4 ms·

This is surprisingly poor production? Peak insolation varies widely, but 1000W/m^2 is a typical value. 5.8L/hr/m^2 means that it's using something like 180kWh/

by mota7 4y ago

This is surprisingly poor production? Peak insolation varies widely, but 1000W/m^2 is a typical value. 5.8L/hr/m^2 means that it's using something like 180kWh/m^3 on raw solar insolation. For comparison, reverse osmosis is around 3kWh/m^3. This means that 20% efficient solar panel would produce around 67 L/hr/m^2 (aka ~11x more). Obviously this is passive versus active, but it's still a surprisingly large difference.

johnbcoughlin 4y ago
Converting water to steam is an extremely inefficient way to separate water from salt.
deleted 4y ago
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someguydave 4y ago
If reverse osmosis desalination only takes 3 kwh/m^3 then you could produce 4 million acre-feet for 14.9 billion kWh which would cost about $1.5 billion per year. That is pocket change for replacing a big portion of Colorado river water. I guess Californian environmentalists love Hetch Hetchy reservoir and making the desert stay dry.
- sacred_numbers 4y ago
  Reverse osmosis desalination does have some capital and operational costs, though, but you're not far off. 5 billion m^3 or 4 million acre-feet would still only be about 2.5 B per year. The problem is that if you fill up the Colorado River the farmers that own the water rights will just drain it down again because they don't pay based on the quantity they use. Or if they do pay based on quantity the price is much lower than the cost of desalination. Desalinating large quantities of water without fixing the water rights situation would be like minting pennies out of gold.
  - someguydave 4y ago
    sure, there would be capital costs but those could be financed, plenty of people would lend 30 year money for such an enterprise. So to be clear you hate agriculture so much you are willing to end it with drought? I like agriculture personally. I would like more of it! There is plenty of desert in the west that could be made to bloom.

by mota7 4y ago

johnbcoughlin 4y ago

Converting water to steam is an extremely inefficient way to separate water from salt.

deleted 4y ago

[deleted]

someguydave 4y ago

If reverse osmosis desalination only takes 3 kwh/m^3 then you could produce 4 million acre-feet for 14.9 billion kWh which would cost about $1.5 billion per year. That is pocket change for replacing a big portion of Colorado river water. I guess Californian environmentalists love Hetch Hetchy reservoir and making the desert stay dry.

sacred_numbers 4y ago
Reverse osmosis desalination does have some capital and operational costs, though, but you're not far off. 5 billion m^3 or 4 million acre-feet would still only be about 2.5 B per year. The problem is that if you fill up the Colorado River the farmers that own the water rights will just drain it down again because they don't pay based on the quantity they use. Or if they do pay based on quantity the price is much lower than the cost of desalination. Desalinating large quantities of water without fixing the water rights situation would be like minting pennies out of gold.
- someguydave 4y ago
  sure, there would be capital costs but those could be financed, plenty of people would lend 30 year money for such an enterprise. So to be clear you hate agriculture so much you are willing to end it with drought? I like agriculture personally. I would like more of it! There is plenty of desert in the west that could be made to bloom.