Hydrogen fuel cells have mainly been used to power vehicles so far, but they could soon find another use: the server farms powering your internet services. Daimler, HPE, Power Innovations and the National Renewable Energy Laboratory are expanding fuel cell use to "micro-grids" inside data centers. Solar and wind power would provide the bulk of the energy, but fuel cells would fill in the gap when power demand is too high or an outage leaves no other choice. Companies wouldn't have to rely quite so heavily on diesel generators or other not-so-eco-friendly backups to cope with demand. And unlike battery backups, there's no limit -- the fuel cell can keep running as long as there's hydrogen.