Getting Pumped: How LA Uses Two Big Lakes to Store Energy like a Giant Battery

LOS ANGELES – If L.A. is going to stop burning fossil fuels by 2045 — a key goal of Mayor Eric Garcetti’s proposed Green New Deal — it must store a lot more of the excess solar and wind energy it produces during the day so it doesn’t have to rely on gas and coal energy to power the city when the sun sets and the wind dies.

There’s a growing focus on building big batteries — for example, the kind that use lithium ions. But L.A. needs energy storage that is far bigger than any traditional battery.

And it’s found one.

The Los Angeles Department of Water and Power has turned two big lakes into a monster battery capable of storing enough energy to power tens of thousands of homes.

It involves using the excess wind and solar power L.A.’s renewable energy sites produce during the day to pump water from Castaic Lake uphill 7.5 miles to Pyramid Lake. Then, late in the day, when the sun goes down and the city’s energy demand spikes, the water gets run downhill through hydroelectric generators at Castaic Lake.

The next day, the cycle starts over again. The same 10,000 acre-feet of water can recirculate over and over, getting pumped uphill during the day and coming downhill at night to power the city.

It’s called pumped storage, and the plant at Castaic is one of the largest such plants in the western United States, but maybe not for long.

LADWP is looking at building an even larger plant at Hoover Dam, so this form of energy storage, if replicated, could be a key to L.A. weaning itself off of fossil fuels.

So Let’s Tour the Castaic Pumped Storage Plant

It’s hidden away — kind of like a superhero’s secret lair — behind locked gates at the end of a winding mountain ridge road off I-5.

Castaic Pumped Storage Plant as seen from a mountain ridge near Ridge Route Road. (Photo by Sharon McNary/KPCC/LAist)

Once you’re inside the gates, the first thing you notice are six gargantuan pipes that flow water from Pyramid Lake 7.5 miles down to Castaic Lake. Water is pumped back uphill in the same 30-foot-diameter pipes.

The pressure is 25 times the force of the water coming out of your home faucet.

Here’s another look at those massive pipes from a different perspective, way up on the mountain looking down at Castaic Lake.

These massive pipes, called penstocks, move water up and down between Castaic and Pyramid Lakes. This is a view looking downhill at Castaic Lake. The Elderberry Forebay at the base of the pipes is part of Castaic Lake. It holds up to 10,000 acre-feet of water that can be recirculated between the two lakes. (Photo by Andrew Cullen for LAist)

Time to head down into the guts of the plant. We step off the elevator to a balcony overlooking a giant windowless chamber four stories tall.

The six turbines are in a vast windowless chamber. The pressure of the water coming downhill in the giant pipes spins the hydroelectric turbines, generating power for Los Angeles. More than 50 LADWP employees keep the plant running.

Below you can see two of the six turbine units. Unit 3 on the left, is covered and is ready to produce electricity as water spins the turbines inside it. Unit 4, on the right, is open for maintenance.

Unit 3, left, produces electricity while Unit 4 sits open for maintenance at Castaic Hydroelectric Power Plant in Castaic, Calif. (Photo by Andrew Cullen for LAist)

The six turbine units look like giant spools sunk into the floor. They put out enough energy, when they are all spinning, to power 83,000 homes over the course of a day. Their output is huge in comparison to LADWP’s largest chemical battery, which is a 20 megawatt lithium ion battery, which can power about 600 homes over a day.

Here is a view of the turbine in Unit 5. It’s been lifted partially above the floor of the turbine room. Each turbine weighs 550 tons. To lift them up takes two cranes that move the length of the room.

Castaic Hydroelectric Power Plant has six reversible 250,000 kilowatt turbines. The plant provides power for Los Angeles during peak use periods. (Photo by Andrew Cullen for LAist)

It takes a lot of pipes and plumbing to control the flow of water in this pumped storage plant. We descend several flights of stairs to get to the bottom of the plant to see the pumps.

At the very bottom of the plant, we’re 90 feet under the water level of the lake.

Massive machinery controls the flow of water through the hydroeletric plant at Castaic Hydroelectric Power Plant in Castaic, Calif. (Photo by Andrew Cullen for LAist)

The pumps are what makes this plant different from an ordinary hydroelectric plant. There are six giant pumps — each with a shiny silver piston arm. They are pushing water back up the mountain to Pyramid Lake in the same 30-foot-diameter pipes that brought it down to Castaic Lake.

Recirculating the water like this takes a lot of energy — but that’s okay. DWP has more wind and solar energy during the day than it can use. So rather than disconnect the solar panels and windmills, or sell the energy cheaply to someone else, DWP uses the extra energy to move the water uphill to Pyramid Lake.

Once the water is waiting uphill at Pyramid Lake, it’s stored energy, ready to flow back downhill to generate energy when L.A. needs it, late in the day.

A pump pulls water from 90 feet under Lake Castaic into the Castaic Hydroelectric Power Plant in Castaic, Calif., and sends it uphill to Pyramid Lake. (Photo by Andrew Cullen for LAist)

This battery-like combination — pumps and turbines — can be built very big. And they use the most reliable force on Earth — gravity.

Elderberry Forebay is a section of Castaic Lake that holds the water that gets recirculated between Pyramid Lake and Castaic to produce electricity.

Runoff from Castaic Hydroelectric Power Plant enters Elderberry Lake, which holds water that can be pumped back up to Pyramid Lake and reused to produce electricity. (Photo by Andrew Cullen for LAist)

Assistant general manager Reiko Kerr says they could pump water from Lake Mohave 20-some miles upstream to Lake Mead to run through Hoover Dam’s giant hydroelectric turbines.

“You already have the dam, you have the generators, you have the transmission lines — you basically need a set of pumps and pipelines,” Kerr said.

The eventual size depends on the number of other agencies that might invest in the project.

“That upper reservoir is huge — Lake Mead — so you could store power in the form of water up there for potentially months, and seasonally,” she said.

The Hoover Dam pumped storage project could come online by 2030, adding to the energy storage L.A. needs to get to 100% renewable energy.

As Relicensing Looms, Aging Dams Face a Reckoning

POTTER VALLEY, Calif. – More than a century ago, the people of Mendocino County in California needed electricity to fit into the industrialized world. So engineers generated power by building two dams and reconfiguring two rivers. For decades thereafter, people fashioned steadily improving lives around the new landscapes. At the same time, beset by environmental insults, the annual runs of salmonids in the Eel River withered.

Inevitably, priorities changed. As building the dams and creating the 9.2-megawatt Potter Valley project solved the need for electricity, a new need developed: irrigation. Tens of thousands of acre-feet of Eel River water were diverted to supply the power station at the headwaters of the Russian River’s East Branch. Then it flowed on, supplying cities and farmers and nurturing Mendocino and Sonoma County’s expanding agriculture – once pears and hops, now dominated by wine grapes.

An aerial view of the Cape Horn Dam on the Eel River. (Photo by Rob Badger)

The current need: repair the harm caused by the dams. That will cost so many tens of millions of dollars that the project’s owner, Pacific Gas & Electric – already losing money on it – is cutting its losses. It will not seek a new federal license.

This decision mimics PG&E’s recent moves away from other small hydroelectric projects, like the 12-megawatt Narrows project on the Yuba River in Nevada County, which PG&E sold last year to a local water agency. It also echoes decisions by the northwestern utility PacifiCorp, which, at a cost of $37 million, breached its 14.7 megawatt Condit Dam on the White Salmon River in Washington.

The Potter Valley Project: More Than Just a Dam

Built starting in 1905 by the Eel River Power and Irrigation Company, the Potter Valley Project grew over time to comprise two dams on the Eel River and two reservoirs: Lake Van Arsdale and Lake Pillsbury. The project eventually served two purposes: to generate power from Eel River water diverted to a powerhouse in Potter Valley, and to bring irrigation water to the Russian River watershed. This water served expanding agricultural areas in Mendocino and Sonoma Counties, including many new vineyards. Since the Russian River watershed is susceptible to flooding, the Army Corps of Engineers completed the Coyote Valley dam in 1958 for flood control. It created Lake Mendocino and provided a new source of both irrigation water and opportunities for recreation. (Graphic by Geoff McGhee/Bill Lane Center for the American West)

Choices Ahead for Owners of Small Hydroelectric Projects Across the West

Dam by dam, owners of smaller hydroelectric projects around the West look at them with a cold eye as relicensing looms. Created with optimism a century ago, dams are now seen as fish-killers and river-distorters. New energy sources are getting cheaper. After decades of operation, owners approach relicensing knowing that, if they are to continue generating a single watt of electricity, they must fix the problems.

Tens of millions of dollars are often at stake. The Federal Energy Regulatory Commission licenses hydroelectric projects for up to 50 years, but sometimes just one year at a time to ensure problems are resolved. Limited revenue from electricity may not justify expensive remediation. Before it was sold off, a financial analysis of the Narrows project showed costs would have outweighed profits by more than $12 million over the first five years.

Depending on how it finally turns out, the narrative of the Potter Valley project could be a cautionary tale for other dam owners whose stakeholders are at odds. Or it could be a roadmap to reconciling competing interests. Whatever the lesson, the project is part of a larger transformation in how people understand debts owed to the environment. And how they are repaid. “[The Potter Valley project] is a subset of a much larger body of problems,” said Scott Greacen, conservation director at Friends of the Eel River, a conservation organization that is seeking to restore natural streamflows. Over the decades, “we took a lot of capital out of natural systems. Now the bills are coming due.”

Fighting climate change is another urgent need. One way is by creating carbon-free electricity – what dams do. The historian Heather Lee Miller, a staffer at Historical Research Associates in Washington, believes that if all governments classify small hydroelectric projects’ energy as renewable, subsidies could change the financial picture.

“Certainly some of the dams are in terrible places,” she said. Others, like PacifiCorp’s 1.1-megawatt project at Wallowa Falls in Oregon, are being relicensed. “There’s a backlog of dams that aren’t in the right spot,” she said, but added that, as the climate changes, it would be wrong to think small hydro-electric projects have no future.

What is the difference between projects like Wallowa Falls being relicensed and those, like Potter Valley, being abandoned by big electric companies? Economics are central. Relicensing the Potter Valley project promised to be daunting even before PG&E, facing hundreds of millions of dollars of wildfire liabilities, declared bankruptcy. “It now looks like PG&E’s overall incentive structure has shifted,” Greacen said. “They have given up.”

Who Decides the Future? A Stakeholder Group Struggles to Find Compromise

The federal government determines the terms of PG&E’s exit. FERC will solicit interest from others to run it. If no one comes forward, it will order PG&E to develop a decommissioning plan that may or may not include removing facilities.

PG&E’s finances are private, but the economic analysis done for the Narrows project on the Yuba River offers guidance.

Jeff Bodington of San Francisco, the financial analyst who did it, said, “these projects made sense at the time they were built and perhaps for decades thereafter. Many still make sense.” But “some may make sense day in and day out, but when a license expires, relicensing can be very costly. A small project cannot absorb big relicensing costs. For each relicensing, he said, “these questions get asked. Are there fish impacts? Recreational impacts? Other impacts?”

The Potter Valley project had many impacts. The region’s congressman, Jared Huffman, created a working group of all stakeholders — water agencies, local and county governments, tribes, federal and state wildlife specialists and environmental groups – to hash out what the project should become and what happens to the dams.

Asked if the Potter Valley project is an electrical project or a water distribution project, Congressman Jared Huffman said simply. “Yes.” He added, “The question is, whether it can be both of those things and a fish recovery project.”

Dams a Mortal Threat to Fish Runs, Scientific and Regulatory Consensus Holds

In the past two decades, the federal government agreed with scientists that salmon and steelhead runs in the Eel River are threatened. A 2010 report from the Center for Watershed Sciences at the University of California, Davis, concluded, “coho salmon, Chinook salmon and steelhead are on a trajectory to extinction in the Eel River basin.”

The culprits listed in that report include early 20th-century commercial fishing and mechanized logging whose clear-cuts on the hillsides caused erosion that silted up the river. Floods in 1955 and 1964 added silt and changed the river’s course. All that hampered fish passage, but not as much as Scott Dam, built in 1922. It blocks dozens of miles of spawning areas. The report said, “the loss of salmonid habitat upstream of Scott Dam means there are fewer areas to serve as refuges for salmonid and steelhead… during environmentally unfriendly periods such as extended droughts.”

The Potter Valley Project takes water from the Eel River, which flows north, and pumps it into the Russian River, which flows south towards wine country. (Graphic by Geoff McGhee/Bill Lane Center for the American West)

Eel River Diversions Were Slashed in 2006… But Then Russian River Fish Suffered

In 2004, the Federal Energy Regulatory commission ordered the diversions cut back from what was then 160,000 acre-feet annually. Now they average 72,000 acre-feet. These inter-basin diversions help fish in the Russian River. The Eel River water flows through a mile-long tunnel to generate electricity at a powerhouse on the banks of the East Fork of the Russian River. The water not used by the Potter Valley Irrigation District and other local diverters ends up behind the Coyote Valley dam in Lake Mendocino and is released periodically into the Russian River.

The state Water Resources Control Board requires the Sonoma County Water Agency to keep minimum stream flows on the Russian River to maintain fish spawning and migration and support recreation. The Eel River water transfers help them do that, according to Don Seymour, a principal engineer at the Sonoma County Water Agency.

The agency has had difficulty meeting its minimum instream flow requirements while not depleting Lake Mendocino. It won’t be easy to serve its urban, industrial and agricultural customers and help its endangered fish recover if there is less water in Lake Mendocino.

Scott Dam on the Eel River, above, completely blocks salmonid migration. A fish ladder could cost $55 to $93 million, and might not work. (Photo by Rob Badger)

Help for Spawning Fish Could Cost Tens of Millions of Dollars – or Hundreds

Joshua Fuller, the National Marine Fisheries Service’s expert on salmonid runs in the Eel River, agrees that the Russian River fish do benefit from the Eel River water — but says access to the upper Eel River is crucial for reviving its salmonids.

Different strategies give fish access to spawning grounds. These include dam removal, a fish ladder, or hauling fish in trucks. Fuller heads one of two working groups in Congressman Huffman’s ad hoc committee weighing Potter Valley’s future. His group on fish passage is about to pick the two best of available solutions.

Good fish ladders are expensive. In August, the Lost Coast Outpost reported that a 2017 engineering report prepared for PG&E “found that constructing a functional fish ladder at Scott Dam would likely cost between $55 million and $93 million.” It would be “challenging to build, complicated to operate, very costly, and would have uncertain effectiveness.” Removing Scott Dam would be at least as expensive. Increasing the size of Coyote Valley dam, which holds back the Russian River, could cost $300 million.

Where could the money come from? As Congressman Huffman said, “If you look around at any stakeholder in either basin, none of them has the capacity to solve this problem and pay for it on their own. The only way to do this is to come together and unlock state and federal money.” His stakeholders group could sign a legal agreement giving the project a way forward without litigation.

PG&E’s January 25 announcement that it wanted out of Potter Valley complicates the plans being developed in the ad hoc committee. Huffman said that the glue binding potentially antagonistic stakeholders “is the fact that everybody’s at risk. There are really lousy solutions” possible “for everyone, no matter what their perspective.”

As Hydropower Profits Dwindle, Paying off Environmental Debt Gets Harder. But Renewable Energy Mandate May Help

The details of the project’s role in two different water basins are unique, but it has one thing in common with others: its owners are disinclined to pay environmental debts. “There’s the broader context of what’s going on in electricity markets,” said an energy consultant who would not speak for attribution. “With historically low wholesale energy prices, utilities, not surprisingly, will operate their lowest-cost units. Particularly if you have old infrastructure.”

But a new reality is emerging. Climate change puts a different perspective on the future of some small projects: states like California mandate a largely, or entirely carbon-free electric portfolio 25 years hence. “Resources that are 100 percent renewable are the new black,” he said. “That creates an opportunity for resources that have been ugly ducklings.” Todd Olson, a spokesman for PacifiCorp, which relicensed the Wallowa dam in 2017, said, “We went through the whole analysis many times over. We ultimately kept it because it is renewable, and there are other community values.”

Residents of Lake, Mendocino, and Sonoma Counties feel the Potter Valley project is crucial to them. “We’re talking about legacies now,” said Fuller of the fisheries service. “This project has been going on so long, cultures, families and generations are built around it. Say the project goes away: life is going to change for people.”

Data doesn’t yet show a clear trend of small hydropower projects’ owners walking away from them, although Mr. Bodington did say, “The trend is more getting taken down than put up.” Dozens of licenses are due for renewal in the next decade. Studies begin years before a license expires; the Potter Valley project’s license expires in 2022.

Whether or not Scott Dam is removed, and whether or not that decision is part of a wider trend, Mr. Huffman does see attitudes on dam removal changing. “Each time there’s a successful dam removal, it is demystified a little bit,” he said. “You should naturally see things get little bit easier, where dam removal makes sense going forward. But it’s always going to be case by case.”

This report first appeared in the … & the West Blog on March 5, 2019. Find the original article here.