Life Cycle Assessment of Metal Organic Frameworks

With the increasing need to reduce carbon emissions into the atmosphere, removal of carbon dioxide in flue gas from power plants is being highlighted as a major factor towards this goal. In March 2023, the UK government announced funding for 8 projects across 2 clusters focussing on Carbon Capture and Storage technologies. The current predominant technology is amine solvents, which binds with the CO2 to isolate it from the flue gas, which can then be removed through a reversible reaction to allow the CO2 to be stored safely and the amines to be used again. However, this regeneration of the solvent is highly energy intensive, and the degradation of amines releases waste products that are harmful to the environment.

An alternative technology that has been gaining greater exposure in recent years are MOFs (metal organic frameworks), which are regular cage-like structures of metal ions and organic linkers which trap CO2, and can then be emptied for storage and the MOF used again. Based on the current TRL for this technology, it is still much more expensive than amines, but as costs come down, it is being seen as the most viable option to replace amines. The regeneration energy is much lower, and there is very little waste product that is harmful to the environment, with the possibility of being completely recyclable.

As MOFs are still relatively new, there is little research to corroborate these claims, so this project will involve mapping the life-cycle of MOFs, from their initial manufacture to their use, and finally to their disposal or recycling into new MOF materials, to allow an effective comparison of the reduction in harmful environmental impacts and greater energy efficiency of the technology compared to current market equivalents.

This will be done by conducting an LCA (life-cycle assessment), a standardised method for assessing a product or service from the acquisition of raw materials through to disposal, laying out the working process in 4 main stages (goal and scope, inventory, impact assessment, interpretation) that can then be used to track the mass quantities, energy balances and environmental impacts of that product or service over its complete life cycle. There are only 2 such studies for MOF CC and for only specific materials and manufacturing processes, so creating a complete and detailed model that can be applied to numerous MOFs would be beneficial. From here, the model will be expanded to include more processes and details, as well as being converted to a larger, industry-scale model.

There are also a number of factors which affect the long-term use of MOFs which need to be tested and analysed. The two main parameters for use of MOFs are temperature and pressure, since the MOF must be heated to roughly 100oC to perform adsorption, and the CO2 is removed by applying a vacuum to the material. As such, the physical degradation of MOF against these factors needs to be studied, to determine the length of time the material can be used for effectively before requiring disposal or recycling. Rigs are being designed and tested to validate temperature and/or pressure swing to determine how robust each MOF is during prolonged use.

The proposed Centre will benefit the following groups

1. Students - develop their professional skills, a broad technical and societal knowledge of the sector and a wider appreciation of the role decarbonised fuel systems will play in the UK and internationally. They will develop a strong network of peers who they can draw on in their professional careers. We will continue to offer our training to other Research Council PhD students and cross-fertilise our training with that offered under other CDT programmes, and similar initiatives where that develops mutual benefit. We will further enhance this offering by encouraging industrialists to undertake some of our training as Professional Development ensuring a broadening of the training cohort beyond academe. Students will be very employable due to their knowledge, skills and broad industrial understanding.
2. Industrial partners - Companies identify research priorities that underpin their long-term business goals and can access state of the art facilities within the HEIs involved to support that research. They do not need to pre-define the scope of their work at the outset, so that the Centre can remain responsive to their developing research needs. They may develop new products, services or models and have access to a potential employee cohort, with an advanced skill base. We have already established a track record in our predecessor CDTs, with graduates now acting as research managers and project supervisors within industry
3. Academic partners - accelerating research within the Energy research community in each HEI. We will develop the next generation of researchers and research leaders with a broader perspective than traditional PhD research and create a bedrock of research expertise within each HEI, developing supervisory skills across a broad range of topics and faculties and supporting HEIs' goals of high quality publications leading to research impacts and an informed group of educators within each HEI. .
4. Government and regulators - we will liaise with national and regional regulators and policy makers. We will conduct research directly aligned with the Government's Clean Growth Strategy, Mission Innovation and with the Industrial Strategy Challenge Fund's theme Prosper from the Energy Revolution, to help meet emission, energy security and affordability targets and we will seek to inform developing energy policy through new findings and impartial scientific advice. We will help to provide the skills base and future innovators to enable growth in the decarbonised energy sector.
5. Wider society and the publics - developing technologies to reduce carbon emissions and reduce the cost of a transition to a low carbon economy. Need to ascertain the publics' views on the proposed new technologies to ensure we are aligned with their views and that there will be general acceptance of the new technologies. Public engagement will be a two-way conversation where researchers will listen to the views of different publics, acknowledging that there are many publics and not just one uniform group. We will actively engage with public from including schools, our local communities and the 'interested' public, seeking to be honest providers of unbiased technical information in a way that is correct yet accessible.