When it comes to purely electric vehicles, hydrogen as an energy source has advantages over a solid-state battery in terms of weight and, above all, charging time. A vehicle can be refuelled with liquid hydrogen in the same way as with petrol or diesel. Since the late 1990s, BMW has been working hard on research into fuel cells, using them to provide the on-board power supply in a BMW 750iL (E32), supply energy to a retail outlet in The Hague in the Netherlands and power tug trains and forklift trucks at its plant in Leipzig.