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High-purity hydrogen from biogas in biogas plant

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Hydrogen from genuine biogas: With a revolutionary chemical looping method, the Graz University of Technology and the start-up Rouge H2 Engineering are manufacturing high-purity hydrogen from biogas directly in a biogas plant for the first time in the world.

Green hydrogen is regarded as a ray of hope in the energy and mobility transition, however it is currently unsuitable for the general public. This is due to a number of factors: Currently, hydrogen is mostly produced centrally from fossil source materials. To be able to send it to gas stations, for example, it must first be compressed or liquefied in a costly and energy-intensive process. To store significant volumes of hydrogen, you’ll require expensive infrastructure with substantial investment costs.

Decentralized hydrogen generation, ideally from locally accessible renewable energy sources, will be unavoidable in the future for a countrywide supply of hydrogen. In 2020, researchers from Graz University of Technology introduced the “Chemical-Looping Hydrogen-Method,” a sustainable technique for decentralized hydrogen generation developed in collaboration with process engineer Viktor Hacker and the Graz start-up Rouge H2 Engineering. The study resulted in a small on-site-on-demand device that can manufacture hydrogen from biogas, biomass, or natural gas, and has won many honors.

Now, hackers and their ilk are causing people to sit up and take attention once more: With tangible outcomes from the Biogas2H2 project, which is still ongoing: They manufacture high-purity hydrogen from genuine biogas, including all contaminants included in the gas, directly at an existing biogas plant in one of the world’s largest industrial demonstration facilities. The Austrian Research Promotion Agency FFG is funding the study.

“We’re demonstrating how a chemical looping system may be incorporated into a biogas plant that already exists.” “High-purity hydrogen for fuel cells is created from genuine biogas, not only in the lab, but on an industrial scale,” says Viktor Hacker of Graz University of Technology’s Institute for Chemical Process Engineering and Environmental Technology. The true biogas originates from the South Styrian kostrom Mureck GmbH, which produces methane gas from pig dung, glycerine phase, silage maize, and grain wastes. An extra pillar has piqued their interest: “The option that our biogas creates green hydrogen for sustainable transportation in addition to energy is of course tremendously interesting for us,” says Managing Director Karl Totter.

Rouge H2 Engineering and Graz University of Technology installed the demonstration system on the company’s Mureck premises in summer 2021, and it will be in use for testing until the end of October. Around 1% of the biogas flow (around 30 liters per minute) is diverted to the 10 kilowatt system, which mixes it with water vapor. The mixture is pumped into the reactor of the facility. Biogas is reformed and synthesis gas is created there. The iron oxide is subsequently reduced to iron by this gas. The iron is then reoxidized to iron oxide when water vapor enters the reactor. This produces hydrogen that is 99.998 percent pure.

This iron-steam process has a 75 percent efficiency. “We could even have a 3 megawatt hydrogen generation plant if we routed the full biogas flow from the Mureck biogas plant (about 480 cubic meters per hour) via a suitably scaled-up chemical looping facility instead of the one percent.” This indicates that the technology is now ready for commercial application. On a broad scale, we can also manufacture decentralized hydrogen from genuine biogas. Our facility just requires a little amount of room. “As a result, we are currently accepting orders from the biogas industry,” says Gernot Voitic, project manager for Rouge H2.

This form of decentralized production has a favorable impact on hydrogen production and, as a result, on its buying price. “At the present, hydrogen is sold at the filling station for 10 euros per kilogram,” Hacker stated. According to the techno-economic analyses conducted as part of our research project, decentrally generated hydrogen for our method would cost 5 euros per kilogram. This puts the method on par with comparable technologies like electrolysis, which costs between 5 and 12 euros per kilogram of hydrogen.

The technique has been successfully tested and can be effortlessly integrated into an existing biogas plant. The following key concerns for countrywide availability remain unanswered: What should happen to hydrogen in the future? And who is the first to take the initiative?

Installing a hydrogen filling station in addition to the biogas-to-hydrogen system is an obvious consideration. The essence of the issue is this: Hydrogen-powered cars must now be refueled at 700 bar pressure, according to requirements, “in order to pack as much hydrogen into the smallest feasible tank and so obtain an appealing range,” adds Viktor Hacker. The chemical looping system creates hydrogen at a pressure of up to 100 bar, which is sufficient for refueling but not enough. It’s difficult and costly to compress hydrogen to 700 pressure. “This compression has to happen someplace, either directly at the factory or, at the very least, at the filling station, which might, of course, be supplied with bottled hydrogen.” The expenses will be paid, which takes us back to the tank price. This compression would not be physically necessary: fuel cell cars can theoretically travel with only 2 bar of pressure, but only for a short distance. As a result, decentralized hydrogen production at biogas facilities would be suited for shorter travels, such as for hydrogen tractors (which are currently unavailable) or hydrogen-powered storage vehicles like forklifts.

Filling hydrogen into gas bottles for travel, running hydrogen lines directly to dwellings equipped with fuel cells, or using it in industrial operations are all alternatives for using hydrogen “from the biogas plant.” “We could very easily foresee using our biogas to make hydrogen and installing a similar system to our site,” says Karl Totter of kostrom Mureck GmbH. However, someone must purchase hydrogen from us. We still need to shift something on the demand side before we can take this investment step.”

It’s no longer about the specific application of hydrogen technology at Graz University of Technology – that’s where Rouge H2 Engineering comes in – but about its continued development. In particular, the Acceptor project, supported by the Austrian Science Fund FWF, began in September 2021, with Hacker and his team focusing on the reactor’s iron-based material’s extendable service life.

Arnes Biogradlija
Creative Content Director at EnergyNews.Biz

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