From Guest Blogger Dixie Somers: The Benefits and Future of Geothermal Energy
The future of energy is changing, and geothermal is emerging as a viable and attractive option for homeowners. Geothermal energy has many benefits, and it is a renewable source of energy. For the sustainable-conscious families, geothermal energy is an environmentally friendly option; it doesn’t produce any greenhouse gases that can damage the atmosphere. Here is some important information about geothermal energy.
What is Geothermal Energy?
Geothermal energy comes from the Earth. Under the Earth’s surface, the temperature remains at a steady 50 to 60 degrees. In the winter, the pump takes this heat from the earth and pumps it into the home. In the summertime, the heat pump can move air from the indoor air into the heat exchanger instead, making the air cooler. This source of energy can be found nearly anywhere.
Benefits of Geothermal Energy
There are several benefits to using geothermal energy, including:
- It is environmentally friendly; hardly any emissions are created by geothermal fields.
- Families can achieve up to 80% savings over conventional energy usage.
- Reservoirs are naturally replenished; geothermal energy is a renewable energy source.
- Geothermal energy is a constant source of energy, and it isn’t dependent on the weather.
- Jobs are being created in the geothermal energy industry.
Efficiency of Geothermal Energy
As a homeowner, one of your main concerns will be the efficiency of geothermal energy. Homeowners should be happy to know that it is considered one of the most energy efficient options. High-efficiency systems are around 48% more efficient than gas furnaces and 75% more efficient than oil furnaces. Geothermal heat pumps are about 400% efficient. Of course, this higher efficiency translates into direct savings for you on energy bills. A more efficient system could easily pay for itself in savings. If you have questions about your own heating system’s efficiency, contact Cape Fear Air Conditioning & Heating Co., Inc. or another HVAC company for an inspection.
Price of Geothermal Heating and Cooling
One of the top questions homeowners have is the cost of installing a geothermal heating and cooling system in their home. Currently, federal and state governments offer incentives for geothermal systems of around 30%. This makes the cost more manageable for homeowners. Based on the size of the house, a geothermal HVAC system starts at about $5,000 per ton. A house can need one to nine tons; obviously, smaller house will need less and vice-versa.
The Future of Geothermal Energy
As more people are looking for cost effective and environmentally safe options for their home, geothermal heating and cooling will continue to grow. Over the next decade, experts believe we will see rapid growth in the geothermal energy industry. New jobs will be created, and geothermal energy may be the solution to the world’s need for energy. For now, it is a safe, efficient option for homeowners.
From the article:
“Geothermal heat pumps are about 400% efficient.”
Heat pumps and refrigeration are not measured in percent efficiency except perhaps by sales personnel. The correct unit is coefficient of performance, which is abbreviated COP. It is similar to EER, but with a difference.
EER is a hybrid unit which is not used by engineers. It uses BTUs for output and watts for input. COP uses watts for both input and output which gives a result which is more intuitive and easier to understand.
An air conditioner which uses 2000 watts of electricity to produce 20,000 watts of cooling would have a COP of 10. Similarly, a heat pumps which uses 2000 watts of electricity and produces 8000 watts of cooling would have a COP of 4. That would indicate that the heat pump would use 1/4 as mush power as resistance heating which would produce the same amount of heat.
COP us used for BOTH heating and cooling. It would be impossible to use percent for cooling and, although it would be possible to use it for heating, why not use the same units for both? That way it is possible to compare efficiency for cooling with efficiency for heating since the same unit is used for both.
This article explains it more thoroughly:
https://en.wikipedia.org/wiki/Coefficient_of_performance
First this is a ground source heat pump installation so it is not emissions free. It is however significantly more efficient than a boiler, and a great deal more efficient than resistance heating.
Individual home units operate a closed cycle meaning that they circulate a water antifreeze mix through an underground heat exchanger made up of coils of pipe – which may be buried like in the image above, or inserted into boreholes.
An ideal unit would be able to heat water at the same time as it chills your home – effectively recovering unwanted heat from the home to further boost efficiency.
In new developments the better solution would be to install district heating and cooling using high capacity shared units.
Such units tend to use open systems linked to a local aquifer and have one or more extraction wells and a similar number of injection wells. Water is extracted from the aquifer, heat is extracted from the water or dumped into it depending whether heating or cooling is at that moment the dominant load, and the used water is then injected back into the aquifer.
Such systems when developed for blocks of flats, or housing developments with district heating have far lower costs per housing unit than individual household systems.
Further advantages of the shared system approach are.
1. It becomes highly cost effective to add large tanks for hot or cold storage enabling the use of off peak electricity so lowering operating costs.
2. It is far easier to run a hybrid system with for example an array of solar water heaters feeding the hot tank to boost overall system efficiency.
3. Such a system can enable a very high percentage of self consumption from a community PV array of wind turbine as power can be constructively used when available rather than exported to the grid.
4. Such a system could potentially participate in grid regulation markets – especially on larger developments as the heat pumps can be turned on or off at a moment’s notice to support the power grid without compromising heating or cooling service – which continues using stored reserves.
For larger systems in geologically active zones, it is possible to drill down to hot water aquifers and use these either for district heating, or for both power generation and heat. Around 90% of Iceland’s buildings are heated this way, whilst in China there is a district heating system running off geological heat serving 1 million people.
Note:- In the US people tend to refer to geothermal heat pumps to mean systems using what is effectively inter-seasonal storage of solar heat extracted from the soil. Europeans would refer to this as ground source heat pumps and reserve the term geothermal for systems where the heat is geological in origin rather than upgraded stored solar heat extracted with a heat pump.
My house has radiant floor heating which uses gas heated water at a temperature not exceeding 120F (49C). Probably that would work well with a geothermal heat pump or, considering that the normal low temperature in January is about 25F (-13C), an air source heat pump.
Radiant floor heating using low temperature water works very well with heat pumps, as the efficiency of a heat pump is better when the required temperature rise is less.
You live in an area where it gets quite cold in January so bear in mind that the efficiency of an air source heat pump reduces the lower the source temperature, and most do not work at all below minus 15 centigrade – so that when you need heat most is the time when it is least available, and in the extreme case, your system might cut out altogether in exceptionally cold periods.
Note:- Your temperature conversion is off 25F is around minus 3 centigrade, so not sure if you typically get a moderate night frost in January, or quite a severe one (minus 13 centigrade is just a little warmer than a domestic freezer)
A ground source heat pump would be a more efficient and reliable heat source during the coldest part of the year albeit at considerably higher installation cost.
You might consider an air source heat pump to provide the majority of heating through spring and autumn when the heat load is less severe and day time temperatures are higher, and retain the gas boiler for top up heat in the coldest weather. That way, you can down-size the system and somewhat moderate your emissions whilst keeping the capital cost manageable.
If you live in a sunny but cold area, you might also consider either solar air heating (Very low costs are possible if you are prepared to make a DIY system) or alternatively use solar water heating to reduce the load on your boiler / heat pump.
Gary,
Probably the best approach from the efficiency standpoint would be to use an air source heat pump down to perhaps 25F and use gas below that. However, the complication is such that I would be very hesitant to do it. A failure of the complicated controls and pumps could be an expensive nuisance. I also have an indirect water heater and tying that into the system would cause extra complication. If such systems were in common use here, were proven to be reliable, and if local service personnel knew how to service them, it could be a good idea.
Ground source heat pumps for both heating and cooling work well all year. The problem is that the entire yard has to be dug up to lay the pipes.
It may be that a solar water heater would make sense. Another possibility would be to use rejected heat from the air conditioning to heat water; there is actually a device made to do that. Perhaps the two could be combined.
Check out this link:
http://www.homedepot.com/p/ZeroEnergy-Heat-Recovery-Water-Heater-System-Zero-Energy-ZE-TSHRU/203715807
I think that some of these things require more knowledge than most service personnel have.