Natural-Gas Chiller Furthers Lab’s Pursuit of Environmental and Energy Savings

Aug. 1, 2011
Avoids electric demand charges, "time-of-day" rates

With a $15 million grant from Howard Hughes Medical Institute and a $10 million grant from Massachusetts Life Sciences Center, Marine Biological Laboratory (MBL) is incorporating energy-efficiency and renewable-energy features into Loeb Laboratory, one of 100 buildings MBL occupies in Woods Hole, Mass.

In 2010, a TECOCHILL STx natural-gas-engine-driven chiller provided by Tecogen was installed in a new rooftop mechanical room above the laboratory. The unit is the fifth Tecogen chiller installed on the 100-plus-acre campus since 1993.

"Before Tecogen, we never had a cooling system, just open windows and the ocean breeze, which is considered authentic Cape Cod air conditioning," Richard Cutler, PE, MBL's director of facilities, management, and projects, said. "But we knew it was time for an upgrade."

Initially, Cutler's team cooled laboratories using portable air-conditioning units and fans, which proved highly inefficient and presented mechanical problems.

Being located in such a remote area presented major logistical challenges, particularly because of constrained power availability during the peak summer months. It soon became clear cooling the laboratories with electricity was not a financially viable option.

"We were looking for a solution that would cut costs dramatically because after using window units, our monthly electric bills remained unacceptably high," Cutler said.

TECOCHILL allows MBL to reduce energy costs significantly by avoiding electricity demand charges during peak cooling season. It resembles an electric chiller in size, weight, and water-flow characteristics, but is able to cool substantial commercial buildings without significant electricity use.

Tecogen's technology is about twice as efficient as the other gas alternative, absorption chilling. It includes hardware required for heat recovery, two thermostatic control valves, and customer pipe connections. MBL is able to use engine waste heat for reheat dehumidification.

TECOCHILL operates at a higher efficiency than electric chillers because it eliminates two significant losses inherent in the generation of electric power: transmission and distribution losses and the wasteful discharge of low-grade heat at the power station. This results in about half of the carbon emissions of the power-plant/electric-chiller alternative.

One hundred percent of the cooling TECOCHILL provides is derived from natural gas, which has the lowest carbon emissions of all fossil fuels. Additionally, TECOCHILL uses R-134a refrigerant, which has 95-percent-reduced ozone-depleting potential.

Several years ago, a noise consultant measured the acoustics around the facility after neighboring homeowners complained about noise. The consultant recommended installation of more natural-gas-engine-driven chillers and fewer electric chillers to reduce noise and vibration, confirming that engine-driven chillers produce lower-frequency noise.

"The consultant described the sounds as a 'low rumbling noise,' which was ideal for us," Cutler said. "We're very cautious with the facilities and try our best not to disturb anyone in the surrounding area."

While installation of a cooling system may not generate the same attention as a major biomedical breakthrough, facility modernization is as important as any project at MBL, Cutler said.

"A comfortable and controlled atmosphere contributes to the overall experience," Cutler said. "I worry about the buildings so the scientists can focus on their research."

Information and photographs courtesy of Tecogen.

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About the Author

Scott Arnold | Executive Editor

Described by a colleague as "a cyborg ... requir(ing) virtually no sleep, no time off, and bland nourishment that can be consumed while at his desk" who was sent "back from the future not to terminate anyone, but with the prime directive 'to edit dry technical copy' in order to save the world at a later date," Scott Arnold joined the editorial staff of HPAC Engineering in 1999. Prior to that, he worked as an editor for daily newspapers and a specialty-publications company. He has a bachelor's degree in journalism from Kent State University.