Breakthrough in cleaning hydrogen with waste heat –

As we strive to meet the European Commission’s ambitious goals of becoming net carbon neutral by 2050, we must ensure that we fully harness all renewable energy sources available to us.

Marco Baresi is the Director of Institutional Affairs at Turboden.

While work on decarbonizing the power sector is advancing rapidly, a number of industrial sectors are still struggling to ‘close the loop’ and become truly sustainable across their product line. Particularly where there is no inclusive regulatory framework to guide them.

One technology that could help solve this conundrum is the exploitation of waste heat recovery from industrial processes.

Energy-intensive industries such as cement, glass, metallurgy and petrochemicals are part of the natural substrate of our economy. There are a large number of industrial processes that waste huge amounts of precious and precious heat, which simply dissipates into the atmosphere. Although such heat is an inevitable by-product of an industrial process, it can be recovered and reused, without combustion or emissions, in line with the ambitions of the EU Green Deal and making a substantial contribution to at least two taxonomies The climate objectives of the regulation of a transition to a circular economy and climate mitigation, while increasing the efficiency of energy use.

Applications of waste heat recovery can include:

  • waste heat from an industrial process that can be used in the same facility or in a related facility; alternatively, it can be reused for thermal production by raising the temperature of the residual heat to supply district heating, for example via the use of an industrial heat pump;
  • The recovery of waste heat from energy-intensive industries or gas compression stations can also be used to produce carbon-free electricity. It is easy to find examples all over Europe and China, but we are only scratching the surface of the true potential of this application;

According to the TASIO project, mentioned as one of the relevant Horizon 2020s on the subject, the potential recovery of waste heat to produce carbon-free electricity in sectors that are difficult to reduce in the EU27 is up to 11 TWh of electricity per year correspond to 3.1 million tonnes of potential avoidance of CO2 emissions

Industry Carbon-free energy potential [TWh/Year]

CO2 avoided

[Million tonnes/year]


(electric arc furnace)

5.98 2.1
Cement 4.59 1.5
A glass 0.62 0.2

Likewise, the potential production of electricity from recovery of waste heat in gas transport and distribution systems (especially gas compressor stations equipped with open cycle gas turbines) is up to 10.43 TWh per year and avoidance of GHG emissions in the range 3.7 million tonnes.

Another potential use for this carbon-free energy from waste heat could be the production of carbonless hydrogen.

“Renewable hydrogen can be produced by electrolysis, using renewable electricity to split water into hydrogen and oxygen. According to the European Commission, the main driver of the production of “renewable” hydrogen is the source of electricity fueling the electrolysis process. . The new REDII modification project unveiled on the 14the of July by the European Commission sets a GHG emission reduction threshold of ≥ 70% for renewable fuels of non-biological origin (including renewable hydrogen) to be taken into account in the renewable energy quotas of the Member States .

Using carbon-free energy from waste heat supplying an electrolyser therefore effectively amounts to using renewable energy sources such as solar and wind power: no additional CO2 emissions are produced.

The cost of hydrogen produced by electrolysis using such a waste heat recovery plant, for example, an Organic Rankine Cycle (ORC) plant manufactured by Turboden, which is part of the Mitsubishi Heavy Industries group ( MHI), could be around 2 to 3 €. / kg. It is cost competitive compared to other renewable hydrogen production methods, thanks to the high efficiency of the ORC process and the ability to operate year round with minimal downtime for maintenance.

Therefore, waste heat recovery represents a cost-effective, clean and reliable source of electrical energy, similar to renewable energy. At European level, in fact, there is a tendency to classify waste heat as a renewable source: according to the European directive on renewable energies and the last technical report of the JRC, “waste heat” can be considered as “renewable” if all three requirements are met:

  1. Consumption must be off-site, ie by a different economic entity;
  2. Waste heat must be sold;
  3. The waste heat must go to any heating network, that is to say to more than one customer and more than one building or site.

In the case of hydrogen production, it is easy to reach points one and two, while the third is difficult to reach since the energy recovered from the waste heat is used more efficiently if it is supplied to just one. hydrogen plant. However, even if the three conditions described above are met, the Commission now explicitly recognizes only waste heat as renewable in the heating and cooling sector (as described in Articles 23 and 24 of the REDII amendment) and has not yet been included in their definition of renewable energy (Article 2 of the same amendment).

Outside of Europe, several US states have adopted energy standards that turn waste heat into electricity into a renewable resource. Some 17 states now have renewable portfolio standards and one resource efficient in four energy efficiency resource standards.

The hydrogen produced from the recovery of residual heat can play an important role in the context of the Energy Transition since it is a fuel and a carbon-free energy carrier that should be considered as “clean”. As well as renewables.

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