About 10% of electricity in the U.S. is created by moving water, or hydropower, according to the U.S. Department of Energy’s Hydropower Vision report, which also found great potential in improving hydropower systems to meet more U.S. energy needs. Now the DOE is investing about $7.5 million into research projects to improve hydropower and reduce electricity costs for consumers.

Part of that investment includes a $999,554 grant to a Missouri S&T research team to improve and evaluate better models for pumped storage hydropower (PSH) — a subset of hydropower that uses water storage in reservoirs to generate energy.

“A pumped storage hydro plant is a special plant that can both generate electricity and consume electricity,” says Rui Bo, the principal investigator on the grant and an assistant professor of electrical and computer engineering.

A PSH plant uses two water reservoirs at different elevations to generate power as the water descends through a turbine. To generate energy continuously, the plant pumps water from the lower reservoir to the upper reservoir and the cycle starts again. The Taum Sauk Energy Center near Lesterville, Mo., is one example of a PSH plant. It is operated by St. Louis-based Ameren, one of the industry partners on this project.

“It may sound odd to use energy to pump the water up and then you’re using the water to generate energy again,” says Bo. “But the reservoirs serve different purposes at different times.”

The process works like a rechargeable battery — storing and expending power when needed, Bo says. 

“You want to generate power when the system is in need of more energy and the price is higher,” Bo explains. “When you pump water, you choose the time when the energy demand or load is low and the price is low.”  

Bo says when operated efficiently, the cycle makes sense economically.

“Hydro plants are also very flexible,” he says. “They can adjust the amount of electricity they generate really quickly. In contrast, a coal-fired power plant involves a complex thermal process that is not as fast.”

Other renewable energies, such as wind and solar, are intermittent resources that depend on the weather to generate energy. The result is that other conventional electricity generation must adjust up and down accordingly to compensate.

PSH plants can help the system deal with this issue to integrate renewables.

“The PSH plants don’t emit air pollutants when generating power, and they can enable the use of more renewable energy. That makes it possible to reduce emissions. It can also defer investment in generation and transmission,” says Bo. “If we don’t operate PSH plants efficiently, we would need other generators to compensate for that.”

Missouri S&T is joining with system operators, research institutions and industry leaders to test new PSH models in real-world conditions. 

“We will use real data to generate real benefits to consumers. If this project is successful, it has the potential to be applied in energy markets across the U.S.,” says Bo.