Geothermal Growth Offers New Options For Underground Contractors

By Jeff Griffin, Senior Editor | November 2009 Vol. 64 No. 11
Astec has developed a special vertical drill designed specifically for the geothermal market.

A good case can be made that using the earth's natural energy storing capabilities is the most cost efficient and environmentally friendly way to heat and cool homes, businesses and institutional buildings.

Geothermal systems draw on the earth's relatively constant temperature to provide heating in the winter and cooling during warm months at operating costs that are substantially less than conventional systems with an ample supply of hot water as a bonus.

Basic components of a home geothermal system are an underground "loop" of HDPE pipe, indoor ground source heat pump (GHP) and a flow center to connect the loop to the heat pump. The system uses the earth's relatively constant temperature to heat or cool the building, then recirculates fluid through the loop. Commercial installations may require multiple loops and heat pumps, depending on the size of the structure.

The loops of pipe are a critical component of a geothermal system and their installation can be the most time consuming part of the process. In a typical residential system, a vertical loop is placed in the hole drilled by a small water well drill. If space permits, horizontal loops can be installed by trenching or horizontal directional drilling. Other options are lake loops and open loops (see box for details).

Geothermal heating and cooling technology has been available for years, but the higher initial cost of an installed geothermal system compared to conventional air conditioning and heating systems, combined with the relatively low cost of natural gas and electricity, have been primary factors that have discouraged widespread use of geothermal systems.

Market change
However, that has changed in recent years.

Escalating energy costs make geothermal systems a serious option for property owners, and proponents of geothermal technology believe its time finally has arrived in North America.

"Interest in geothermal heating and cooling is growing rapidly – everything we hear is upbeat," says Jim Bose, Ph.D., P.E, executive director of the International Ground Source Heat Pump Association (IGSHPA). "Ground source heat pump systems finally are mainstream and are capturing a growing share of the market."

Bose became involved early in development of geothermal heating and cooling technology, and was involved in the first installation at an Oklahoma State University laboratory. He has been a proponent ever since.

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