Three questions for ... Paolo Gabrielli

Paolo Gabrielli, Senior Scientist at ETH Zurich, Interview: Corinna Herbst

The chemical industry is responsible for 5% of global_CO2 emissions. However, given the widespread use of high-carbon raw materials, the decarbonization of the industry faces major challenges.

How can we effectively manage the transition from fossil feedstocks to more sustainable alternatives in the chemical industry?

Despite the particular challenges of decarbonizing this industry, there are now several technological pathways for producing chemicals with _net CO2 emissions based on biomass, recycling and carbon capture, utilization and storage. In carbon capture and storage (CCS), chemicals are synthesized from fossil fuels as in business-as-usual (BAU) using current organic chemistry. However, all_{CO2 emissions} generated along the chain are captured and permanently stored in suitable underground geological structures or in building materials. Where available,_CO2 can be captured from point emitters (such as refineries or ammonia production plants), by direct air capture (DAC) or by a combination of these processes. Overall, CCS routes are now available on a commercial scale. While they are seen as key to reducing emissions from hard-to-remove industries, they are dependent on the continued use of fossil fuels and the availability of large_{CO2 storage capacities}, which leads to problems with the social acceptance of CCS deployment.

"There are several paths to a_CO2-free chemical industry"

What other options are there?

In carbon capture and utilization (CCU), the chemical industry achieves net-zero carbon emissions by swapping the origin of carbon for C-based chemicals: from fossil carbon to the carbon in_CO2 previously captured from point emitters and/or from the air. CCU requires the development of a new chemical industry, organic chemistry and catalysts that convert_CO2 into the desired C-based product, as well as low-carbon hydrogen and energy as inputs for product synthesis, as these are no longer derived from fossil hydrocarbons. In addition, CCU strategies would require the development and deployment of large_CO2 and hydrogen infrastructures for the transportation of_CO2 and hydrogen from production to consumption sites. Biomass contains both the carbon and hydrogen atoms and the energy required to synthesize chemical products. However, the chemical structure of biomass feedstocks is less favorable than that of fossil fuels, e.g. in terms of higher water content and lower energy content.

What role could biomass play in the decarbonization of the chemical industry?

When biomass is used,_CO2 is captured from the air during biomass growth through photosynthesis and then released during synthesis and at the end of the life of the biomass-based product, resulting in net zero_{CO2 emissions}. While biomass is a promising feedstock for building a new chemical industry, this is also true for several other sectors. Therefore, its use could be hampered by its availability and the land and water resources required for its cultivation. When available, residual biomass can be used as a raw material without compromising available natural resources.

First publication in the GIT-Labor journal 11-12/2023