Why don't we get our drinking water by taking salt out seawater? (2008)(scientificamerican.com)
scientificamerican.com
Why don't we get our drinking water by taking salt out seawater? (2008)
https://www.scientificamerican.com/article/why-dont-we-get-our-drinking-water-from-the-ocean/
356 comments
See also: a way to potentially do this with no energy input (exploiting density differences): https://www.science.org/doi/10.1126/science.183.4121.157
Basically you put a reverse-osmosis membrane at least 231 meters deep in the ocean. If you put it deeper, you could potentially extract both freshwater and energy.
Basically you put a reverse-osmosis membrane at least 231 meters deep in the ocean. If you put it deeper, you could potentially extract both freshwater and energy.
Practical Engineering just did a great video on Desalination.
Why Is Desalination So Difficult? - https://www.youtube.com/watch?v=mxqOPdEUNTs
Why Is Desalination So Difficult? - https://www.youtube.com/watch?v=mxqOPdEUNTs
Indirectly related: https://seawatergreenhouse.com/
"The idea behind the process is simple. It combines two unlimited resources - sunlight and seawater - to provide ideal growing conditions for crops in hot, arid environments.
The innovation utilises the cooling and humidifying power of water vapour produced from evaporating salt water. Using modeling and simulation techniques developed in collaboration with our partners at Aston University, we are able to process local climate data to predict greenhouse performance and inform the design. The combined effect of reducing temperature and increasing humidity, together with providing a protected environment for crops, results in up to 90% reduction in evapotranspiration. This greatly reduces irrigation requirements, which can be provided by desalination, and improved growing conditions.
As a result operating costs are lower, yields increase, and farmers can benefit from year-round production of high-value horticultural produce. "
"The idea behind the process is simple. It combines two unlimited resources - sunlight and seawater - to provide ideal growing conditions for crops in hot, arid environments.
The innovation utilises the cooling and humidifying power of water vapour produced from evaporating salt water. Using modeling and simulation techniques developed in collaboration with our partners at Aston University, we are able to process local climate data to predict greenhouse performance and inform the design. The combined effect of reducing temperature and increasing humidity, together with providing a protected environment for crops, results in up to 90% reduction in evapotranspiration. This greatly reduces irrigation requirements, which can be provided by desalination, and improved growing conditions.
As a result operating costs are lower, yields increase, and farmers can benefit from year-round production of high-value horticultural produce. "
It'd be helpful to know the minimal energy requirement to desalinate a gallon of water. With perfect technology, how expensive (in terms of energy) would it be? What's our current level of efficiency?
All comments seem to focus on the cost/energy requirements of the filtration process.. but the elephant in the room is the waste. How to safely dispose off the waste water after filtration completes? That water is virtually useless
Fun fact: A good number of Greek islands end up using desalination.
E.g. https://www.nationalgeographic.com/science/article/partner-c....
And this is not by choice: Greece has to deal with extreme volatility in resource consumption throughout the year. Add to that it has ~6000 islands (around 200 being inhabited year round -- 227 as I google). And the tourist island/islet focus changes throughout the years. With this context, there can be no "I will create a pipeline of fresh water" or any other project like that really.
E.g. https://www.nationalgeographic.com/science/article/partner-c....
And this is not by choice: Greece has to deal with extreme volatility in resource consumption throughout the year. Add to that it has ~6000 islands (around 200 being inhabited year round -- 227 as I google). And the tourist island/islet focus changes throughout the years. With this context, there can be no "I will create a pipeline of fresh water" or any other project like that really.
The article sidesteps something that seems important to my naïve eye: Water is easy to store if you don't have very much of it, so this is the kind of thing you can do when the sun is shining and store for nights and rainy days. Storing water for a year or two would be hard, of course.
Isreal does. California also has desalination, no?
If power costs are the driver then solar will be the answer
If power costs are the driver then solar will be the answer
I've read that we are starting up use other sources of heat to do desalination projects. There's so many sources of heat that we are just dissipating into the atmosphere. Nuclear or other power plants is an obvious choice.
Spoiler: desalination requires a lot of energy.
We actually do --- we just let the sun do it for us. ;-)
Great video explaining this in some more detail: https://youtu.be/mxqOPdEUNTs
I found this a few years ago (uses only a simple low-tech design, simple materials, and heat from the sun. I don't know how efficient it really is)
http://www.gabrielediamanti.com/projects/eliodomestico/
http://www.gabrielediamanti.com/projects/eliodomestico/
Feels like a problem that will be solved as soon as incentives will be here, and cost of fresh water from other sources depleted or protected. The costs mentioned in this 15 years old article aren't that high in a world where we have to be careful with water.
I wonder what is the reality now.
I wonder what is the reality now.
Because it's expensive. There, saved you a click.
Question: why is desalinated water costs calculated based on as if the water was immediately thrown back into the ocean? Wouldn't it rather be recycled after once desalinated?
So many newer attempts since then it feels like, different approaches
Like this Creating Drinking Water Using Ocean Wave Power (https://news.ycombinator.com/item?id=10522700)
But what happens to them? Initiatives never seem to go anywhere far....... energy requirements.... no financial incentive/interest? Same sort of tepid interest as general climate change initiatives?
Like this Creating Drinking Water Using Ocean Wave Power (https://news.ycombinator.com/item?id=10522700)
But what happens to them? Initiatives never seem to go anywhere far....... energy requirements.... no financial incentive/interest? Same sort of tepid interest as general climate change initiatives?
Also Scientific American, 8 years later (2016): Israel Proves the Desalination Era Is Here (https://www.scientificamerican.com/article/israel-proves-the...)
Why not using the sun to evaporate it, then collect the salt?
Temperature have risen in the last 15 years, unless one wants to extract water only by desalination, it should be feasible, and could at least help less densely populated areas near the sea. Maintenance aside, energy costs would be negligible.
Knowing that the vast majority of water use is not the water flowing to homes for drinking, plants and washing, the government (local or federal) could subsidize it for individuals while taxing industrial water consumers.
As mentioned in another post. Basic utilities can easily become affordable with proper regulation.
As mentioned in another post. Basic utilities can easily become affordable with proper regulation.
If you want anything to be economical or "worth it," you create the conditions where you are providing something to external parties, and the money will come in to sustain it. The economics of desalination are trivially viable if you can set up a stable financial regulatory environment in the region that has competitive taxation internationally.
Desalination is economical in the middle east because they export oil. In Israel it's economical because they export tech knowhow, and have foreign income sources from their diaspora networks. Some people will moan about "tax havens! for the filthy rich!" But really it's just viable habitation for locations without a lot of resources to export. Favourable capital rules are a valuable export. We do this in customs-free zones around the world today. If you have those rules in an area that needs a desalination plant to survive, I guarantee you it's going to work really, really well.
Desalination is economical in the middle east because they export oil. In Israel it's economical because they export tech knowhow, and have foreign income sources from their diaspora networks. Some people will moan about "tax havens! for the filthy rich!" But really it's just viable habitation for locations without a lot of resources to export. Favourable capital rules are a valuable export. We do this in customs-free zones around the world today. If you have those rules in an area that needs a desalination plant to survive, I guarantee you it's going to work really, really well.
I wonder how much it would cost in electricity to run a current through salt water to produce hydrogen and oxygen, then run the hydrogen through a hydrogen powered generator to recover most of the electricity and the fresh water byproduct?
Are state of the art systems more efficient than the ion-pumps in cell membranes?
I remember reading about light driven sodium and chloride pumps, if we could make these transport ions across some biomembrane we could desalinate water.
I remember reading about light driven sodium and chloride pumps, if we could make these transport ions across some biomembrane we could desalinate water.
There’s an enormous amount of lithium in desalinated water iirc
What about that small cheap device invention thing that can be used by people who live on the coast to produce enough drinking water?
Same reason as always: cost. If it was easy we'd be doing it long ago kn every boat and every coastal city.
Can desalination and electrolysis be combined so we have two useful bi-products?
Clean drinking water. Hydrogen for for fuel.
Clean drinking water. Hydrogen for for fuel.
We do in some places. But in other places like California NIMBYs and greens decided putting extra salty brine back into the ocean was worse than taking fresh water run off from the inland, worsening desertification
Really mostly nimbys. Greens have relented.
Nuclear desalination would solve a lot of the fresh water problems but we can't have solutions now can we?
Really mostly nimbys. Greens have relented.
Nuclear desalination would solve a lot of the fresh water problems but we can't have solutions now can we?
Where's that guy advocating for the desalination plants in Phoenix now?
In the bay area, I'm paying ~$2.80 per cubic meter.
I don't see why it's not feasible.
Yes, there are transmission/pumping costs. Assuming the water we're getting now is free, that's still only ~50-75% increase in cost over current costs.