Energy is the largest single expense for desalination plants, accounting for as much as half of the costs to make drinking water from the sea, according to a report.
Desalination plants on average use about 15,000 kilowatt-hours of power for every million gallons of fresh water that’s produced, the Pacific Institute said today in a report. In comparison, wastewater reuse draws as much as 8,300 kilowatt-hours of power for the same volume and importing a similar amount of water into Southern California requires as much as 14,000 kilowatt-hours of electricity, it said.
There are 17 desalination plants proposed in California and two in Mexico to help supply area homes and businesses, according to Heather Cooley, co-director of the institute’s water program. While the projects may ease water strains for area utilities, they’ll increase suppliers’ exposure to variable energy prices, she said by phone.
“While you may be improving your water reliability, you may be increasing your vulnerability to energy price changes over time,” Cooley said.
A 25 percent increase in energy expenses would raise the cost of producing water by about 9 percent and 15 percent at reverse osmosis and thermal desalination plants respectively, according to the report. Electricity prices in California are projected to rise by about 27 percent from 2008 to 2020 in inflation-adjusted dollars as power grid infrastructure is maintained or replaced, capacity is added and more renewable energy is integrated.
Poseidon Resources’s Carlsbad desalination plant in Southern California where construction began this year is one of the 17 projects and will be the Western Hemisphere’s largest when completed. San Diego’s water authority has agreed to buy the water for 30 years. JPMorgan Chase & Co. last year led a $922 million public-private bond offering for the plant.
The high energy requirements for desalination raise concerns about emissions, Cooley said. “If we are dramatically increasing our production from seawater desalination, that could dramatically increase our greenhouse-gas emissions at a time when we’re trying to reduce them.”
Producers can mitigate those effects by incorporating renewable energy and energy-efficiency measures or purchasing carbon offsets, she said.