District heating – a hot topic?
Tracing its history back to the bath houses of ancient Rome, district heating describes a system where there is a considerable distance between the place the heat is generated (power plant) and the place the heat is used (the building). These systems have been seen throughout history, for example they have been present in Europe since the Middle Ages and were initially recorded in the US where the first steam district heating service became operational in 1853.
The popularity of district heating has ebbed and flowed for the past 100 years but has enjoyed something of a renaissance in the past 40-50 years as these plants can provide better efficiency than standalone boilers and can be run using a wide range of fossil fuels. In fact there is research which shows that district heating with combined heat and power is the cheapest way to cut emissions as well as displaying one of the lowest carbon footprints of any of the fossil driven systems.
Today these systems can be found in large numbers in the majority of larger cities, especially in central and northern Europe (providing heating, cooling and hot water), the exception to this rule being the UK.
It is however true to say that there has been growing interest in the UK around this type of technology that can provide comfort levels to large numbers of people in a very energy conscious and cost effective way (following on from the initial investment).
So is this something that we should be considering more seriously as part of delivering the overall energy provision for this country?
It has been estimated that the heating needs of homes, businesses and industry in the UK account for around 49% of the total energy demand and 47% of carbon emissions. As we know today, in the UK, the majority of households and non-domestic buildings have their own heating systems, with gas being the predominant fuel source.
It would be untrue to say that there has been no district heating uptake as there have been a handful of schemes here since the 1950s – however this has been estimated to be less than 2% of the UK heat demand.
Looking at the rest of Europe in terms of district heating, the situation is very different and in Finland, for example this form of heating accounts for 49% of the total supply and in Denmark the figure is actually 60%.
What is particularly interesting, given the energy savings that the UK needs to achieve by 2020, is that even where district heating makes a lower overall contribution to supplying the heating needs, it is still often a major source in larger cities. An example of this being Austria where district heating accounts for just 18% of the total heat supply, but it provides 36% of Vienna’s heat supply that incorporates 270,000 households.
Scale of demand
District heating can be an excellent solution for a range of scaled projects from one-off office buildings, schools, colleges, hotels, hospitals and apartment complexes, right though to whole neighbourhoods.
Another factor which will influence the potential future direction of district heating is the increasing amount of people living in higher density flats and apartments in the UK which currently accounts for 19% of the total housing stock, 40% of which sits in the social sector. Although housing clusters also offer possibilities – as long as there is a minimum of 55 houses per hectare, which is considered the point of financial viability and the Department of Energy and Climate Change (DECC) has suggested that a minimum heat density of 3,000kW per square km p.a. should be applicable within the equation.
Fuelled by demand or cost?
One of the main reasons for the lack of adoption of district heating in the UK has been the relatively high cost of instigating this form of heating in comparison with, for example, conventional gas or electric based heating systems.
However, one thing that is certain is that with recent announcements that we are at risk of electricity blackouts in the UK by 2015 as a direct result of the EU rulings and the power station closures, other solutions will need to be revisited and reviewed.
Ofgem has predicted that there will be just a 4% buffer in supplies compared to the current 14% capacity, so part of the solution will have to come from using the energy that we do have access to more effectively. This will in turn increase the pressure from district heating supporters. Interestingly analysis has shown that in the right conditions district heating could supply 14% of the UK heat demand, which would mean that in one step, the adoption of district heating could solve the shortfall problem.
Although the initial costs are high there are some fuel-source combinations and particular types of building that can reduce the cost. An example of this is where systems can use the waste heat from conveniently sited power stations, since this heat is essentially already produced and is readily available. Other examples include where a system replaces an existing electric heating system or to deliver supplies to commercial premises and high rise apartments in areas of population density.
Add to this the fact that heating pipes are not specific to the technology used to generate the heat, this means that they can be connected to a range of sources of heat supply including CHP, biomass, energy from waste, ground source heat pumps, geothermal heat or large power stations. This flexibility also means that pipes also have a longer life than generating plant networks.
All of which offers a very compelling argument that suggests that district heating should be playing a much greater role within the heating delivery mix in the UK than is currently the case.
A recent example of a UK based district heating project was completed in St Leonards which is a residential area of East Kilbride. In the 1960s the decision was taken to build multi-storey flats to help meet the housing needs which resulted in the development of the Clyde Tower, which at 56m is the tallest in the area, as well as their smaller neighbours Calder Tower and White Cart Tower.
Much in need of a makeover these high rise blocks have just undergone a major external and internal refurbishment and Grundfos Pumps worked with local consultants Hulley & Kirkwood and contractors James Frew Ltd, to deliver the optimal bespoke solutions.
Today each tower block has its own up to date district heating plant room complete with a Grundfos pump solution including energy efficient TPED inline pumps, Hydro MPC-E variable speed booster sets, pressurisation units, pressure step degassers and dirt separators.
Where to now?
With increasing uncertainty about where the power we will need for the future will be coming from, and with the gap between demand and sup
ply widening, there has never been a better time to get serious about delivering district heating in all its forms.
One thing that we will need to be able to rely on however is companies who have the expertise to help facilitate these changes. Grundfos Pumps is one such company who have the experience, expertise, product portfolio and who have worked on a wide range of projects globally and who can deliver – regardless of the demand.