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The geothermal heat pump (GHP) industry enjoyed eight years of prosperity created by an energy tax credit that ended on Dec. 31, 2016. The Energy-Efficient Property Credit was created to assist with the first cost hurdle a prospective GHP consumer would have to overcome to install the system in their building. The credits were for both residential, at 30 percent toward the total cost of the installation of the geothermal system, and commercial installation, which was 10 percent of the total installation. The residential rebate accounted for the approximate cost of the loop or fuel of the system, a renewable source of energy.
The loss of the rebate has created a big deficit in not only production of GHP systems but jobs in the industry as well. There is currently a new bill awaiting approval, H.R. 1090, that will modify the tax credit for residential energy efficient properties to extend through 2021 the credits for expenditures for fuel cell property, small wind energy property and geothermal heat pump property. For each extended credit, the bill phases out the current credit rate of 30 percent of expenditures by reducing it to 26 percent or 22 percent, depending on the date that the property is placed in service.
Although rebates provide big incentives, they also can cause a false market. That’s not to say there isn’t still a market for GHPs but because the rebate incentive has expired, the systems are considered too expensive by the average consumer. Unfortunately, factored in with the total investment of a GHP system is the fuel source installation cost. So, a conventional system that costs $15,000 installed, is more inviting to a consumer than a geothermal system for the same property at $25,000 to $30,000. Since the oil or gas for a conventional system is not purchased at one time, it is not considered in the cost of the installation. On the other hand, a GHP system requires the energy be installed at the same time the unit is installed in the building, which requires more of an upfront cost.
We need to do a better job at presenting the benefits of a GHP system, as there are many. If they’re explained to the purchaser, it can and will reduce the need for a rebate. Those benefits include:
Conventional systems versus GHPs
Most conventional systems depend on fossil fuel for heating the space and hot water, which is purchased in incremental portions after the fact. Due to many reasons including geo-political issues, weather, supply, demand and various other conditions, the cost of fuel varies. A fossil fuel system also needs electricity to operate, and the efficiency ratings do not reflect the electrical usage. Conventional systems require extra equipment for cooling, and there are also venting considerations and open flames. Most fossil fuels are susceptible to geo-political affairs. Eastern European countries are installing GHPs to prevent the loss of heat by governments shifting demands of natural gas. Prices of oil fluctuate with storms. Many fossil fuels are unregulated, subject to inflation and cost what the market will bear. Additionally, the incentives offered only benefit the supplier of the fuel.
A fossil fuel furnace can only return 75 percent to 95 percent of the input of your source to the space, and then the source is destroyed and not able to be reused. You must buy more at the present rate, forever.
A GHP system garners the required energy from the ground, will return five times the energy investment, and the fuel source is permanent. It is not regulated or unregulated; it is yours. It is completely unaffected by any outside economic issue; it is the only fuel source that will provide a return on investment, forever. Additionally, the GHP sources’ costs can be amortized in many ways, including:
In the end, the cost of the financing, plus the cost of operation, is usually less than the total expenditure using any of the fossil fuels. In most cases, the total cost of the source will be recovered in three to seven years. That is an average of a 20 percent return on your investment. You will not lose your principle. You could call it an Energy Annuity; the realized savings often is in the hundreds of thousands of dollars!
ASHP vs geothermal
What makes a geothermal heat pump system better than air source heat pumps (ASHP)? There are a few facts that make the GHP work efficiently:
The operation of an ASHP system depends on the ambient air outside. The efficiency of an ASHP system varies every time the outside temperature changes. In the heating cycle, the colder the air becomes, the less heat the unit can produce; the unit must work harder to accomplish a heat requirement that is rising. You also need to augment the heat with electric heat or another source. The system has the same problem with the cooling cycle; the hotter it gets outside, the less ability you have to reject the warm air in your building to the outside. These difficulties add to the cost of operation and reduces the life expectancy of the ASHP system.
A GHP depends on the temperature of the earth. The earth serves as a large solar battery and maintains a steadier temperature than the air seasonally. Since the temperature of the earth is less fluctuating, the energy production of the GHP and efficiency is more constant. The earth temperature is warmer than the air in the winter through the heating season, allowing the GHP to absorb more heat at lower outside temperatures, and in the cooling season, the ground is cooler than the air, thereby allowing the GHP to reject more heat it has gathered from inside the building to the ground. If you consider what the total heat output of a GHP system is, and how much the unit will get from the ground (heat of extraction), you will see it is approximately 73 percent of the total output of the unit. The other 27 percent comes from refrigeration.
Heat of Extraction (HOE) ÷ Total Heat Output (TC) = BTUs from source
The longevity of the GHPs is sometimes compared to a refrigerator. A refrigerator operates in a constant temperature year-round. Therefore, the operation is completely predictable. The appliance also works by moving a temperature from the constant air temperature in the room to a refrigerant and then into a space to keep all your produce at a temperature to preserve freshness. After the style of the cabinet of the refrigerator becomes outdated, it is oftentimes moved to the garage or “man cave” to keep your favorite beverage at a nice, cool temperature for many years to come. The fact that the unit is supplied with a constant temperature adds to the life of the unit. A GHP is expected to have a life cycle two times longer than other conventional fossil fuel systems.
There are three general means to install the source, each should be evaluated for the most economical means fitting the property; each can be modified to fit the situation; and each is dependent on the heat loss and gain of the building. These means include:
All the options can be modified for the property. If you have enough water available on the property, and it is of good quality — not full of minerals and debris — and you have a method to discharge the borrowed water, it is the most efficient and probably the lowest cost of installation. There are a few variations of this concept such as standing column wells, that can also be investigated.
If the well is not a desired way to go, and you have a fair area of land available to you, you can opt for a horizontal loop constructed of high density polyethylene pipe (HDPE), heat welded together and buried. HDPE pipe is a plastic material chosen for good heat transfer and maintains its strength with a warranty of 50 years or more.
Horizontal installations depend on land area and type of soil. This usually is next in cost of installation. This type of loop is excavated as opposed to drilled. If the land area is restricted for a horizontal loop, then the other alternative is a vertical loop. The vertical method is the more expensive but uses the least area of the property.
It is most important to obtain an accurate heat loss and gain of the building, type and condition of the water and soil. A loop must gather the required BTUs for the building that reside in the temperature of the ground, the source. A loop is a direct result of the heat loss and gain of the building. The collected BTUs just need to be carried to the GSHP by the loop.
The installation of all loops should be designed by an experienced designer. If you do not know one, you can contact the International Ground Source Heat Pump Association (IGSHPA). This organization has set many standards for the installation of ground source heat pumps. IGSHPA also offers training and certifications for designers and trainers. You could also contact your local utility. I am sure one of them would be able to direct you to people in the know.
The equipment must be properly sized for application, comfort, longevity and efficiency. There are many software programs available to demonstrate how the equipment will perform in different sets of circumstances.
Installation practices are of the utmost importance with GHPs; there are no “rule of thumbs,” a loop must be figured. There are no constants in the lengths of the loop; pumps must be sized. You can’t just “throw one in.” The correct type and size of the pump and the correct loop length, all contribute to efficiency and life cycle of this type of installation. Knowing when you can use a central pump and when to use fractional horsepower circulators are all decided by an analysis of the system. None of this figuring is very difficult, and there are plenty of people to help you with this. The methods used to determine pump sizing and heat loss and gain, have been employed for similar processes and used for centuries. Boilers use water, move water and distribute heat. Water systems in a building bring fluids in and move them around the building. The difference being the requirements of the equipment. The collection of BTUs needs to satisfy the requirements of the building. The requirements must be met and are less forgiving than a boiler that usually was oversized and had more capacity than required.
The manufacturers of the equipment, IGSHPA, utilities and people like myself, offer all kinds of training easily accessible for the contractor to be able to garner the skills needed to build and install a GSHP system. A properly installed system will offer a trouble-free, economical and comfortable life of 20 years and up.
Fluid-based heat pump applications
There is an application for fluid-based heat pumps, called water source heat pumps (WSHP), from which GHPs were derived. A WSHP was developed when buildings grew so tall that the climate inside the buildings varied and needed to be individually controlled. Their use grew as cities grew up with skyscrapers. In this application, there is a water tower on the building that would reject the heat that was moved from cooled spaces, and a boiler to heat the water when different spaces needed heat. This could occur simultaneously.
With incrementally sized and controlled WSHPs, we had the ability to accurately operate the climate of the building. The equipment used in these buildings has changed over the years to adapt to indoor air quality and efficiency standards. Boilers, chillers are used to maintain fluid temperatures and the water tower method of rejecting heat is still widely used. A water tower has a few drawbacks, which includes the amount and the quality of the fluid used to reject the temperatures created by heating and cooling. Other drawbacks include the risk of health hazards such as Legionnaires virus and shortages of water. To reduce the water usage of a water tower, loops are now being used to reject some of the heat, thereby reducing the size of the water tower and greatly reducing the amount of water needed to operate the tower. A sealed loop system is not subject to a constantly replenished water supply or harsh weather conditions or violent storms. The use of loops to assist a water tower, controlling the use and quality of water is called a Hybrid loop. Here the installation of a GHP has improved the system it was derived from. A GHP absorbs and rejects heat into its loop.
Many new buildings such as collages and hospitals are exploring and installing the use of Hybrid systems because of the availability, quality and the expense of maintaining a water system.
Bottom line is GHP systems are the most efficient comfort system available today. They are not the most expensive systems — rebated or not. They can be installed in almost any situation. They benefit everyone who is involved with them, including:
A homeowner or building owner with the lowest operating cost, clean non-scorched air, easily maintaining good levels of humidity, increasing indoor air quality.
As a contractor or an engineer, you would be remiss not to be ready to discuss geothermal systems with your customers. GHPs have been used for more than 40 years, and we know they work. Change is good — difficult — but good. We should accept it and step up. For you in your trade to accept this technology and embrace it, would put you in the forefront of your competitors.