Heating, Cooling and HVAC

Renewable energy resources will be of increasing importance as we transition from finite fossil fuels to more sustainable alternatives. Although pre-dating solar and wind energy, geothermal has largely been overlooked as a technology for reducing carbon emissions and fossil fuel dependence. But rising fossil fuel prices and a growing interest in energy efficiency have increased demand for geothermal heat pumps.

Geothermal energy can be extracted from deep underground hot springs to generate electricity, or through heat pumps that extract heat stored below ground level (the latter is the focus of this article). Geothermal heat pumps (also called ground source or geoexchange systems) take advantage of another form of solar energy — instead of capturing solar energy directly, they transfer the solar heat stored in the shallow earth into efficient home heating. The process is reversed on hot days, as cooler air is pumped in from underground during the summer. (See How Geothermal Heat Pumps Work” for more information).

The ancient Greeks and Romans used thermal springs for bathing, a practice that continues worldwide. Heat pumps have been around since the early 1940’s but due to the consistently low price and convenience of natural gas, have not gained much attention. However, since natural gas prices began to rise in 2001, geothermal heat pumps have increased in popularity as the economics have improved when compared to the costs of home heating oil and natural gas.

Geothermal heat pump
Geothermal-heat-pump systems are either open loop, which inject water into the ground after it is used for heating/cooling, or closed loop, where the fluid is continually circulated. Many states require a special permit for open loop systems that discharge fluids below the surface, and in some states they are not eligible for the same tax credits as closed-loop systems.

Market Penetration & Growth Potential
Although geothermal heat pumps have been recognized by the EPA as one of the most efficient technologies available for space conditioning, just 8 percent of single family homes utilized geothermal heat pumps. Electricity is used to extract heat from the ground in the heating process, and conversely, reject heat to the ground in the cooling process, a more efficient process than burning natural gas to generate heat. New installations of geothermal heat pumps are growing by about 20% per year, according to the Geothermal Heat Pump Consortium.

Geothermal heat pumps provide economic and environmental benefits. They are three to four times more energy efficient than natural gas furnaces, making them less expensive to operate and maintain in the long run. Cooling/heating bills can be reduced by up to 60 percent as fossil fuels are avoided, and the only energy required is for the heat pump to transfer warmer (or cooler in summer) air into the home.

A geothermal heat pump also lowers the heating and cooling bills of the homeowner. Consider as an example an 1850 square foot house near Portland, Oregon.

Estimated annual heating/cooling bill $270 month, $3,250 per year Cost with geothermal heat $108 month, $1,300 per year Annual savings $1,950

Using a geothermal heat pump also makes homeowners less susceptible to fluctuations in the price of coal, natural gas, and petroleum. For example, the price of natural gas for residential heating increased by approximately 65 percent between 1999 and 2005, according to the Energy Information Administration. Natural gas prices are expected to continue to rise, with some analysts saying they may double or triple in the next few years.

Geothermal heat pump systems are not cheap however, with the cost including the duct work, underground installation and system equipment averaging between $18,000 and $35,000 for a single family home, depending on the size and installer.

Some of that cost can be recouped through tax credits available to homeowners who install geothermal heat pumps. The federal government offers a $300 tax credit, while 26 states also provide tax credits. For example, Oregon offers up to $1,500 in tax credits for installing a ground source heat pump. After tax credits, geothermal heat pumps can still take 6 to 10 years or more to pay back the investment based on today’s energy prices. However, as fossil fuel reserves continue to diminish while demand increases, the payback period could be greatly accelerated.

Because of the substantial up-front cost, financing remains a critical issue for increased geothermal heat pump market penetration. Despite considerable long term savings, the upfront costs are not within reach of many middle and lower income families.

Geothermal heat pumps reduce carbon emissions as no direct fossil fuels are required. The carbon emissions from geothermal electricity generation are minimal compared to natural gas, coal and oil fired power plants. According data from the Energy Information Administration, geothermal heat pumps emit only 15 percent of the CO2 of burning natural gas, and less than 10 percent of coal-fired heating systems.

By purchasing their remaining electricity from renewable resources, homeowners can make their heating and cooling requirements carbon free.

Electric utilities benefit from geothermal heat pumps because they reduce demand and can delay or eliminate the need to expand generating capacity. Homes with geothermal systems use less electricity at peak times, therefore new power plants may not be needed. Since investment in new plants is ultimately passed on to consumers, geothermal heat pumps can aid in delaying rate increases.

For geothermal heat pumps to gain in popularity, government and industry collaboration are required. To make the systems accessible to a wider audience, local and federal tax incentives need to be expanded, while lending institutions could create financing institutions where the loans are paid back through the savings. Geothermal heating systems remain largely a mystery to most consumers, so a marketing effort is required by industry. A breakthrough in drilling technology to lower the cost of installation could accelerate the payback period and make geothermal heat pumps more attractive.

Source: http://www.energyefficienthomearticles.com