Ground Source Heat Pumps
Ground source heat pumps are a form of renewable energy generator that absorb heat from the ground and use it to provide hot water and heating, primarily for domestic residences. Ground source heat pumps are one of three types of pump system, the others being air and water, and are perhaps the most efficient of the options, with an estimated 75% of domestic heating needs being met by the system.
In spite of this, ground source heat pumps are probably one of the most under utilised sustainable energy generators in the UK, although they are starting to grow in popularity and the government are expecting to see installation figures surpass the 2.5 million mark by 2025. However, at this rate the UK is still roughly 20 years behind other areas of Europe, most notably Sweden and other Northern European countries where ground source heat pumps are much more common.
Advantages of Ground Source Heat Pumps
For homeowners wanting to adopt a green lifestyle, the biggest advantage of a ground source heat pump is the ability to reduce carbon emissions. The exact environmental effect is dependent upon the type of fuel that is being replaced, and the efficiency of the system, but generally homeowners can expect a reduction of between 350 and 5410 kilograms of carbon dioxide per year.
An advantage that ground source heat pumps have over other forms of pump systems is that they're entirely hidden underground and, in most cases, planning permission is not required prior to installation. Furthermore, the temperature of the ground at the depth the pipes are typically laid remains quite stable all year round, so the systems are rarely, if ever, affected by the cold British winters.
Ground source heat pumps can provide steady and consistent heating that's adequate even in the most severe of conditions as long as your house is well insulated with as little air leakage as possible. It's especially suitable for underfloor heating which can usually increase traditional electricity costs quite significantly.
Maintenance of ground source heat pumps is virtually non-existent. They have a 20 year life span and usually come with a 10 year warranty, which emphasises their durability. An annual check is all that's needed, and with the pipes being underground there's no worry about damage from storms, ice or snow.
Disadvantages of Ground Source Heat Pumps
As with all power generators, whether that be fossil or renewable fuel, there are a few downsides. Obviously, sustainable fuels are not as efficient as fossil fuels. If they were, everyone would be using renewable energy. The main problem with heat pumps is that heat is absorbed at the very low temperature from the ground and then compressed, but this compression can't produce as high a temperature as a conventional boiler.
It will take longer for homes to heat up, and the radiators and water will never reach particularly high temperatures. During the winter, heating may need to be left running constantly to maintain warmth, which will use more energy than a central heating system would use.
Ground source heat pumps are also not completely carbon neutral. They need electricity to run. Of course, the electricity they use is far less than heating an entire property in this manner, but for those that really want to offset their carbon footprint, a different type of generator, perhaps solar panels, may be a better option. They're also far more efficient.
Finally, the installation process is rather involved, and a large area of land is required. It may not be suitable for those with small gardens, and is certainly not suitable for those with no garden at all. These systems are also not going to be very efficient in older homes with single glazed windows as too much heat could escape through air leaks. Getting an older home into a suitable state could increase costs substantially.
Ground Source Heat Pump Costs
Ground source heat pump systems can cost anywhere between £9,000 and £17,000 to install, so they're certainly not the cheapest renewable energy generators available. A good rule of thumb is that a system should cost around £1000 per kWh of energy. On top of this, there will be running costs for the electricity used to power the system. Although the exact amount will be dependent on the size of the system and the amount of energy produced, this will roughly be around £500 per year.
The high upfront costs can be a bit daunting for some homeowners, but there are a number of options available that can provide help towards the installation costs, as well as plans in place to provide ongoing financial assistance for new owners of sustainable energy systems.
Homeowners in England, Wales and Scotland with a ground source heat pump who do not rely on other heating methods such as a gas central heating system can apply for a Renewable Heat Premium Payment from the government. Under this scheme, you will receive a voucher worth £1000 prior to installation, and a further voucher worth £250 following a successful and approved installation.
From summer 2013, homeowners should also be eligible for the Renewable Heat Incentive which provides ongoing payment for a period of roughly 20 years to help out with running costs. Tariffs for this have yet to be confirmed, although businesses can already apply and receive a rate of 3.4 - 4.7 pence per kWh generated.
Local authorities can also offer grants and loans with competitive interest rates, though exactly what's available differs depending on location. It's always best to check to see what's on offer in your area.
Savings & Earnings
The average household producing 75% of their heating from a ground source heat pump can expect a saving of around £600 - £700 per year on energy bills. The introduction of phase 2 of the Renewable Heat Incentive in 2013 is estimated to pay out about £850 per year to individuals. Based on these figures, and the installation of a £10000 generator, the system could pay for itself within 7 years, leaving homeowners with an additional £1500 per year in pocket.
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