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New Cogen Power Plant to Deliver Increased Efficiency

By Dan McGuire

MIT's new cogeneration plant became operational Sept. 11 after two-and-a-half years of construction and upgrades. The new plant is an effort by MIT to economize its power generation and transfer facilities.

"The idea behind the whole project was to upgrade our plant and provide a more stable pricing structure," said Superintendent of Utilities Roger Moore.

The cost of construction of the $37-million plant, which includes a campus-wide upgrade of building connections and a new gas main, will be paid for in six years, aided by savings from lower energy costs.

In cogeneration, the combustion exhaust gases created by electricity-producing turbines are then used to heat steam for other energy resources

The plant will make a significant contribution for cleaner air, according to a Physical Plant report. It is 18 percent more efficient than generating electricity and steam independently.

The plant also has systems that reduce the emissions of sulfur dioxide, carbon monoxide, and other pollutants by 45 percent.

Much of the reduction comes from a switch in the fuel used. The previously oil-fired boilers will now run on gasoline. "Gas is a friendlier sort of fuel," Moore said.

Upgrades accompany installation

The entire electrical system, parts of which were 40 to 45 years old, were rebuilt as part of the project. The new plant also required the installation of a larger gas pipeline.

The cogeneration plant uses a combustion turbine to produce heat and power.

The new turbine is "essentially a jet engine fitted with a power turbine that connects to an electric generator," Moore said. The plant recovers the heat energy of the turbine by directing the exhaust gasses through a heat recovery steam generator that heats the water to 440F (227C).

The generator can generate 100,000 pounds of steam an hour at 200 pounds per square inch, Moore said. On the coldest days, the plant can produce an additional 70,000 pounds of steam an hour with additional firing.