Promoting circular carbon in the chemical industry

By Erwin Douma, Frank Steffen and Ruirui Zong-Rühe

The chemical industry is the world’s largest industrial energy consumer and is heavily reliant on fossil fuels. In terms of direct CO2 emissions, however, it ranks third, largely because around half of the sector’s energy input serves as feedstock for hydrogen and carbon, with the other half used as process energy. While emissions from process energy go directly into the atmosphere, carbon from fossil feedstock is embedded into the chemical industry’s final products. Besides striving to decarbonize chemical processes, the chemical industry must also create a more circular value chain for its embedded carbon. This will require new solutions to major technological, economic, and infrastructural hurdles.

The chemical sector embeds approximately 450 megatons of fossil carbon feedstock into its products each year. With demand for many chemical products growing, including plastic, this is expected to reach 590 megatons by 2030. While the industry is beginning to address the issue of sustainability, based on current trajectories, only 22% of the 590 megatons will be covered by sustainable sources of carbon. The picture is clear – progress needs to accelerate.

There are currently three promising drop-in solutions for creating circular chemical feedstock, each of which has its own advantages and limitations: recycling, biomass materials, and carbon capture and utilization (CCU).

Recycling: Technologically advanced but challenges remain

Recycling currently has the highest technological readiness of the three options. Most materials recycled are plastics: technologies to extract carbon from sources other than polymer are currently scarce. Some of the processes are well established, with mechanical recycling currently the dominant method. Its lower process temperatures (150-300°C) make it more energy efficient than alternatives.

For recycling to make a bigger contribution to circular carbon in the chemical industry, it must overcome one main challenge: Both mechanical and chemical recycling processes are very sensitive to feedstock quality, requiring clean, well sorted waste input. And that’s not easy to source. Despite improvements to collection and sorting systems, waste management infrastructure remains limited, especially outside Europe. Demand for plastic waste as a sustainable feedstock will hit approximately 210 megatons a year by 2030. But based on current projections, recyclers will only be able to supply about half of this – a serious bottleneck.

Biomass: Technological development required

Biomass offers an organic, renewable alternative to fossil-based feedstocks and can be produced from a variety of sources, including crops, sewage, and agricultural waste. C2 compounds currently make up more than three quarters of embedded bio-based carbon, with bioethanol accounting for 99%. Biomass technologies have now been around for several decades and are divided into three generations, each with their own pros and cons.

First-generation biomass is from edible crops such as corn, soybeans, and sugarcane. The technologies are mature and there is some high-volume commercialization. However, first-generation biomass competes with food production, leading to conflicts of resources and land use.

Second-generation biomass is made from cellulose, typically sourced from non-food crops and waste biomass. It’s commercially less mature, but some technologies for commodity chemicals are available. Second-generation biomass doesn’t compete with food crops, but pretreatment is expensive and there are still conflicts of land use.

Third-generation biomass uses algae as a feedstock, meaning it does not compete with food supplies and requires minimal land. It can also offer a much higher yield potential than the first two generations of biomass. However, the technologies required are still in their early stages, with significant research and investment still required to reach commercial maturity.

Carbon capture and utilization: Still a long way from scalability

The CO2 available from emissions is 16 times more than the global chemical industry’s expected carbon demand in 2030. CCU technologies can be retrofitted to most industrial and power plants to leverage CO2 from a wide range of sources. Captured CO2 can then be used as feedstock to produce chemicals, building materials (e.g., carbonates) or synthetic fuels.

However, just 0.003% of available CO2 is expected to be utilized by 2030. High costs and immature technologies mean commercialization is still low, with little sign of major growth in the near future. Significant technological and economic improvements are required to make CO2-based products competitive with their fossil-based peers. One ton of CCU-based ethylene, for instance, costs between USD 2,100-2,200; but fossil-based ethylene is valued at USD 500-900, including USD 100-300 of a hypothetical carbon tax.

What’s next?

Implementing a more sustainable supply of carbon feedstock is vital for the chemicals industry, but the path to circularity will not be easy. Each of the sector’s three key solutions faces major challenges: the availability of a suitable waste stream for recycling, and technological and economic hurdles for biomass and CCU.

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