What makes a geothermal system different from conventional systems?
A geothermal system utilizes the energy from the sun, which is stored in the earth, to heat and cool homes and buildings. Typically, electric power is used only to operate the unit's fan, compressor, and pump. So, unlike conventional systems, geothermal systems do not burn fossil fuel to generate heat--they simply transfer heat to and from the earth.
How efficient is a geothermal system?
A geothermal system is more than three times as efficient as the most efficient conventional system. Because geothermal systems do not burn combustible fuel to make heat, they provide three to four units of energy for every one unit used to power the system.
Do geothermal systems require much maintenance?
No. In fact, geothermal systems are practically maintenance free. When installed properly, the buried loop will last for generations. And the other half of the operation--the unit's fan, compressor, and pump--is housed indoors, protected from the harsh weather conditions. Geothermal Specialist, Inc. does make the recommendation that the unit receives annual maintenance to help maintain its high-efficiency standards.
Why is geothermal energy not used as abundantly as other renewable energy sources such as wind and solar energy?
Geothermal technology is divided into two areas of conservation. First: Generation of electricity. This requires earth temperature close enough to the surface to create steam in order to rotate turbines to generate electricity. Areas of volcanic activity or where magma may present are unstable for constructing geothermal generation but may yield huge amounts of electrical energy. These areas are usually far from populated areas. Secondly: Geothermal HVAC systems have the ability to transfer heat energy for both heating and cooling purposes which in turn conserves energy compared to conventional technologies. Using refrigeration systems known as water source heat pumps are extremely efficient means of cooling and heating which can offer alternatives to offset costs of operation from conventional air source systems and offset the carbon emissions of directly heating from combustion source natural gas, propane (LP) or fuel oil and also offset 30%-75% of the electricity (generated by those same fossil fuels) to energize conventional air source AC cooling. the typical savings both monetary and carbon emissions range in the 40%-80% depending on the application.
Is physically using geothermal energy expensive or is it just the construction of geothermal power plants that are expensive?
We are quite limited in the areas to use geothermal for electrical generation in the US... such as Yellow Stone, Mt. St. Helen, Hawaii, ETC... the second geothermal technology mentioned above relies on HVAC refrigeration systems (such as manufactured by Bosch, Climate Master, Enertech Group, etc...) and are readily available and somewhat affordable. A nominal Federal Energy Tax credit historically offset the higher investment by homeowners (NO longer available beyond Dec. 2016).
How long does it take to install a geothermal heat pump or geothermal power plant?
A geothermal heat pump may take from as little as a day to as long as a week depending on the circumstances. A generating plant is likely decades due to government regulations and environmental activism that typically opposes exploiting natural settings.
If the world were to increase its use of geothermal energy, how would global warming be decreased?
I am not sure of the effect. Although the carbon emission issue is offset, the concept of using earth's temperature to create steam will release significant moisture and heat into the atmosphere. There is a theory that presents the ancient (or prehistoric) earth as having a global greenhouse effect where the cloudy atmosphere shielded the sun yet held the warmth far into the north and south. This evidenced by fossils of tropical plants, insects, and animal life where conventional logic would not permit their life otherwise. Global warming is truly better served as being referred to as Climate Change. Who is to say the earth can't adapt itself? Who is to say we have the right (let alone ability) to have a measurable effect as mankind on nature at a global scale. The rules of nature have been set into place. We should not purposely pollute or destroy but should not obligate our technology nor limit ourselves from working with nature to provide an easier existence.
What is a closed-loop system?
The term "closed-loop" is used to describe a geothermal heat pump system that uses a continuous loop of special buried plastic pipe as a heat exchanger. The pipe is connected to the indoor heat pump to form a sealed, underground loop through which an antifreeze solution is circulated. Unlike an open-loop system that consumes water from a well, a closed-loop system recirculates its heat-transferring solution in a pressurized pipe.
Where can this loop be located?
That depends on land availability and terrain. most closed-loops are trenched horizontally in yards adjacent to the building. But any area near a home or business with appropriate soil conditions and adequate square footage will work.
How deep and long will my trenches be?
Trenches are normally four to six feet deep and up to 400 feet long, depending on how many pipes are in the trench. One of the advantages of a horizontal loop system is being able to lay the trenches according to the shape of the land. As a rule of thumb, 500-600 feet of pipe is required per ton of system capacity. A well-insulated 2,000 square-foot home would need about a three-ton system with 1,500-1,800 feet of pipe.
How many pipes are in the trench?
Normally, a run of pipe is laid at five feet then looped back over itself at three feet once the bottom pipe is covered with soil. This allows more length of pipe to be put in one trench and has no adverse effect on system efficiency. Other loop designs use four or six pipes and allow for shorter trenches if land area is limited.
What if I don't have enough room for a horizontal loop?
Closed-loop systems can also be vertical. Holes are bored to about 125-150 feet per ton of heat pump capacity. U-shaped loops of pipe are inserted in the holes. the holes are then backfilled with a sealing solution.
How long will the loop pipe last?
Closed-loop systems should only be installed using high-density polyethylene or polybutylene pipe. Properly installed, these pipes will last for many decades. They are inert to chemicals normally found in soil and have good heat conducting properties. PVC pipe should not be used under any circumstances.
How are the pipe sections of the loop joined?
The only acceptable method to connect pipe sections is by thermal fusion. Pipe connections are heated and fused together to form a joint stronger than the original pipe. The mechanical joining of pipe for an earth loop is never an accepted practice. The use of barbed fittings, clamps, and glue joints is certain to result in loop failure due to leaks.
Will an earth loop affect my lawn or landscape?
No. Research has proven that loops have no adverse effect pm grass, trees, or shrubs. Most horizontal loop installations use trenches about six inches wide. This, of course, will leave temporary bare areas that can be restored with grass seed of sod. Vertical loops require little space and result in minimal lawn damage.
Can in install an earth loop myself?
It is not recommended. In addition to the thermal fusion of the pipe, good earth-to-coil contact is very important for successful loop operation. Nonprofessional installations may result in less than optimum system performance.
Can I reclaim heat from my septic system disposal field?
No. An earth loop will reach temperatures below freezing during extreme conditions and may freeze your septic system. Such usage is banned in many areas.
I have a pond nearby. Can I put a loop in it?
Yes, if it's deep enough and large enough. A minimum of six feet in depth at its lowest level during the year is needed for a pond to be considered. The amount of surface area required depends on the heating and cooling load of the structure.
That is an open-loop system?
The term "open-loop" is commonly used to describe a geothermal heat pump system that uses groundwater from a conventional well as a heat source. The groundwater is pumped into the heat pump unit where heat is extracted, then the water is recycled back to the water table. Since groundwater is relatively constant temperature year-round, it is an excellent heat source.
What do I do with the discharge water?
There are a number of ways to recycle water after it has passed through the heat pump. The open discharge method is the easiest and least expensive. Open discharge simply involves releasing the water into a stream, river, lake, pond, ditch, or drainage tile. Obviously, one of these alternatives must be readily available and must possess the capacity to accept the amount of water used by the heat pump before open discharge is feasible.
A second means of water discharge is the return well. A return well is a second wellbore that returns the water to the ground aquifer. A return well must have enough capacity to dispose of the water passed through the heat pump. A new return well should be installed by a qualified well driller. Likewise, a professional should test the capacity of an existing well before it is used as a return.
How much groundwater does an open-loop system need?
Geothermal heat pumps used in open-loop systems need differing amounts of water depending on the size of the unit and the manufacturer's specifications. The water requirement of a specific model is usually expressed in gallons per minute (g.p.m.) and is listed in the specifications for that unit. Your heating contractor should be able to provide this information. Generally, the average system will use 1.5 g.p.m. per ton of capacity while operating.
Your well and pump combination should be large enough to supply the water needed by the heat pump in addition to your domestic water requirements. You will probably need to enlarge your pressure tank or modify your plumbing to supply adequate water to the heat pump.
What problems can be caused by poor water quality?
Poor water quality can cause serious problems in open-loop systems. Your water should be tested for hardness, acidity and iron content before a heat pump is installed. Your contractor or equipment manufacturer can tell you what level of water is acceptable. Mineral deposits can build up inside the heat pump's heat exchanger. Sometimes a periodic cleaning with a mild acid solution is all that's needed to remove the build-up. Impurities, particularly iron, can eventually clog a return well. If you water has a high iron content you, should be sure that the discharge water is not aerated before it's injected into a return well. Finally, you should opt against using water from a spring, pond, lake or river as a source for your heat pump system. unless it's proven to be free of excessive particles and organic matter. They can clog a heat pump system and make it inoperable in short time.
Does an open-loop system cause environmental damage?
No. They are pollution free. The heat pump merely removes or adds heat to the water. No pollutants are added whatsoever. The only change in the water returned to the environment is a slight increase or decrease in temperature.
Some people are concerned that open-loop systems contribute to the depletion of our groundwater resources. This issue is not critical in some parts of North America because of abundant supplies of groundwater.
Q. Are there any laws that apply to open-loop installations?
In some locations, all or parts of the installation may be subject to local ordinances, codes, covenants or licensing requirements. Check with local authorities to determine if any restrictions apply in your area.