Today, we rely heavily on an electricity supply to power many applications, including very important transport and emergency systems. There are several off-grid work situations that require electricity and sometimes situations arise, such as natural disasters, when the grid electricity supply fails. In some cases this can be catastrophic and back up power is a necessity of emergency planning. Back up power can be provided at a range of scales, but conventional solutions cause substantial atmospheric emissions (eg. diesel generators). Hydrogen can be used with fuel cells to provide a zero-emission electricity source which can start up within seconds and has the added benefit of being silent.