Desalination affected by California powerplant ruling

The powerplant with which California's new 189,000 m³/d Carlsbad seawater reverse-osmosis (SWRO) plant is co-located has been ordered to cease once-through cooling by 2017. The Huntington beach powerplant, site of another proposed desalination plant, has been given until 2020.

The Encina power station (bottom left) with the site for the Carlsbad desalination plant ringed.

The Encina power station (bottom left) with the site for the Carlsbad desalination plant ringed.

The ruling on 5 May 2010 by the California Water Resources Control Board is intended to protect sealife from the process of once-through cooling, which in California sucks in 18 billion gallons (68 x 1012 m³) per day of seawater and returns it to the sea with the extracted warmth from the power station. The board estimates that the process kills more than 2.6 million fish and 19 billion fish larvae annually.

The 19 powerplants affected by the ruling, which does not apply to desalination plants, will mostly have to install closed-loop cooling (with cooling towers) within a decade, although some have later schedules, in one case leading up to 2025. At least three powerplants are likely to close.

According to Poseidon Resources, the owner of the Carlsbad and Huntington Beach projects, it was always anticipated that the Carlsbad desalination plant would outlive the life of the Encina powerplant's once-through cooling system.

"In fact, the Encina powerplant submitted an application several years ago to repower its facility using a different technology," says Poseidon's Scott Maloni. "That application is pending before the California Energy Commission."

Assuming that the policy is not over turned by the courts, then it will take affect for the Encina plant in 2016 at the earliest. At that point, the Carlsbad desalination plant will have been in operation for approximately four years and its state discharge permit will come up for renewal.

Poseidon has a long-term exclusive agreement with the powerplant to use its cooling water system for the Carlsbad desalter, when the energy company eventually decommissions it. This will require no physical change to the design and construction of the desalination plant.

However, operations related to the temperature of the source water and the operation of the seawater intake pumps will have to be changed, which collectively will increase power consumption by less than 10%, says Maloni.

Poseidon has already made plans to relocate the Huntington Beach desalination plant to allow the AES powerplant room to install its necessary additional plant. A subsequent city environmental impact report is out for public comment until 21 June 2010.

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