Geo Exchange Technology
What is Geo-exchange
Geo-exchange is a heating and cooling system that uses solar energy stored in the ground or water. Using pipes buried in the ground as a collector and a geothermal heat pump, heat energy is absorbed at one location and transferred to another. Heat at a low temperature level is transformed into heat at a high temperature level at which it can be used to heat your home or business.
One of the most important characteristics of a heat pump is the efficiency of the unit. Because Ground Source Heat Pumps extract heat from relatively warm soil (or groundwater) in the winter and deliver heat to the same relatively cool soil (or groundwater) in the summer, this leads to a very high efficiency and lower energy use. Typically Ground Source Heat Pumps use only a small amount of electricity and return up to five times more energy than they consume.
Geothermal heat pumps can be used for any application which requires heating or cooling:
- Home heating/cooling
- Commercial heating/cooling
- Swimming pools
- Hot water
- Dairy farms
- Commercial applications
- Can be set up for extremely efficient operation
- Can be used to heat and cool
- Geothermal uses renewable energy
- Clean operation. No combustion on site
- Long Life (50+ years for a closed loop ground loop)
- Low maintenance
- No noisy outdoor units
How does it work
There are three main elements to a Ground Source Heat Pump system.
- The ground loop.
- A heat pump.
- Heat distribution system
The ground loop
Despite the variation in temperature we experience throughout the year, the temperature below ground stays fairly consistent all year, regardless of climate or season. Geo-exchange uses an earth loop to extract heat from the ground. This is comprised of lengths of HDPE pipe buried in the ground, or a body of water. The pipe is usually a closed circuit and is filled with a mixture of water and Glycol. In winter, the water solution is pumped around the pipe absorbing the energy from the surrounding earth and carrying it into the building. In the building, the heat pump extracts this heat from the water solution and transfers it into the building. In summer, the process is reversed and the water solution carries the heat from the building via the heat pump and rejects the heat energy back into the earth. There a number of options for the ground loop:
- Horizontal Loop
If adequate land area is available, a horizontal closed loop is composed of pipes run in trenches in the ground, pipes are placed in trenches up to 150m long and averaging 1.5m deep. The length and the width of the trenches is dependent on the size of area requiring heating or cooling.
- Vertical Loop
A drilling rig is used to bore a number of holes of 50-120 metres deep. The number of holes drilled is dependent on the size of area requiring heating or cooling. Pipe pairs in the hole are joined on the bottom with a u-bend. The borehole is backfilled with a grout to give good thermal connection to the surrounding rock or soil. For very small sites this may be the only feasible option. Vertical loops are perfect for properties on small parcels of land or locations with shallow rock where trenching is not possible.
- Pond Loop
A pond, dam or body of water can be used as a collector by installing coils of pipe into the water. The coils of pipe are attached to a frame and sunk to the bottom of the pond. The amount of pipe is dependent on the size of area requiring heating or cooling. The pond loop is probably the most economical way of installing a loop as generally no excavation is required.
- Open Loop
This type of system uses well or surface body water as the heat exchange fluid that circulates directly through the ground source heat pump system. Once it has circulated through the system, the water returns to the ground through the well, a recharge well, or surface discharge. This option is obviously practical only where there is an adequate supply of relatively clean water, and all local codes and regulations regarding groundwater discharge are met.
Benefits of a ground source heat pump
No flame, no fuel store and no risk of burns
- Environmentally friendly
The only carbon cost is the energy used to bring in the heat from the heat source.
- Reduced CO2 emmissions
The heat collected by the earth loops is carbon-free. The energy used by the heat pumps to transfer the heat to the building will involve some CO2 production, depending on how it is generated. Utilising green electricity, your heating system can produce zero carbon emissions!!!
- Cost effective
The initial investment required to install a ground source heat pump is considerably more than a conventional gas or oil boiler. However, the running costs associated with a heat pump are significantly lower - 20% to 50%.
The collector pipes are under ground and invisible. The heat pump can be located inside or outside the house