Power provided by the CHP system is three times more efficient than power generated by a central station, according to Ceres Power.
Over 37,000 units will be sold to British Gas for four years from 2011, with 20,000 going to Calor over a five-year period.
Dr Brian Count, chairman of Ceres, said: "We have secured a second major supply and distribution agreement and this additional contract helps further underpin our investment in the UK-based volume fuel cell manufacturing facility."
E.ON chief executive Paul Golby recently said that carbon capture technology was vital to helping the government meet its carbon emissions targets.
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