Total Phase Out of Once-Through Cooling Power Plants by 2029

The end is near for aging power plants in California that use the ecologically detrimental process called “once-through cooling” (OTC), according to a tracking progress report from the California Energy Commission.

OTC is where power plants divert water from oceans, estuaries, lakes or rivers to cool steam after it has passed through a turbine to create power.

The water diversion entraps billions of aquatic organisms annually, including fish larvae and shellfish. It also removes water from habitats used by aquatic organisms and fauna.

In 2010, the State Water Resources Control Board (SWRCB) began requiring a phase out of the process at 19 OTC power plants to address the diversion of 16 billion gallons of the state’s coastal and estuarine waters daily.

Under the SWRCB policy, plant operators are required to install evaporative cooling technology to reduce water intake at OTC plants.

The policy includes recommendations by the California Independent System Operator, the California Public Utilities Commission, and the Energy Commission. Safeguarding the state’s critical energy needs is also integral to the policy focus.

Some plant owners are choosing to retire facilities rather than spend money to update current models. Since 2015, power plant owners have retired seven power plants that use OTC, according to the tracking progress report. Some plant owners are repowering plants with non-water cooled systems.

Plants using OTC have to adhere with the policy by 2024, except for the Los Angeles Department of Water and Power which was granted a compliance extension to 2029.

All power plants in California are expected to comply with the policy by 2030. Renewable energy is expected to make up for the lost energy capacity from retiring plants early.