On Wednesday, we visited Hafslund Energy which provides district heating for the city of Oslo, Norway. I loved visiting the district heating plant because we do not have an equivalent system within the United States so we got to learn about something new.
At Colgate, we have a similar system in which there is one heating plant that is responsible for heating the entire campus. In the same respect, the Hafslund Energy is responsible for heating apartment and commercial buildings in Oslo. District heating works by heating water in a central plant, and then circulating the hot water (just over boiling temperature because it is under pressure) throughout the pipes within the network. Once inside the building, the hot water runs through the pipes, radiates heat and thus heats the building.
In order to heat the water, Hafslund burns residential and industrial waste primarily along with wood pellets, electricity, and oil if it gets cold enough. This entire system is responsible for both space heating and hot water heating within the buildings that use it. After learning about the district heating system in a lecture format, we got to take a tour of the district heating plant. Steffen showed us multiple components of the entire heating system which helped solidify everything that we had just learned.
There are many benefits to a centralized heating plant. Steffen mentioned that one of the biggest benefits of central heating is that is uses completely renewable resources. Geothermal heating pumps are not an option in densely packed commercial buildings (which are the main consumers of district heating). With district heating, the primary source of energy is waste, then wood and electricity which are both renewable sources as well. Additionally, district heating’s flexibility between waste, wood, electricity, and oil allows multiple sources of energy to be used to ensure energy security as discussed in MacKay. District heating also eliminates the need for a hot water heater within a building. By eliminating a hot water heater, energy is saved because there is no energy being put into keeping the water hot while it is not in use.
A possible setback to a district heating system would be that there is reduced efficiency because hot water must travel from the plant to the building possibly across Oslo, and heat is lost during journey. Because Hafslund realized this potential setback to the system, there are several steps the plant has taken in order to reduce heat loss as much as possible. The pipes carrying the hot water to buildings have very thick insulation with a high R value. As discussed in Wolfson, the higher the R value, the better the insulation and thus less heat loss. In addition to heavily insulating, Hafslund makes sure to seal the seams of the pipes to make sure no heat escapes through the seams.
Overall, we had a great day at Hafslund Energy and learned a lot about district heating!