London is going all in with sustainable energy. The world's largest solar-powered bridge — spanning the River Thames — was unveiled Wednesday (Jan. 22) in the British metropolis.

The roof of Blackfriars Bridge, a Victorian-era road and foot-traffic bridge in central London, was covered with 4,400 solar panels, as part of a five-year project to help cut emissions from the Blackfriars railway station on the bridge's northern bank, reported The Guardian. The solar panels are expected to provide up to half of the energy needed to power the busy railway station, said officials from First Capital Connect, which runs Blackfriars station.

"Electric trains are already the greenest form of public transport — this roof gives our passengers an even more sustainable journey," David Statham, managing director of First Capital Connect, told The Guardian. "The distinctive roof has also turned our station into an iconic landmark visible for miles along the River Thames."

Follow Denise Chow on Twitter @denisechow. Follow LiveScience @livescience, Facebook & Google+.