A big wind turbine or array of solar panels is all very well, but you need to store the power you generate, else its wasted. Battery technology has barely advanced in the last century. The base standard is still lead-acid, but that may be about to change. A new Vanadium battery has been launched which might change the economics of renewable energy and off-grid living. VRB Power Systems makes large scale power storage units based on “flow” batteries.