Researchers from Graz, Austria, directly produce high-purity hydrogen from real biogas at the existing biogas plant.
Picture: Green hydrogen is seen as a beacon of hope for the energy and mobile revolution, but it is not yet suitable for mass production. see more
Credit: peterschreiber.media-AdobeStock
Green hydrogen is seen as a beacon of hope for the energy and mobility revolution, but it is not yet suitable for mass production. There are several reasons. At present, the production of hydrogen is mainly concentrated on fossil raw materials. It must then be compressed or liquefied in an expensive and energy-consuming process in order to be transported to, for example, a gas station. There needs expensive infrastructure with high investment costs to store large amounts of hydrogen.
Therefore, for nationwide hydrogen supply, decentralized production will be indispensable in the future, and it will ideally use locally available renewable energy to achieve climate neutrality. In 2020, researchers at the Graz University of Technology (TU Graz) led by process engineer Viktor Hacker and Graz-based startup Rouge H2 Engineering jointly proposed a sustainable decentralized hydrogen production process, the so-called "chemical-cycle Hydrogen method". The research results that have won multiple awards have resulted in a compact on-site on-demand plant that can produce hydrogen from biogas, biomass or natural gas.
Now Hacker and his team once again let people sit up and pay attention. This time it is about the specific results of the ongoing project Biogas2H2. In one of the world's largest industrial-related demonstration plants, they directly produce high-purity hydrogen from real biogas in the existing biogas plant, including all impurities present in the gas. The project was funded by the Austrian Research Promotion Agency FFG.
Hydrogen in biogas in southern Styria
"We proved that a chemical recycling system can be integrated into an existing biogas plant. The high-purity hydrogen used for fuel cells is produced from real biogas, not only in the laboratory but actually on an industrial scale," from the Institute The Viktor Hacker explained. Chemical engineering and environmental technology of TU Graz. The real biogas-methane gas from pig manure, glycerin phase, silage corn and grain residues-comes from Ökostrom Mureck GmbH, a company in Southern Styria. There, they are very interested in this additional pillar. Managing Director Karl Totter said that in addition to electricity, the choice of biogas to generate green hydrogen for sustainable mobility is certainly very exciting.
Rouge H2 Engineering and TU Graz built a demonstration plant at the company's Murek site in the summer of 2021 and will be put into operation for testing by the end of October. This 10-kilowatt plant splits approximately 1% of the biogas flow (approximately 30 liters per minute) and mixes it with steam. The mixture flows into the reactor of the plant. There, the biogas is reformed and syngas is produced. This gas then reduces the iron oxide to iron. The steam then enters the reactor to re-oxidize the iron to iron oxide. This will release hydrogen with a purity of 99.998%.
This iron/steam process can achieve 75% efficiency. "If it is not one percent, we will guide the entire biogas stream (approximately 480 cubic meters per hour) of the Murek Biogas Plant through the correspondingly upgraded chemical recycling plant, and we can even reach a 3 MW hydrogen production plant. This means The technology is now ready for commercial use. We can also mass-produce decentralized hydrogen from real biogas. All it needs is a little space in our factory. Therefore, we are open to orders from the biogas industry. Effective immediately,” Rouge H2 project manager Gernot Voitic emphasized.
This decentralized production also has a positive impact on the production price, and thus on the purchase price of hydrogen. Hacker added: "Currently, the hydrogen price provided by hydrogen refueling stations is 10 Euros/kg. The technical and economic analysis as part of our research project predicts that the price of hydrogen for the dispersed production of hydrogen from our process is 5 Euros/kg. This makes This process is competitive with other technologies such as electrolysis (5-12 Euro/kg hydrogen).
The technology has been proven effective and can also be integrated smoothly into existing biogas plants. However, key issues regarding national availability remain unresolved. These include: how should hydrogen be handled in the future? And: who will take the first step?
In addition to plants that produce hydrogen from biogas, the idea of installing a hydrogen refueling station is obvious. But the crux of the problem is that hydrogen-powered cars must currently be refueled at a pressure of 700 bar, "in order to put as much hydrogen as possible into the smallest possible tank, so as to achieve an attractive cruising range," Victor Ha Ke explained. The chemical cycle unit produces hydrogen at a pressure of up to 100 bar, which is relatively high but not enough to refuel. Compressing hydrogen to 700 bar is tricky and expensive. "This compression must be done somewhere, either directly at the production site, or at the filling station at the latest. Of course, it can also be supplied with bottled hydrogen. The cost will increase, which brings us back to the price of the pump again."
Technically speaking, this compression is not necessary: in principle, fuel cell vehicles can also be driven at a pressure of only 2 bar-but not too far. Therefore, decentralized hydrogen production directly in the biogas plant will help shorten the journey, for example for hydrogen tractors (currently not even on the market) or for hydrogen power storage vehicles such as forklifts.
Other possibilities for using hydrogen "from a biogas plant" are filling it into gas cylinders for further transportation, laying hydrogen pipelines directly to households equipped with fuel cells, or using it in industrial processes. For advanced and junior Karl Totter, Ökostrom Mureck GmbH's path is very clear: "We can imagine using our biogas to produce hydrogen and adding corresponding factories on our site. But someone must buy hydrogen from us. In demand On the one hand, there must still be some action so that we can take this investment step." For TU Graz's hydrogen research, it is no longer a specific application of technology—this is where Rouge H2 Engineering comes in—but about it. Further development. Specifically, the Acceptor project (funded by the Austrian Science Foundation FWF) was launched in September 2021, in which Hacker and his team will focus on the scalable service life of iron-based materials in the reactor.
The research topic is based on the professional field of "mobility and production", which is one of the five strategic research focus areas of the Graz University of Technology.
Viktor HACKER TU Graz | Institute of Chemical Engineering and Environmental Technology Tel: 43 316 873 8780 Mobile: 43 660 316 8812 viktor.hacker@tugraz.at
Gernot VOITIC Rouge H2 Engineering Tel: 43 316 37 50 07 gernot@rgh2.com
Karl TOTTER Ökostrom Mureck GmbH Tel: 43 664 2752893 totter@sebamureck.at
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Susanne Filzwieser Graz University of Technology susanne.filzwieser@tugraz.at Office: 316 873 4566
Copyright © 2021 American Association for the Advancement of Science (AAAS)
Copyright © 2021 American Association for the Advancement of Science (AAAS)