Can Danish district heating improve our energy security?

Date: 27 August 2014

Comment by Jim Coyle and Thomas Ruperto, Rupcoe:
You would be forgiven for thinking that district heating systems were only relevant in old communist-planned towns in places such as China and Russia; however, district heating is used in Denmark, a representative democracy that is also dependent on oil imports for heating. It is also growing in popularity in Great Britain.

During the 1973 oil crisis the people of Denmark experienced a very difficult winter. Denmark relied on oil imports for more than 90% of its energy and when oil prices rose significantly, as they did in 1973, people could no longer afford to heat their homes. In the winter of 1973 Danish factories had to suspend operations, while families were forced to huddle under blankets to stay warm.

This experience prompted Denmark to embark on a project to reduce its reliance on the international oil markets and one way in which did this was to develop its renewable energy industry with the introduction of more wind farms. Denmark has been the largest producer of wind power in the world ever since.

In addition to renewable energy, Denmark started building district heating systems. These are huge boilers that provide heating for whole areas of towns and villages. Heat is pumped through pipes, just as it is in a typical American home heating system, but on a scale similar to water and gas distribution.

The idea is really simple: rather than pumping gas to every home, where it is burned in small, inefficient heaters, the energy is burned in large boilers and the heat and hot water are distributed to local homes and businesses.

Surplus heat is used
Another ingenious feature of the Danish district heating systems is that surplus heat from electricity generating stations, factories, server farms and public transport networks is gathered and directed into the public heating network. This reduces waste, reduces the carbon footprint and, most importantly, means that less fuel is used.

Denmark’s district heating systems are currently supplying heat to 63% of homes in the country, which is now a net exporter of oil. It is estimated that Denmark will be able to continue to export oil until at least 2018.

The recycling of heat has also been investigated by other countries. According to a report by engineering consultancy BuroHappold, London’s wasted heat would provide heat for 70% of the city and massively reduce household energy bills if it could be captured and channeled into district heating systems.

Combined heat and power stations (CHP)
Countries can also save money by building combined heat and power stations. These are power stations that channel heat ‒ a by-product of generating electricity ‒ and add it to the district network.

Most power stations are only 30% to 50% efficient, with up to 70% of all energy used to generate electricity being completely wasted. CHP power stations are up to 90% efficient.

Plumbing networks
To accomplish this engineering feat, Denmark has a huge plumbing network running beneath its towns. Pipes collect heat from factories, transport systems and incinerators and combine it with heat generated from both standard and renewable sources, such as solar thermal energy, wind turbines, and traditional gas and coal power stations.

If America took a similar approach and created district heat and hot water systems, our own energy reserves could last for many more years to come and homeowners would not be faced with such high energy bills each winter.

The Guardian newspaper reports that the British government is already trying to build its own district heating networks. Around 2% of British homes are currently connected to district heating and it is hoped that 40% of homes will be connected by 2050.

District heating initiatives need to be implemented at a local level, which may be an advantage as community groups can work together to construct district heating plants. Some American companies have also already implemented district heating. Veolia Energy provides heating by way of steam, which can be integrated with any type of HVAC system.

Many people find this concept unworkable at first; however, we already deliver cold water, electricity, gas and telecommunications to homes, so why not deliver hot water and heat? One of the biggest obstacles is the distance from the main boilers to homes, as for every additional meter of piping required there is a greater opportunity for heat to be wasted.

Pipes need to be well insulated to prevent waste; however, district heating certainly works in Denmark and the savings made on the principle of economies of scale mean that everybody not only gets cheaper heating and hot water but also the supply is more secure and Denmark is no longer totally dependent on buying oil for its energy needs.

District heating is good for the environment, good for household budgets and good for America. What are we waiting for?

Read more