A growing number of European pig farmers are turning to slurry, a natural renewable resource, to help save on fuel bills.
One of Sweden’s largest pig breeding farms, which produces up to 24,000 pigs a year, has devised an innovative way to recycle heat from slurry to keep its sheds warm and save thousands of krona at the same time.
Alternative heating method
Farmer Johan Nilsson built his new facility at Gårsta near Őstra Ingelstad in south Sweden, and wanted to move away from the traditional way of keeping the piglets warms by using straw beds and heat lamps. Instead, he invested in an under-floor heating system, using ground source heat pumps – even though he didn’t have the ground to provide the heat.
Instead of boring hoses, or digging trenches, installer Lars-Erik Bengstsson put the heat pump’s collector hoses in the concrete castings under the slurry gutters. He was following the example set by some Danish pig farmers, who have also experimented with heat pumps, inserting the coils inside their slurry tanks to capture and recycle the heat from them for their pig buildings.
“Pig slurry has a temperature of about 37 degrees C when it is fresh,” he said. “It heats the surrounding concrete to about 15 degrees C, which is extremely efficient.”
The hoses were located in 16 different parts of the new building and gathered together in a large coil for three NIBE Fighter 1310 heat pumps, each with an output of 30kW.
“They were installed about four years ago and have run for a combined total of 140,000 hours and during that time they have consumed 570,000 kWh,” said Bengstsson. “But at the same time, they have delivered nearly 3.3 million kWh. That’s a heating factor of 5.5, with more than 2.5 gigawatt hours extracted from the slurry over the four-year period.
“And the heat pumps just keep running and running and running,” said a happy Nilsson. “One small adjustment was required at the very beginning, but since then it has been a question of pressing some menu buttons and seeing how much money has been saved.”
Anaerobic digestion power
Pig producers in other parts of Europe, including the Netherlands, Germany and Italy also are using slurry and other natural resources to provide energy for their farms, or to sell off to the public.
German pig producer/businessman, Ulrich Wessel-Ellermann developed his own small gas network around his farm at Bohmte in Lower Saxony. Wessel-Ellermann commissioned anaerobic digestion, AD, plant manufacturer EnviTec to build a state-of-the-art plant to supply heat and power for his farm, a local engineering shop, agribusiness and a sports center via three combined heat and power (CHP) plants.
Wessel-Ellermann explained that by creating a microgas network, he was able to transport the gas cheaply over gas lines, keeping heat losses to a minimum and increasing the plant’s overall energy efficiency.
He is using liquid pig manure combined with maize and rye silage for feedstock to produce the biogas that generates heat and electricity for his farm and the other nearby businesses.
The liquid remains are used in the fields as a liquid fertilizer, while the dried material is pressed into pellets and sold off as high-grade fertilizer.
A sophisticated computer program manages the entire operation and the plant is being used by the manufacturer as a research facility.
“Thanks to three-dimensional visualization and numerous ways to record results, we really are in an ideal position to precisely examine biogas production and to continue to perfect it,” he said.
In Italy, EnviTec has built another AD plant that is using slurry from 25,000 pigs on nearby farms as feedstock to produce biogas to generate electricity for the country’s national grid.
Wind, solar power
Heat is not the only renewable resource being exploited by European pig producers. In England, a number of pig farmers are harnessing the wind and the sun to help them reduce rising fuel bills.
Suffolk pig and poultry farmer, Simon Brice and his wife Alison have resorted to using both wind power and solar energy to help them restore their business after a devastating fire tore through their pig sheds last year.
Caused by an electrical fault in the piggery’s wet feeding system, the early morning fire destroyed the pig shed and killed more than 300 pigs – part of a 1,500 herd under contract to finish – on the site in Suffolk, on the eastern side of the country.
At first, Brice had to rely on a back-up generator that provided enough power for the hen house. However, they were determined to rebuild the business back up to it full capacity of 3,000 pigs (which account for about 80% of their business) and more than 4,000 chickens. They immediately looked into ways in which they could save some of the money lost – and become more efficient and sustainable for the future, as well.
“We had to depopulate after the fire and having researched renewable energy systems before, I decided to invest in some form of wind energy, because that seemed to offer one of the quickest ways to make a noticeable impact,” said Brice.
After a year, the pig business is back up and running at full speed with the introduction of three small-scale 5 kilowatt wind turbines, which stand 15 meters high, a new pig shed and the first batch of pigs. It also has reached full capacity on the poultry side, with 4,000 chickens.
A spokesman for the installer, Windcrop Ltd, commented the 5 kilowatt generators were designed to reduce installation time, minimize the ground space required and make planning permission easier to obtain.
“In a typical installation with around 5 meters per second average wind speed, these systems will produce approximately 8,000kWh of electricity each year. In a high wind area, this could go as high as 20,000kWh,” he said.
According to Brice, “Although I haven’t had a bill through yet, my digital meter reader shows that the wind turbines have already cut my electricity costs by at least half and I am now working with another company to put some solar panels on the buildings in the near future.”
He added that his plans to rebuild the farm with a particular focus on energy conservation and reducing its carbon footprint, which as garnered a positive reaction from neighboring farmers.
“Several of them have commented on how good the turbines look, although most of them have also asked whether I‘ve found them to be noisy. They are about 100 meters from the farm house, but I can honestly say that even on a really windy day the sound of the trees rustling and the buildings creaking is noisier than the turbines.”
