A well-designed fuel-cell system can use 90 percent of the energy in the fuel it consumes.

In 2007, Whole Foods market installed a 200-kilowatt phosphoric acid cell in a supermarket in Connecticut, where subsidies fund 25 to 40 percent of the cost of a fuel-cell system.

He said the Octagon would soon switch to a fuel cell system for heat and electricity, partly to cut energy costs at a time of a depressed rental market.