Are District Heating Networks as Efficient as we Think?

When investing in renewable heating, it’s important to know what efficiency your new system is going to run at. Some recent examples have shown that many district heating networks run at far lower efficiencies than expected- causing their eco credentials to be called into question.

district heating

A district heating network is a localized way of heating a number of buildings at once, using a series of steam or water-carrying pumps. They can be used to heat anything from a small cluster of holiday homes to huge areas of cities, as demonstrated in Stockholm. Here in the UK, networks are usually powered by biomass, and although less than 2% of the country’s heat demand is provided in this way, it has been repeatedly hailed as an up-and-coming technology and repeatedly recieves support from the government’s RHI scheme.

But, just as a car’s fuel economy is often significantly lower than quoted by the manufacturer, the efficiency that many smaller district heating networks has been shown to be much lower in practice than in theory.

Many owners of district heating network systems have claimed that, though their boilers are apparently running at a high efficiency, only 45-60% of heat is reaching the building where it is needed. This waste of heat is enough to negate the positive effects of using biomass and drive up the carbon emissions of such a system.

 Investigating the issues

 Currently, the extent to which district heating networks are running at low efficiencies is unclear, and an investigation from Ofgem would be required to find out if the reported poor rates are anomalies or a genuine trend. If it was found out to be the latter, the role of district heating networks within the role of the RHI would be called into question.

A spokeswoman from Ofgem commented: “As administrator of the scheme, Ofgem does collect data on efficiency. This is analysed for payment purposes and to ensure eligibility requirements of the scheme are met.”

 Why might the efficiency of district heating networks be slipping?

 Regardless of the role they play within the RHI, most customers will be eager to know the causes for the poor efficiency in certain district heating networks. One reason could be the way in which the use of these systems varies between summer and winter. While heat is constantly needed during the winter months for heating the entire building, it is only required for water during the summer, and while unused water sits in the pipes or is recirculated, it cools down.

If this problem is proven to be the case amongst the majority of smaller district heating networks, we may be seeing a few alterations in the coming months within the RHI in regards to these systems. While they may encourage communities to reconsider their energy use and group together to make positive changes, small-scale district heating networks might not have what it takes to reduce carbon emissions in the long-run.

Image sourced: Mike1024

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