The effect that fossil fuels are having on the climate emergency is driving an international push to use low-carbon sources of energy. At the moment, the best options for producing low-carbon energy on a large scale are wind and solar power. But despite improvements over the last few years to both their performance and cost, a significant problem remains: the wind doesn’t always blow, and the sun doesn’t always shine. A power grid that relies on these fluctuating sources struggles to constantly match supply and demand, and so renewable energy sometimes goes to waste because it’s not produced when needed.
