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”.
