By LIZ GALST

The business for ground-source heat pumps is so hot that when some people driving in and around Seattle see Gerard Maloney’s EarthHeat van, with the company’s phone number on the side, they call from their cellphones. “Really, we have people doing this, Mr. Maloney said.
Like other energy alternatives, ground-source heat pumps have won new admirers as energy costs have skyrocketed. The pumps, also called geothermal heat pumps, use the relatively constant temperature just below the earth’s surface - two meters below, in many cases - to draw warm air into a building in winter and remove warm air in summer. Advocates say the systems can save building owners 25 percent to 65 percent on energy costs while reducing carbon dioxide emissions.
Around the United States, owners of the small businesses that constitute most of the $2.5 billion ground-source heat pump industry report that demand for their systems and services has surged.
“We started as many jobs by April of 2008 as we had done in all of 2007,” said Bruce Wollaber, president of Comfort Engineered Systems in Nolensville, Tennessee, a designer and installer of heat pump systems. Bill Beattie, coowner of Rockford Geothermal in Illinois, said, “If we stay on track, we’re probably going to grow by about 40 percent this year.”
All this comes while the industry is struggling to manage its growth; it has a goal of capturing 30 percent of the heating and air-conditioning market by 2030. System manufacturers have a backlog of orders, installers say. Trained workers are increasingly difficult to come by. Still, said Jim Bose, executive director of the International Ground Source Heat Pump Association, an industry and advocacy group, “it’s not a pipe dream. It can be done.”
The systems use a network of waterfilled pipes laid either horizontally (2 meters under) or vertically (often 60 to 90 meters down), that attach to a heat exchanger.
The technology can be used almost anywhere, on any type of building. “We’ve got them all the way from Texas to the Arctic Circle,” said Mr. Bose, a professor of engineering technology at Oklahoma State University in Stillwater.
And even without financial incentives from the government or energy utilities, says John Shonder of the Energy Department’s Oak Ridge National Laboratory in Tennessee, “ground-source heat pumps have the lowest life-cycle costs in several cost studies that I’ve done” of heating and air-conditioning systems. The systems pay for themselves in three to eight years, depending on “location and energy prices,” Mr. Shonder said.
The industry’s expansion is slowed by a lack of trained contractors.
“I’ve got drillers who are booked out for six months,” said Jack DiEnna, executive director of the Geothermal National and International Initiative, an industry group in Washington.