Danbury based FuelCell Energy , Inc., a leader in the design, manufacture, operation and service of ultra-clean, efficient and reliable fuel cell power plants, announced a significant industry milestone by generating four billion kilowatt hours of virtually pollutant-free electricity from the global fleet of Direct FuelCell power plants since the first commercial installation in 2003. Adequate to power more than 362,000 average U.S. homes for one year, this power was efficiently produced by fuel cells electrochemically, quietly emitting water vapor rather than pollutants.