Canadian company Hydrostor, which specializes in storing energy from renewable sources for later use, is opening its U.S. headquarters in downtown Denver.

The Toronto-based business announced the decision Wednesday. Tom Duckett, Hydrostor’s chief development officer, said the company plans to hire 20 more people this year, boosting the Denver staff to about 30.

The company employs roughly 100 people worldwide.

Hydrostor chose Denver as its U.S. base in part because of its industrial activity. Duckett said the company’s technology employs a lot of mining and conventional fossil fuel construction techniques while using power from renewable sources.

Mining and oil and gas have long been mainstays of the state’s economy. Colorado also has a growing renewable energy industry.

Duckett said the company’s strategy is to look at markets that have a growing renewable energy sector.

Denver’s other advantages are its central location and talent pool, Duckett said. Colorado is close to California, where Hydrostor is preparing to build a 500-megawatt energy-storage plant in Kern County, and to potential markets in Arizona and Nevada.

Hydrostor operates a plant in Ontario and expects to start construction next year of one in New South Wales in Australia. The company said it has another 15 projects in the pipeline. Duckett said a plant is planned in Colorado.

The ability to store excess power generated from wind and solar plants to use when the wind isn’t blowing and the sun isn’t shining is considered essential to expanding the use of renewables and reducing reliance on fossil fuels. The basic technology used to store compressed air underground as way to tap the energy later has been around for about 40 years.

However, unlike some models, Hydrostor’s proprietary technology doesn’t use fossil fuels in the process, Duckett said. The company said its method, which involves pumping water to store compressed air underground and water pressure to release it, doesn’t create emissions.

And unlike batteries that hold energy from renewable sources, Hydrostor’s plant has a lifespan of 50 years and can provide up to eight hours of electricity, Duckett said. The process is dubbed “long-duration” energy storage.

A 2023 paper written by staff members at the National Renewable Energy Laboratory in Golden said closed-loop pumped storage hydropower systems have the lowest potential of adding to the problem of climate change when looking at the full impacts of material and construction.

Hydrostor uses electricity from renewable sources to power compressors at a plant, producing heated compressed air that is stored above ground. A video on the company’s website shows how cooled compressed air is then pushed underground into a water-filled rock cavern. The air displaces the water, which is lifted to a reservoir on the surface.

When energy is needed, the process is reversed. Using gravity, the water on the surface flows into the cavern, pushing the air above ground. The air is reheated and spins turbines to generate electricity.

Duckett said the company uses existing technology, equipment and supply chains. “We just put it together in another way to have it be a clean, long-duration energy solution.”