"We have shown that bio-butanol would be a valuable addition to the renewable fuel options for Europe..."
Writing, reading and discussing the bio-economy, it is sometimes easy to forget that innovations in this sector aren’t all from the 21st century. As early as 1826 ethanol (a chemical compound with multiple uses, including as a clean-burning fuel source) was used to power an engine, a generation later, Louis Pasteur first observed butanol (an alcohol produced from petrochemical or biological sources) as a product of fermentation. Fast forward to 1916 and ABE fermentation is first used to produce acetone, butanol, and ethanol from carbohydrates such as starch and glucose. This was developed during World War I, as acetone was used to produce cordite, a substance essential for the British war industry. These military demands led to mass production of ABE and during this period we also saw the development of biobutanol, with it being produced from plant based rather than from fossil based sources.
Biobutanol is an exciting alternative to first generation biofuels such as biodiesel and bioethanol. Its similarity to petrol means that with effective pumping systems it could be easily implemented immediately within the existing infrastructure. Its density ensures that a litre of biobutanol will get your car almost as far as a litre of regular petrol would but with up to 85% less greenhouse gas emissions. As well as its potential as a transport fuel, biobutanol is also a building block chemical used extensively in the paints, coatings, adhesives and inks markets.
However, despite the many benefits, opportunities and properties that ABE fermentation can offer due to the costs of production, inefficiencies in the process and the stubbornly low cost and organisational advantages of fossil-based equivalents, biobutanol has not gained a significant presence in the market.
Until now that is. The ButaNexT (‘Next Generation Bio-butanol’) project aims to overcome these technical and economic constraints to the use of bio-butanol both as a commodity chemical and advanced biofuel. The project began in 2015, with a consortium that brought together the leading experts in Europe to further optimise the value chain for biobutanol. Together they have developed and demonstrated, at pilot scale, a more cost-competitive, efficient and environmentally friendly process to convert sustainable renewable feedstocks into biobutanol. Their work has been validated by a full environmental, resource, techno-economic and social impact assessment of the entire chain.
UK based Green Biologics are the project co-ordinator and experts in fermentation (microorganism and technology development) and butanol commercialization.
Speaking at the Innovation in the bioeconomy Conference in Brussels on April 12th, at which the results of ButaNexT project were presented, Project coordinator Tim Davies from Green Biologics gave us some insights into the next stages of biobutanol development; “ButaNext partners made significant advances in the bio-butanol production process, addressing every aspect of its value chain. We have shown that bio-butanol would be a valuable addition to the renewable fuel options for Europe with environmental benefits. Some challenges do remain and in particular production economics still need to improve. However, Green Biologics do have a commercial bio-butanol plant operating in the USA, so the prospects for a European manufacturing centre using renewable feedstocks remains a feasible prospect.”
The project had a multi-layered innovation process:
FLEXIBLE BIOMASS CONVERSION: Tecnicas Reunidas, together with CENER, have developed a new two-step pre-treatment process which is able to convert different lignocellulosic biomass and wastes in such a way that provides higher yields in subsequent stages. Crucially, the new milling unit significantly reduces the biomass particle size - to less than half a millimetre. This allows for milder conditions in the subsequent thermochemical treatment, and an improved conversion rate during the hydrolysis stage. It is expected that both capital and operating costs can be reduced – the unit reduces the energy consumption up to 25% compared to the conventional technologies studied.
TAILOR MADE ENZYME COCKTAILS: MetGen designed and developed tailor-made enzyme solutions for non-food lignocellulosic feedstocks. The optimised cocktails increased total sugar yield by 70% to 90% compared to the initial offerings, in only half of the hydrolysis time.
HIGH PRODUCTIVITY FERMENTATION PROCESS: Green Biologics has developed an improved clostridial strain specifically for use with lignocellulosic feedstocks. The fermentation was coupled with membrane technology developed by the Flemish Institute for Technological Research (VITO) to achieve in situ product recovery (ISPR). This hybrid fermentation concept not only alleviates product inhibition but also leads to partial product purification and enrichment, thus improving water balances and reducing energy consumption in further downstream processing.
INTEGRATION AND UPSCALING: The innovations were combined at a pilot plant, installed at the Second Generation Biofuels Centre operated by CENER - Spain’s National Renewable Energy Centre - in Navarra, Spain.
Dr. Holly Smith, Head of Fermentation, Green Biologics tells us more about the improvements they have made to the fermentation process; “We have developed strains with increased tolerance to butanol and shown that when these strains were grown in the presence of higher solvent concentrations they maintained a 25% higher rate of sugar usage than the original strain. We also developed strains with increased tolerance to feedstock inhibitors and shown that these strains have up to 40% higher rate of solvent production. We have shown that it is possible to use second generation feedstocks with these microbes."
Within the project, researchers at the University of Castilla-La Mancha (UCLM) also investigated different fuel blends incorporating biobutanol. They found that, in general, biobutanol as a blend component does not reduce engine efficiency and is beneficial for reducing particulate emissions. Bu10D (10% biobutanol, 90% diesel) and Bu10B10D (10% biobutanol, 10% biodiesel and 80% diesel) were identified as the most promising blends to substitute 100% diesel fuel.
Most of the innovations and developments achieved in the ButaNexT project will also have a broader impact than for biobutanol being used a as a fuel alone. They can also be used for transforming lignocellulosic biomass into other biofuels and biobased chemicals.
The ButaNexT project is a fantastic example of how the bio-economy can bring together international expertise to overcome its challenges. For generations the potential of bio-butanol has not been able to be fully realised but now this consortium has shown the path to how an advanced biofuel business can be built from sustainable feedstock. I think we'll be covering bio-butanol on our pages a lot more in the coming years!
The ButaNexT consortium consists of Green Biologics, CENER - National Renewable Energy Centre of Spain, C-Tech Innovation, E4tech, Greenovate! Europe, MetGen, Tecnicas Reunidas, Universidad De Castilla La Mancha, VITO - Flemish Institute for Technological Research and Zabala Innovation Consulting. The project received funding from the European Union Horizon 2020 Research and Innovation Programme under grant agreement n° 640462.
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