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Don’t blow off steam—microturbines make cheap, clean energy from waste heat
By Lindsay Audin

Distributed power holds promise for reducing peak loads and improving the security of the energy grid. But the usual solution, diesel generators, involves nuisances like fuel storage, fire-safety concerns, and emissions permits. Buildings served by utility or district steam systems, however, can take advantage of microturbines—devices that eliminate those problems while producing almost-free power.

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As the name implies, microturbines are small, taking up a footprint about a yard square. They don’t generate stand-alone power, but use waste heat from high-pressure or district steam systems to produce energy, in a process adapted from manufacturing facilities like pulp mills. They cut emissions of nitrous oxides and carbon dioxide by 50 percent or more compared to diesel-powered generators.

One company, Douglas Energy of California, has a grant from the Department of Energy to install prototype systems in cities with high electricity prices. The company’s 150-kW unit can handle the energy demands of a 200,000-square-foot commercial building in a moderate climate. At the Rolex Realty Building in New York City, the system feeds an absorption chiller that produces chilled water and requires no permits or emissions treatment. The company estimates its microturbines will last 20 years with regular maintenance.

More than 100 U.S. cities and many multibuilding facilities such as colleges are served by steam systems. With federal and state energy agencies offering grants to offset installation costs, microturbines could pave the way to a cleaner, energy-efficient future.