Don’t call it waste – if handled properly, it can turn into hydrogen

Circularity is one way to help achieve a green transition. Now everything can get a second life and even what we thought was trash can be a valuable resource. The same applies to industrial by-products. If the production of biogas and methane from organic waste is not something new, neither is the green hydrogen that scientists are trying to produce from this type of waste.

in Germany Fraunhofer Institute for Manufacturing and Automation Engineering IPA research is now focused on the production of carbon-negative hydrogen using biomass and plant waste. Scientists are investigating several HyBECCS (Hydrogen bioenergy with carbon capture and storage) to get H.2 waste that would otherwise remain garbage. From bacteria-based processing in bioreactors to thermochemical gasification methods, there are many options.

Waste as a source of hydrogen

The German Environment Agency Reports indicate that the country generates 15 million tons of organic waste, including household waste, agricultural and food production waste. This section is for composting plants or incinerators. The European Environment Agency He also emphasized the importance of properly treating these wastes to produce heat or sustainable fuel. Thus, obtaining hydrogen from waste will create added value.

“In previous projects where food industry waste was converted into hydrogen, I was struck by the size of the CO2 fraction. The biggest achievement was the production of a biochar source.2It is a byproduct of hydrogen production. This means that H2 They can be used in a climate-neutral way and carbon dioxide can be stored,” explains Johannes Voll. He is head of the Sustainable Development Group at Fraunhofer IPA in Stuttgart.

Bacteria can produce hydrogen

Proper management of organic waste helps reduce emissions. Landfills release carbon dioxide and methane, some of the main greenhouse gases that pollute the air. Anaerobic composting is one of the main methods of waste treatment in biological treatment plants – an alternative to composting. Waste must be placed in an airtight container. The bacteria then break down the waste and allow the methane to accumulate, and the remaining material can be used as a sustainable fertilizer.

In one technique that Bean and his team are testing, the so-called purple bacteria – This is their color – they are the main players. These photosynthetic bacteria can convert agricultural and food waste into hydrogen. In other words, they can produce H2 through the light. Professor Robin Ghosh’s team from the institute Biomaterials and biomolecular systems University of Stuttgart I found a way to grow these bacteria without light. This is a great achievement because they do not require more complex photobioreactors to grow them,” explains Voll.

According to the scientist, another year of research will help to move the concept from the laboratory scale to a larger scale.

Fire decomposition and fermentation

Another method that scientists are currently testing is pyrolysis of methane. In this process, biogas is converted into hydrogen and solid carbon. As the ancient Greek etymology suggests – literally replacing fire – it means that a substance is dissolved by fire. Moreover, this thermal decomposition takes place at temperatures of more than 500 degrees without any air.

Full: “On the one hand, we get a gas fraction that contains hydrogen. On the other hand, we get solid carbon as a product. This makes storage easier – no further conversion is required.”

Johannes Vol
© Fraunhofer IPA, Photo: Rainer Bez

Johannes Vol

Head of Sustainable Development at the Fraunhofer IPA Biointelligent Technologies Group

He and his team are experimenting with different ways to extract hydrogen from bio-waste.

The Fraunhofer team is currently testing another method dark fermentation. This process can be considered as part of the entire biogas production process. In essence, the waste streams themselves are fed into the bioreactor – just like conventional bio-waste treatment procedures – but for a shorter period of time. This ensures that hydrogen and carbon dioxide do not turn into methane.

“The main drawback of this process is that we don’t get a very high yield of hydrogen compared to other methods,” Voll points out. “On the other hand, it is an energy-efficient procedure that can be performed in standard bioreactors. This is an improvement on biogas processing because there is another product besides biogas, which is hydrogen.”

genetically modified bacteria

Bean also cites genetic manipulation of bacterial streams. According to him, genetic engineering will make the bacteria behave the way scientists want them to. Microorganisms will then play a role in fermentation processes or biohydrogen and HyBECCS. In this way, higher yields and higher efficiency can be achieved. “If we make bioprocesses more waste-friendly by developing smart and self-adaptive control systems, we will achieve more efficient biosmart systems,” adds the team leader.

hydrogen axes

The Stuttgart group has also developed a new model for the hydrogen-based economy. Industrial hydrogen nodes in Baden-Württemberg That’s the name of a study demonstrating the potential of green hydrogen to meet certain energy needs, such as moving heavy goods, in the region. Specifically, several hydrogen production centers have been developed as part of the model. Strategic axis placement played a key role in making the model successful.

“We thought about how to achieve a hydrogen economy without requiring a capital overhaul of the entire energy system. The main premise was to think about decentralized production and the use of centers, for example using biogas, photovoltaics, wind energy or biogas. plants. This was the next step – to find a local market that would not require the creation of a large infrastructure. This is how we wanted to prove that decentralized production is possible. And then all these cores can continue to grow towards the goal of a hydrogen economy.

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