CARBON CAPTURE AND STORAGE ( CCS ) TECHNOLOGIES FORM PART OF THE MEASURES THAT MUST BE IMPLEMENTED TO MEET THE COP26 TARGETS AND ARE THEREFORE SEEN AS INTEGRAL TO THE ENERGY TRANSITION AND BEYOND . BY RO LAZAROVITCH , PARTNER , DARREN SPALDING , PARTNER AND SUYIN TAN , SENIOR ASSOCIATE , AT BRACEWELL ( UK ) LLP .

The UN Climate Change Conference in 2021 , COP26 , highlighted the scale of global carbon emissions and the speed with which they must be addressed in order to meet net zero targets by 2050 . Carbon capture and storage ( CCS ) is a suite of technologies that captures carbon dioxide ( CO 2 ) primarily from large point sources such as biomass or fossil-fuelled power generation , or industrial facilities , or , to a lesser extent , the atmosphere . The captured CO 2 can either be used in a range of industrial applications , within the broader field of carbon capture , utilisation and storage ( CCUS ), or injected into underground geological formations including appropriate depleted oil and gas reservoirs and saline or basalt rock formations for permanent storage .

This article explores the main CCS technologies that exist today , their advantages , the challenges to be overcome for their commercial viability at the scale required to constitute a meaningful part in the energy transition , and the role that project finance can play in this journey .

CCS today Three main types of CCS technologies – postcombustion , oxyfuel and pre-combustion – focus on capturing CO 2 at its source , which is generally regarded to be more effective than atmospheric CO 2 removal . 1

• Post-combustion – Post-combustion CO 2 capture occurs after the combustion process takes place , separating CO 2 from the mixture of combustion exhaust gases ( or flue gases ) produced after fuel is burnt in power stations and industrial plants . Materials that selectively absorb or react only with CO 2 such as amine , an ammonia-derived solvent are used to filter out CO 2 from the other gases for liquefaction and transport for other uses or underground storage in a suitable geological formation . Amine solvent technology is decades old and extensively used in the oil and gas industry , particularly for separating CO 2 from natural gas to produce purified natural gas for sale . It is also used in generating CO 2 for sparkling drinks . The last decade has seen its adaptation for use on combustion gases .

Given the very high energy intensity and costs of capturing and liquefying 100 % of the CO 2 , typical capture levels have been around

80 %– 90 %. Recent studies indicate that more advanced amine solvents can improve capture to around 99 % with lower energy requirements and little cost increase . It is expected that further effectiveness studies will improve the design of future CCS plants . 2

Post-combustion technologies can also be applied to work directly with current industrial processes and power plants without any adaptation to the plant ’ s design . 3 This allows for retrofitting to existing plants by being added at their back end and is cost-effective as it leverages the existing power plant , supporting infrastructure , and technical know-how . 4 Such retrofitting can help address emissions from existing fossil-fuelled power plants in the near and medium term without having to shut them down . 5

There are , however , some challenges with retrofitting post-combustion technology to a conventional power plant . These include cost and efficiency penalties , ie the power generation loss , from installing the technology as well as an initial increase in carbon emissions at the energy input stage due to the increased fuel consumption and increased freshwater consumption required by the application of CCS technologies . 6 Impact assessment methodologies are still being refined in order to improve the reliability of quantitative assessments of the net environmental impact of using CCS technologies , 7 but CCS technologies are likely to become more efficient as they advance from being the emerging technologies they are today to more mature technologies .

• Oxyfuel – Oxyfuel carbon capture operates by using pure oxygen in power station boilers rather than normal air . Fuel combustion that occurs in pure oxygen rather than normal air which contains a large proportion of nitrogen generates waste gas that contains predominantly CO 2 , around 90 %, and water vapour . In contrast , fuel combustion in normal air produces a mix of waste gases , of which CO 2 comprises only 3 %– 15 %. 8

There are some challenges with retrofitting postcombustion technology to a conventional power plant

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