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Combined Heat and Power


Swampscott High School, built in 2006, uses hot water to heat their school buildings and a Senior Center. With an annual 7,000 MMBtu hot water demand and a good spark spread (ratio of electricity to gas price), this was a good candidate for Combined Heat and Power (CHP).


Groom Energy engineers evaluated a natural-gas engine driven CHP system that produces 510,000 Btu/hr of hot water and 75 kW of electrical power. The combined efficiency of the CHP system is 81%.The system generates about 760 Massachusetts Alternative Energy Credits (AECs) per year and, although the High School does not benefit from tax incentives, when combined with a great utility incentive, the CHP system has a 5-year payback.


Annual Energy Generated (kWh) 413,250
Annual Hot Water Generated 2,815
Installed Cost After Incentives $193,750
Payback (years) 5.04
IRR (10 years) 16.6%
NPV (10 years) $128,721

From the Blog

CHP – can you use the heat?