There are several more benefits of geothermal heating system listed by the U.S Department of Energy:
On average, geothermal heat pump system costs about $2,500 per ton of capacity, or roughly $7,500 for a 3-ton unit (typical residential size). In comparison, other systems would cost about $4,000 with air conditioning. When included in the mortgage, the homeowner has a positive cash flow from the beginning. For example, the extra $3,500 might add $30 per month to a monthly mortgage payment. The energy cost savings will easily exceed this added amount over the course of the year.
On a retrofit, geothermal energy's high efficiency typically means much lower utility bills, allowing the investment to be recouped in two to ten years. In addition, some utility companies have financing packages that make the purchase of a geothermal system even less expensive. Still others provide special rates for homes with geothermal systems.
Because they use fewer mechanical components, and because those components are sheltered from the elements, leaves, dirt, and possible vandalism, geothermal heat pumps are durable and highly reliable. The underground piping used in the system often has 25 - 50 years warranties, and the geothermal heat pumps typically last 20 years or more.
Geothermal heat pump systems have fewer maintenance requirements than most other systems. When properly installed, the underground components are virtually worry-free. The components in the living space are easily accessible, which increases the convenience factor and helps ensure that the upkeep is done on a timely basis.
Like typical forced-air furnace or central air-conditioning system, a geothermal system uses ductwork. A two-speed geothermal heat pump is so quiet inside a house that users do not know it is operating:there are no telltale blasts of cold or hot air, depending on whether it's the heating or cooling season. Geothermal heat pumps also improve humidity control naturally.
Geothermal heat pumps use no outside condensing units (as you get with conventional air conditioners), so there's no noise or humming to bother either you or your neighbors.