Horizontal Loop
A horizontal closed loop field is composed of pipes that run horizontally in the ground. It is closed loop heat exchanger system with 1.5-2m depth underground. A long horizontal trench, deeper than the frost line, is dug and U-shaped or slinky coils are placed horizontally inside the same trench. Excavation for horizontal loop fields is about half the cost of vertical drilling, so this is the most common layout used wherever there is adequate land available.
Vertical Loop
A vertical closed loop field is composed of pipes that run vertically in the ground in holes that are bored in the ground, typically 50-200m deep. The borehole is normally filled with a bentonite based grout that surrounds the pipe to provide a thermal connection to the earth’s soil or rock to improve the heat transfer. Thermally enhanced grouts consisting of high thermal conductivity compounds are commonly used to improve this earth to pipe heat transfer. Grouting is an important environmental practice because it protects the ground water from contamination and also prevents artesian wells from flooding the property.
Closed Pond Loop
A closed pond loop is common where there is close proximity to a body of water. Closed pond loops consist of either pipe or stainless steel flat heat exchangers that are sunk to the bottom of the pond, lake or ocean. A pond loop offers many advantages where poor water quality precludes an open loop, where drilling costs are high or in cooling dominate locations.
Supply and Reinjection Loop
A supply and reinjection loop consists of one or more vertical water wells for the supply water. After the heat energy is removed or rejected the water is returned to the same aquifer in earth through one or more vertical water well. This type of system offers distinct advantages because no water is wasted, contaminated or discharged above the earth’s surface.
Standing Column
Standing column systems were first used in the eastern USA in the late 1980’s. This type of system uses vertical water wells to circulate ground water from the earth and then return it into the same vertical water well. The supply water is pumped from near the earth’s surface and with return water being sent to the bottom of the well. This type of systems work well in areas where there is subsurface hard rock drilling conditions and adequate ground water.
Pile (Building Foundation) Loop
Pile loop systems are relatively new and were first introduced in the early 1990’s. A pile loop system consists of pipe that is installed inside building foundation piles. A pile system cannot support the full heating and cooling load of any building and is normally combined with another type of earth loop system. By combining the pile system with other loop technologies the property owner can take full advantage of the building footprint and reduce initial installation costs.
Municipal Water Loop
Municipal water loop systems have received the full support of the US government with legislation passed by congress in 1992. Municipal systems have proven to be safe, reliable, cost efficient and non-contaminating. These systems use the water that is already flowing under a city and the thousands of kilometers of piping that is already in place. A municipal water system works well in congested city areas where other types of loop systems would be impractical. They represent a significant source of earth energy that is virtually untapped and allows the municipal water provider to sell both energy and water and increase their profits. The energy they sell costs them nothing. The water utility provider can sell this energy at a moderate cost with only minimal infrastructure expenditure. These systems represent an amazing amount of energy that is unused and wasted every year.
Effluent (Waste Water) Loop
Effluent waste water loop systems represent the most underutilized energy source that is available today. These systems use water that is normally “thrown away!” Within the waste water system of every city there is a vast amount of energy that can be used for heating and cooling buildings. In the winter heat energy is removed and in the summer heat energy is added. Every city worldwide should find ways to capture this energy and use it for geothermal heat pump systems. The energy experts at Innergie Technologies can provide engineering expertise to capitalize on this unused energy source that flows beneath every city.
Hybrid system technology is used to combine various geothermal loop systems. A hybrid “combination” system is more energy efficient than any single stand-alone technology. One example is to combine a vertical closed loop system with a cooling tower or boiler. However, there are many combinations that are possible. Hybrid systems are the best example of a truly integrated energy system and will perform excellently while offering numerous project owner benefits and protection of the earth’s environment.
