– It is a very smart use of surplus energy. When there is an energy crisis in Europe, we must use energy wisely. That’s what Jørgen Nordahl in Statkraft says. We meet him inside the treatment plant at Ladehammeren in Trondheim. Among the pools with sewage for approximately half the city’s population, he tells about the system that makes it possible to use one’s excrement to heat the neighbour’s apartment. Sedimentation basin inside the mountain at the Ladehammeren treatment plant in Trondheim. Photo: Statkraft – We are lucky in Trondheim to have a district heating network that has been built over the past 40 years and 25 miles of district heating network that covers most of the city, says Nordahl. Mytji drit and mytji heat The process of turning the dobe search into heat starts down here, 200 meters into the mountain. Stian Grønnesby is process operator and explains: – First we sort out toilet paper and things like that. It is sent for incineration. We also remove particles from the water. We make biofertilizer and biogas from that mass. Jørgen Nordahl in Statkraft. Photo: Statkraft And it is this gas that is used in the district heating plant. The sludge that is separated in the treatment plant is both heated and cooled before being kept in airtight tanks for a minimum of 15 days. Bacteria break down organic matter and in this process biogas is formed. This gas fires a boiler that boils water and it is this water that, among other things, goes to district heating. The energy from here creates enough heat for approximately 1,000 apartments, according to Statkraft. Valuable raw material It is not just energy in the form of heat that comes out of treatment plants in Norwegian municipalities. Another product is biofertiliser. A nutritious mass full of phosphorus, among other things. – We take waste and turn it into a resource. Both as energy, but it is perhaps even more important to take care of the nutrients, says Jens Måge. He is a specialist adviser at Waste Norway and has a good idea of what resources we can get out of our waste. – What we take out of the soil as food contains a lot of valuable nutrients that must be returned and used for new food production. If not, we deplete the soil. Måge says agriculture is good at getting a lot of food out of our soil, but points out that it is not sustainable to add artificial fertilizers. – Fertilizers come from fossil resources. Especially phosphorus, which is a scarce resource worldwide, he says. Jens Måge in Waste Norway. Photo: Avfall Norge All phosphorus for fertilizer in Norway is imported and the largest sources are Russia, China and Morocco. After Russia attacked Ukraine earlier this year, trade has been cut. – This means that we are very vulnerable and we are talking about the fact that we have a fertilizer crisis. Thus, this becomes a very important part of a biogas plant. The adviser believes that we need to get away from the idea that this is a residue and a by-product. He calls the sludge, or biofertiliser, i.e. what is left of treated sewage a main product, which is extremely important to utilise. – We have to go from seeing waste as something disgusting, to seeing it as a resource. This also applies to the waste we humans ourselves produce every time we go to the toilet, concludes Måge. The district heating system at Ladehammeren. Photo: Statkraft
ttn-69
Sewage in Trondheim becomes district heating – enough energy to heat a thousand apartments – news Trøndelag
