Revolutionizing Hydropower with Battery Technology for Greater Grid Stability

In a recent study published in Renewable and Sustainable Energy Reviews, scientists from Idaho National Laboratory explored the advantages of hydro-hybrids. They received support from the Department of Energy's Water Power Technologies Office.

Utility-scale batteries could transform the way renewable energy is used. Combined with solar and wind power, these batteries can store excess energy during periods of high production and low demand, making it available when demand increases.

Hydropower currently accounts for 29 % of renewable energy in the U.S., but the benefits and profitability of integrating utility-scale batteries with hydropower, known as hydro-hybrids, have not been thoroughly studied, though there is interest from renewable energy companies.

There are a lot of environmental constraints and procedures that go into building a new dam. Hydropower is not growing as quickly as wind and solar, and most of the hydropower studies are about expanding existing infrastructure. We believe coupling battery storage with hydroelectric plants should be studied more because water is so important, and we want to use it sustainably. Adding batteries helps with that.

Venkat Durvasulu, Power Systems Engineer, Idaho National Laboratory

Advantages of Hydro-Hybrids

Batteries offer all kinds of benefits like reduced cost of maintenance, increased production, and investment and production tax benefits.

Hill Balliet, Power Systems Engineer and Study Contributor, Idaho National Laboratory

One advantage of hydro-hybrids over solar and wind energy is their predictability. Solar power operators cannot control the amount of sunlight reaching their panels; for example, output can drop by as much as 70 % on cloudy days. In contrast, operators of hydroelectric plants can regulate their energy output, especially when they have access to reservoirs.

With solar and wind, you are tied to the forecast, which is not always predictable. With hydropower, it is possible to calculate a few days out roughly how much water will be coming downstream, and hydropower owners can get a good idea of how much power they can generate.

Venkat Durvasulu, Power Systems Engineer, Idaho National Laboratory

Hydropower's predictability, combined with utility-scale batteries, can enhance the use of the plant's interconnection headroom, increasing the profitability and grid benefits of hydro-hybrids. Headroom refers to the gap between a power plant's output and the capacity of its grid connection. Operating within this headroom helps avoid costly regulatory reviews and connection upgrades.

Balliet said, “Hydro-hybrids store excess power when headroom goes down and put more into the grid when it goes up. Not only that, but adding batteries can make relicensing much easier.”

The ability of hydro-hybrids to restore a grid following a blackout is another significant benefit.

“If you add a battery to a hydropower plant, you can start up from a blackout and supply power to critical services, like police, fire stations, and hospitals, which is not feasible with solar and wind,” Balliet said.

Impact Considerations

Hydropower plant operators must consider the needs of all downstream users, including local wildlife, indigenous communities, other hydropower facilities, and people who rely on the water for irrigation, drinking, or recreation.

Durvasulu said, “Rivers are essential to life and are associated with the heritage of many indigenous populations. Federal agencies need to ensure the river ecology is preserved. If not properly maintained, hydropower plants can affect the oxygen content and temperature of water downstream, which can contribute to ecological damage.”

Meeting these environmental and community requirements can be expensive for hydropower operators, often accounting for 5 % to 10 % of electricity costs. By installing utility-scale batteries, operators can offset some of this expense. Batteries charged during periods of low demand can help maintain power supply to the grid when the river's flow cannot be fully utilized during peak demand.

“Batteries add a level of flexibility that can help hydropower operators meet the needs of all the various groups that rely on water,” Balliet said.

Barriers to Research

Current models for hydro-hybrid research often overlook key savings, such as reduced maintenance costs, decreased wear and tear, grid stability, voltage regulation, production tax credits, and carbon credits, which pose a significant challenge.

To address this, Durvasulu, Balliet, and their colleagues developed "Hydro + Storage Sizing," an online tool that helps estimate the profitability of different battery sizes while factoring in these savings.

Balliet said, “There are other untapped values and opportunities, too. More jobs, improved load-carrying capacity, lower operational and environmental costs, better water management, and greater profits.”

Without tools like this, decisions regarding hydropower hybridization are likely to remain one-time evaluations, missing opportunities to increase the value of hydropower for facility owners, the grid, stakeholders, and the environment.

“At the end of the day, it is about the ecology and management of water. You have to make money to stay in business, but you have to balance that with all the other living things that rely on the water, and batteries help with that. We want to ignite that idea; it is important to think about those kinds of things,” Durvasulu said.

Journal Reference:

Durvasulu, V., et al. (2024) Rationale for adding batteries to hydropower plants and tradeoffs in hybrid system operation: A review. Renewable and Sustainable Energy Reviews. doi.org/10.1016/j.rser.2024.114673.