Study 27: Energy hybridisation in industrial processes

Emissions from the industrial sector are on a downward trend, as a result of decarbonisation efforts by manufacturers on the one hand, and high energy prices on the other.

Among industrial processes that are high emitters, some are difficult to decarbonise due to the lack of low-carbon alternatives compatible with these processes, or because such alternatives are not widely available or competitive.

This is particularly the case for high temperatures (above 300°C), for example in the metallurgy, materials and chemical industries. Hybridisation can therefore be a suitable solution for reducing emissions from these processes.

This study is limited to hybridisation solutions:

• Between natural gas and electricity, or between natural gas and hydrogen.
• Direct, meaning that two energy sources are used immediately and locally in the production process, without involving any significant intermediate stages of conversion or storage.

The objectives of the study are as follows:

• For industrial operators and specifiers, to identify short-term opportunities for decarbonisation projects through energy hybridisation.
• For solution providers and specifiers, to understand and gain a better grasp of possible combinations of technologies and the technological needs of client sectors.

The study is divided into two parts: 

1) The first part of the study provides an overview of electrical solutions and the low-carbon hydrogen value chain, as well as a description of the thermal processes used in sectors that are difficult to decarbonise due to the high temperatures required (in excess of 300°C): the materials, metallurgy and chemical industries.

2) In a second stage, case studies were carried out to assess the technical and economic benefits of hybridisation. The case studies involved hybridising the processes under consideration by:

• The injection of hydrogen at a rate suitable for the smelting furnace burners,
• Electric heating of the pre-firing zone of the brick and tile kiln,
• Electrification of the dryer using a heat pump to improve heat recovery.

Among the findings of this study are:

• The hybridisation methods presented in the second part of the report all ensure the long-term viability of the processes without compromising the quality of the end products; hybridisation acts as an energy supplement, without, however, affecting the heat transfer mechanism of the existing process.
• From an economic perspective, the results for the French market show an increase in costs for projects involving both metallurgy and materials.
• In the case of metallurgical smelting furnaces, the scenario of using hydrogen when its cost is competitive results in a modest reduction in CO₂ emissions, but at a lower cost.
• In the case of tunnel kilns, hybridisation using electric heating elements remains limited and uncompetitive.
• As regards the rotary dryer, the heat pump’s performance, combined with heat recovery, ensures that the project is cost-effective.