Decarbonisation Technology - February 2022 Issue

CCUS: status and priorities for research and development An update on CCUS R&D that could significantly reduce net CO 2 emissions by way of identifying research gaps, opportunities, and priorities in CCUS

Dr Himmat Singh Scientist ‘G’ & Prof (Retd)

Introduction With the rise in demand for energy globally, CO 2 levels have risen sharply, from preindustrial levels of 280 ppm a century ago to over 380 ppm in 2009. These levels are projected to increase even more dramatically over the next 50 years as global energy demand is anticipated to double (Alivisatos & Buchanan, 2010). Carbon capture, utilisation and storage (CCUS) is considered a critical carbon dioxide (CO 2 ) mitigation technology. The CCUS process can be used to capture CO 2 emissions from power plants (fuelled by coal, natural gas, and biomass), oil and gas production, oil refineries, industrial applications such as cement, iron and steel production, and fertiliser manufacturing. The captured CO 2 can then be used (CCU) or permanently stored (CCS). Achieving Paris Agreement (PA) targets will require a significant acceleration of the development and deployment of technologies that dramatically reduce CO 2 emissions. McKinsey’s analysis of the net-zero pathways for Europe indicates that some 40% of the necessary emissions abatement could come from technologies that are either still in R&D or demonstrated but not yet mature. The remaining 60% could be achieved by widely deploying proven, mature technologies (McKinsey & Co, 2020). CCUS developments to date are noteworthy, but additional extensive and far-reaching efforts are required to combat climate change. The IEA’s Energy Technology Perspectives 2016 report estimated that CCUS could provide 12% of the GHG emission reductions in the power sector alone. The IPCCC 2°C by 2050 scenario requires the capture of 6.4 Gt/a of CO 2 from the power and industrial sectors combined (IEA, 2016). Carbon capture combined with sequestration

is the main means of reducing net CO 2 emissions in the near term and could serve as a bridging strategy to a time when non-carbon energy technologies are broadly deployed. Conversion of CO 2 (such as reduction to methane or methanol) could help reduce the amount needing to be sequestered. However, the magnitude of the problem of unfettered carbon emissions to the environment is daunting. Continued use of fossil fuel while capping the atmospheric concentration of CO 2 at levels of less than 500 ppm is projected to require the capture of ~10 Gt of CO 2 per year globally – over a quarter of the CO 2 that is generated globally today – and the problem continues to grow as energy use grows (Alivisatos & Buchanan, 2010), (IEA, 2020). The CO 2 capture options can be classified as post, pre-, and oxy-fuel combustion (Cuellar-Franca & Azapagic, 2015). Post-combustion carbon capture is most effective at sites where large quantities of CO 2 are generated, including: large electrical power plants fuelled by fossil fuels or biomass; major industrial sites (e.g., for cement, steel or aluminum production or ethanol fermentation); or facilities in which natural gas, petroleum, synthetic fuels, or fossil-based hydrogen is produced. A typical 550 MW coal-fired power plant produces about 2 million ft 3 of flue gas per minute at atmospheric pressure. This large volume of flue gas contains CO 2 at concentrations of about 12–14% along with water, nitrogen, oxygen, and traces of sulphur oxides, nitrogen oxides, and other materials originating from the fuel and the air used for combustion. Thus, capturing CO 2 from this complex mixture at high levels of purity requires highly efficient separation techniques. Pre-combustion capture is primarily applicable