Processing Magazine

Energy consumption biggest expense for desalination plants

May 7, 2013
desalination plant
An average desalination facility uses 15,000 kilowatt-hours of power to produce a million gallons of fresh water.

According to a new report from the Pacific Institute, the biggest expense for desalination plants is energy, accounting for as much as half of the entire bill.

An average desalination facility uses 15,000 kilowatt-hours of power to produce a million gallons of fresh water, researchers from the Pacific Institute said. By contrast, a wastewater reuse plant requires 8,300 kilowatt-hours of power for the same amount of water, whereas importing the same amount of water into Southern California draws about 14,000 kilowatt-hours of power, the researchers said.

At present, plans for the construction of 17 desalination facilities in California and two in Mexico have been drawn up to deal with a shortage of fresh water for businesses and households in the area, said Heather Cooley, co-director of the water program at the Pacific Institute. Those plants would contribute to relieving the drought problem and would lift some of the pressure on local utilities but they would also make suppliers more dependent on fluctuating energy prices, Cooley told Bloomberg.

The authors of the report estimate that if energy expenses rose by 25 percent, the cost of water production at reverse osmosis and thermal desalination facilities would increase by 9 percent and 15 percent respectively. Meanwhile, it is predicted that the price of electricity in California will go up 27 percent between 2008 and 2020, due to infrastructural maintenance, capacity expansion and the addition of renewable energy to the mix, Bloomberg said.

RELATED: Texas studies feasibility of Gulf of Mexico desalination plant

One of the 17 plants at various stages of planning is the Poseidon Resources desalination plant in Carlsbad in Southern California, which will be the largest facility of this type in the Western Hemisphere. Its construction was launched last year, after San Diego's water authority agreed to buy the water it will produce over a period of 30 years.

However, the high energy requirements of the facility have raised concerns about greenhouse gas emissions. Cooley explained that an increase in production from seawater desalination would contribute to a dramatic rise in emissions at a time when state and federal authorities are aiming to reduce them. Those risks can be reduced if producers incorporate more renewable energy or purchase carbon offsets, she added.

Meanwhile, the state is seeking more information about the potential environmental impact of the desalination plant. The California Coastal Commission sent a notice to Poseidon, explaining that its application was incomplete and failed to provide details about its impact on nearby wetlands, among other issues, the Huntington Beach Independent reported. In response to the letter from the commission, Poseidon explained that it had already answered all questions asked at all previous inquires related to the project.