Hundreds of condominium units heated and cooled by geothermal power have recently hit the market in New England, heralding the wholesale arrival of the "green" alternative energy system in this area.

A Case in Point

Most prominent among the new developments is Monarch on the Merrimack, a 600-unit loft conversion of an old mill in Lawrence, Massachusetts. The project is being undertaken by MassInnovations, LLC, of Fitchburg, Massachusetts.

Units at the condominium will be heated and cooled by water that is drawn from 20 wells that were drilled hundreds of feet down to tap the Earth's renewable heat.

In the wintertime, the groundwater, which remains at a consistent temperature of between 50 and 55 degrees, is passed through a heat pump, which works like a refrigerator except in reverse, extracting heat from the water and gently elevating the room temperature in the living areas. In the summer, the heat pump switches modes, pulling warmth from the condominium and transferring it to the circulating water, which is then sent back underground. Because no water is ever used by the geothermal system—it is drawn up and returned at an equal rate—there is no danger of the well ever running dry.

The cost to run a geothermal system is projected to be 25 to 40 percent less than the costs of conventional heating and cooling, or about $50 a month for a 1,200-square-foot unit. In addition, geothermal heat is much safer and cleaner than conventional sources of heat. A heat pump is powered by electricity, so there is no onsite combustion of fossil fuels and no storage of fuels on site, and, as a result of these two differences, much cleaner air in the building and on the property.