Hydropower Plant Back Online After Winter Rains

By Published On: January 5, 2022

The Department of Water Resources’ Hyatt hydropower plant at Oroville Dam in Butte County is back generating electricity, thanks to recent heavy precipitation, the agency reported Jan. 4.

Not all the turbines are operating, though. Only one 30 MW unit is supplying hydropower to the California Independent System Operator. Rather than racing toward the turbines, most of the water behind the dam is being released from the lake to irrigate parched agricultural operations. Even that one unit is not running at full bore. It “is capable of producing around 100 MW at peak operation,” Liza Whitmore, DWR spokesperson told Current. The capacity of the total plant is 750 MW, making it the fourth-largest hydropower plant in the state when water supplies are flush, according to the California Energy Commission. But it produces about half that amount, around 300-400 MW, in a year of “average” precipitation.

Hydropower in California is traditionally used to meet demand spikes in the summer, particularly in late summer, rather than in wintertime. “Providing clean hydropower to the state energy grid allows DWR to assist in meeting the state’s clean energy goals,” Department Director Karla Nemeth said in a statement this week.

The Hyatt plant was forced offline in prime season on Aug. 5 after lake levels dropped too low for turbine intakes after two years of drought.

Ryan Endean, DWR spokesperson, said before the turbines were completely shut off in August, output had dwindled to just 10 MW. Oroville Dam is part of DWR’s massive state water supply project.

Looked at as a whole, the state water project actually consumes twice as much energy as it produces. That’s because massive amounts of electricity are needed to push water uphill into Southern California from Northern California. DWR times that push so that it’s not drawing power during the state’s peak demand for electricity, and so that it can sell hydropower into CAISO when that power is needed.

First snow survey reveals tripling of average snowpack

The Department’s first snow survey of the season recorded the snow depth at a whopping 78.5 inches, 202% of the average for the date at the reference location near South Lake Tahoe. Statewide the snowpack was well over double or 160% of average on Dec. 30.

“We could not have asked for a better December in terms of Sierra snow and rain,” said Nemeth. “We need more storms and average temperatures this winter and spring, and we can’t be sure it’s coming,” she added.

Last year, the California Independent System Operator anticipated a reduction in 2021 summer hydroelectric resources because of the worsening drought conditions. A loss of 1,000 MW of hydro in the state was predicted in late June.

At the end of September, four new natural gas-fired generators totaling 120 MW were added to the California grid at a cost of $196 million pursuant to Gov. Gavin Newsom’s July emergency order to bring on as much power to meet late afternoon demand.

2021 hydro 3rd largest source of electricity

Overall figures for 2021 show hydroelectricity provided an average of just 5% of total generation in the CAISO market between April and September. But a closer look at peak times shows hydro making a larger contribution. High overall power prices at peak made hydro more attractive in the CAISO competitive queue, increasing its share to 10% during those key summer hours, the Energy Information Agency reported Dec. 1. That made hydro “the third-largest source of electricity after natural gas and electricity imports from other grid operators in California and out of state,”  according to EIA.

Source: EIA based on CAISO data

About half of the hydropower in the U.S., or 80 GW in 2020, is generated in Washington, California and Oregon. Last year Washington produced 27% of the power,  California 13%, and Oregon 10% of the 2020 hydro supply.

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