Let's see: It takes 5kW/h to produce a cubic meter of fresh water from sea water via reverse osmosis.[0] The population of just LA is a bit over 3 million.[1]

Let's see: It takes 5kW/h to produce a cubic meter of fresh water from sea water via reverse osmosis.[0] The population of just LA is a bit over 3 million.[1] The average U.S. citizen consumes 2842 cubic meters of water per year. 5 kWh/m^3 * 8765 h/year * 3,000,000 people * 2842 m^3/person-year = 4863662 kW = 4863 MW. I will conservatively estimate that a nuclear power plant will produce 800 MW.[3] So: 4863 MW / 800 MW/plant = 6 That means we're talking about six full-size nuclear power plants running 24/7 with their entire energy output going toward desalinization to supply LA alone. Extrapolating further, I get that it would take twenty nuclear power plants running full-time to meet just half of the demand for the entirety of southern California. Does that answer your question? (I know my sources aren't all that authoritative--they are just what Google pulled up. Feel free to redo the calculations with more accurate numbers, or just to double-check my arithmetic.) [0] http://lightbucket.wordpress.com/2008/04/04/large-scale-desalination-is-there-enough-energy-to-do-it/ http://lightbucket.wordpress.com/2008/04/04/large-scale-desa... [1] http://en.wikipedia.org/wiki/Southern_California http://en.wikipedia.org/wiki/Southern_California [2] http://www.waterfootprint.org/ http://www.waterfootprint.org/ [3] http://wiki.answers.com/Q/What_is_the_average_output_MW_of_a_nuclear_power_plant http://wiki.answers.com/Q/What_is_the_average_output_MW_of_a...