Sustainable biorefining with ground-breaking ultrasonic fractionation
Rising emissions and the depletion of natural resources are of increasing concern to industries worldwide, compounding the need for more sustainable production methods.
Dr Andy West, Chief Chemist at Sonichem, discusses the potential of a ground-breaking ultrasonic fractionation process to convert by-products of forestry and agriculture operations into valuable biochemicals, reducing reliance on fossil fuels and contributing to a circular economy.
Climate change is the defining crisis of our time, brought about by a growing global population and ongoing economic growth in the developing world. Since the industrial revolution in the 18th century, carbon dioxide levels in the earth’s atmosphere have increased from about 280 to over 400 parts per million, and a major contributor to this is modern society’s excessive dependence on coal, oil, and gas.1
Fossil fuels contributed to around 84 percent of global primary energy in 2019, and are continually extracted, processed, and refined to produce chemical-based products that are the foundation of everything from healthcare to technology.2
Without fundamental transformations in all aspects of society – including food production, land use, transportation, and infrastructure – the climate crisis threatens to endanger future generations. However, we are far from powerless in the face of this global threat, especially considering the scope of international efforts to phase out fossil feedstocks and waste-intensive manufacturing of industrial chemicals. A number of innovative cleantech companies are making pioneering advancements in biorefinery technology that employ the power of renewable resources, reduce unnecessary waste, and pave the way to an alternative, more sustainable future.
New directions for biorefineries
One logical strategy that can help to mitigate climate change and encourage decarbonisation is to find ways to supply our chemical and fuel needs from renewable resources like crops, plants, and trees. However, traditional biorefineries – biomass conversion facilities analogous to petroleum-based refineries – often rely on imported or food-grade crops as a starting material for biochemical production, which increases costs and removes valuable resources from a pressured global supply.
Faced with supply chain issues, government emissions regulations, and the costs and environmental footprint of shipping, chemicals companies are seeking ways to ‘reshore’ their input materials and take advantage of low-value by-products from local forestry and agricultural operations as a more viable resource.
Realising the value of discarded biomass
At present, poor waste management systems in the forestry and agricultural sectors mean that a significant portion of biomass potential is lost each year. By-products from farmlands and forests – including low-value agricultural remains like peanut shells, corn leaves, and manure, as well as forestry surplus like tree stumps, woodchips, and sawdust4 – are typically left to decay, burned in their natural form, or transformed through high-energy processes into wood pellets that are shipped to international power plants and incinerated, in turn releasing greenhouse gases. In fact, when a tree is chopped down for industrial use, only 55 percent of its wood forms a timber product; the remaining 45 percent is low-value by-products.
This approach completely ignores the potential of non-food biomass as a starting material for biochemical and biomaterial production. Replacing these processes with alternative clean technologies that optimise the economic and environmental added value of forests and farmlands is key to a sustainable future.
Transforming chemical production
One ground-breaking biorefinery solution, developed by the UK company Sonichem (formerly Bio-Sep), takes advantage of a sustainable ultrasonic fractionation technology to upcycle leftover agroforestry by-products, like woodchips and sawdust, into profitable commodities.
This process is unique, low energy, and cost effective, and it generates three high-value biochemicals for commercial use, with minimal waste and without releasing the carbon sequestered by plants into the atmosphere.
Dr West explains the significance of this technology: “Wood is made up of three components: cellulose and hemicellulose – which form a matrix – and lignin, an aromatic biochemical that binds the matrix together. Ultrasonic processing can separate these components, converting discarded agriculture and forestry produce into valuable platform biochemicals with wide market potential. Our processing method effectively produces sustainable bio-based alternatives to traditional, finite petrochemicals.”
Realising the bioeconomic potential of woody biomass
Finding green alternatives to the many petroleum-based products – plastics, fertilisers, clothing, digital devices, detergents, and medical equipment – that are integral to modern society is key, and Sonichem’s solution goes some way to fulfilling this. Its ultrasonic processing methods produce platform biochemicals with a wide variety of crucial applications and high economic value; one tonne of woody biomass costs just 45 GBP, and generates approximately 365 GBP of biochemicals, demonstrating its bioeconomic potential.
For example, microcrystalline cellulose produced through ultrasonic fractionation has an average particle size of about 100 microns, making it ideal for further applications in food and beverages, cosmetics, and performance composites.
Similarly, the technology extracts a pure, low molecular weight and highly soluble lignin – the most valuable of the three biochemicals – and uses it to replace toxic petrochemicals like phenol, channelling the binding properties of this biopolymer to make sustainable resins. It can also be added to industrial composites like cement as an admixture to improve flow, spun into carbon fibres, and incorporated into cosmetic products to add UV protection and antioxidant properties.
The third component of wood is hemicellulose, which is extracted as monomeric sugars with potential applications in the biomanufacturing of natural surfactants, dyes, nutraceuticals, pharmaceuticals, and even jet fuel.
Reimagining composites
While these fractionated plant constituents have useful individual properties, Sonichem is also investigating an alternative, innovative way to create a wood composite from ultrasound-treated agroforestry by-products.
Composite materials have benefitted society for thousands of years, from the ancient mixing of mud and straw to create bricks, to the innovations that led to the formation of plastics and fibreglass.
Now, as scientists and engineers seek to minimise the environmental footprint of composite production, there is an increasing focus on incorporating biomaterials to enhance the viability of these flexible materials, while optimising other properties such as structural integrity, stability, and resistance to corrosion and oxidation.
Dr West adds: “Our current focus is optimising the structure and manufacturing methodology of a mouldable and completely recyclable composite made from lignin and cellulose, which will enable the creation of products with all the properties of wood, but without generating any waste.”
The future of biorefinery
The rise of alternative chemicals, composites, and commodities is a crucial avenue for the environmentally conscious world, and biorefining is helping to decouple chemical production from the detrimental exploitation of natural resources. Sonichem is uniquely harnessing the benefits of woody biomass to produce commercially viable, customer-validated platform chemicals in an operational pilot plant, with clear plans for commercialisation and technology rollout moving forward.
Dr West concludes: “Sonichem is creating alternative chemicals by optimising the use of the world’s resources and avoiding excess waste. As we scale up our company, it is becoming clear that our ultrasonic processing techniques have the potential to tackle issues that impact the global climate crisis, contributing to a circular economy and delivering significant socio-economic benefits for a greener vision of the future.”
References
- Ritchie, H., Roser, M. and Rosado, P. 2020. Atmospheric concentrations. Our World in Data. Available at: https://ourworldindata.org/atmospheric-concentrations.
- Ritchie, H., Roser, M. and Rosado, P. 2022. Fossil fuels. Our World in Data. Available at: https://ourworldindata.org/fossil-fuels.
- Kolawole, F. et al. 2016. Microstructural study of pre-treated and enzymatic hydrolyzed bamboo. Leonardo Electronic Journal of Practices and Technologies, 15, 235-252.
- Gupta, J. et al. Agro-forestry waste management – A Review. Chemosphere, 287(3), 132321. doi: 10.1016/j.chemosphere.2021.132321
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