The Texas-based startup Quidnet Energy just completed a test showing it can store energy for up to six months by pumping water underground. Using water to store electricity is hardly a new concept-pumped hydropower storage has been around for over a century. But the company hopes its twist on the technology could help bring cheap,...

This is today's edition ofThe Download,our weekday newsletter that provides a daily dose of what's going on in the world of technology. This startup wants to use the Earth as a massive battery Texas-based startup Quidnet Energy just completed a test showing it can store energy for up to six months by pumping water underground....