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Gårsta just outside Hammenhög in Österlen is a major pig breeding farm. 24,000 pigs are born every year in the new facility, an operation that is normally very energy-consuming.“Piglets need to be kept warm”, says owner Johan Nilsson. Traditionally they have a bed of straw and a heat lamp, but this is a very inefﬁcient solution. Therefore, underﬂoor heating was introduced a few years ago. “The alternative for most people is to burn straw”, says Johan Nilsson.“But this requires a special building to be built, and also requires a lot of man and machine hours to take care of it all. In addition, it can run out, something that is not always noticed until it’s too late.
When Gårstad’s large facility was built, they chose to invest in ground source heating - but without the ground! Instead of boring holes or digging ditches, they chose to put the collector hose in the castings under the slurry gutters. 8,000 metres in total.”Pig slurry has a temperature of about 37 degrees when it is fresh,” says Lars-Erik Bengtsson at the local plumber, Bengtsson Smide & VVS, who planned and carried out the installation.“It heats the surrounding concrete to about 15 degrees, which is extremely ef.cient because the system only needs to be a temperature of around 40 degrees.” The heat extracted from the gutters does not affect the quality of the slurry. The slightly lowered temperature causes the evaporation of ammonia and other gases to decrease slightly.The hoses are located in 16 different parts of the building that house 50 sows each, and are gathered in a huge coil for three NIBE FIGHTER 1310s, each of 30 kW output.
“The pumps have run for about 140,000 hours combined,” says Lars-Erik, “and during that time have consumed 570,000 kWh. But at the same time they have delivered nearly 3.3 million kWh of heat. That’s a heating factor of 5.5!” More than 2.5 gigawatt hours have been extracted from the slurry. Over 4.5 years! If one calculates at an average electricity price of 0.80 SEK per unit, it means a saving of nearly 2 million SEK.“This kind of installation costs about 600,000 SEK, so the entire investment is largely paid for after a year and a half!”