Danbury-based FuelCell Energy has reached a clean power generation milestone with a total of more than 8 million megawatt hours having been generated by SureSource fuel cell power plants globally since the first commercial installation.  The plants are operating on three continents.  According to the U.S. Environmental Protection Agency, 8 million megawatt hours of clean energy production is enough to offset about 13 billion pounds of carbon dioxide emissions.  The EPA says it's also adequate to power over 725,000 average size U-S homes for one year, 1.8 million German homes for one year or 2.235 million South Korean homes for one year.