Ground source heat pumps are hugely popular in Germany and Scandinavia but are relatively scarce in the UK. NCE meets the experts hoping to redress this imbalance.
At the United Nation’s climate change summit in Copenhagen last December, Britain was set some tough challenges to reduce its carbon emissions.
An increase in microgeneration - where individual homes and businesses generate energy to meet their own needs - was declared essential to a low-carbon, energy-stable future.
One source of microgeneration in particular has been set an ambitious target. Ground source heat pump technology (GSHP) is currently installed in 20,000 homes throughout the UK. At Copenhagen it was suggested that the figure should be closer to 450,000 by 2020.
GSHPs extract heat from the earth to heat water. They work by circulating a mixture of water and antifreeze around a ground loop, which can be buried a few metres below the ground, or placed deeper in a borehole. As liquid travels around the loop it absorbs heat from the ground, before returning to the surface where it is used in central heating and hot water systems. As the ground below the surface stays at a more or less constant temperature throughout the year, a pump can be in constant use.
The UK has a long way to go to deliver the installation targets set in Copenhagen and is far behind Scandinavia, Germany and North America in the development of this sustainable energy source. One area of concern in particular is the lack of engineering and construction expertise within the microgeneration sector.
“The level of knowledge, skills and expertise available in the UK really needs to develop if we are to deliver the growth that is essential to deliver these high expectations,” says GSHP specialist, Loopmaster Europe co-director Iain Howley. “While we have come far, there is so much more work to be done to raise the level of understanding across the construction industry to acceptable standards.”
Environment Agency technical specialist Jenny Thomas says the Agency is an enthusiastic supporter of GSHPs. Closed loop systems are not currently regulated by the Agency, a situation that differs considerably from practices in other European countries.
The publication of good practice guidelines in what is for many uncharted territory is, she says, a priority for the organisation. Thomas says that the Agency is also working towards “simplifying regulations and speeding up the cumbersome application process for a pump”.
“Our job is to make the design fit the energy requirement, not just the budget”
In 1984, Sweden was in a similar position to the UK in terms of its spread of energy sources. Today, GSHP’s represent a big business, with some 60% of Swedish home owners citing it as a requirement when purchasing a house. On a larger, more commercial scale, Arlanda airport, airline SAS’s headquarters building and retail giant IKEA have installed ground source heat systems.
The CO2 savings can be significant -maximum annual CO2 savings for an average household have been cited as 7t if replacing an electric heating system, 6.5t if replacing solid fuel, 1.8t if replacing oil and 1.2t if replacing gas.
There is also the rising price of gas and oil to consider.
Reading University geotechnical expert professor Rayner Mayer has written papers highlighting the future costs of oil and gas supplies. “What price do you put on gas and oil in 10 years time?” he asks.
“Oil supply could have already peaked and we expect the gas supply to peak in around 10 years as well. Twenty-five per cent of the schools in the Reading area alone are currently oil heated. Schools and universities will simply not be able to afford to heat and cool themsleves with their current systems.”
Loopmaster Europe co-director Andy Howley, Iain Howley’s brother, says that there is still time for the technology to improve, and the knowledge base to grow. Their company is concentrating on understanding the impact of different variables in ensuring that their designs deliver their energy expectations.
“Each site has its own geology, the chalk aquifers of the London Basin are a case in point” says Howley. “The old rule of thumb measurements are just not acceptable.
“Each design needs to take into account all variables if a system is to deliver to maximum potential. It’s our job to make the design fit the energy requirements, not just the budget.”