U.S. Marine Corps Air Station (USA)

United States Marine Corps Air Station, South Carolina, USA

Background

The U.S. Marine Corps Air Station in Beaufort, South Carolina, wanted to cut costs by using efficient cogeneration to meet its power needs and to reduce electrical usage during periods of maximum demand with a peak shaving strategy. It also needed a more reliable and efficient system than the plant’s set of 15 x 100 kW microturbines.

Solution

Jenbacher*, together with Trane as the main contractor, installed a containerized power plant solution—a 1 MW natural-gas fueled JMC 320 engine with hot water heat recovery from the engine cooling water and exhaust.

The project was part of a comprehensive energy savings performance contract (ESPC) involving energy efficiency and demand side management. The hot water heat recovery system on the engine supplies a 30,000-gallon hot water storage tank, which allows hot water demand to be decoupled from electricity production.

Dispatched for thermal load during the winter months, the system operates eight to twenty four hours per day, depending on weather conditions. In the summer, it operates only one to four hours per day to reduce peak electrical demand during the afternoon and early evening, when utility demand charges are the highest.

Results

In addition to supplying combined heat and power (CHP), the ESPC project also optimized the legacy district heating system by converting from a high temperature water circuit to a low temperature circuit, reducing line losses. It also simplified the district heating system, focusing just on the buildings with the largest and most consistent thermal loads on the base. Buildings with smaller thermal loads were decentralized with electric boilers and geothermal heat pumps.

Customer advantages

• Cost savings. The base estimates it is saving about $300,000 per year in energy costs. Two-thirds of that is attributed to demand charge savings, and one-third to thermal savings in fuel that the base offsets with the heat recovery from the engines.
• Flexible. The Jenbacher engine can withstand high ambient temperatures before deration, delivering the station a major benefit as hot summer days carry the highest electrical cost.
• Reliable. The new Jenbacher powered system delivers a high level of reliability when compared to the previous installation.