District heating networks, as in Denmark, could transform UK energy landscape

Comment by Marcos DeCastro, director of consulting engineer company Crofton Design

District heating networks offer the opportunity to raise our energy efficiency, reduce carbon emissions and cut energy bills. With government backing and the will to succeed, it is a real, clean possibility, says Marcos DeCastro, director of Crofton Design:

The UK government is committed to reducing greenhouse gas emissions by at least 80% by 2050, relative to 1990 levels. To achieve this much more emphasis needs to be placed on installing district heating networks in the UK’s major cities, and that will require enabling legislation – sooner rather than later.

The general consensus is that new nuclear facilities are needed to decarbonise the UK’s electricity network. The government is looking at a broad range of options (2050 Pathway & Carbon Plan), but UK citizens must decide whether they want a nuclear or a renewables world.

It is useful to look at how Denmark and Germany dealt with the 1979 oil crisis. Initially Germany increased production of nuclear facilities, while Denmark banned nuclear and increased renewables. However, in 1998 the Germans changed tack and also banned new nuclear plants. The Danish remained on the renewables course; indeed their 2050 plan includes increasing renewables and recognises the benefits this may have on green energy exports.

What has this to do with the need for district heating networks in the UK? Well, the nuclear route makes it increasingly difficult for renewables and district heating networks to be an option. The government’s own research shows that over 50% of UK energy is used for heating. Further it finds that heat networks could supply up to 14% of the UK heat demand, and 50% of this is in areas dense enough to make heat networks economically viable. So there is a serious case to start developing networks in UK cities.

Advantages of district heating networks
District heating networks carry significant advantages. First, supply and demand of energy can be managed more efficiently, because networks provide both thermal and electrical demand (if combined heat and power is used) at a local and district level. Local and district CHP and renewable plants, serving local and district heating networks, could operate in much the same way at the government is suggesting an electricity smart grid might work, where PV arrays would feed into the network.

Research from Imperial College shows that electricity demand throughout the year is fairly constant at around 50GW on average, while heat demand swings from 75GW in summer to up to 300GW in winter.

Hydroelectric dams store large amounts of electrical energy but the UK has very few methods for storing and delivering thermal energy. But a heat network could connect the thermal energy with the UK’s generation facilities at a local, district and perhaps even a regional level.

And networks could reduce peak electrical demand by cooling buildings using absorption chillers – run off heat networks – rather than traditional electric-based systems.

In addition, district heating networks feeding off renewable technologies such as solar thermal, biomass and waste could dramatically reduce CO2 emissions and potentially significantly reducing the UK’s reliance on volatile global energy markets.

Development issues
However, the UK heat network is not sufficiently developed. As well as the investment needed, installing the necessary pipework for a complete system in London alone would probably take 20-30 years. All the more reason to start now.

Over the last three decades Denmark has gone from being an energy intensive country, to very low carbon today, which is largely due to district heating networks. Its similar climate to the UK suggests that a district heating network would work here too.

We have the expertise and know how to start installing district heating networks in our major cities immediately. But despite various guidelines and papers on the issue from DECC, nothing is moving forward very quickly. It is one thing to say local authorities should have the necessary funding; the government must legislate to get the whole process going.

The Danish government kicked off its process 30 years ago by introducing a Waste Heat Act. This led to the installation of district heating networks in Danish cities – Danish local governments were charged with zoning areas that generated excess heat and those that required extra heat, so a network could be planned and heat stored and redistributed accordingly.

Local authorities were funded partly by central government, and partly through their own arrangements. Co-operatives were also set up, where groups of residents were encouraged to club together to pay for the necessary infrastructure to connect them to the network. Today 63% of Danish residential housing is connected to district heating networks.

Moving ahead
A large capital cost means funding is the main issue in the UK. One option would be to raise money via very small increases in council tax. It might be a tough sell at first, but in the long term the taxpayer would benefit from a lower carbon economy.

With the London Plan 10 years ago, the Greater London Authority (GLA) made a start in the UK by ensuring that most residential schemes developed in the capital from that point on would have the necessary infrastructure to connect to a district heating network. However, there is no regulation relating to older, existing residential properties, and no network yet to connect them.

Our priority must be to start building district heating networks in the UK’s largest cities, and the government has to legislate to kick start this process and establish a national district heating board, similar to the Electrical (Supply) Act 1926 and the creation of the Central Electricity Board.