The hydrogen fuel cell has the potential to power all electric engines. The fuel cell could replace the not so clean batteries in electric cars. Fuel cells can also power trains which would eliminate diesel-powered engines and/or the need to maintain expensive and not so efficient electrification networks. The German state of Schleswig-Holstein has now announced plans to run its entire 1,100 km (700m) railway network using fuel cell equipment by 2025. Japan and the UK have tested hydrogen-powered passenger trains and last year China saw the debut of a fully operational hydrogen-powered tram in Qingdao. Schleswig-Holstein plans that all propulsion hydrogen will come from renewable, zero-carbon sources, predominately wind.