Geothermal 101
On a sunny day, when the great burning star stands high in the noon sky, its rays come barreling down upon the Earth, thus bringing heat. However, the following day may see the clouds reign in the sky, blocking the sun, its rays, and its heat. The next day may bring the sun out from behind the clouds or may hide it again. Who knows?
The point is that the sun’s ability to heat the earth is not constant. It is dependent on other types of weather. If the clouds, the rain, or the wind show up on the scene, the sun’s wonderful heat-giving capacity is ruined. Or is it? The sun radiates an abundant amount of energy to the Earth everyday (even when it is cold outside). Like a giant storage medium, the Earth and its groundwater absorb about half of this precious solar energy. So, even though the weather may be cold or rainy or foggy, the Earth still gathers and stores the sun’s energy.
Because it does this, the Earth remains at a constant temperature range (from about 45 degrees F to 70 degrees F in North America). This interesting characteristic has already been recognized and utilized by even the smallest of creatures. The gopher burrows underground to make his home utilizing the Earth’s stable temperature range all year. In the summer, the ground is cooler than the outside air, and in the winter, the ground is warmer than the outside air. The gopher uses this fact to stay comfortable no matter what the weather condition.
Humans, too, can utilize this virtually limitless source of energy to heat and cool our homes, businesses, and schools.
- Tax Credits
- The most energy-efficient, environmentally clean, and cost-effective space conditioning system available, according to the Environmental Protection Agency.
- EPA found that geothermal heat pumps can reduce energy consumption--and corresponding emissions--by over 40% compared to air source heat pumps and by over 70% compared to electric resistance heating with standard air-conditioning equipment. Combining geothermal with other energy-efficient measures, such as window or insulation upgrades, can increase these savings even further.
- Geothermal heat pumps use the Earth's energy storage capability to heat and cool buildings, and to provide hot water. The earth is a huge energy storage device that absorbs 47% of the sun's energy -- more than 500 times more energy than mankind needs every year -- in the form of clean, renewable energy. Geothermal heat pumps take this heat during the heating season at an efficiency approaching or exceeding 400%, and return it during the cooling season.
- EPA found that, even on a source fuel basis -- accounting for ALL losses in the fuel cycle including electricity generation at power plants -- geothermal systems are much more efficient than competing fuel technologies. They are an average of 48% more efficient than the best gas furnaces on a source fuel basis, and over 75% more efficient than oil furnaces. In fact, today's best geothermal systems outperform the best gas technology, gas heat pumps, by an average of 36% in heating mode and 43% in cooling mode!
- Geothermal heat pumps have fewer mechanical components, making them more reliable and less prone to failure. The ground loop has an expected life of over 50 years and requires no maintenance.
- Surveys by utilities indicate a higher level of consumer satisfaction for geothermal heat pumps than for conventional systems. Polls consistently show that more than 95% of all geothermal heat and cooling customers would recommend geothermal to a family member or friend.
- Geothermal heat pumps represent a savings to homeowners of 30 to 70% in the heating mode, and 20 to 50% in the cooling mode compared to conventional systems.
Vertical Loop: This loop is used when the area around your land is limited. The vertical loop is installed by drilling holes to a depth of between 250-300 feet.
Horizontal Loop: The horizontal loop is the most common construction type and is built using trenches approximately 8 feet in depth by 400 feet long.
BTU (British Thermal Unit): The amount of heat needed to raise the temperature of one pound of water one degree Fahrenheit. BTU is used to signify the heating and cooling capacity of a system and the heat losses and gains of buildings and homes.
BTUH: The number of BTUs produced in one hour.
Closed-loop heat-pump system: A heat-pump system that uses a loop of buried plastic pipe as a heat exchanger. Loops can be horizontal or vertical.
COP (Coefficient of Performance): The ratio of heating or cooling provided by a heat pump (or other refrigeration machine) to the energy consumed by the system under designated operating conditions. The higher the COP, the more efficient the system.
Compressor: The central part of a heat pump system. The compressor increases the pressure and temperature of the refrigerant and simultaneously reduces its volume while causing the refrigerant to move through the system.
Condenser: A heat exchanger in which hot, pressurized (gaseous) refrigerant is condensed by transferring heat to cooler surrounding air, water or earth.
Cycling losses: The actual efficiency of a heating or cooling system is reduced because of start-up and shut-down losses. Over sizing a heating or cooling system increases cycling losses.
Desuperheater: A device for recovering superheat from the compressor discharge gas of a heat pump or central air conditioner for use in heating or preheating water.
Fossil fuel: Any of several types of combustible fuels formed from the decomposition of organic matter. Examples are natural gas, propane, fuel oil, oil and coal.
Geothermal heat pump: A heat pump system that uses the earth as a heat source and heat sink.
Heat exchanger: A device designed to transfer heat between two physically separated fluids or mediums of different temperatures.
Heat pump: A mechanical device used for heating and cooling, which operates by pumping heat from a cooler to a warmer location. Heat pumps can extract heat from air, water or the earth. They are classNameified as either air-source or water-source units.
Heat sink: The medium—air, water or earth—which receives heat rejected from a heat pump.
Heat source: The medium—air, water or earth—from which heat is extracted by a heat pump.
Open-loop heat-pump system: A heat-pump system that uses groundwater from a well or surface water from a lake, pond or river as a heat source. The water is returned to the environment.
Payback: A method of calculating how long it will take to recover the difference in cost between two different heating and cooling systems by using the energy and maintenance-cost savings from the more efficient system.
Supplemental heating: A heating system used during extremely cold weather, when additional heat is needed to moderate indoor temperatures. May be in the form of fossil fuel or electric resistance.