Still unknown to the general public among renewable energies, it could occupy a place of choice in the future in the French energy mix.
Fatal heat, resulting largely from industrial activities, represents a source of energy that is little exploited today in view of its potential.
In addition, it is a carbon-free energy that can be used to heat homes, businesses or even public facilities.
What is fatal heat
?
Fatal heat is a "production of heat derived from a production site, which is not its primary purpose, and which, therefore, is not necessarily recovered", according to Cerema, a public establishment. which depends on the Ministry of Ecological Transition.
The sources of production of this waste heat are diverse: industries, data centers, waste incinerators, wastewater treatment plants... So many sites whose energy consumption actually produces heat. , part of which is discarded and lost.
Recovering waste heat therefore allows it to be reused in different ways.
"Two complementary axes of thermal recovery" exist, according to the Agency for the Environment and Energy Management (Ademe): the reuse of this heat to meet the needs specific to the emitting company, and the recovery outside to heat other businesses, homes via a district heating network or even to produce electricity.
Recovery of waste heat.
© FMM Graphic Studio
Some examples of existing and future systems in France
The city of Dunkirk in the north is a pioneer in this field (since 1986): it has the largest network in France for the recovery of fatal industrial heat, which required 32 million euros of investment to connect the blast furnaces of ArcelorMittal to the district heating network.
The recovered waste heat is now used to heat nearly 16,000 equipment and homes.
This device – which should soon be extended to 12,000 additional dwellings – makes it possible to avoid the emission of 20,000 tonnes of CO2 each year, according to Cerema.
In the same direction, the agglomeration of Mulhouse (Haut-Rhin) will be equipped by the end of 2025-2026 with a new heating network 50 km long and supplied by several industrialists.
The investment – between 140 and 150 million euros – should make it possible to transport waste heat up to 200 GWh / year, ie the heating needs of 20,000 housing equivalents.
In another genre, an aquatic center – also a training site for the Paris-2024 Olympics – and a district located in Saint-Denis (Seine-Saint-Denis) will soon be heated by the heat of a data center .
The investment of a few million euros will allow waste heat from the Equinix company to supply these facilities and homes with heating and collective hot water using heat pumps.
An under-exploited waste heat potential in France
Fatal heat today represents a large energy reservoir that is still largely untapped in France.
"Today, the big potential is in industry. Household waste incineration units (UIOM) are, for their part, increasingly optimized and data centers represent a growing potential since there are there are more and more of them also on the territory", explains Marina Boucher, energy engineer and coordinator of the 2030 industry center at Ademe.
The theoretical waste heat deposits represent 109.5 TWh in industry, 4.4 TWh in UIOMs and 3.6 TWh in data centers, according to an Ademe report published in 2017. According to Marina Boucher, "we has captured around 10 TWh since 2015 in industry. This is not nothing, but it remains low in view of the national deposit of industrial waste heat for example".
The environmental agency estimated with Les Echos, in 2020, that the easily recoverable waste heat deposit would be 12 TWh/year, enough to heat a million homes.
Know-how in the reuse of waste heat exists in France: some 178 projects in this direction were financed between 2015 and 2020, according to a note from Ademe published in March 2022. "Existing technology is ripe" confirms Nicolas Goldberg, senior energy manager for the consulting firm Colombus Consulting, before specifying that the potential for fatal heat is "probably under-exploited".
According to the energy expert, several obstacles currently explain why this renewable and recovered energy (EnR&R) is not fully exploited: "Where are we going to get this energy? This means reviewing the industrial processes of production already installed, this also implies major developments with the routing of large pipes, the digging of large trenches. There is really progress to be made in the exploitation of waste heat."
Added to this are geographical disparities in France: in a country which still uses gas and electricity for the most part, the district heating network (through which this recovered waste heat passes) varies from region to region. other.
The Ile-de-France region, for example, has the largest proportion of homes heated by the urban heating network (around 15%) when the Occitanie region is only heated by 1% in this way, as shown by a study of Butagaz and Synasav published in July 2022.
Fatal heat, a "direct gain" to reduce carbon emissions
Like biomass – energy from the combustion of materials such as wood, plants, agricultural waste and organic household waste – the recovery of waste heat is a renewable energy of the future in the energy mix used for heating households in France.
“Capturing waste heat means recovering energy that was previously lost and erased from consumption that could originally be covered by gas or other fossil fuels. So the gain will be direct in in terms of reducing carbon emissions", explains Marina Boucher.
“Heat production is quite carbon-intensive in normal times: most collective and individual housing is currently heated either with district heating networks which have a share of fossil fuels, or with fossil fuels”, adds Nicolas Goldberg.
“So when it comes to reducing emissions, the potential for decarbonizing waste heat is enormous.”
Difficult, however, to quantify how many tonnes of CO2 will be saved by using this energy because "each installation to recover waste heat will be unique", specifies the energy specialist.
As part of the ecological transition, the French executive intends to encourage this development in the years to come.
In its multiannual energy programs – a roadmap for France's energy strategy – for the period 2019-2028, the State sets, among other objectives, by 2028 "the multiplication by five or six" of the quantity of industrial waste heat recovered compared to 2016. In other words, the aim is to go from 0.4 TWh operated in 2016 to 0.84 TWh in 2023, then between 2.3 TWh and 3 TWh in 2028.
"The development of urban heating networks is a major focus, and waste heat is one of the levers for greening networks (in the French energy sector)", concludes Marina Boucher.
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