Student research pinpoints room for improvement in heat networks

PhD students in Sweden are, through their research, identifying the impact of a variety of energy efficiency measures in the country’s district heating networks and the resulting environmental impact.

Chris Bales, Professor of Energy Technology at Dalarna University (right) told Decentralized Energy of two elements to the current research, which are bearing fruit.
Chris Bales, Professor of Energy Technology at Dalorna University
The studies are taking place within two different doctoral schools, one covering Sweden called Reesbe, and looking at energy efficiency measures in a district heating environment, which involves 21 PhD students scattered across different universities with four companies.

The other called SHINE is an international research school with 13 PhD students, of which six are focusing on how solar-thermal integrates into district heating. That project is funded by the EU Marie Curie programme and at eight different universities.

“In one of these projects we have somebody employed both by the housing company but also paid for by the district heating company, both of which are owned by the municipality. We are chiefly looking at the conflict of interest in those different companies having the same owner.”

“Students are looking at what the impact on the district heating network is like for energy efficiency measures in an individual building or group of buildings, what is the knock on effect for the district heating system is and what is the environmental impact when you look at the bigger system and not just the building itself.”

“The majority of Swedish towns have district heat networks and they are not owned by big utilities, they are owned by municipalities. They are run at a profit so the profit goes to the municipality as an income stream. These utilities are of small scale typically.”

One of the issues arising is that when there is a high level of renewables and waste heat in a heat network, the energy efficiency measures in the building don’t have as big an impact as they would with a high carbon content fuel.

“In some cases at certain times of the year they can even lead to increases in C02 due to knock on effects on the electric grid and imports and exports from different countries ” it’s a more complex situation when you have a high extent of renewables.”

There is also an issue about how environmental impacts for energy from waste are allocated within district heating.

“For primary energy and greenhouse emissions, waste incineration and recovery of waste heat from industry there are different definitions of how much of the energy, used in the base industry, where you are getting the heat from, is then apportioned to the district heat?

“The students found that because of the use of different definitions there are different results in the environmental impact of energy efficiency measures in buildings. So there is a need for harmonisation of these different types of definitions, methods and the use of statistics.”

“There’s a basic principle for how you allocate waste incineration and waste heat from industry, ” says Bales. “At present, it’s also possible for politicians to choose which way they want to go and that’s not good.”

“There should be a fundamental process. The logical process is that the original user of the resource should be the one to pay for ità‚ and have the environmental impact allocated to it and if the waste can be used for incineration ” that’s just an added benefit.

“We have these challenges some of which were known before the research started but the depths and breadth weren’t really known.”

Bales added that he would be in favour of this issue being regulated at an international stage.

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