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 !