Recent years have seen a drive for urgent action to address the decades of accumulated emissions from the industrialisation of the globe. It is evident that there is a need for new fuels to decarbonise energy provision, however, there will be a period of transition during which fossil fuels will continue to be used, hence, amelioration of ongoing emissions is essential to prevent further increases in atmospheric carbon dioxide (CO2) levels. The drive for net zero aligns with the United Nations Sustainable Development Goals, and technologies developed for the removal of CO2 from process streams have potential to realise the Paris Agreement goal of limiting the post-industrial global temperature increase to 1.5 C; however current technologies have limitations in their efficiencies and in that they produce toxic wastes. Thus, a solution offering environmental and economic benefits in a holistic process from systems development to application is sought through this study.
Existing scrubbing technologies for the removal of CO2 use basic amines to chemically scavenge the acidic gas, but there is a large energy penalty to reverse the process and recover the CO2. Alongside this there is also the potential environmental impact of toxic releases of the chemicals used to ecosystems. By comparison, physical methods of capture, such as adsorption on inorganic or carbon materials, can offer easier regeneration but can suffer from reduced capacities and selectivites by nature of the weaker interactions.
The project focusses on using current understanding of carbon materials engineering, in conjunction with characterization of sorption properties, to iteratively synthesize, test and retro-engineer an optimal hydrochar for selective CO2 uptake and storage. The hydrochar materials will be derived from unwanted biomass, providing a route to valorisation of waste streams. For example, these will be from sources such as food and agricultural wastes, or other industrial by-products, which can be valorised by conversion into adsorbents. Selected materials will be subject to hydrothermal treatment to lock in the porous nature of the feedstock and prevent routes to degradation, creating stable sorbents that can be reused in cyclic processes, further increasing the positive impact of the work.