How to use geothermal energy?
One of the methods to generate electricity from geothermal energy is by pumping hot water into sedimentary hotspots. The steam generated by this method is used to produce electricity. The condensed steam is again circulated into the permeable sedimentary stream of a hotspot.
Another method is by using volcanic magma. The temperature of partially molten magma is approximately 650 degree Celsius. This heat is used to boil water to generate electricity.
Some geothermal plants also use the hardened magma that is extremely hot. This system uses hot dry rock. Pipes are looped through these hot dry rocks through which water is circulated. The heat of the rocks converts the water into steam prior to transferring the heat to a steam generator.
A heat pump is a device that uses a small amount of energy to move heat from one location to another. Heat pumps are usually used to pull heat out of the air or ground to heat a home or office building, or they can be switched into reverse to cool a building. If you know how an air conditioner works, you already know a lot about how a heat pump works, because heat pumps and air conditioners operate in very similar ways.
Heat pumps are a unique kind of heating system, because they can do the work of both a furnace and an air conditioner. Thus, there’s no need to install separate systems to heat and cool your home. Heat pumps can also work extremely efficiently, because they simply transfer heat, rather than burn fuel to create it.
Basic principles of geothermal heating and cooling system operation:
A geothermal heat pump system uses the ground you already own to heat and cool your home for less. Geothermal works by using the difference in temperature between the outside air and the ground. The ground is like your own solar panel, absorbing fifty percent of the suns energy which keeps the ground temperature a constant fifty five degrees. When the summer sun produces those ninety five degree days, the ground remains at its constant fifty five degree temperature. In the winter, the ground temperature remains around fifty five degrees, even with the snow.
To exploit these temperature differences holes are drilled anywhere from fifty to hundreds of feet deep to house a system of piping known as the loop field. These holes are filled with a grout to improve heat transfer with the earth. The loop field is brought into the home where it connects with the geothermal heat pump. The system circulates a water mixture through the entire loop.
In the winter, the water absorbs the heat in the earth which is then compressed by the heat pump to a warmer temperature and distributed throughout the home as heat. For every unit of electricity used in this process, four units of heat are produced. The most efficient gas furnaces are ninety four percent efficient. Geothermal is four hundred percent efficient.
The operating costs of a geothermal system can be up to seventy percent less than conventional systems. In the summer, the same process is reversed except now the ground acts as a heat sake instead of a heat source. Heat and humidity from the home are pulled out and rejected back into the earth. Cool air is distributed throughout the home providing air conditioning. The geothermal heat pump is also equipped with a desuperheater which is used to preheat hot water saving you even more money!
The basic elements of a geothermal heat pump (GHP) system include a:
Ground loop — system of fluid-filled plastic pipes buried in the shallow ground, or placed in a body of water, near the building.
Heat pump — removes heat from the fluid in the pipes, concentrates it, and transfers it to the building (for cooling, this process is reversed).
Air delivery system — conventional ductwork used to distribute heated or cooled air throughout the building.
Simply put, a GHP works much like the refrigerator in your kitchen, with the addition of a few extra valves that allow heat-exchange fluid to follow two different paths: one for heating and one for cooling. The GHP takes heat from a warm area and exchanges the heat to a cooler area, and vice versa. The beauty of such a system is that it can be used for both heating and cooling—doing away with the need for separate furnace and air-conditioning systems—and for free hot water heating during the summer months.
Geothermal heat pumps use electricity to heat and cool, just like a conventional heat pump. However, unlike a conventional heat pump, GHPs use the relatively constant temperature of the shallow Earth as a source of heat in the winter and as a repository for heat in the summer.
In the winter, the fluid passing through the underground (or underwater) loops of piping is warmed by the Earth’s heat. The collected heat is extracted and concentrated by the heat pump, and distributed through the building’s ductwork.
To cool the building in the summer, this process is reversed — the heat pump moves heat from the indoor air into the underground loops, where it is transferred to the relatively cooler ground. The heat removed from the indoor air during the summer can also be used to produce some of your hot water, or to heat swimming pools, instead of transferring it to the ground.
Types of GHP Systems
Geothermal heat pumps are generally classified as “closed-loop” or “open-loop” systems based on the type of ground loop that they use:
Closed-loop systems. Closed-loop systems circulate a solution of water and antifreeze through a series of sealed loops of piping. The loops can be installed in the ground horizontally or vertically, or they can be placed in a body of water, such as a pond.
Open-loop systems. Open-loop systems circulate water drawn from a ground or surface water source. Once the heat has been transferred into or out of the water, the water is returned to a well or surface discharge (instead of being recirculated through the system). Open-loop systems are not recommended for residential use.
A Geothermal Heat Pump’s Main Components
The Evaporator – (e.g. the squiggly thing in the cold part of your fridge) takes the heat from the water in the ground loop;
The Compressor – (this is what makes the noise in a fridge) moves the refrigerant round the heat pump and compresses the gaseous refrigerant to the temperature needed for the heat distribution circuit;
The Condenser – (the hot part at the back of your fridge) gives up heat to a hot water tank that feeds
the distribution system.
Advantages of geothermal heat pump systems:
- A 25 to 40 percent reduction in heating and cooling costs
- Standard, simple controls
- No need for a highly specialized chiller technician or boiler operator
- Highly durable piping (the life expectancy is between 30 and 50 years)
- No high-maintenance, freezing-prone cooling tower
- No boiler to clean or maintain
- No air conditioning equipment on roof to cause leaks
- No harmful chemicals
- No danger of fire, asphyxiation, or explosion from coal, gas, or oil
- Nothing outside to vandalize or steal
- No central system to fail or shut down the entire building.
The geothermal heat pump includes three principal components:
- Geothermal earth connection subsystem
- Geothermal heat pump subsystem
- Geothermal heat distribution subsystem.
Geothermal Earth Connection
Using the Earth as a heat source/sink, a series of pipes, commonly called a “loop,” is buried in the ground near the building to be heated and cooled. The loop can be buried either vertically or horizontally. A pump circulates a fluid (water, or a mixture of water and antifreeze) that absorbs heat from, or relinquishes heat to, the surrounding soil, depending on whether the ambient air is colder or warmer than the soil.
Heat Pump Subsystem
For heating, a geothermal heat pump removes the heat from the fluid in the Earth connection, concentrates it, and then transfers it to the building. For cooling, the process is reversed.
Heat Distribution Subsystem
Conventional ductwork is generally used to distribute heated or cooled air from the geothermal heat pump throughout the building.
Residential Hot Water