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|
|IRR (10 years)||16.6%|
|NPV (10 years)||$128,721|