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Green Industrial Hydrogen via Reversible High-Temperature Electrolysis

Periodic Reporting for period 2 - GrInHy (Green Industrial Hydrogen via Reversible High-Temperature Electrolysis)

Reporting period: 2017-09-01 to 2019-02-28

High-temperature electrolysis (HTE) is one of the most promising technologies to address the European Commission´s roadmap towards a competitive low-carbon economy in 2050. The decarbonization of Europe’s industry, transport and energy sector by higher shares of renewable energy sources (RES) requires a high flexibility in energy production, load management and large-scale storages. A reversible HTE providing green hydrogen or electricity to these sectors is a possible solution as a cross-sectoral technology. Since a significant share of energy input is provided as heat – preferably from waste heat, the HTE achieves outstanding electrical efficiencies resulting in an electricity demand of <40 kWh_AC instead of 51-60 kWh_AC per kg hydrogen in SoA low-temperature electrolysis.

Central element of GrInHy is the manufacturing, integration and operation of the worldwide most powerful reversible HTE prototype at an integrated iron-and-steel works. As a Research and Innovation Action, the project also focused on the improvement of robustness and durability of the HTE technology on cell and stack level.

The project’s main objectives were as follows:

• Up-scaling of an HTE system (150 kW_AC,EC) that can also be operated reversibly as fuel cell using either natural gas or hydrogen as fuels

• Operation for at least 7,000 h meeting the hydrogen quality standards of the steel industry

• Proof of reaching an overall electrical efficiency of at least 80 %_LHV (ca. 95 %_HHV) based on available steam from waste heat

• Reaching a lifetime at stack level of greater than 10,000 h with a degradation rate below 1 %/1,000 h

• Elaboration of a viable Exploitation Roadmap while showing the feasibility of future cost targets
Over the project duration of 36 months, all project’s objectives and milestones were reached with only minor deviations. A flexible and dynamically applicable prototype was successfully designed and manufactured with a nominal electrolyser capacity of 150 kW_AC,EC (40 Nm³_H2/h) and a maximal power of 200 kW_AC,EC (50 Nm³/h). The prototype system was set-up in June 2017 and connected to a hydrogen processing unit in order to meet the integrated iron-and-steel-works requirements in terms of H2 purity and pressure. An efficiency of the HTE of 78 %_LHV,EC (without drying and compression) was measured. This was related to the 88 % bi-directional power electronics efficiency, compared to 94 % as specified, which would result in an HTE efficiency of 84 %_LHV,EC.

Additionally, the fuel cell (FC) operation showed the system’s fuel adaptability: Operated with natural gas in fuel cell mode, the system reached the nominal power of 25 kW_AC,NG-FC and a maximum AC efficiency of 52 %_LHV,NG-FC at 80 % load (20 kW_AC,NG-FC). With hydrogen, the nominal power was 30 kW_AC,H2-FC and a maximum AC efficiency 48 %_LHV,H2-FC. The reversible HTE was tested for typical dynamic cycles derived from load management and grid balancing.

The prototype was operated for approximately 10,000 h in electrolysis, fuel cell or hot-standby mode. Several optimizations on hardware and software level were performed, both for the reversible HTE and the hydrogen processing unit. In total, about 90,000 Nm³ of hydrogen were produced during electrolysis operation of which more than 41,000 Nm³ with a quality of 3.8 at 10 bar(g) were used for annealing processes at Salzgitter’s integrated iron-and-steel works.

Cells and stacks were optimized and tested e.g. for degradation and mechanical properties on cell and stack level resulting in material improvements and optimized stack integration. Due to contaminations and failures of the test bench, the foreseen 10,000 h continued stack testing was aborted after 8,300 h. Another stack under optimized test conditions reached degradation rates well below the project target of <1 %/kh for more than 5,000 h. More than 80,000 ultra-fast load cycles (direct on/off-switching of current) on cell level and more than 16,000 cycles at stack level were performed without increased impact on the degradation rate.

The technology’s cost structure, potential business cases and environmental performance were assessed in accompanying studies. Based on all results, a comprehensive exploitation roadmap was elaborated laying the foundation for the HTE towards a marketable product.

GrInHy achieved a high-level of public awareness during scientific conferences, international fairs and dedicated hydrogen technology workshops. The project reached numerous political decision makers, researchers and possible costumers while exchanging results with other FCH2-JU projects. Due to its results, GrInHy was nominated for the FCH JU Awards 2018 “Best Project Innovation”.
The consortium has implemented a reversible HTE system that is world-wide leading in terms of scale, efficiency, operation and fuel flexibility and first-time integration in an industrial environment. As unique feature, the HTE system operation is able to switch from electrolyser to fuel cell mode using either natural gas or hydrogen as fuel. Even the potential usage of process gases from steel production processes was investigated and found to be suitable after additional reforming and cleaning steps.

The main impact of GrInHy are the proof-of-concept of the technology and its potentials in an industrial environment and the exploitation of the project’s results to improve the HTE's Technology Readiness Level. Most of the results will be directly realized in the successor project, GrInHy2.0 that already has been started in January 2019.

GrInHy’s prototype operation showed that an electrical AC efficiency of 84 %_LHV,EC based on steam from waste heat is possible. This indicates approx. 25 % higher electrical efficiencies compared to low-temperature electrolysers. This power consumption of below 40 kWh_AC per kg hydrogen will be verified in GrInHy2.0. Since electricity costs have a share of about 70-80 % of total costs in the long-term, HTE is a key technology to achieve economic feasibility for hydrogen production from RES.

GrInHy provided a comprehensive scale-up study of the HTE to reach the multi-MW class lowering the costs to less than 1,000 €/kW_AC,EC within the next five years. In GrInHy2.0 the world wide first HTE of the MW class will be operated at the integrated iron-and-steel works in Salzgitter.

The operation of the next HTE prototype generation in Salzgitter will also intensify SZFG’s and SZMF’s efforts to investigate alternative steel production pathways that directly avoid CO2 emissions (Carbon Direct Avoidance). A very promising approach is Salzgitter’s SALCOS concept which is based on the substitution of carbon with hydrogen as a reducing agent resulting in CO2 reductions of up to 95 % or more than 150 million tons of CO2 per year in the EU 28. In this context, GrInHy and GrInHy2.0 are a technological preliminary study of an energy efficient hydrogen production providing green hydrogen for the steel industry in the future.
GrInHy stack testing
GrInHy Joint Workshop Pic 2
GrInHy Joint Workshop Pic 1
GrInHy RSOC System 2018