Smith College Energy Center - 3.5-MW CHP Plant - Case Study
LOCATION: Northampton, MA
FACILITY PEAK LOAD: 3.5 megawatts (MW)
EQUIPMENT: 3.5 MW Solar Turbine, Rentech
HRSG, package boiler and two York
FUEL: Natural Gas
USE OF THERMAL ENERGY: Heating, cooling &
hot water for the campus.
USE OF ELECTRICAL ENERGY: Displaces
campus loads previously supplied by the
AVERAGE CAPACITY FACTOR: 75 %
CHP IN OPERATION SINCE: September 2008
The Smith College Cogeneration Plant has been in operation since 2008 and is housed in the existing central power plant originally constructed in 1946. Its power process systems include a Solar Centaur® 40 combustion gas turbine, a Rentech heat recovery steam generator (HRSG), a 65,000‐lb/hr low‐emissions packaged boiler, control room and auxiliary equipment. The HRSG utilizes the exhaust heat from the gas turbine to produce steam for heating in the winter and also to power steam absorption chillers, which supply the campus with chilled water. Two existing 55,000‐lb/hr, oil/gas‐fired, packaged Keystone boilers, provide backup and additional steam capacity to meet campus demand. A 10‐inch main steam transmission line connects the plant to the 110 buildings on campus through 5 miles of underground piping. When the gas turbine is generating power at its full 3.5 MW capacity, the HRSG is capable of producing 20,000 lb/hr of 125 psig steam.
Reasons for Installing CHP
The energy requirements of Ford Hall, a new science and engineering facility, stimulated the rethinking of the existing power plant. It was determined that steam production could be increased and accomplished more cost‐effectively through a combustion turbine based CHP system.
CHP Equipment Configuration & Operation
Prior to 1946, each building on campus was individually heated with coal. In 1946, the central campus heating plant was installed equipped with three 40,000‐lb/hr, Edge Moor boilers designed to burn pulverized coal and oil. Two 55,000‐lb/hr, oil/gas‐fired, Keystone packaged boilers were added in the 1970s to accommodate the campus’s growth. In 2005, to allow installation of the new CHP system, a mechanical dust collector was demolished, along with Smith’s 1940s‐vintage coalcapable boilers and coal and ash handling equipment. The turbine has the capability to operate on low sulfur distillate as a backup, but Smith College has chosen not to utilize that alternate fuel source at this time. Two York absorption steam chillers were added in the spring of 2010, replacing 1,000 tons of cooling capacity previously provided by electric chillers. During 2010, the CHP plant produced 210 million lbs of steam and over 8,000,000 kWh of electrical power to supply nearly 3 million gross square feet of building space.