Connecticut boasts the largest concentration of fuel-cell companies in the United States, including leading fuel-cell manufacturers UTC Power, Proton OnSite and Fuel Cell Energy.

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Companies like long-term player Ballard Power Systems, Linde, UTC Power and Air Liquide (which has built 50 big hydrogen generators) have made this a big business.

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Mike Brown, an executive with UTC Power, a leading fuel-cell maker, said the fuel cells need to last at least four or five years for the technology to be competitive.

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Similarly, in Glastonbury, CT, a Whole Foods grocery store kept the coolers running during a power outage with its 200-kW fuel cell made by UTC Power, which dramatically reduced inventory losses resulting from food spoilage.

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