Geothermal heat pumps. Emerging giant?

The geothermal heat pump (GHP) is the ideal heating/cooling system for the 1990s with benefits for the consumer, the utility, and the environment. Although the GHP capital cost is comparable to the new high-efficiency air source heat pumps, GHPs use less energy thereby offering homeowners and building operators lower lifecycle costs. The utility benefits by better load balance, thereby reducing need for new capacity; the consumer benefits by reduced utility bills and fewer brownouts; and the nation benefits by lower energy consumption, lower power costs for industry, and fewer adverse environmental impacts. GHPs consist of two major types. One type, the earth-coupled GHP, uses sealed horizontal or vertical pipes as heat exchangers through which water is circulated to transfer heat. The second type, the water-source GHP, pumps water from a well or pond through the GHP, returning it to an injection well, a pond, or a stream for disposal. Because of their simplicity, earth-coupled systems have come to dominate the GHP market.