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Published: Friday, Jul. 17, 2009

New rules would limit power plants' use of ocean water for cooling

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State water officials have proposed a set of stringent new rules that are intended to eliminate or greatly reduce a harmful type of ocean-water cooling at power plants such as Diablo Canyon nuclear plant and Morro Bay.

It is unclear what effect the new rules would have on Diablo Canyon. They contain two exemptions for which nuclear plant operators could apply for reasons of safety or cost.

Known as once-through cooling, the process involves pumping massive amounts of ocean water through the cooling system to condense steam after it has passed through the electrical generators. It damages ocean life in a number of ways including killing millions of larvae and, in some cases, sucking in and drowning seals.

The new rules are intended to force plant owners to use less damaging cooling methods by reducing intake of ocean water by at least 93 percent or finding other ways to reduce damage to ocean life.

Options available to plant owners include the use of giant radiators to condense the steam, called dry cooling, or using evaporation towers or other wet-cooling techniques that use substantially less water.

Officials with Dynegy, owners of the Morro Bay power plant, are hinting that the expense of complying with the new rules at older plants like the one in Morro Bay may be too great and the plant might close as a result.

The 50-year-old Morro Bay plant uses natural gas fired boilers. Although proposals have been made to renovate the plant, Dynegy is not moving ahead with those plans.

“But we would not want to speculate on the future of the Morro Bay plant,” added David Byford, Dynegy spokesman.

As it is, the antiquated plant operates “very seldom,” usually only during the summer when demand for electricity is at its highest, Byford said. The plant has contracts to sell power until 2013.

The State Water Resources Control Board proposed the new rules June 30. They are several years in the making and involved consultation with numerous other state agencies and stakeholders.

“The State Water Board staff’s intent with this draft policy is to assure that California’s coastal waters are protected while making certain that essential electrical power is available to Californians,” said Dorothy Rice, the board’s executive director.

Emily Christensen, spokeswoman at Diablo Canyon, said plant owners Pacific Gas and Electric Company are encouraged by the board’s commitment to electrical reliability and are reviewing whether to apply for either of the exemptions.

In one exemption, PG&E could argue that the rules conflict with Nuclear Regulatory Commission safety requirements. In another, the utility could argue that the cost of the new rules is “wholly disproportionate to the environmental benefits.”

In either case, the utility would have to propose alternate methods of reducing ocean impacts. The Morro Bay plant would have until 2016 to be in compliance; Diablo Canyon’s deadline is 2022.

Ongoing disagreement The proposed rules are the latest chapter in an ongoing disagreement between PG&E and state water officials over once-through cooling.

Diablo Canyon’s water discharge permit has expired and the plant is operating under an extension while the two parties try to reach an agreement on how to offset the effects of ocean-water cooling.

The nuclear plant typically circulates nearly 2.3 billion gallons of seawater a day. This water carries with it an estimated 1.5 billion fish and crab larvae a day, according to state water board documents.

Many, if not all, of the larvae are killed by the nearly 20-degree temperature increase or are eaten by barnacles and other crustaceans that line the cooling water pipes. The heated water has also altered the marine ecology of the plant’s water discharge cove.

PG&E biologists have argued that the effect of the larvae mortality is minimal because most would not reach adulthood under normal circumstances. State officials have proposed land conservation deals and the creation of artificial reefs as ways of offsetting the mortality but no deals have been reached.

Of the state’s 19 power plants that use once-through cooling, others have more dramatic impacts on wildlife. Some plants use narrow offshore pipes to draw in their cooling water.

These pipes create enough suction to draw in fish and marine mammals. The worst is the state’s other nuclear power plant, San Onofre in Southern California.

State records show that between 1978 and 2000, 64 harbor seals, 153 sea lions and four sea turtles were found dead in San Onofre’s intake structure. Power plants in Ormond Beach and Redondo Beach, both in Los Angeles County, have killed lesser numbers of seals.

Diablo Canyon avoids this problem because its intake pipes are large enough that the suction they create is weak enough that fish and animals can swim out of it. No marine mammals have died in Diablo Canyon’s intake structure although divers removed seven live sea turtles from the structure from 1985 to 2001.

A 60-day public comment period on the new rules begins Sept. 30. The state water board is expected to vote whether or not to adopt the rules late this year or early next year.