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We really need to re-think our water sources in CA. We have nearly unlimited solar potential that can be used to power desalination and pumping of the water wer

We really need to re-think our water sources in CA. We have nearly unlimited solar potential that can be used to power desalination and pumping of the water were we need it. Best part - we don’t need to worry about power storage (just transmission, which is not trivial, but can be done), it’s not an issue if we cannot desalinate at night.

tdeck 5y ago
I was curious about the energy requirements, so I did some envelope math. The average US household consumes 11,000 KW-hours of energy per year. Let's say an average person uses 80-100 gallons of water a day, so a low end of about 30,000 gallons of water per year. One article [1] suggests desalination takes about 15kJ/kg water at the most efficient plants. That translates to 473 kilowatt hours of energy required per household each year: 30000 gallons * 3.79 kg/gallon * 15 kilojoules So that's about a 4% increase in household energy usage just for domestic water for one person (domestic is less than 10% of our water use in CA). I'm not sure what conclusion to draw from this, but I suspect that it isn't practical to use desalination as a primary source of water. I also expect that much salt would become an environmental problem to dispose of. Once we drain our aquifer, the water shortage will be really severe and we'll need to cut back on agriculture regardless of desalination, but it could help a lot in urban areas. [1]: http://www.desware.net/Energy-Requirements-Desalination-Processes.aspx#:~:text=Theoretically%2C%20about%200.86%20kWh%20of,the%20type%20of%20process%20used http://www.desware.net/Energy-Requirements-Desalination-Proc....
- sologoub 5y ago
  Seems to work just fine for Israeli farming: https://www.scientificamerican.com/article/israel-proves-the-desalination-era-is-here/ https://www.scientificamerican.com/article/israel-proves-the... Percentage of household use is a strange measure to use here - Ivanpah plant produces nearly 400 MW and it’s relatively small plant. We have a lot of desert to go around. Producing more solar for the regular grid is not very practical because we can’t use all that up during daylight. If you have dedicated use for desalination that is concurrent with peak production of power, you can bring online a lot more production without risking destabilizing your grid. In effect, desalination can be used to balance the excess supply of solar - the more sunlight we get the more water we can produce. Water is relatively easy to store, modulating the demand to match the available excess supply.

tdeck 5y ago

I was curious about the energy requirements, so I did some envelope math. The average US household consumes 11,000 KW-hours of energy per year. Let's say an average person uses 80-100 gallons of water a day, so a low end of about 30,000 gallons of water per year. One article [1] suggests desalination takes about 15kJ/kg water at the most efficient plants. That translates to 473 kilowatt hours of energy required per household each year: 30000 gallons * 3.79 kg/gallon * 15 kilojoules So that's about a 4% increase in household energy usage just for domestic water for one person (domestic is less than 10% of our water use in CA). I'm not sure what conclusion to draw from this, but I suspect that it isn't practical to use desalination as a primary source of water. I also expect that much salt would become an environmental problem to dispose of. Once we drain our aquifer, the water shortage will be really severe and we'll need to cut back on agriculture regardless of desalination, but it could help a lot in urban areas. [1]: http://www.desware.net/Energy-Requirements-Desalination-Processes.aspx#:~:text=Theoretically%2C%20about%200.86%20kWh%20of,the%20type%20of%20process%20used http://www.desware.net/Energy-Requirements-Desalination-Proc....

sologoub 5y ago
Seems to work just fine for Israeli farming: https://www.scientificamerican.com/article/israel-proves-the-desalination-era-is-here/ https://www.scientificamerican.com/article/israel-proves-the... Percentage of household use is a strange measure to use here - Ivanpah plant produces nearly 400 MW and it’s relatively small plant. We have a lot of desert to go around. Producing more solar for the regular grid is not very practical because we can’t use all that up during daylight. If you have dedicated use for desalination that is concurrent with peak production of power, you can bring online a lot more production without risking destabilizing your grid. In effect, desalination can be used to balance the excess supply of solar - the more sunlight we get the more water we can produce. Water is relatively easy to store, modulating the demand to match the available excess supply.