ECo – Efficient Co-Electrolyser for Efficient Renewable Energy Storage

The cement industry is a major contributor to industrial CO₂ emissions and its product will continue to be an indispensable building material in the future. Therefore, the European cement industry has committed itself to contributing to climate protection measures and thus to curbing its CO₂ emissions. Although fossil CO₂ emissions from cement clinker production have been significantly reduced in the last decades, the remaining emissions, and in particular those resulting from the decomposition of raw-materials, can only be significantly further abated by carbon capture. Carbon leakage and cement imports from markets that are not part of a carbon trading system may become a threat to the corresponding European markets and their respective jobs. For this reason the cement industry (including VDZ as representative of the German cement industry) is strongly engaged in the development of several research projects, which are currently discussing carbon capture methods. Due to the legal, social and environmental uncertainties of long-term CO₂ storage, the reuse of CO₂ (e.g. the conversion to methane) is seen as essential step towards carbon capture applications and further CO₂ reduction. CO₂ capture technologies, although an essential part of all CO₂ reduction scenarios, are not yet ready for large-scale deployment in the cement industry.

In order to comply with ambitious CO₂ reduction targets, the use of fluctuating renewable power sources such as wind and solar is increasing worldwide. Therefore, highly efficient pathways are needed to help balancing a growing electricity production/consumption mismatch. ECo project (Efficient Co-Electrolyser for Efficient Renewable Energy Storage) is a European research project that is focused on conversion of excess renewable electricity into distributable and storable hydrocarbons, such as methane, via simultaneous electrolysis of steam and CO₂ through SOEC (Solid Oxide Electrolysis Cells). The aim of ECo is to move the current technology readiness level (TRL) 3 to level 5 and bring the technology from proof-of-concept to validation of the technology in a relevant environment, making it ready for future prototype demonstration.

From the cement industry perspective, the aim of ECo project was to utilise CO₂ for co-electrolysis SOEC in combination with electricity production from renewable sources for storage as methane presented an interesting approach to handling CO₂ emissions from the cement industry in a future sustainable energy system.

ECo project was a three-year European funded project, which involved nine partners from both academia and industry across six European countries that started in May 2016. In relation to the work program, ECo aimed to:

• Develop and enhance improved solid oxide cells (SOEC) based on novel cell structure including electrode backbone structures and infiltration and design of electrolyte/electrode interfaces to achieve high performances and high efficiencies at ~100 °C lower operating temperatures than state-of-the-art. The goal is to reduce thermally activated degradation processes, as well as to improve integration with hydrocarbon production, without disregarding the reduction of Overall costs;
• Investigate durability under realistic co-electrolysis operating conditions that include dynamic electricity input from fluctuating sources. ECo is aiming to achieve degradation rates below 1%/1000 h at stack level under relevant operating conditions;
• Design a plant to integrate the co-electrolysis with fluctuating electricity input and catalytic processes for hydrocarbon production, with special emphasis on methanation (considering both external and internal) and perform selected validation tests under the thus needed operating conditions:
  
  1. Test a co-electrolysis system under realistic conditions for final validation of the obtained results at larger scale;
  2. Demonstrate economic viability for overall process efficiencies exceeding 60% using results obtained in the project for the case of storage media such as methane and compare to traditional technologies with the aim to identify critical performance parameters that have to be improved;
  3. Perform a life cycle assessment with CO₂ from different sources (cement industry or biogas) and electricity from preferably renewable sources to prove the recycling potential of the concept