What is your opinion of ground source heat pumps, do you think they have what it takes to make it mainstream in American homes? — Bryan Long, Port Hueneme, CAToday, geothermal heat pump (sometimes referred to as ground source, GeoExchange, earth-coupled, or water-source heat pump) installations are increasing by double digits. Before I answer your question specifically, let me tell you a little about geothermal heat pumps (GHPs) in general. GHPs represent one of three types of geothermal technology. The first is electricity production from high temperature resources; the second is “direct use,” which utilizes lower temperature resources for a number of applications, including home heating, aquaculture regulation, agriculture, and industrial purposes. The third use — GHP — is an electrically powered system that uses the earth’s relatively constant temperature to provide heating, cooling and hot water for homes and commercial buildings. GHP has been in use since the late 1940s. According to the Ground Source Heat Pump Association (GSHPA), GHPs circulate water or antifreeze solution through plastic pipes buried beneath the earth’s surface. During the winter, the fluid collects heat from the earth and carries it through the system and into the building. During the summer, the system reverses itself to cool the building by pulling heat from the building, carrying it through the system and placing it in the ground. This process creates free hot water in the summer and delivers substantial hot water savings in the winter. GHPs have definite mainstream potential. GHPs have the capability to be used anywhere in the country — and, in fact, they’re used in every U.S. state and several outside countries. Current data shows continued growth across all market sectors. Over the past few years, as oil and gas prices have soared, GHP sales have increased annually from 22 to upwards of 50 percent. Still, GHPs have significant untapped potential. The U.S. General Accounting Office estimates that if GHPs were installed nationwide, they could save several billion dollars in annual energy costs and substantially reduce pollution. Although GHP systems cost more upfront than conventional systems, investments can be recouped in as little as three years, according to GSHPA. In fact, GHPs are one of the most energy-efficient, environmentally clean, and cost-effective space conditioning systems available, according to the EPA. Geothermal heat pumps can reduce energy consumption — and corresponding emissions — up to 44 percent compared to air-source heat pumps and up to 72 percent compared to electric resistance heating with standard air-conditioning equipment. GHPs generate no on site emissions and have the lowest emissions among all heating and cooling technologies. Your decision to install a GHP is an environmentally conscious choice. The link below provides more information about GHP and the incentives available for installation. 26 states now offer incentives for geothermal heat pumps. Additionally, the federal government offers a $300 dollar incentive for heat pump installations. Stronger federal incentives to reduce the upfront cost to consumers and businesses, as well as support for improving information, training and related market development could help accelerate their deployment. Today, GHPs could be retrofitted to almost any house or school in the country. This would go a long way toward reducing pollution — every 100,000 homes with geothermal heat pump systems reduce foreign oil consumption by 2.15 million barrels annually and reduce electricity consumption by 799 million kilowatt hours annually. As people consider the long-term impacts of their choices — both environmentally and financially — I have no doubt that GHPs will become mainstream.