Sustainable chemistry with "Carbontrans": Residual waste becomes synthesis fuel

A plant in Leuna should become a pioneer in chemical recycling

The chemical industry needs cycles. Germany's landfills are full of residual waste that has not previously been recycled. As climate protection movements gather speed, efforts to solve this problem are gaining momentum. Researchers from Saxony and Saxony-Anhalt are now planning a facility that could soon be used to convert waste into synthetic fuels in Leuna, a centre of the chemical industry.

Getting rid of discarded material from yellow recycling bins and processed residual waste from black general waste bins using environmentally friendly chemical recycling: this may initially sound both crazy and visionary, but it is a question Prof. Bernd Meyer has been considering for a long time – and the basis for a project now more relevant than ever. The process engineer is Head of the Freiberg "Carbon Cycle Technologies" branch of the Fraunhofer Institute for Microstructure of Materials and Systems IMWS in Halle (Saale) and Director of the Institute of Energy Process Engineering and Chemical Engineering (IEC) at TU Bergakademie Freiberg. That makes him one of the leading figures in a group of organisations committed to "Carbontrans" – a platform for the carbon cycle economy in Leuna, a centre of the chemical industry in southern Saxony-Anhalt.

Planning and operation for the project, which could have a major and lasting impact on sustainable chemistry in the state, are being coordinated through the Fraunhofer Chemical and Biosystems Technology High-Performance Centre under the leadership of Bernd Meyer. The High-Performance Centre brings together stakeholders including Merseburg University of Applied Sciences, the Fraunhofer Center for Chemical-Biotechnological Processes CBP in Leuna, and the following businesses: MIBRAG, ROMONTA, InfraLeuna and RWE Power. The underlying idea is that waste should in future no longer simply be burned as a fuel, but instead become part of the chemical value chain as a secondary raw material.

In search of new recycling options

The researcher puts the project's main objective like this: "We must establish chemical recycling as the most sustainable way of feeding waste back into the carbon cycle". As large quantities of "substitute fuels" – residual material, for example left over when the contents of yellow recycling bins or black general waste bins are sorted – are currently burned in waste-fired or coal-fired power plants, the interdisciplinary association is looking for new ways of recycling. Another pressing reason is that coal-based electricity generation is set to end in the foreseeable future.

"A very good option," explains Bernd Meyer, "is gasification, which produces pure synthesis gas that can in turn be converted into new plastics or synthetic fuels – in a closed, environmentally friendly system." Meyer firmly believes that those chemical products or fuels "will be in great demand in the future not least because they can significantly reduce levels of CO₂ in polymer chemistry and long-distance transport, which still depends on combustion engines".

Motorists could fill up with synthetic fuels

This idea has fallen on fertile ground in Saxony-Anhalt: with "Carbontrans", Fraunhofer IMWS is seeking to make a key contribution to a low-emission carbon cycle economy. A plant – the researchers are calling it a "demonstration platform" – is to be built in Leuna for gasifying carbon-containing waste, on its own and together with agricultural and forestry waste. The centrepiece of the new technology is a reactor that is to convert the carbon-containing base material with oxygen O₂ and water vapour H₂O at temperatures of over 1000°C. The synthesis gas produced from the carbon (C) will contain carbon dioxide CO₂ as well as carbon monoxide CO and hydrogen H₂. Adding hydrogen H₂ enables the otherwise separated CO₂ to be used for chemical syntheses, i.e. converted into chemical products. This is a major boost for Leuna as an industry centre, not least as because it is also to be home to an electrolysis platform for generating "green" hydrogen H₂ and "green" oxygen O₂ in a climate-neutral way using "green" electricity from renewable energy.

The "Carbontrans" plant could process up to 35,000 metric tons of carbon-containing waste each year. The resulting 10,000 metric tons of synthesis gas (CO and H₂) could be used directly for the production of methanol at the Leuna chemical park – or converted into fuels in a subsequent synthesis process. Other chemical compounds such as ethanol or acetone could also be produced synthetically. Following a test phase, Bernd Meyer believes that it will be worth considering supplying filling stations with the synthetic fuel. Support for the ambitious project is coming from the state governments of Saxony and Saxony-Anhalt. Saxony-Anhalt intends to provide 15 million euros; additional funds could come from structural development funds, and significant sums from the federal government.

All project partners hard at work

The planning phase for the pilot plant is to be completed by the end of 2021. "As of this year, we have been examining the technical feasibility and approvability, and quantifying the costs," explains Bernd Meyer. If the German federal government also grants its approval, planning could be completed in three years and the construction of a research reactor to provide data on operation could begin in 2022. That is the challenge. "We need fundamentally to revise the plant technology previously used for coal," according to Bernd Meyer. All parties involved are hard at work on the concept, applying for planning funds so that they can research, compare and ultimately find the genuinely sustainable way forward. This also means developing the legal framework.

Global demand for the technology

Bernd Meyer is not put off by the many steps it takes to make vision a reality. In fact, he is happy "to be able to combine experience from previous research with new technology". The researchers in Freiberg are now working on proving that high-quality synthesis gas is produced and that efficient, stable, continuous operation of the gasification reactor is possible. After the trial stage, the innovative technology could be used in the Leuna infrastructure in 2024 before going into full operation with "Carbontrans", says Bernd Meyer.

"The technology platform fits perfectly with Saxony-Anhalt's chemical specialisation; the location is ideal for the pilot plant," believes Prof. Dr. Ralf B. Wehrspohn, Head of Fraunhofer IMWS until October 2019 and now Executive Vice President, Technology Marketing and Business Models at the Fraunhofer-Gesellschaft. According to Wehrspohn, if the platform is successful, it could be scaled up to an industrial scale. "We see great demand for this technology in other regions, too, and indeed worldwide," says Wehrspohn. Talks are apparently already underway with companies from China and New Zealand. Bernd Meyer believes there is great interest in German technology. "We are in the right place at the right time.“

Author: Manuela Bock