A Finnish startup company named Polar Night Energy worked with a local utility to pioneer something that did not exist anywhere else in the world until now -- a giant sand battery. It is what it sounds like: a tower filled with 100 tons of sand, designed to be super-heated with renewable electricity which can then store heat for months. Power generated during the summer could be used later to heat homes in the winter. The main purpose of the design "is to be enable the upscaling of solar and wind," said Markku Ylonen, cofounder and CTO of the startup. This will help address mismatch between production and demand for renewable energy. Though the technology is patented, all of the parts are available off-the-shelf from manufacturers, so it’s possible to grow quickly. "Finland has to be the proving ground, since we’re building a physical product. But we want to spread the technology around the world as fast as possible." Said Ylonen.