Decarbonisation Technology - August 2023 Issue

Metal-organic frameworks for carbon capture How the industrial-scale, cost-effective manufacture of MOFs and speciality nanomaterials could enable energy-efficient carbon capture and storage

James Stephenson Promethean Particles

L eading scientific opinion increasingly points to human activity having a large, detrimental impact on our planet. One effect of this activity has been an unprecedented rise in global warming driven predominantly by increased emissions of greenhouse gases such as carbon dioxide (CO2). The issues and consequences surrounding global warming have been well studied. Global surface temperatures have already reached 1.1°C above pre-industrial levels (IPCC, 2023). Exceeding a 1.5°C rise in average temperatures could risk the earth’s stability and life support systems (IPCC, 2018). This startling recognition has led to an acceleration in demand for new solutions to help tackle climate change and, with it, a particular emphasis on decarbonisation. There are multiple decarbonisation approaches that can be employed to reduce the overall carbon footprint, which we have coined the ‘Decarbonisation Mix’. Many climate change proponents advocate strongly for the prioritisation of energy efficiency improvements and fuel switching to less carbon-intensive variants. However, many hard-to-abate industries (power generation, steel, cement, chemicals) cannot simply switch to different fuels or efficiently electrify their processes, at least in the near term. As such, a third element of the mix has to be carbon removals. Carbon capture is therefore increasingly being recognised as a critical technology in the range of solutions needed to effect decarbonisation and help limit climate change. Despite the views of some, it is not an underhand way to ‘greenwash’ the continued use of fossil fuels. The UK government, the German government,

and the Intergovernmental Panel on Climate Change (IPCC) have all recently opined that CO2 removal and carbon capture are now necessary approaches for the world to have any chance of limiting global warming to the 1.5°C goal established in the Paris Agreement. The UK government’s recent announcement of £20 billion in funding earlier this year to support the development of carbon capture and storage (CCS) projects highlights this emphatically.

Carbon capture is increasingly being recognised as a critical technology in the range of solutions needed to effect decarbonisation

Current technological options for CCS systems are limited The most widely used commercial carbon capture technology today is amine scrubbing. The first amine scrubbers were designed and implemented in the 1930s, and the process is largely the same today, despite some significant improvements in the performance of the amine solvents used. A typical configuration for a CO2 scrubbing system is shown in Figure 1 . CO2 containing flue gas enters the bottom of the absorber and rises upwards. The CO2 is absorbed by the downward flowing amine, which then flows out of the bottom of the absorber and into the stripper. Here, the CO2 rich amine is intensively heated to desorb and separate the CO2. The reboiler at the bottom of the stripper provides