We are told that the UK produces more than enough waste heat to heat all our homes, hospitals and public buildings. We just don’t have the means to transport that heat from generation into the user locations.

The waste heat is produced by industry and power generation, typically this is vented into the sky or cooling reservoirs. This does no- one any good.

This waste heat should be being captured and transferred into a heat distribution network that would convey the heat to wherever it needs to be used. In an ideal world, multiple sources of waste heat generation would be connected into a district or metropolitan heat distribution network.

As Toby Heysham, the managing director of energy generation and heat distribution specialist, Pinnacle Power, notes, the city that best exemplifies a fully built-out district heat distribution network is Copenhagen.

Denmark’s capital city has what is probably the world’s largest, oldest and most successful such system, which provides some 97 per cent of the city with clean, reliable and affordable heating. Here in the UK, Heysham points out, a number of city councils, including Edinburgh and Glasgow city councils, have plans to deploy large scale heat networks.

The best example in Scotland is Aberdeen Heat & Power; Dundee has aspirations to deliver a project using Low Carbon Infrastructure Transition Project funding, alongside an RWE/Glenrothes DHN that Fife Council are working on. West Dunbartonshire Council are also exploring a system in Clydebank.

However, by comparison with the continent, the UK’s approach to district heating is far behind. A good part of the reason for this is that a district or city heat distribution network needs to be treated like a public utility, with government or local government funding some or all of the initial pipelaying. It is also a highly technical undertaking, since a good district heating system has to be capable of linking to a variety of heat sources and users.

As Heysham explains, the most common system found in the UK is a smaller version, the communal systems deployed in the basement of flatted dwellings. Such systems are usually poorly designed and far from using waste heat, they generally use either gas, oil or grid electricity to generate heat.

"What should happen with such systems is that a big affordable housing complex installs communal plant, with a distribution system running through the building. This then has a Heat Interface Unit in every flat, a ‘virtual boiler’ that allows the resident to turn on/off the heating. The issues in the existing blocks is that they are losing typically 50 to 70 per cent of the heat into the communal corridors and in many cases there is no control inside the flat," he says. Many tower block dwellers face having to have all the windows open so the heating system doesn’t cook them in the middle of winter, or paying massive heat bills because the system is designed incorrectly.

"You should be looking at a heat loss from the in-building distribution system of around 10 per cent by running the distribution network at a lower temperature, insulating it properly, designing the system to realistic useage parameters and not oversizing everything. However, most distributed heating systems are poorly designed, the are massively oversized so cost too much to install and operate. The only people paying for this poor design are the customers. We believe that the main problem is in the structure of the install. There is no link from the design to the operations and customer service. If they were linked together there would be feedback coming into the designers who would be able to adapt and improve," he comments.

Government legislation will be required if we are going to see anything like a coherent use of waste heat, or district heating networks in the UK. "What you need is a legislative and incentive regime that brings about the collocation of waste heat producers such as electricity generators, with big heat users. You also need people like ourselves who can actively bring heat generators and then find the funding and do the engineering to distribute that into users," he notes.

Heysham says that while renewable generation has a role in heat distribution networks, this should be thought of as a low carbon solution to heating, rather than a pure renewables play. It works best when the distribution network is capturing the waste heat produced as the result of another process. Logically it is pretty obvious that taking electricity and turning it into heat is nowhere near as efficient as simply reusing waste heat.

As well as district heating, Pinnacle Power is very interested in the future of distributed energy systems generally, including localised private electricity networks running largely from local generation facilities. Heysham points out that as well as providing a nearby estate with heating, via its waste heat output, a power generator could run a private power network to the estate offering a considerable discount on the market electricity price. The reason this is not happening more already is the complex legislation around it

"If you think about it, a power generation system might be selling its power to the National Grid at 5p while consumers in a local estate are paying the power company of their choice around 12p to 14p per kilowatt hour. That gives plenty of scope for the power company to sell its power at, say, a 10 to 20 per cent reduction, direct to consumers on the estate. Planning and subsidy policy could bring this about, and to some extent, it is doing so – but not in a very uniform or coherent fashion," he comments. 