A factory pipe blows white smoke into the air

Catalysis: a key to greenhouse gas emission reduction?

13 February 2024
Converting CO2 to fuels for climate solutions
Rapid increases in global CO2 levels, fuelled by fossil fuel consumption, are driving urgent calls for mitigation. Innovations in converting CO2 into valuable fuels and chemicals offer promising solutions to combat climate change while promoting sustainability.

By Pradeep Murthy, PhD candidate at University of Sydney

Given the excess carbon dioxide (CO2) resulting from excessive fossil fuel consumption, urgent mitigation is necessary.

The global CO2 concentration has surged at a rapid rate of 1.5 to 3 parts per million (ppm) annually between 2006 and 2023, leading to climate induced disasters like ice caps melting, bushfires, and storms. The United Nations aims to reduce 15-32 GtCO2-e (gigatonnes of CO2 equivalent emissions) of global emissions by 2030, while the Australian Government targets a contribution of 900 MtCO2-e. While ambitious, these goals can be achieved through technological advancements and greener practices.

Efforts to capture and store CO2, as seen with companies such as Climeworks in Switzerland are expensive and pose risks. A more profitable approach is to not just capture, but also convert CO2 into valuable fuels and chemicals like methane, carbon monoxide, ethanol, or methanol that can be used for mining, aviation, transport, or domestic applications. These chemicals can be generated by reacting CO2 with hydrogen (H2), which like captured CO2, can also be cleanly obtained via electrolysis (that is, electrical splitting) of water (H2O) sourced renewably from the sea or from waste treatment. This process is known as hydrogenation.

This is an important process, as CO2 is a stable molecule and difficult to convert. However, reacting CO2 with hydrogen can overcome this limitation and generate economically viable fuels. Sourcing green (renewable) instead of grey (non-renewable) CO2 or H2 is more costly, but is also expected to gain popularity with time, therefore becoming more affordable.

The fastest means of accomplishing this is by utilising a material known as a catalyst, which can accelerate the chemical reaction by attracting the key gases onto its surface to be reacted and then releasing the products. Utilising a catalyst, especially at the nano-level, significantly enhances surface area, increasing CO2 consumption and fuel generation. Cost-effective catalysts such as copper and nickel boost revenue.

Catalysts also reduce the energy needed for chemical reactions. Though thermochemical, electrochemical, and photochemical methods exist, solar energy stands out as an attractive option. Despite lower efficiency, ongoing research promises improved solar energy utilisation, reducing operating costs and fostering a more environmentally-friendly process. There is a vast amount of research being conducted in this space, and more extensive efforts should be made to commercialise such plants that can generate clean, renewable energy fuels from CO2.

Carbon Recycling International, based in Iceland, exemplifies successful catalytic conversion of CO2 to methanol. With a copper-based catalyst, they generate clean energy and have been operating a commercial plant since 2022. These practices, integrated with electrolysis and renewable sources, provide a clear direction for globally commissioning similar plants.

Overall, enhancing public awareness of catalysis, electrolysis, and renewable energy sources is crucial in controlling atmospheric CO2 levels. Continued research and development can expedite the conversion of CO2 into profitable fuels and chemicals, offering a viable solution to our ongoing climate change crisis.

NOAA, ESRL Global Monitoring Division - Global Greenhouse Gas Reference Network, US Department of Commerce (2023). https://www.esrl.noaa.gov/gmd/ccgg/trends/global.html (accessed December 16, 2023).

United Nations Environment Programme, Emissions Gap Report 2019, Nairobi, 2019. https://wedocs.unep.org/bitstream/handle/20.500.11822/30797/EGR2019.pdf?sequence=1&isAllowed=y.

Australian Government, Australia’s 2030 climate change target, Canberra, 2015. https://www.environment.gov.au/system/files/resources/c42c11a8-4df7-4d4f-bf92-4f14735c9baa/files/factsheet-australias-2030-climate-change-target.pdf.

Climeworks, Journey toward net zero with Climeworks’ carbon removal service, (2023).

P.S. Murthy, W. Liang, Y. Jiang, J. Huang, Cu-Based Nanocatalysts for CO2 Hydrogenation to Methanol, Energy & Fuels 35 (2021) 8558–8584. https://doi.org/10.1021/acs.energyfuels.1c00625.

Carbon Recycling International, CRI - Carbon Recycling International, (2020). https://www.carbonrecycling.is/ (accessed May 11, 2020).

Header image: Anne Nygård on Unsplash

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