Decarbonisation Technology - November 2022

Fossil-fuel driven

100% CO emissions

Flue gases 10%

Waste heat 100%

Process heat 100%

Heat-pump driven

Process heat 100%

Waste heat 25%

0% - 33% CO emissions

Fossil fuel 110%


Steam boiler Process heat Fossil fuel





= 90%

Example using a heat pump



Process heat Electric power


> 4.0

Valid for hydrogen as well if used as fuel gas


Electric power 25%

Waste-heat recovery 75%

COP = Coecient of performance

Figure 5 Efficiency comparison of heat transformation industrial heat pump vs fossil fuels

plants, for example, represent a continuous flow of low-temperature heat that can be made usable again. Moreover, new megawatt-scale electrolysers are being installed almost weekly in many places around the globe, representing a huge, untapped potential of low-grade waste heat. Example: chemical industry An example from the chemical industry highlights the possibility of smoothly integrating a heat pump into existing systems: In the industrial production of bioethanol, the ethanol/ water mixture obtained through fermentation is separated by a multistage distillation at approximately 80 to 100°C. The distillation column is usually heated with low-pressure steam generated from natural gas in a power

plant or boiler. The purified ethanol steam is then condensed in a water-cooled condenser and the heat is released into the environment via cooling towers. The heat from condensing the ethanol can be transferred into the circuit of a heat pump, and the heat from the distillation can be fed back in as usable heat. A temperature rise from 70°C to 110°C can result in a COP of 4, while thermal outputs of up to approximately 50 MW can be achieved for each machine. Example: hydrogen electrolysis No system has perfect efficiency, and this holds especially true for large-scale electrolysis in the production of green hydrogen. A typical hydrogen plant using modern electrolyser technology reaches efficiencies between 60 and

25% Waste heat


100% Renewable electricity


75% Energy stored in H

Figure 6 Even the most advanced commercially available hydrogen electrolysers can turn only 75% of the input electricity into chemical energy in the form of hydrogen


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