Climate change mitigation potential of carbon capture and utilization in the chemical industry.

Chemical production is set to become the single largest driver of global oil consumption by 2030. To reduce oil consumption and resulting greenhouse gas (GHG) emissions, carbon dioxide can be captured from stacks or air and utilized as alternative carbon source for chemicals. Here, we show that carbon capture and utilization (CCU) has the technical potential to decouple chemical production from fossil resources, reducing annual GHG emissions by up to 3.5 Gt CO2-eq in 2030. Exploiting this potential, however, requires more than 18.1 PWh of low-carbon electricity, corresponding to 55% of the projected global electricity production in 2030. Most large-scale CCU technologies are found to be less efficient in reducing GHG emissions per unit low-carbon electricity when benchmarked to power-to-X efficiencies reported for other large-scale applications including electro-mobility (e-mobility) and heat pumps. Once and where these other demands are satisfied, CCU in the chemical industry could efficiently contribute to climate change mitigation.

Renewable carbon feedstock for polymers: environmental benefits from synergistic use of biomass and CO2.

Polymer production is a major source of greenhouse gas (GHG) emissions. To reduce GHG emissions, the polymer industry needs to shift towards renewable carbon feedstocks such as biomass and CO2. Both feedstocks have been shown to reduce GHG emissions in polymer production, however often at the expense of increased utilization of the limited resources biomass and renewable electricity. Here, we explore synergetic effects between biomass and CO2 utilization to reduce both GHG emissions and renewable resource use. For this purpose, we use life cycle assessment (LCA) to quantify the environmental benefits of the combined utilization of biomass and CO2 in the polyurethane supply chain. Our results show that the combined utilization reduces GHG emissions by 13% more than the individual utilization of either biomass or CO2. The synergies between bio- and CO2-based production save about 25% of the limited resources biomass and renewable electricity. The synergistic use of biomass and CO2 also reduces burden shifting from climate change to other environmental impacts, e.g., metal depletion or land use. Our results show how the combined utilization of biomass and CO2 in polymer supply chains reduces both GHG emissions and resource use by exploiting synergies between the feedstocks.

Sustainable Conversion of Carbon Dioxide: An Integrated Review of Catalysis and Life Cycle Assessment.

CO2 conversion covers a wide range of possible application areas from fuels to bulk and commodity chemicals and even to specialty products with biological activity such as pharmaceuticals. In the present review, we discuss selected examples in these areas in a combined analysis of the state-of-the-art of synthetic methodologies and processes with their life cycle assessment. Thereby, we attempted to assess the potential to reduce the environmental footprint in these application fields relative to the current petrochemical value chain. This analysis and discussion differs significantly from a viewpoint on CO2 utilization as a measure for global CO2 mitigation. Whereas the latter focuses on reducing the end-of-pipe problem "CO2 emissions" from todays' industries, the approach taken here tries to identify opportunities by exploiting a novel feedstock that avoids the utilization of fossil resource in transition toward more sustainable future production. Thus, the motivation to develop CO2-based chemistry does not depend primarily on the absolute amount of CO2 emissions that can be remediated by a single technology. Rather, CO2-based chemistry is stimulated by the significance of the relative improvement in carbon balance and other critical factors defining the environmental impact of chemical production in all relevant sectors in accord with the principles of green chemistry.

Electrified hydrocarbon-to-oxygenates coupled to hydrogen evolution for efficient greenhouse gas mitigation.

Chemicals manufacture is among the top greenhouse gas contributors. More than half of the associated emissions are attributable to the sum of ammonia plus oxygenates such as methanol, ethylene glycol and terephthalic acid. Here we explore the impact of electrolyzer systems that couple electrically-powered anodic hydrocarbon-to-oxygenate conversion with cathodic H2 evolution reaction from water. We find that, once anodic hydrocarbon-to-oxygenate conversion is developed with high selectivities, greenhouse gas emissions associated with fossil-based NH3 and oxygenates manufacture can be reduced by up to 88%. We report that low-carbon electricity is not mandatory to enable a net reduction in greenhouse gas emissions: global chemical industry emissions can be reduced by up to 39% even with electricity having the carbon footprint per MWh available in the United States or China today. We conclude with considerations and recommendations for researchers who wish to embark on this research direction.

Sugar-to-What? An Environmental Merit Order Curve for Biobased Chemicals and Plastics.

The chemical industry aims to reduce its greenhouse gas emissions (GHGs) by adopting biomass as a renewable carbon feedstock. However, biomass is a limited resource. Thus, biomass should preferentially be used in processes that most reduce GHG emissions. However, a lack of harmonization in current life cycle assessment (LCA) literature makes the identification of efficient processes difficult. In this study, 46 fermentation processes from literature are harmonized and analyzed on the basis of their GHG reduction compared with fossil benchmarks. The GHG reduction per amount of sugar used is defined as Sugar-to-X efficiency and used as a performance metric in the following. The analyzed processes span a wide range of Sugar-to-X efficiencies from -3.3 to 6.7 kg of CO2 equiv per kg of sugar input. Diverting sugar from bioethanol production for fuels to the fermentation and bioconversion processes with the highest Sugar-to-X efficiency could reduce the chemical industry's GHG emissions by an additional 130 MT of CO2 equiv without requiring any more biobased feedstocks.

Achieving net-zero greenhouse gas emission plastics by a circular carbon economy.

Mitigating life-cycle greenhouse gas emissions of plastics is perceived as energy intensive and costly. We developed a bottom-up model that represents the life cycle of 90% of global plastics to examine pathways to net-zero emission plastics. Our results show that net-zero emission plastics can be achieved by combining biomass and carbon dioxide (CO2) utilization with an effective recycling rate of 70% while saving 34 to 53% of energy. Operational costs for net-zero emission plastics are in the same range as those for linear fossil-based production with carbon capture and storage and could even be substantially reduced. Realizing the full cost-saving potential of 288 billion US dollars requires low-cost supply of biomass and CO2, high-cost supply of oil, and incentivizing large-scale recycling and lowering investment barriers for all technologies that use renewable carbon feedstock.