Duke University’s $25 million renovation of its East Campus steam plant included converting to natural gas boilers. For about 50 years, the plant’s coal-fired boilers supplied steam through underground pipes and tunnels to heat campus buildings until the plant closed in 1978. The new plant has 15 Miura LX series gas-fired steam boilers, which provide 35 percent more steam capacity to the campus, and will simultaneously reduce the University’s environmental footprint.

The gas boilers require less water and time to produce steam—and at lower emissions of greenhouse gases than coal. Instead of using lots of energy to fire up one to three large coal boilers, the plant can calibrate among 15 smaller gas boilers based on demand.

“We can have [the boilers] on cold standby and have them come on as necessary, which creates a significant reduction in the energy losses associated with a typical start-up, purge and warm-up cycle of a boiler,” said Russell Thompson, director of utilities and engineering for Duke Facilities Management.

At full capacity, the Miura boilers in the East Campus steam plant will provide Duke with a 110,000 lb.-per-hour base load year-round and up to about 130,000 lbs. during peak-need times.

Another benefit for the campus is that the boilers produce BHP outputs comparable to larger units, but with less water consumption and a more compact footprint. This enabled Duke to install the boilers in the steam plant without having to expand any part of the historic brick building.

“From a total production standpoint, we have gone from producing 95% of our steam with coal to producing 85% of our steam with natural gas,” Thompson said. That reduced coal usage translates to a reduction of 30,000 metric tons of CO2. “It is our first big step in our Climate Commitment Challenge to reduce our carbon footprint,” he added. The steam plant conversion is part of Duke’s overall goal to become a climate-neutral campus.