NEW YORK CITY-Out of the 16 million multifamily buildings throughout the US, only two of them have their own large capacity “green” fuel cells. The newest of the two is located at the Octagon on Roosevelt Island, a stone’s throw away from Manhattan. The luxury 500-unit LEED-certified rental building is now powered by a 400-kilowatt fuel cell, which was unveiled to the public at a ceremony on Thursday morning.

The cell, developed by architecture and development firm Becker + Becker and manufactured by United Technologies Power, provides 1.7 million btu/hour of heat for combined power and heat applications, in addition to 400kW of sustained power. The current largest residential fuel cell is located at 360 State St. in New Haven, CT.

Bruce Redman Becker, president of Becker + Becker, tells GlobeSt.com that the fuel cell works like a battery, but bigger. “It has electrochemical reactions,” Becker says. “They are fired by hydrogen, so there are three stages of the fuel cell,” he says, explaining that the first step involves forming the natural gas into hydrogen, then combining the hydrogen with oxygen to create electricity, heat and water.