"A heat pump
just moves heat," said Conn Abnee, executive director of the Geothermal
Heat Pump Consortium, a national advocacy group. "It doesn't generate
heat."
During the summer,
refrigerants in the heat pumps pick up warmth from the air and put
it into the water, which travels through the system and back down
the well to the aquifer.
All of this
happens automatically, depending on the air temperature and the unit's
temperature setting.
"That heat pump
really never knows what the temperature is outdoors," Abnee said.
"It thinks the temperature year-round is 50 degrees."
The heat pumps
and well pumps need electricity to run, but are much more fuel efficient
than other forms of heating and cooling because they have the temperature
boost from the tepid water. It's not an oil or electric heat system,
trying to raise sub-freezing winter air to a comfortable temperature
from scratch.
Maine Air Conditioning
estimates that its previous geothermal projects average between 65
cents and $1.07 per square foot in energy costs, which includes heat,
lights, ventilation and so forth. That's half the likely cost for
a non-geothermal project, Martin said.Geothermal heating itself is
not new. People have been using warm water from the earth as a heat
source, in geologically select regions, for 10,000 years. And heat
pumps that extract warmth from even tepid water have been available
for decades.
Today, there
are about 400,000 geothermal systems being used nationwide, Abnee
said. Unit sales are growing at a 23 percent annual rate to an estimated
68,000 in 1998.
Still, the technique
is rare, when viewed in the context of the overall market for heating
and cooling systems. It represents less than 1 percent of all installed
systems nationwide, Abnee said.
In Maine, geothermal
is at least that rare. Oil dominates the heating market, followed
by gas and propane. Alternative energy systems of all types represent
only a tiny splinter of the total market, state officials said.
