Geothermal heating (known as Ground Source Heat Pumps, or GSHP’s) at its most basic is just transferring heat energy between the Earth and your home. In the winter when you need to heat, you simply transfer the heat from the earth into your home. In the summer when you need to cool, it is just the opposite; heat is taken from your house, and put back into the earth.Geothermal systems can be installed basically anywhere, and have no need for natural hot springs or geysers under your house. This system just uses a heat exchanger in the earth to transfer the heat energy.The United States E.P.A. has called ground source heat pumps
The most energy efficient, environmentally clean and cost effective space conditioning system available.
Geothermal systems provide highly efficient, clean, quiet and renewable heating and cooling at a very low cost.
Heat pumps move heat energy from one place to another. That’s it, that’s all they do (hence the name “pump”).The heat pump in your refrigerator moves the heat from the inside of the insulated box and releases it into the room. The heat pump in window air conditioner takes the heat out of a room and vents it to the outside. A ground source heat pump can remove heat from the ground and release it into a structure or it can remove heat from a structure and release it into the ground.The efficiency of this heat transfer greatly depends on the load and the source temperatures.Think of a hot summer day. A window air conditioner must remove heat from the room and reject it into the already hot summer air. While the temperature of the refrigerant far exceeds the ambient outdoor temperature it has reduced capacity to release heat as the temperature increases. If the air conditioner could release the heat it has removed from the room into the cool earth below the home it could get rid of the heat much faster than trying to reject it into the hot summer air.Now think of a cold winter day. The colder it gets outside a home, the less efficient it is to remove heat from the cold ambient air and deliver it to the warm home.The earth provides a thermal mass with a consistent moderate temperature.The sun provided the thermal energy. The earth absorbed it. Heat pumps can move it.
A Geothermal Heat Pump can effectively save you 50-70% per year on your heating costs. The system as a whole is incredibly efficient and cost effective, so instead of paying hundreds per month on expensive heating oil or electricity, you pay hundreds a year to simply run the pump.
Geothermal Heat Pumps can heat or cool at 350-450% efficiency. That means it can produce about 4 times as much heat than energy it takes in. No other heating and cooling system can match those kinds of efficiencies.
Geothermal heat pumps use electricity to transfer the heat from the earth into your home, this means
The heat is from solar energy that is stored in the earth, and is completely renewable. It will not run out, and prices of it will not greatly fluctuate like heating fuels.
In the wintertime, heat pumps pull the heat from the earth and put it into your home, and in the summer, they do the exact opposite; they take the heat from your home and put it back in the earth. This means that you don’t have to have an air conditioning system for the summer and a furnace for the winter. One system that can do it all more efficiently than anything else.
Heat pumps are the most reliable heating units on the market. They are simple in design and have few moving parts, so they rarely break down. A couple very minor electrical part replacements are the most that the majority of system owners see in the lifetime of the system.Maintenance on the system is also very simple, just change the air filter every few years like you would a conventional system, and your system is good to go. No chimneys or furnaces to clean in addition to that.With no noisy burners to fire up, or loud fans to kick in to force the air through your house, heat pumps are also very quiet.
As an extra system add-on, a desuperheater can generate your domestic hot water as a by-product of the heat pump’s operation. This again reduces your yearly heating costs.
The ground loop component of a geothermal system is basically a heat exchanger with the earth. Fluid is circulated through it to facilitate that heat exchange between the earth and your home. During the summer, heat is taken from the house, put in the circulating fluid in the ground loop, and then expelled into the ground. The winter is the exact opposite.All ground loops only serve that function, to be a heat exchanger for the system. The loop type is mainly dependent on the location of the system (soil type, land available, static water level, etc).
Horizontal Directional Drilling is an absolutely fantastic method of installing geothermal ground loops. Traditionally to install geothermal ground loops, thousands of feet of 8-10ft. deep trenching, or massive vertical boreholes were needed to achieve the size of ground loop needed for the system. Horizontal trenching is a massive oredeal, which tears up a large amount of land, and can take weeks to fully excavate, lay the tubing, screen the dirt, then backfill all of the trenches. Vertical boreholes take up less land, but require large vertical drilling rigs and can cost an estimated $2,500-5,500 per borehole. Most houses would need anywhere from 3-8 boreholes with 10-15' spacing to fully satisfy the heating and cooling load. HDD is the solution to both of these ineffective ground loops. A small, directional drilling machine is moved in, and shoots a drill bit under the ground, which comes up hundreds of feet away, in the exact position you want it. The earth loop is then tied to the end of the drill bit, and is pulled back through when the bit is being extracted. Sufficient land is required (as is with all geothermal ground loops), but if it is, then HDD can be a cost effective and minimally invasive ground loop installation method that will give you more flexibility in your ground loop, and take much less time.
A horizontal ground loop is one of the most commonly installed ground loop types. Horizontal ground loop installation is accomplished two different ways, either by Horizontal Trenching or by Directional Drilling.In Horizontal Trenching, the pipe is buried at a depth of 8-10 feet to provide adequate frost protection. A large amount of land is needed to run those trenches, but if that land is available, it can be an easy and economical way of building a ground loop system.Directional Drilling is the method we use at Lesters Water Works. We use a directional bore machine to drill into the ground and once the drill rod hits the target depth, usually 15-20’, the operator then bores horizontally at least 200 feet at that depth. Once this has been achieved the operator then runs the rod out of the ground to pullback the geothermal u-shaped loops.The size of the loop and amount of trenching needed are dependent on things like your heating load need and soil type. The heating load will be the greatest factor in the sizing of the loop field, and obviously the larger the house, the larger the heating load, the larger the ground loop field needed to supply that heat. Typically a 200’ Bore hole with 400′ of geothermal loop handles 1 ton of heating and cooling.Soil type is also a very important point to consider because some soils, like gravel and dry sand, don’t provide as good of a heat conductor as soils like wet dirt, clay, or ground water.
Like most things, the cost of the whole thing is the bottom line deciding factor. But direct initial costs cannot be the only comparison. Geothermal systems will usually cost more to install initially, but will easily pay themselves off over time just in money saved from cheap operation. The typical payback period we are seeing is usually 3-6 years, depending on your situation. Federal and state discounts are often available specifically for these systems, and when paired with a renewable energy loan, can potentially cost you no extra money per year to install and heat with a geothermal system AND pay back the loan. All of that for the same cost of just heating your house with a conventional system.
The operating costs of a geothermal system are roughly 1/3rd of the operating costs of a traditional heating system. So instead of paying $3000 per year to heat your home, you could be paying around $1000.With the renewable system, you are using ‘free’ energy directly from the earth, and the only operational cost is the electricity needed to transfer that energy from the earth into your home.The instant the geothermal system is installed, it saves a significant amount of money over the conventional system.
With the large stimulus recently passed by the federal government, there is an abundance of money set aside by state programs for renewable energy loans. These loans are becoming more and more readily available, and are offered at low fixed rates. With the energy savings associated with geothermal heating, the principal and interest of the loan can be paid, and then some. Many homeowners are enjoying a geothermal heating system without the large upfront fee, and are still in the positive with money while paying back the principal and interest on the loan.
The bottom line is a geothermal heating system will save you thousands of dollars per year on heating costs. No longer with you have to worry about the volatility of heating fuel costs and availability. No longer will you be worried about the environmental affects of heating your home.The value added to your home from a renewable heating system is also a great bonus.Geothermal heating is clean, cheap and efficient heating in almost any situation.
IGSHPA International Ground Source Heat Pump Association – The main accreditation organization of geothermal heat pumps.
US Dept. of EnergyGeothermal Technologies Program within the US Department of Energy.
Energy Star – Geothermal Heat PumpsThe Geothermal Heat Pump section of Energy Star, which rates products based on energy efficiency.
Geothermal Help Geothermal Help – Industry website providing consumer education, articles, featured projects, forums, etc.
GeoExchangeGeothermal Heat Pump Consortium
CoGEHPAColorado Geo Energy Heat Pump Association
MGEAMichigan Geothermal Energy Association
DSIREOnline renewable energy tax incentive list for all federal, state and utility companies.