Answer: Geothermal energy is not suitable for domestic use, and isn’t readily available in the UK. Theoretically this is a very efficient source of heat, but it’s not practical. Ground source heat pumps are feasible for UK homeowners, allowing them to heat their property renewably.
“Geothermal energy” is an oft-misunderstood phrase. It is energy sourced through heat omitting from the core of the earth, and is considered clean and sustainable. Geothermal energy can be obtained at shallower depths in areas with active geology (geysers, volcanoes, hot springs and so on) – as in Iceland. Geothermal heat plants generate electricity by piping up hot steam and water from deep underground.
However, in the UK it would require drilling 500 to 2,500 square metres in order to achieve the required heat. Therefore, the complexity and costs of the process means it is unsuitable for domestic use in the UK.
What is feasible, however, is extracting heat from the sun that is absorbed in the soil; a natural and consistent source of heat. This is called ground source heat, mistakenly labelled in some circles as geothermal. This heat is obtained via ground source heat pumps (GSHPs). It works by simply transferring heat between the ground and your home’s heating system. Geothermal heating systems and ground source heat pumps are very different, but both have pros and cons.
Smart Renewable Heat specialises in ground source heat pumps.
With this in mind, we’ve listed the advantages and disadvantages of geothermal energy and ground source heat for domestic purposes.
Geothermal energy is mostly considered as environmentally friendly. The carbon footprint of a system or plant is comparatively small; producing just one-eighth of the carbon emissions of a typical coal power plant creating the same amount of electricity. Furthermore, reservoirs are naturally replenished, providing a long-term and renewable source of energy. Scientists say that this source can be available for another 4-5 billion years.
Geothermal energy is highly stable and reliable. The power output can be predicted much more accurately than other forms of power production, including solar and wind – both of which are subject to low-energy fluctuations. Geothermal energy plants are therefore great for meeting the base load energy demand. They also have a high capacity factor.
There is enormous potential in using geothermal energy, although not for domestic sites. The heat at the earth’s core can reach temperatures of up to 6000 degrees celsius, and can produce extraordinary amounts of electricity and sustainable energy. Estimates for geothermal energy plants range between 0.035 to 2 terawatts (TW); much more than we’re currently on track to tap.
Also read: Is geothermal heating renewable?
The greatest obstacle is that the use of geothermal energy is incredibly location-specific. It is not readily available in the UK and not feasible to produce and use. Furthermore, if the resource is transported over long distances, it is highly cost ineffective and significant energy losses can be incurred if transported over hot water. Property owners in the UK therefore look for ground source heat pumps as an alternative.
Although they are mostly sustainable, there are some environmental issues with geothermal energy. There are some greenhouse gases below the earth’s surface that can migrate into the atmosphere. This is particularly the case around geothermal energy power plants, which are said to emit sulfur dioxide and silica. Reservoirs also contain traces of toxic chemicals including arsenic, mercury and boron. Nonetheless, environmental impacts are far less than those incurred by coal and other fossil fuels, and using energy resources of this kind are encouraged.
Other than being a feasible sustainable energy source in the UK, there are several advantages.
Firstly, GSHPs are incredibly cost-effective. They are significantly cheaper to run than direct electric heaters, than oil burners, and than gas burners – because they’re fully-automated and only require minimal amounts of electricity for their most basic component: the compressor.
Furthermore, despite the fact that GSHPs may cost up to £20,000, they are a great long-term investment as households can make savings up to £1,400 a year. These savings can be continued for up to 50 years because GSHPs have a long-life span. As they provide a reliable and steady source of heat, these pumps can even increase the value of your property.
GSHPs run on energy from the ground, so just like geothermal energy plants, they provide a constant and infinite supply. GSHPs save on carbon emissions, and are officially classified as renewable. Even better is if a renewable source of electricity powers them, they can be completely emission-free!
Using GSHPs has other great advantages for your home. They are incredibly safe because there isn’t any combustion involved in the energy generating process, and there are no harmful emissions: so you can be worry-free. They are low-maintenance, simply requiring an annual health check by a qualified engineer.
Finally, the UK government provides incentives to assist with the installation of renewable heat systems. Homeowners, social and private landlords may be eligible for assistance through the Renewable Heat Incentive (RHI) scheme and these tariffs are higher for GSHPs than other forms of renewable technologies such as air source heat pumps.
Moreover, it is possible to receive financial assistance through the Home Energy Scotland Loan. These sorts of initiatives are making it easier for you to tap into this sustainable resource.
GSHPs have a relatively high upfront cost and the installation process requires careful planning to understand the local geology, the movement of heat, and your heating requirements.
Furthermore, it is critical to acquire the necessary planning permissions: this is almost never required but it’s always worth checking with your local authority to be sure. Some homeowners opt for air source heat pumps (ASHPs) instead, which transfer heat from the outside air.
ASHPs are still a renewable source of heat, they are cheaper, easier to install and take up less ground space. Despite this, GSHPs are generally more efficient than ASHPs – particularly in the winter when outside air temperatures are very cold. Therefore, although GSHPs can save you a lot of money and good planning will allow you to yield enormous benefits in the long-term.
Another important consideration for GSHPs is any soil limitations. The rate of heat transfer depends on the quality of the surrounding soil: the mineral composition, organic matter content and volume fractions of air and water. Soils with higher water content and higher bulk density make better conductors. Yet, this important consideration is part of the initial planning process.
Lastly, GSHPs are not 100% sustainable, due to the fluids used for heat transfer and the reliance on electricity for operation. No fear: this can be mitigated by using biodegradable fluids, and coupled with a renewable electricity source such as solar panels. Despite this, GSHPs are far more sustainable than any other non-renewable source of heat.
Getting heat from the ground is a great opportunity, because of its sustainability and efficiency.
Whilst geothermal energy is not feasible for domestic use in the UK, ground source heat pumps are ready and available. There are always pros and cons to consider before installing a ground source heat pump, but the benefits are superb for homeowners that want to enjoy cost-savings and reduced carbon emissions.
For more information about installing a ground source heat pump, request a quote today.
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