The development and demonstration of the power-to-H2-to-power advanced plant concept at Engie Solutions' combined heat and power (CHP) plant in Saillat-sur-Vienne was successfully executed. This involved integrating H2 conversion, storage, and gas turbine re-electrification technologies, ensuring compliance with all safety regulations. Authorization to operate the demonstrator plant with H2 was obtained, and the electrolyser, along with its deoxygenation unit, was designed, manufactured, pre-commissioned, and delivered to the site. The Centrax-packaged Siemens Energy SGT-400 gas turbine underwent successful upgrades, manufacturing, factory testing, delivery, installation, and commissioning of its test core engine. The power plant was updated and integrated with new components including an electrolyser, hydrogen compressor, hydrogen storage, and a natural gas/hydrogen fuel mixing station.
In 2022, the project partners conducted the first pilot plant demonstration campaign, achieving successful implementation of the power-to-H2-to-power concept with natural gas/hydrogen blends up to 30% H2.
SIEMENS Energy developed an advanced combustion system technology for operation with natural gas/H2 blends up to 100% H2 in DLE (dry low emission) mode. Rigorous combustion rig test campaigns at the SIEMENS Energy Clean Energy Center validated the final combustion technology design. These tests included operation with natural gas, 100% H2, and various blends thereof under real engine conditions, confirming operational boundary conditions, metal temperatures, and NOx emissions that met project objectives. Excellent rig to engine correlation was achieved for emissions and flashback characteristics across the entire fuel blend range.
The development of the combustion system involved extensive collaboration among the project research institutions, advancing optical diagnostic techniques for combustion rig tests, including H2 investigations. UDE optimized the probe design for flame imaging tests. DLR conducted comprehensive wall temperature measurements during combustion with up to 100% H2, achieving high-frequency and precise temperature measurements. ULUND identified the YAG;Li phosphor as most suitable for high-temperature measurements, enabling more accurate and reliable temperature monitoring. UCL upgraded its facilities to conduct thermoacoustic studies with 100% H2 combustion as well as methane/H2 mixtures. In addition, it implemented a Laser Induced Breakdown Spectroscopy (LIBS) system for fuel-air mixture characterization.
The completion of the hydrogen combustion system technology final design, followed the product definition, manufacturing of the engine set hardware, the demonstrator engine testing at the Lincoln engine test facility with natural gas and the delivery of the engine at the pilot site in France for testing with up to 100% H2.
The second campaign in 2023 demonstrated the integrated plant with the new hydrogen gas turbine technology operating with blends from 0-100% H2. This marked also the world's first integrated industrial power-to-H2-to-power solution using 100% green H2 for carbon-free electricity generation. The testing campaign achieved the objectives of more than 10 hours operation above 80% H2 with less than 25 ppm NOx emissions.
A techno-economic evaluation of the HYFLEXPOWER pilot unit analyzed its feasibility under current and future market conditions, focusing on the Levelized Cost of H2 (LCOH) and Levelized Cost of Energy (LCOE), highlighting economic viability with low electricity prices, high carbon costs for CO2 emissions and declining electrolysis costs. The HYFLEXPOWER project concepts environmental benefits were assessed through Life Cycle Assessment (LCA), indicated a 95% reduction in greenhouse gas emissions compared to conventional natural gas operations. Finally, the social impact of the project and its public perception were evaluated through a comprehensive survey-based assessment. The results indicated positive to neutral social impact in all investigated categories (local community, workers and work environment, consumers, and society).
Members of the HYFLEXPOWER consortium disseminated their findings through public events and over ten papers and presentations at renowned conferences. The public events took place at the pilot demonstration site in Saillat-sur-Vienne, in Brussels, and during a summer school at the National Technical University of Athens.
