Although we have the ability to produce massive amounts of clean energy today, the problem is that we can’t store all of that power, which means it’s not always reliable.

And while lithium-ion batteries have started to meet some of the need for storage, the metals needed to make them are not plentiful enough for large-scale energy hoarding. So entrepreneurs around the world have been looking for alternatives.

Enter Hydrostor, a Canadian startup, that’s storing energy by injecting compressed air into deep underground caverns. The technology works by using excess electricity to run compressors and trap the pressurized air in a container. Physics dictates that, when compressed, a gas will heat up. Hydrostor captures this heat and stores it in insulated hot water tanks. The compressed gas is then injected into underground caverns as deep as 600 meters.

Then the process is reversed. When the company needs that energy back, it releases the compressed air, adds the stored heat, and runs the gas through air turbines to generate electricity.

The exciting news about Hydrostor is that it hasn’t only attracted financial support from the Canadian government, but has also caught the eye of a gas-and oil company, which sees great potential in the technology, to help it move away from the dirty fossil fuel sector.