The sun does not always shine, and the wind does not always blow, so energy storage is key to getting the utility grid to rely more heavily on renewables.

But batteries are expensive. So one company is experimenting with storing energy in sand – because it’s cheap and readily available.

Jason Miller is engineering manager at Echogen Power Systems, a company that uses heat energy to generate power.

Building on its existing technologies, Echogen is developing a new system to convert electrical energy into heat, and then transfer that heat into large silos of sand or blocks of concrete.

Miller: “So we’re taking electricity from the grid to create a thermal reservoir or heat source. That heat source can then later be used as the energy input to a power cycle to generate electricity on demand.”

The company’s been awarded a $3 million federal grant to develop and test this approach.

Miller says the system would not be as efficient as lithium-ion batteries. But, because it relies on cheap materials, it could lower the cost of long-term energy storage.

And that could help utilities send solar power to the grid … even when the sun is not shining.

Reporting credit: Sarah Kennedy/ChavoBart Digital Media.