Three things to know about the unexploited potential of public district heating systems

With­in the energy sec­tor, heat­ing is and will remain a major part of the energy con­sump­tion (about half of the energy demand in build­ings). Dis­trict heat­ing could be a great vec­tor of the energy trans­ition as it is a way of integ­rat­ing clean energy on a large-scale. How­ever, this poten­tial remains very much under-exploited as 90 % of the heat sup­plied through net­works is still fossil-based (75 % in Europe, the more adanced con­tin­ent when it comes to the integ­ra­tion of renew­able energy in dis­trict heat­ing sys­tems), and only 9 % of the glob­al heat­ing demand (indus­tri­al and build­ings) is provided through dis­trict heating.

Dis­trict heat­ing is a col­lect­ive heat dis­tri­bu­tion sys­tem. In France, it usu­ally also encom­passes the pro­duc­tion plants. In the heat plants, a flu­id – steam or water – is heated by incin­er­a­tion heat, bio­mass boil­ers, or geo­therm­al energy. This hot flu­id is then trans­por­ted through insu­lated pipes to sub-sta­tions, con­nect­ing the dis­trict heat­ing sys­tem to sec­ond­ary sys­tems. The sec­ond­ary sys­tem cor­res­ponds to the dis­tri­bu­tion sys­tem inside build­ings – for instance, the pipes run­ning through build­ings from the sub­sta­tion to the radi­at­ors. This sec­ond­ary sys­tem is dis­tinct from dis­trict heat­ing and is not reg­u­lated under the same con­tract. The type of build­ings sup­plied by dis­trict heat­ing can vary from coun­try to country.

In most cases, dis­trict heat­ing is developed in areas where there are already build­ings con­sum­ing much heat, such as hos­pit­als, malls, office build­ings, or social hous­ing. Private hous­ing like col­lect­ive hous­ing or indi­vidu­al hous­ing can also be con­nec­ted to the sys­tem, but not in every coun­try. In France, the old­est dis­trict heat­ing sys­tems date back from before the 1950s in some major cit­ies like Par­is, Stras­bourg or Gren­oble¹. For instance, Par­is had its dis­trict heat­ing in 1927. It is still under oper­a­tion and works with steam. From the 1950s to the 1970s, dis­trict heat­ing sys­tems were developed in many cit­ies but mainly restric­ted to new neigh­bour­hood or around incin­er­a­tion plants to use the heat. In the 1980s, the oil crisis led to the devel­op­ment of geo­therm­al based dis­trict heat­ing, like in the Parisi­an region. How­ever, these sys­tems quickly became eco­nom­ic­ally unvi­able due to the com­pet­i­tion with gas.

Dis­trict heat­ing, as an energy util­ity, is a pub­lic ser­vice. The loc­al pub­lic author­ity owns the sys­tem and is respons­ible for its oper­a­tion. In France, oper­a­tion and main­ten­ance are often del­eg­ated to a private oper­at­or through a Pub­lic Ser­vice Del­eg­a­tion. These con­tracts can last for dec­ades (usu­ally about 25 years), and the private oper­at­or bears the invest­ments². How­ever, more and more loc­al pub­lic author­it­ies are con­sid­er­ing their dis­trict heat­ing sys­tem as a great lever for the eco­lo­gic­al transition.

Heat­ing and cool­ing accounts for roughly half of the energy con­sumed in the European Uni­on³ but cur­rently dom­in­ated by fossil fuels⁴. Dis­trict heat­ing could sup­port large-scale sus­tain­able heat pro­duc­tion. Indeed, instead of ask­ing thou­sands of fam­il­ies to change their old fuel boil­er, the whole neigh­bour­hood can move from fossil fuels to sus­tain­able energy by chan­ging the fuel-based pro­duc­tion plant to, for instance, a bio­mass-based one. Moreover, by lower­ing the flu­id tem­per­at­ure and adding thermal stor­ages, it is easi­er to integ­rate a great­er vari­ety of loc­al and sus­tain­able pro­duc­tion means: indus­tri­al waste heat, shal­low geo­therm­al energy, large-scale heat pumps, etc. Dis­trict heat­ing is also a great team­mate: it can be coupled with a cool­ing sys­tem or be used as a way of stor­ing renew­able elec­tri­city production.

By integ­rat­ing a vari­ety of loc­al resources, dis­trict heat­ing is a great lever for many loc­al trans­itions. It is a lever for loc­al pub­lic author­it­ies to act on decar­bon­isa­tion, air pol­lu­tion, energy poverty, etc. It can even become an object of loc­al demo­cracy if cit­izens are integ­rated to its plan­ning and gov­ernance. It can also pro­mote loc­al energy sov­er­eignty by secur­ing a loc­al energy sup­ply and reduce energy depend­ence. For instance, Dunkirk is the biggest French dis­trict heat­ing sys­tem based on indus­tri­al heat recov­ery. Since the oil crisis, the muni­cip­al­ity wanted to have more energy sov­er­eignty and be able to con­trol the prices of heat. They developed in 1986 a dis­trict heat­ing recov­er­ing waste heat from Arcelor-Mit­tal, a major steel man­u­fac­turer. Thanks to this recu­per­a­tion, Arcelor-Mit­tal has to burn less of its remain­ing gas, improv­ing both the air qual­ity and the loc­al attractivity.

In 2009, the Heat Funds, a French pub­lic sub­sidy sup­port­ing the devel­op­ment of renew­able heat was set up. It aims at mak­ing renew­able and recovered heat com­pet­it­ive with gas-based solu­tions. It par­ti­cip­ated to secur­ing the remain­ing geo­therm­al-based dis­trict heat­ing and helped the devel­op­ment of new ones, based on at least 50 % of renew­able or recovered heat. Thanks to this new dynam­ic, France has now 898 dis­trict heat­ing sys­tems in oper­a­tion, with 62.6 % of renew­able or recovered heat pro­duc­tion in aver­age⁵.

You have prob­ably already heard about green elec­tri­city with wind tur­bines or sol­ar pan­els. You have prob­ably heard about bio­gas, green gases, and hydro­gen. But had you heard about sus­tain­able dis­trict heat­ing sys­tems? Can you name one com­pany provid­ing dis­trict heating?

Dis­trict heat­ing is under-rep­res­en­ted in the energy sec­tor, and not a lot of insti­tu­tions are solely advoc­at­ing for these sys­tems in a vis­ible way. The major European net­work pro­mot­ing dis­trict heat­ing is named Euroheat&Power… a name giv­ing no expli­cit indic­a­tion on its focus towards dis­trict energy. Many French com­pan­ies provid­ing dis­trict heat­ing are also major act­ors of the elec­tri­city and gas mar­kets, which can lead to intern­al interest con­flicts. Moreover, some coun­tries – like France – had his­tor­ic­ally made the polit­ic­al choice to nation­ally devel­op the gas and elec­tri­city networks.

Dis­trict heat­ing is under-rep­res­en­ted in the energy sec­tor, and not a lot of insti­tu­tions are solely advoc­at­ing for these sys­tems in a vis­ible way.

With these two util­it­ies in place and the under-rep­res­ent­a­tion of dis­trict heat­ing, it can be hard for loc­al pub­lic author­it­ies to 1) gain know­ledge about dis­trict heat­ing, 2) jus­ti­fy the devel­op­ment of a new energy util­ity when two are already fully oper­a­tion­al and able to provide heat. To add to the second point, a dis­trict heat­ing sys­tem needs a high level of heat demand and dens­ity to be eco­nom­ic­ally viable. In places where there is no man­dat­ory con­nec­tion to the sys­tem, it can be hard to achieve and secure this level of demand. Indeed, there are a lot of solu­tions – sus­tain­able or not – to be provided with heat­ing and hot water: indi­vidu­al gas or fuel boil­ers, elec­tric­al heat­ing, indi­vidu­al heat pump, sol­ar thermal pan­els, etc. Some of these solu­tions are also sup­por­ted by pub­lic policies, like the set­ting up of indi­vidu­al heat pumps or elec­tric­al heat­ing – a very inef­fi­cient heat­ing means, but quite developed in France due to the low price of elec­tri­city and the policies sup­port­ing nuc­le­ar-based electricity.

Two things make it even harder for dis­trict heat­ing to be vis­ible. First, its invis­ib­il­ity! The whole sys­tem runs under­ground, and heat is not as vis­ible in our land­scapes as elec­tri­city. The only vis­ible parts are plants, which can lead to a rather unpop­u­lar opin­ion on dis­trict heat­ing… Second, the dis­con­nec­tion to final users. As men­tioned earli­er, dis­trict heat­ing is dis­tinct from the sec­ond­ary sys­tem. The cus­tom­ers are the build­ing own­ers, not the final users, and there is no dir­ect link between heat users and dis­trict heat­ing act­ors. Many cus­tom­ers do not even know that they are provided heat through dis­trict heating!