Uncovering the realistic potential of chemical looping ammonia production routes (Flexible Funding 2023)

Dr Ewa Marek, University of Cambridge, was awarded funding in the UKCCSRC’s Flexible Funding 2023 call to look at “Uncovering the realistic potential of chemical looping ammonia production routes”.

Transforming Ammonia Production: The Potential of Chemical Looping
As global ammonia demand rises, the need for sustainable production methods becomes more pressing. Traditional ammonia synthesis, using the Haber-Bosch process and steam-methane reforming, remains energy-intensive and environmentally impactful. Our recent project, funded by the UKCCSRC and a collaboration between the University of Cambridge and Newcastle University, explored the potential of chemical looping ammonia production (CLAP) and other innovative routes.

CLAP: Delivering components with solid materials
Chemical looping ammonia production (CLAP) works by breaking the overall NH₃ synthesis into two steps, described for two possible options in Table 1. In the first step, H₂ reacts with a solid material containing nitrogen to release the product NH₃; in the second step, the solid intermediate is regenerated by exposing it to N₂. This step-wise approach helps overcome the thermodynamic constraints of direct NH₃ synthesis but involves different process routes and conditions than Haber-Bosch, which makes a fair comparison difficult. Since CLAP routes are also more complex, assessing their potential and their environmental performance can be more challenging than for conventional technologies.

Economic and Environmental Insights
Our techno-economic and life-cycle assessments compared CLAP to traditional methods (Haber-Bosch, with CH4 reforming or water electrolysis) and to emerging electrochemical routes. While CLAP is currently more capital-intensive, it could become cost-competitive if costs of electrolysers decrease. Importantly, hydrogen production remains the largest source of emissions, overshadowing other factors like impact from using a large amount of catalytic solids or emissions connected to compression trains. The study also found that the global warming potential of ammonia production is highly sensitive to the electricity mix and so the location of the NH₃ plant was considered, which emphasises the importance of using low-carbon electricity and energy sources.

Efficiency and Future Prospects
Both electrically driven Haber-Bosch processes and CLAP offer better energy efficiency than the traditional steam-methane reforming method. When powered by low-carbon electricity, such as hydropower, these technologies hold significant promise for reducing the carbon footprint of ammonia production.

In summary, while new technologies like CLAP face challenges, they offer exciting opportunities for more sustainable ammonia production. As research advances and costs evolve, CLAP and similar innovations could play a key role in creating a greener ammonia industry.

Our project findings were presented by Dr Theodoris Papalas and Alex Harrison during the Early Career Researcher Net Zero Conference in Birmingham. They came back to Cambridge with the 3rd place prize based on a vote of conference attendees. Well done!

Besides this success, Alex and Theodoris had a chance to discuss new opportunities in the energy technologies field with early career researchers (ECRs) from a variety of disciplines beyond engineering, such as social science and economics, giving a broader view of the state of the field as a whole.

Theodoris and Alex and their 3rd place award-winning poster at the ERC meeting in Birmingham

Read more on Ewa’s Flexible Funding 2023 project page.