In one of the ways water and energy are married, hydroelectric power typically works by harnessing the energy of running or falling water to spin turbines to run generators that make electricity. Additionally, a powerful form of grid energy storage occurs when hydroelectric plants have reservoirs at different elevations. At times of low electricity demand, the excess electricity can be used to pump water back to a higher reservoir. The plant can make use of gravity again, directing the water through the turbines when demand goes up.
Mary Ann Capeheart, University of Arizona Water Resources Research Center Graduate Outreach Assistant, writes about the impact of drought in the western states on energy production (Drought Diminishes Hydropower Capacity in Western U.S.)
Hydropower production is taking a hit in river basins in the U.S. West, where prolonged drought has reduced water volumes available for power production. The generation of hydroelectricity depends on the funneling of large quantities of water from elevated heights through power plants typically found inside dam structures. When the water levels at lakes and reservoirs held back by these dams drop below benchmark elevations, the force of water pressure needed to turn the blades of hydro turbines is lessened, affecting productivity. As a result, electricity production on these dams has been curtailed or even discontinued.
Hydropower represents 19 percent of total electricity produced globally. It is one of the cleanest forms of energy production and the most widely-used renewable source of energy in the world. It is also one of the cheapest forms of energy, outside of the considerable initial costs of dam infrastructure, which are primarily government financed. The United States is one of the largest producers of hydroelectricity, along with China, Canada, and Brazil.
Capeheart discusses reduced electricity production at various points on the Colorado River, explaining, “There are more than 53 dams on the Colorado River and its tributaries. Twelve of these produce hydropower.” Details may be found at the link above.
Wind and solar production may be on the rise, but reliance on these is not foolproof, for various reasons, one of which has to do with water shortages. A Southern California Edison facility that has been using pumped hydro to store excess energy from wind and solar is at a loss this year. A Los Angeles Times article from Saturday (“How Edison Uses Water to Store Excess Power”) talks about the John S. Easton power station, formerly a thriving part of SCE’s portfolio.
The Easton plant came online over 100 years ago. Recently—with the rise of large wind farms and solar arrays, plus residential rooftop solar—those charged with maintaining grid stability are struggling at times. “Just as insufficient electricity causes problems—power reductions and blackouts—too many electrons can damage the power grid and anything connected to it,” the article says. But a way to stockpile excess wind and solar energy in the region was found: use the excess power to run Easton’s turbines in reverse, pumping the water back up to a mountain reservoir.
Four years of drought, however, have greatly depleted the primary source water of the system, a man-made lake called Shaver Lake, bringing both power generation and storage to a halt.
Below is an excerpt of the LA Times article describing the Eastwood plant when it is functioning, and the current predicament.
Eastwood and its eight sister hydropower plants at the Big Creek system have been an important part of Edison’s shrinking electricity generation fleet. (The other units produce electricity but don’t provide storage.)
Buried 1,000 feet in granite rock, Eastwood is an engineering marvel, built in these mountains from 1983 to 1987, about a 90-minute drive east of Fresno. Some 89 Edison employees keep the Big Creek system running in this town of 200 residents.
The heart of the $277-million Eastwood power plant lies behind a towering security gate. The trip down a long cave to the turbine that spins 200 feet beneath Shaver Lake feels like a scene from “Journey to the Center of the Earth.”
At the end of the trip is the generator, surrounded by a trough where water flows, causing the turbine to spin. The ability to recycle water through the pump station is what has made it such an attractive concept.
“That’s the nice thing about hydro,” Preheim said. “You can use it over and over and over.”
Edison began to draw water to feed the first of Big Creek’s nine power houses about 100 years ago. The first power lines—then the world’s longest—reached Los Angeles from Big Creek in 1913
“Most technologies don’t last 100 years,” Preheim said.
At one time, Big Creek served as Edison’s third-largest source of electricity generation, behind the San Onofre nuclear plant and Mohave coal power station. Big Creek has outlived them both.
Now, second to Edison’s 1,054-megawatt Mountainview natural gas plant, Big Creek accounts for 5% of the utility’s electricity generation.
Unlike natural gas and nuclear plants, Eastwood and other hydro facilities can ramp up in as little as six minutes.
“Hydro is a very important resource,” said Andrew McMillan, Big Creek’s manager of dispatch operations. “We’re a life boat.”
But hydro is vulnerable to the vagaries of Mother Nature.
“The water level,” McMillan said of Big Creek’s lakes, “is down 33.7 feet.”
That adds another wrinkle to the complexity of a state electricity system that already is facing unprecedented change. State regulators were warned in late July that managing wind and solar power will soon get much more complicated.