HELIA - Sustainable Hydrogen Production via Metal-Steam Redox Cycles in Circulating Fluidized Bed Systems

The HELIA project will develop advanced hydrogen production technology by retrofitting existing fossil fuel-fired
circulating fluidized bed (CFB) with a carbon-free oxidation process. In central or northern Europe, metal energy carriers will undergo oxidation with water vapor in CFB boilers, efficiently generating hydrogen while co-producing heat and power. The system allows for the potential integration of variable renewable energy sources to maximize hydrogen yield, with AI-enabled control. Modifications to CFB boilers include the appropriate feeding and extraction of metal/metal oxide particles, optimized hydrodynamics, and controlled treatment of water vapor in the off-gas stream to ensure high-purity hydrogen production and effective heat recovery. The resulting metal oxides are regenerated to metal via a renewable hydrogen-based reduction process powered by stable solar energy in southern Europe. This establishes a closed oxidation-reduction cycle, functioning as a sustainable hydrogen carrier with minimal waste. The water required for oxidation in the CFB boilers and for electrolysis in the reduction plants is supplied by an innovative seawater desalination system, designed to maximize freshwater production while minimizing brine discharge, and enabling the recovery of valuable elements from the salts (e.g., lithium and potassium). Experimental investigations on multiple scales (thermo-gravimetric analysis, 1 kg lab-scale batch, 100 kW, and 1 MW) supports the technological development and validation of computational models, covering both particle-level and system-level approaches (steady-state, dynamic modeling, and CFD). The project evaluates environmental, techno-economic, and socio-economic impacts, market potential, and synergies with the steel industry. By retrofitting existing CFB infrastructure and integrating renewables, HELIA advances polygeneration of hydrogen, heat, and power, targeting TRL6 with robust hydrogen safety and management strategies.

Goals

The main objective of HELIA project is to investigate the feasibility of retrofitting existing fossil fuel-fired CFB power plants with a carbon-free oxidation process that produces hydrogen and releases heat for electricity and district heating generation, with the potential integration of variable renewable energy sources supported by AI-enabled control. In central and northern Europe, metals will react with water vapor/oxygen in CFB boilers to produce hydrogen and metal oxides, which are subsequently regenerated back to metals via a renewable hydrogen-based reduction process powered by stable solar and wind energy. The water required for the oxidation process as well as for electrolysis is supplied by an advanced seawater desalination plant, designed to maximize freshwater production while producing brine that allows for the recovery of valuable elements from the salts (e.g., lithium and potassium). The proposed closed-loop oxidation-reduction system in this project enables the polygeneration of power, heat, and hydrogen with zero carbon emissions and minimal waste, while efficiently integrating renewable energy and innovative seawater management. The technology will be tested at various scales (TGA, 1-kg lab-scale batch, 100 kW, and 1 MW), targeting a TRL of 6, and will be rigorously evaluated using different metals. Beyond technical validation, the project will perform comprehensive assessments of economic viability, environmental impact, and social benefits, thereby contributing to climate neutrality, fostering circular economy advantages, and strengthening EU energy security.

Project manager