What are so-called ‘water batteries’?

Answer: Secondary reservoirs that supplement other renewable energy sources.

October 17, 2022 • Government Technology News Staff

One of solar energy’s biggest drawbacks is that we only get it when the sun is up, unless we have ways to store what we don’t use to tap into when the sun goes down. One way to do this is to turn water into batteries … of sorts.

The San Diego County Water Authority has proposed a project that would use the San Vicente Reservoir to make these water batteries. By building a smaller upper reservoir connected to the main one, the city of San Diego would be able to store 4,000 megawatts of energy per day. That’s enough to light up 135,000 homes when it gets dark and there’s no more solar power to draw on.

“During off-peak periods — when power is inexpensive and renewable supplies from wind and solar facilities exceed demand — turbines will pump water to the upper reservoir where it will act as a battery of stored potential energy,” according to the authority’s website. Then when the energy is needed, it will be discharged to flow downhill, through turbines, and back into the main reservoir, meaning no water will be wasted in the process.

‘Water batteries’ could store solar and wind power for when it’s needed

The San Diego County Water Authority has an unusual plan to use the city’s scenic San Vicente Reservoir to store solar power so it’s available after sunset. The project, and others like it, could help unlock America’s clean energy future.

Perhaps a decade from now, if all goes smoothly, large underground pipes will connect this lake to a new reservoir, a much smaller one, built in a nearby canyon about 1100 feet higher in elevation. When the sun is high in the sky, California’s abundant solar power will pump water into that upper reservoir.

It’s a way to store the electricity. When the sun goes down and solar power disappears, operators would open a valve and the force of 8 million tons of water, falling back downhill through those same pipes, would drive turbines capable of generating 500 megawatts of electricity for up to eight hours. That’s enough to power 130,000 typical homes.

Neena Kuzmich, deputy director of engineering for the San Diego County Water Authority, has been working on plans for pumped energy storage at the San Vicente reservoir. Dan Charles for NPR

“It’s a water battery!” says Neena Kuzmich, Deputy Director of Engineering for the water authority. She says energy storage facilities like these will be increasingly vital as California starts to rely more on energy from wind and solar, which produce electricity on their own schedules, unbothered by the demands of consumers.

Californians learned this during a heat wave this past summer. “Everybody in the state of California, I believe, got a text message at 5:30 in the evening to turn off their appliances,” Kuzmich says. The sun was going down, solar generation was disappearing, and the remaining power plants, many of them burning gas, couldn’t keep up with demand. The alert worked; People stopped using so much power, and the grid survived.

Yet earlier on that same day, there was so much solar power available that the grid couldn’t take it all. Grid operators “curtailed,” or turned away, more than 2000 megawatt hours of electricity that solar generators could have delivered, enough to power a small city. That electricity was wasted, and there was no way to store it for later, when grid operators desperately needed it.

“We have a problem if we’re going to have these continuous heat waves,” Kuzmich says. “We need a facility to store energy so that we don’t need to turn off our appliances.”

Pumped hydro has a history

The technology that San Diego is proposing, called pumped hydro energy storage, is already operating at more than 40 sites in the United States. Some of the largest ones, which can generate more than 1000 MW for up to eight hours, were built during the 1970s and 1980s to store electricity that nuclear power plants generated during the night. But few new plants have been built over the past 30 years in the U.S. China has continued to build such plants.

One of the reservoirs of the Huanggou pumped storage hydropower station, in Hailin, in northeast China’s Heilongjiang Province on June 29, 2022. The power station has a generating capacity of 1200 megawatts. Wang Jianwei/Xinhua News Agency/Getty Ima

Now, the need to store power from renewable sources is reviving interest in this old technology in the U.S.

“Just in the past several years, 92 new projects have come into the development pipeline,” says Malcolm Woolf, president and CEO of the National Hydropower Association. Most of the projects, however, are in the planning stages and still need regulatory approval and financing.

Thanks to the climate bill that President Biden signed in August, these projects now qualify for the same 30 percent tax credit that solar and wind projects enjoy. “That is an absolute game-changer,” Woolf says. “A number of these projects that have been in the pipeline for a number of years now suddenly are a whole lot more bankable.”

Water batteries have a lot of competitors, when it comes to storing energy. Some companies, including the car company GM, are exploring ways for the electric grid to draw emergency power from the batteries in millions of privately owned electric cars. Others are working on ways to store electricity by compressing air or making hydrogen. Still others are focused on ways to manage the demand for electricity, rather than the supply. Electric water heaters, for instance, could be remotely controlled to run when electricity is plentiful and shut down when it’s scarce.

Pumping water, however, has some advantages. It’s a proven way to store massive amounts of power. The San Vicente project would store roughly as much electricity as the batteries in 50,000 of Tesla’s long range Model 3 cars. Water batteries also don’t require hard-to-find battery materials like cobalt and lithium, and the plants can keep working for more than a century.

Sign at the upper reservoir construction area gives details of Public Service Company’s Cabin Creek Pumped Storage project, a hydroelectric power installation at an elevation above 10,000 feet near Georgetown, Colorado on April 22, 1965. Denver Post/Getty Images

The biggest problem with them, at least according to some, is that it’s hard to find places to build them. They need large amounts of water, topography that allows construction of a lower and higher reservoir, and regulatory permission to disturb the landscape.

Woolf, however, says the perception of pumped hydro’s limited prospects “is a myth that I am working hard to disabuse folks of.” Pumped hydro facilities, he says, don’t have to be as massive as those of the past century, and they don’t need to disturb free-flowing streams and rivers. Many proposals are for “closed-loop” systems that use the same water over and over, moving it back and forth between two big ponds, one higher than the other, like sand in an hourglass.

Three of the proposed projects in the U.S. that appear closest to breaking ground, in Montana, Oregon, and southern California, all would operate as closed loops.

Kelly Catlett, director of hydropower reform at American Rivers, an environmental advocacy organization which has highlighted the environmental harm caused by dams, says that “there are good pumped storage projects, and there are not-so-good pumped storage projects.”

Her group won’t support projects that build new dams on streams and rivers, disrupting sensitive aquatic ecosystems. But San Diego’s plan, she says, “looks like something that we could potentially support” because it uses an existing reservoir and doesn’t disturb any flowing streams. Also, she says, “I’m unaware of any opposition by indigenous nations, which is another really important factor, as they have borne a lot of the impacts of hydropower development over the decades.”

The board of the San Diego County Water Authority, and San Diego’s city council, are expected to vote soon on whether to move ahead with a detailed engineering design of pumped hydro storage at the San Vicente reservoir. The state of California is chipping in $18 million. The design work, followed by regulatory approvals, financing, and actual construction, is likely to take a decade or more.

Water batteries could soon power 130,000 homes in San Diego at night time

The project is called pumped hydro energy storage.

Loukia Papadopoulos
Created: Oct 14, 2022 08:13 AM EST

The San Diego County Water Authority is planning to use its San Vicente Reservoir to store solar power making clean energy in the region viable, according to an article by NPR published on Friday.

Powering 130,000 homes

The project will take ten years to be built and will see large underground pipes connect San Vicente’s lake to a new reservoir about 1100 feet higher. California’s solar power will pump water into that upper reservoir, storing electricity.

At night, when solar power is unavailable, operators would open a valve releasing the force of 8 million tons of water and driving turbines capable of generating 500 megawatts of electricity for up to eight hours, enough to power 130,000 homes.

“It’s a water battery!” Neena Kuzmich, Deputy Director of Engineering for the water authority, told NPR. A type of battery that is set to be more common as energy systems switch to renewables.

During the day, especially in heat waves, California has so much solar power available that the grid can’t take it all. During the last heat wave, grid operators turned away more than 2000 megawatt hours of electricity. This was wasted electricity that could not be stored for night use where it was needed most.

“We have a problem if we’re going to have these continuous heat waves,” Kuzmich says. “We need a facility to store energy so that we don’t need to turn off our appliances.”

The technology that San Diego wants to install is called pumped hydro energy storage, and a few of these have been built over the past 30 years in the US. Now, there is renewed interest in them.

“Just in the past several years, 92 new projects have come into the development pipeline,” told NPR Malcolm Woolf, president, and CEO of the National Hydropower Association. However, most of them are just in the planning stages.

Qualifying for tax credits

Luckily, the climate bill President Biden signed in August ensures they now qualify for the same 30 percent tax credit from which solar and wind projects benefit. “That is an absolute game-changer,” Woolf says. “A number of these projects that have been in the pipeline for a number of years now suddenly are a whole lot more bankable.”

Even better, the technology has evolved to be more efficient and less disturbing to the natural environment in which it is built. Woolf says pumped hydro facilities don’t have to be as massive as those of the past century and don’t need to disturb free-flowing streams and rivers.

Even Kelly Catlett, director of hydropower reform at American Rivers, an environmental advocacy organization that has in the past warned about the environmental harm caused by dams, says that “there are good pumped storage projects” and that San Diego’s looks like one of them.

Catlett says, “Looks like something that we could potentially support. I’m unaware of any opposition by indigenous nations, which is another really important factor, as they have borne a lot of the impacts of hydropower development over the decades.”

Does that mean that San Diego will soon benefit from stored renewable energy? One can only hope!

‘Water Batteries’ Could Power 135,000 Homes in San Diego

Pumped storage hydropower could make solar and wind energy available for nighttime use and cloudy days.

By  Angely Mercado Published October 17, 2022

The San Diego Water Authority wants to keep the lights on, even when the Sun goes down. It plans to use San Vicente Reservoir to store solar power energy in so-called water batteries to maximize the city’s renewable energy potential, NPR reports.

Cities across California have an abundance of sunny days, which is perfect for providing renewable energy… as long as the Sun is up. The proposed project could store 4,000 megawatt-hours of energy per day, which could power 135,000 homes after the Sun goes down. To make this possible, the San Diego Water Authority would create a smaller upper reservoir just above the existing San Vicente Reservoir. These would be connected by a tunnel system and an underground powerhouse.

“During off-peak periods – when power is inexpensive and renewable supplies from wind and solar facilities exceed demand – turbines will pump water to the upper reservoir where it will act as a battery of stored potential energy,” the San Diego County Water Authority’s website explains.

During times of high energy usage in the area, the system would discharge energy that was stored in the water from the upper reservoir to flow downhill through the turbines. The exchange would be closed-loop system, which means it won’t consume water while putting energy into the local grid.

Systems like this are called pumped storage hydropower, and the principle is already in operation at sites all over the country, according to NPR. Many were built in the 1970s and 1980s to store nuclear energy. The new project would take up to a decade to approve, plan, and construct.

Power storage initiatives like this one could qualify for the 30% tax credit that wind and solar projects are also eligible for, which would motivate investment in more of these projects. There are several closed-loop energy storage projects proposed currently, like one in Oregon that could be completed by 2040 and power about 125,000 homes in the Pacific Northwest, according to the Swan Lake Energy Storage Project’s website.

California officials are hard-pressed to find solutions for the state’s strained grid. Extreme heat and a historic drought have made the state’s residents vulnerable to blackouts. The high temperatures and dry conditions have significantly lowered water levels in large water reservoirs around California, which has slashed the reservoirs’ ability to provide hydroelectric power. The heat was so bad this past September that Twitter’s data center in Sacramento failed.

State officials have pushed even harder for renewable energy sources this year. In April, California’s grid briefly ran on 97.6% renewable energy, breaking a previous record. And as of April, California was also the fourth-largest electricity provider in the country. Pumped storage hydropower projects could not only lower emissions for the state but also be a safety net for communities at risk of power outages.