ever read.
Yay! More jobs for Massachusetts!
[deleted]
Links to the actual papers (PDF):
Part 1: http://www.stanford.edu/group/efmh/jacobson/Articles/I/JDEnP...
Part 2: http://www.stanford.edu/group/efmh/jacobson/Articles/I/DJEnP...
Part 1: http://www.stanford.edu/group/efmh/jacobson/Articles/I/JDEnP...
Part 2: http://www.stanford.edu/group/efmh/jacobson/Articles/I/DJEnP...
This reminds me of the quote, "In a five year period we can get one superb programming language. Only we can't control when the five year period will begin."
Yeah, we'll be totally on alternative energy in 20 years. It's just that we don't know when this "20 years" will begin...
Yeah, we'll be totally on alternative energy in 20 years. It's just that we don't know when this "20 years" will begin...
It's simply time to think very much outside of the box and separate the wheat from the chaff in a truly scientific and unbiased way..
Low Energy Nuclear Reactions, also known as Cold Fusion: http://www.lenr-canr.org/
"Finding and facilitating breakthrough clean energy technologies."
http://peswiki.com/index.php/Main_Page
"In a July 9, 1998 keynote address at the Fifth International Conference on Composites Engineering in Las Vegas, Dr. Deborah D. L. Chung, professor of Mechanical and Aerospace Engineering at University at Buffalo (UB), reported that she had observed apparent negative resistance in interfaces between layers of carbon fibers in a composite material. Professor Chung holds the Niagara Mohawk Chair in Materials Research at UB and is internationally recognized for her work in smart materials and carbon composites. The apparent negative resistance was observed in a direction perpendicular to the fiber layers. "
http://www.energyfromthevacuum.com/Disc3.htm
"The reflexive response from mainstream science about the possibility of producing free energy from the vacuum is that it is not possible as this would violate the second law of thermodynamics.
Over the last 20 years the absolute status of the second law has come under increased scrutiny, more than during any other period in its 180-year history. Since the early 1980's, roughly 50 papers representing over 20 challenges have appeared in the refereed scientific literature."
http://www.energyfromthevacuum.com/Disc8/index.html
Time to go back to the ORIGINAL work by Maxwell and dive into the quaternion notations and not follow the crippled rewritten version by Heaviside.
Low Energy Nuclear Reactions, also known as Cold Fusion: http://www.lenr-canr.org/
"Finding and facilitating breakthrough clean energy technologies."
http://peswiki.com/index.php/Main_Page
"In a July 9, 1998 keynote address at the Fifth International Conference on Composites Engineering in Las Vegas, Dr. Deborah D. L. Chung, professor of Mechanical and Aerospace Engineering at University at Buffalo (UB), reported that she had observed apparent negative resistance in interfaces between layers of carbon fibers in a composite material. Professor Chung holds the Niagara Mohawk Chair in Materials Research at UB and is internationally recognized for her work in smart materials and carbon composites. The apparent negative resistance was observed in a direction perpendicular to the fiber layers. "
http://www.energyfromthevacuum.com/Disc3.htm
"The reflexive response from mainstream science about the possibility of producing free energy from the vacuum is that it is not possible as this would violate the second law of thermodynamics.
Over the last 20 years the absolute status of the second law has come under increased scrutiny, more than during any other period in its 180-year history. Since the early 1980's, roughly 50 papers representing over 20 challenges have appeared in the refereed scientific literature."
http://www.energyfromthevacuum.com/Disc8/index.html
Time to go back to the ORIGINAL work by Maxwell and dive into the quaternion notations and not follow the crippled rewritten version by Heaviside.
Vehicles, ships and trains would be powered by electricity and hydrogen fuel cells. Aircraft would run on liquid hydrogen.
Hydrogen carries a lot of energy for its weight. Unfortunately, it's not all that compact. I've seen comments online that even liquid hydrogen doesn't so much fall as floats downward. Still, for all that, I can see ships and trains, maybe even busses, using hydrogen. As you increase the size of a vehicle, the internal space increases by the third power, so space is not such an issue for large vehicles.
A good interim step would be for the US to go to natural gas for vehicular energy. We have a lot of it. It would be more efficient, and it would help decrease the importance of petroleum in our industrial infrastructure.
Hydrogen carries a lot of energy for its weight. Unfortunately, it's not all that compact. I've seen comments online that even liquid hydrogen doesn't so much fall as floats downward. Still, for all that, I can see ships and trains, maybe even busses, using hydrogen. As you increase the size of a vehicle, the internal space increases by the third power, so space is not such an issue for large vehicles.
A good interim step would be for the US to go to natural gas for vehicular energy. We have a lot of it. It would be more efficient, and it would help decrease the importance of petroleum in our industrial infrastructure.
Guess The Venus Project is not so far fetched as it seems: http://www.thevenusproject.com/
But.. do we have the will and determination to dodge our own demise?
But.. do we have the will and determination to dodge our own demise?
How viable are algae-based biofuels?
Not bad, but far from a whole solution. Background: used to work for one of the raceway-pond based companies trying to commercialize this technology.
The current frontrunner, IMHO, is NASA's Algae Omega project, to grow freshwater algae on sewage in membrane bags in the ocean. But there are serious problems. The one that isn't likely to be solved is the photosynthetic limit: plants just aren't very efficient at turning solar heat into chemical work.
Yes, we will have more algae biofuels over time. No, this will not replace petroleum singlehandedly.
The current frontrunner, IMHO, is NASA's Algae Omega project, to grow freshwater algae on sewage in membrane bags in the ocean. But there are serious problems. The one that isn't likely to be solved is the photosynthetic limit: plants just aren't very efficient at turning solar heat into chemical work.
Yes, we will have more algae biofuels over time. No, this will not replace petroleum singlehandedly.
What kind of yields can you get from the raceway method?
I highly recommend watching this Saul Griffith talk, "Climate Change Recalculated"
http://fora.tv/2009/01/16/Saul_Griffith_Climate_Change_Recal...
I guess in California it's easy to say "we can use solar". But I look outside my window here in London and it's overcast and hazy. I don't recall it was windy either when I went out for a sandwich.
Well I guess that pretty much settles it then. It's not windy or sunny today in London so renewable energy is surely a pipe dream.
Thermomax evacuated tubes (developed in England) can get your bathwater and washing-input water nice and toasty, saving tons of carbon. They can even do this in the middle of an English winter. The trick is to use this as a water pre-heat. This way, you have complete control and reliability of your hot water, but you get the benefits of the sun's free energy input.
The north sea is windy: http://en.wikipedia.org/wiki/London_Array
IIRC one of the options presented in “Sustainable Energy—Without the Hot Air” paper (http://www.withouthotair.com/) was setting up an array of solar panels in North Africa and selling the generated power to Britain.
arizona should be paved over as a massive photovoltaic lot. you don't need to live there anyway you won't have water soon. as for questions of putting that energy into the grid, we already do it, just because energy is locally produced doesn't mean it is locally consumed.
That's along the lines of one of the bigger proposals I've seen - to cover large inhospitable and hot places like the Sahara. It doesn't have to be with expensive photovoltaic panels, you can take Spain's route and use the mirrors-heating-molten-salt technology instead.
Technology for super-efficient thermal insulation is literally centuries old now. Just what are the barriers to solar-thermal with storage?
You need water to run a Photovoltaic farm. Mirrors or Solar panels, you need to keep them clean. The efficiency of both degrades with dust, which is not in short supply in the desert. While not technically necessary in the immediate process of power generation, as a practical mater, access to water is required for all power generation except wind.
EMPs?
Having read Prof Mackay's e-book[1] on the subject, I am massively, massively unconvinced by that article.
[1] http://www.withouthotair.com/
[1] http://www.withouthotair.com/
Intermittent renewables aren't a complete solution to our energy needs because they aren't available when we need them. They either need to be supplemented with fossil fuels or we'd need to build an energy storage system that would cost as much, if not more, than the energy production system.