Germany’s National Hydrogen Strategy requires the decentralised production of carbon-neutral hydrogen (H2) to be ramped up at a local level, as well as at solar and wind plants. One promising solution is the , developed by the Fraunhofer Institute for Environmental, Safety and Energy Technology (UMSICHT), that transforms foul waste including sewage sludge, industrial and agricultural biomass residues into a hydrogen-rich synthetic gas.
Now a new research project involving UMSICHT, the Fraunhofer Institute for Thin Films (IST) and the hazardous waste disposal company Veolia Süd aims to build on the TCR (thermo-catalytic reforming) process, to refine ultrapure green H2 from syn-gas that is suitable for use in fuel cells and semiconductor manufacturing applications.
The conversion process is multi-layered. In a first step, the biomass residues are gently broken down at a TCR plant at less than 500°C and a by-product carbonisate (biochar) is extracted. The vapours are catalytically refined at 700°C in the post-reformer, then cooled, at which point crude bio-oil and water are separated off and the remaining H2-rich synthesis gas (approximately 50 percent H2) is cleaned. In a second step, the hydrogen is purified using special metal-coated membranes developed by IST. The Federal Ministry for Education and Research (BMBF) is funding this stage of the research.
The benefit of the TCR® process compared to many other H2 pyrolysis techniques is its high energy efficiency. For example, the process heat for the plant comes from residual biomass, and the syn-gas can be used on site in a combined heat and power plant to generate electricity for gas and fuel synthesis.
Furthermore, the by-products open up new revenue streams. The bio–oil can be refined and further processed into fuel, and biochar can either be used in-situ as a catalyst in the TCR plant or sold as soil conditioner where it sequesters carbon in the ground.