(AP) — A renewable energy plant being commissioned in Oregon on Wednesday that combines solar power, wind power and massive batteries to store the energy generated there is the first utility-scale plant of its kind in North America.

Wind and solar are clean sources of power, but utilities have been forced to fill in gaps when the wind isn’t blowing and the sun isn’t shining with fossil fuels like coal or natural gas.

At the Oregon plant, massive lithium batteries will store up to 120 megawatt-hours of power generated by the 300-megawatt wind farms and 50-megawatt solar farm so it can be released to the electric grid on demand.

to combine integrated wind, solar and battery storage at such a large scale in one location, giving it even more flexibility to generate continuous output without relying on fossil fuels to fill in the gaps.

The project is “getting closer and closer to having something with a very stable output profile that we traditionally think of being what’s capable with a fuel-based generation power plant,” said Jason Burwen, vice president of energy storage at the American Clean Power Association, an advocacy group for the clean power industry.

Under the partnership, PGE owns one-third of the wind output and purchases all the facility’s power for its renewable energy portfolio.

The vast majority of such projects are solar power with battery storage, largely because of tax credits, but projects in the pipeline include offshore wind-plus-battery, hydroelectric-plus-battery and at least nine facilities like the one in Oregon that will combine solar, wind and storage.