Considering cogeneration: clean power whose time has come ... back.

Author:Johnston, Marsha W.
Position:CURRENTS
 
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Behind the manicured lawns and spotless streets of the U.S. Marine Corps Recruiting Depot on San Diego Harbor rises a gleaming maze of pipes and towers. It's a 25-megawatt combined heat and power (CHP) electricity plant that recycles its exhaust.

At the entrance to the plant, Dave Hermanson, west coast general manager for EPCOR Operations, points across an open field to the sleek new terminal at San Diego International Airport and a slice of as-yet undeveloped Navy-owned coastline. "We're talking to the airport about their expansion," he says. "We've been looking for a better use for some of our excess steam capacity, and we could put in an absorption chiller to make cold water, run a pipe under the field and provide green air conditioning to the new terminal," he says. EPCOR is also offering this natural air conditioning, as well as clean electricity, to Nickelodeon. The network wants to build a resort on adjacent U.S. Navy land.

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The CHP plant is the smallest of three owned and operated in San Diego by EPCOR's company Primary Energy for the Marine Corps and the Navy. At all three, natural gas turbines drive electrical generators. The hot gas exhaust from those turbines goes to a heat recovery steam generator, providing 100 percent of the steam requirements (for heating and cooling) for the USMC Depot, San Diego Naval Station (Navasta) and North Island Naval Air Station. The steam generator also produces electricity.

Such CHP technology is also referred to as cogeneration or distributed generation and, increasingly, as "recycled energy." The principle is the same--convert unused energy waste streams from a given source, often fossil fuel, into electricity or useful thermal energy. Furthermore, do it locally to eliminate the energy loss from costly transmission. The result is little or no increase in fossil fuel consumption and significant cuts in carbon emissions.

The concept of making a fuel do double duty for greatest efficiency is not new. "District heating," circulating steam heat to multiple central city buildings from steam-generated electric power plants, has been used for decades in Europe. "Under Governor Jerry Brown [now the state's attorney general], California led the country in cogeneration," say Hermanson. "And that allowed consumers to build alternative energy projects, and the utilities had to buy the energy at the rate they would have spent to make it."

And state and local legislators are passing...

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