The process of decarbonising the energy sector and expanding renewable energies is underway in many countries. And it is also perfectly understandable because of the climate change. However, it is impossible to do without carbon in the chemicals and derived products sector. The chemical industry has a permanent and increasing demand for carbon, which is contained in many products.
Today, a total of 450 million tonnes of carbon are embedded in chemicals and polymers, most of which come from fossil resources. The challenge is to meet the significantly increasing demand for renewable carbon by 2050. This means that the chemical sector is currently undergoing the biggest transformation since the industrial revolution. The demand for fixed carbon will continue to rise in the future. A circular economy, therefore, appears to be indispensable, as Ferdinand Kähler diagnosed in the trade journal ‘Prozesstechnik’ at the end of 2021.
To replace the use of fossil carbon with renewable carbon sources and thus create a sustainable change, there are essentially three options: Biomass, Recycling and CCU (Carbon Capture and Utilisation). Through a truly circular economy, the carbon cycle can thus be closed. It is possible to produce all of today’s chemicals and downstream products from renewable carbon that has then been extracted from biomass, captured CO2 or recycled. However, a 15-fold increase in renewable carbon production by 2050 would be necessary to meet demands.
Strategies and Methods for a Circular Economy
A dedicated strategy for a carbon economy requires building new structures through new processes, such as biotechnology, wood chemistry or electrochemistry, to produce raw materials more efficiently from biomass or CO2. This can produce products that often have properties not found in conventional petrochemical products. For example, such a strategy may involve replacing petrochemical plastic packaging with packaging made from paper, cellulose or natural fibres.
The use of organic waste is likely to be key to the transition to a bio-based circular economy. The utilisation of biomass is particularly useful where functional and complex molecular units of the biomass remain after chemical conversion and can be further utilised. This applies, for example, to oleochemistry, natural rubber and lignin, as well as to numerous novel biobased components such as organic acids and furan-based products. Industrial biotechnology can help to produce complex molecules in short, low-impact and customised processes.
Sophisticated recycling is also promising: with chemical recycling, almost all waste fractions – especially mixed ones – can be recycled and converted into high-quality input materials. With mechanical and chemical recycling, larger parts of the carbon thus remain in the cycle – but not all of it. Besides recycling, other sources of renewable carbon are therefore needed to close the gaps in the cycle and minimise losses. Various intermediate and end products can also be produced by combining CO2 with green hydrogen, such as methane and methanol. The Fischer-Tropsch reaction also makes it possible to produce synthetic naphtha from CO2 and hydrogen.
The specifications for a circular economy are now in place and, with the right framework conditions, can certainly be implemented to lead the chemical industry to a real transformation.