Is Geothermal Worth the Price?
The rising cost of energy has given homeowners the opportunity to explore alternatives. Geothermal heat pumps are one available option. Even though geothermal heat pumps are expensive, their efficiency and reliability will provide a value capable of overcoming the high installation cost. The tremendous benefits this system provides will allow the recovery of the lofty cost.
Geothermal heat pumps differ from other heat pumps in that they use ground heat instead of extracting heat out of the air. This provides greater efficiency especially as the air temperature becomes very cold. “While many parts of the country experience seasonal temperature extremes – from scorching heat in the summer to sub-zero cold in the winter – a few feet below the earth’s surface the ground remains at a relatively constant temperature. Depending on latitude, ground temperatures range from 45°F (7°C) to 75°F (21°C). Like a cave, this ground temperature is warmer than the air above it during the winter and cooler than the air in the summer. This allows the system to reach fairly high efficiencies (300%-600%) on the coldest of winter nights, compared to 175%-250% for air-source heat pumps on cool days” (“Geothermal Heat,” 2011). With this capability the advantages become very favorable, which can significantly outweigh the additional cost.
According to The National Association of Home Builders (NAHB), “The initial cost of a geothermal heat pump system varies greatly according to local labor rates, lot geology and size . . . equipment costs can be 50-100% more expensive for a geothermal heat pump system…” (NAHB, 2001). These higher costs result from the required ground circulation loop, or source for the supply water. There are four different ways of achieving this: closed loop horizontal, closed loop vertical, closed loop in a lake or pond, and open loop. The open loop requires two wells drilled down into the ground. Water is drawn from one, with the energy removed and returned through the other. The closed horizontal and vertical loops require pipe buried underground to circulate the same water through and back after the energy is withdrawn. The lake or pond loop works the same way as the closed loop, except the circulation loop uses the body of water as heat sink.
The biggest advantage of geothermal heat pumps is their efficiency. For every dollar of energy used, three dollars of free energy is withdrawn from the ground. This is what makes the entire system so efficient. You are not actually using the purchased energy from a utility company to heat or cool. It is used to circulate and handle the renewable energy collected from the ground. This is accomplished through a circulation pump, a compressor, and a heat exchanger coil.
Reliability is another major advantage of geothermal heat pumps. With the pump, compressor and blower fan, the only moving parts, there is very little to go wrong. “System life is estimated at 25 years...