Top PG&E; Hydro Plant Hampered by Demand

Round-the-clock demand on the state’s energy grid has hampered the ability of Pacific Gas & Electric’s largest hydroelectric plant to operate, forcing temporary shutdowns and limiting output of the massive Helms powerhouse to well below its 1,200-megawatt capacity.

During the spring snowmelt in the Sierra Nevada, Helms can light up much, if not all, of San Francisco. It generates almost 10 times as much power as PG&E;’s next-largest hydroelectric plant.

But in the current electricity crisis, it has turned into a chronic problem for state power regulators, both reflecting and, increasingly, contributing to California’s ongoing power shortages.

“When supplies are tight, every little bit helps,” PG&E; spokesman Jon Tremayne said. “If Helms were to be offline it would definitely have an impact.”

Helms was an engineering marvel when it began operating in the early 1980s, even if it never quite lived up to its billing. Its premise, to serve as a giant $1-billion battery powered by the flow of water in the Sierra Nevada, was groundbreaking for California.

PG&E; found a chunk of mountain along the Kings River--about 70 miles east of Fresno--and built two dams to create two lakes, one 1,600 feet higher than the other. Between the lakes, workers bored a massive canyon deep into the granite and built a plant with 460,000-horsepower turbines.

During the day, when the state needed electricity the most, PG&E; sent the river coursing down a 25-foot wide pipe that connected the two lakes, the steep drop creating energy that set the turbines spinning. At night, when the electricity demand was low, the water was pumped back up the mountain, from lower to upper lake.

The plan was to connect Helms with Diablo Canyon and use the nighttime nuclear power to offset the power needed to pump the Kings River water back up the mountain. Critics say it never quite worked that way.

“It was an interesting concept but it didn’t meet PG&E;’s claim that this power would be pennies on the dollar,” said Doug Bosco, a former state legislator and congressman who held state hearings in 1981 on construction cost overruns of the Helms project. “No one bothered to consider what happens when there’s not enough water to pump up and down the mountain. I don’t know to this day if it’s ever been economical.”

Scarce rainfall in November and December has indeed cut into Helms’ water supply.

Federal rules limit how low PG&E; can let the water level drop in Helms’ upper lake, Tremayne said. The plant skimmed the limit over the weekend, but received an infusion Monday night and early Tuesday, said Kellan Fluckiger, chief operating officer of the California Independent System Operator.

In recent weeks, the water supply has been so low at times that the plant is almost “sucking mud,” officials said.

PG&E; contends that the crucial element in the plant’s struggle is not lack of rain, but California’s soaking up every available electron.

“There’s just not as much excess electricity in the grid for us to use for pumping, even in the middle of the night,” Tremayne said.

Some, however, wonder whether PG&E;’s financial struggles factor into its management of Helms, perhaps to consumers’ detriment.

The utility has relied on the difference between higher daytime fuel prices and cheaper nighttime rates to make money from Helms because it takes more energy to pump the plant’s water supply uphill than it generates cascading down. That price differential has evaporated during the crisis.

Sen. Debra Bowen (D-Marina del Rey), an environmentalist and head of the Senate Energy and Utilities Committee, has requested information about the plant’s operations.

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Times staff writer Nancy Rivera Brooks contributed to this story.

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Ebbing Power Flow

High demand for electricity and a low water supply have limited output of the Helms powerhouse, Pacific Gas & Electric’s largest hydroelectric plant.

Source: PG&E;