Imperial College London

Patrick Brandl

Faculty of Natural SciencesCentre for Environmental Policy

Research Postgraduate



patrick.brandl16 Website CV




601Weeks BuildingSouth Kensington Campus





Publication Type

6 results found

Brandl P, Bui M, Hallett JP, Mac Dowell Net al., 2021, Beyond 90% capture: Possible, but at what cost?, International Journal of Greenhouse Gas Control, Vol: 105, Pages: 1-16, ISSN: 1750-5836

Carbon capture and storage (CCS) will have an essential role in meeting our climate change mitigation targets. CCS technologies are technically mature and will likely be deployed to decarbonise power, industry, heat, and removal of CO2 from the atmosphere. The assumption of a 90% CO2 capture rate has become ubiquitous in the literature, which has led to doubt around whether CO2 capture rates above 90% are even feasible. However, in the context of a 1.5 °C target, going beyond 90% capture will be vital, with residual emissions needing to be indirectly captured via carbon dioxide removal (CDR) technologies. Whilst there will be trade-offs between the cost of increased rates of CO2 capture, and the cost of offsets, understanding where this lies is key to minimising the dependence on CDR. This study quantifies the maximum limit of feasible CO2 capture rate for a range of power and industrial sources of CO2, beyond which abatement becomes uneconomical. In no case, was a capture rate of 90% found to be optimal, with capture rates of up to 98% possible at a relatively low marginal cost. Flue gas composition was found to be a key determinant of the cost of capture, with more dilute streams exhibiting a more pronounced minimum. Indirect capture by deploying complementary CDR is also assessed. The results show that current policy initiatives are unlikely to be sufficient to enable the economically viable deployment of CCS in all but a very few niche sectors of the economy.

Journal article


The invention relates to a method for obtaining an air product by means of an air separation plant (100), which comprises a rectification column system (10), which has a high-pressure column (11) operated at a first pressure level and a low-pressure column (12) operated at a second pressure level below the first pressure level. According to the invention, a first compressed air stream at a first pressure level and a second compressed air stream at a third pressure level above the first pressure level are provided and are subjected to cooling, the first compressed air stream is fed into the rectification column system (11) and the second compressed air stream, expanded by means of an expansion turbine (5) to the first pressure level, but not to a pressure level lower than the first pressure level, is fed into the rectification column system (11), and a liquid material stream is led out of the rectification column system (10) and, in the liquid state, the pressure of said material stream is increased, and said material stream is converted into the gaseous or supercritical state and is led out of the air separation plant (100) as the at least one air product. The invention is characterized in that the second compressed air stream is fed to the expansion turbine (5), which is used in the expansion of the second compressed air stream to the first pressure level, at a temperature level lying at least 10 K below the critical temperature, that said expansion turbine (5) is operated in such a way that a two-phase mixture is formed at the outlet thereof, which two-phase mixture has, at the outlet, a gas proportion of 5 to 25%, in relation to the whole two-phase mixture, and that no further expansion turbines are used to expand compressed air in the method. The invention further relates to a corresponding air separation plant (100).


Mac Dowell N, Hallett JP, 2018, Challenges and opportunities for the utilisation of ionic liquids as solvents for CO2 capture, Molecular Systems Design & Engineering, Vol: 3, Pages: 560-571, ISSN: 2058-9689

Ionic Liquids have been extensively investigated as promising materials for several gas separationprocesses, including CO2capture. They have the potential to outperform traditional solvents, interms of their capacity, selectivity, regenerability and stability. In fact, hundreds of ionic liquidshave been investigated as potential sorbents for CO2capture. However, most studies focus onenhancing equilibrium capacity, and neglect to consider other properties, such as transport prop-erties, and hence ignore the effect that the overall set of properties have on process performance,and therefore on cost. In this study, we propose a new methodology for their evaluation using arange of monetised and non-monetised process performance indices. Our results demonstratethat whilst most research effort is focused on improving CO2solubility, viscosity, a transport prop-erty, and heat capacity, a thermochemical property, might preclude the use of ionic liquids, eventhose which are highly CO2-philic, and therefore increased effort on addressing the challengesassociated with heat capacity and viscosity is an urgent necessity. This work highlights a rangeof potential challenges that ionic liquids will face before they can be applied at process scale, andidentifies some key research opportunities.

Journal article

Brandl P, Soltani SM, Fennell PS, Mac Dowell Net al., 2017, Evaluation of cooling requirements of post-combustion CO2 capture applied to coal-fired power plants, Chemical Engineering Research and Design, Vol: 122, Pages: 1-10, ISSN: 1744-3598

Whilst CO2 capture and storage (CCS) technology is widely regarded as being an important tool in mitigating anthropogenic climate change, care must be taken that its extensive deployment does not substantially increase the water requirements of electricity generation. In this work, we present an evaluation of the cooling demand of an amine-based post-combustion CO2 capture process integrated with a coal-fired power plant. It is found that the addition of a capture unit translates into an increase in the total cooling duty of ≈47% (subcritical), ≈33% (supercritical) and ≈31% (ultra-supercritical) compared to a power plant without capture. However, as the temperature at which this cooling is required varies appreciably throughout the integrated power capture process, it is found that his increase in cooling duty (MW) does not necessarily lead to an increase in cooling water usage (kg/MW). Via a heat integration approach, we demonstrate how astute cascading of cooling water can enable a reduction of cooling water requirements of a decarbonised power plant relative to an unmitigated facility. This is in contrast to previous suggestions that the addition of CCS would double the water footprint.

Journal article

Lee JM, Rochelle G, Styring P, Fennell P, Wilson G, Trusler M, Clough P, Blamey J, Dunstan M, MacDowell N, Lyth S, Yao J, Hills T, Gazzani M, Brandl P, Anantharaman R, Brandani S, Stolaroff J, Mazzotti M, Maitland G, Müller C, Dowson G, Gibbins J, Ocone R, Sedransk Campbell K, Erans M, Zheng L, Sutter D, Armutlulu A, Smit Bet al., 2016, CCS - A technology for now: general discussion., Faraday Discuss, Vol: 192, Pages: 125-151, ISSN: 1359-6640

Journal article

Smit B, Styring P, Wilson G, Rochelle G, Donat F, Yao J, Trusler M, Adjiman C, Lyth S, Lee J-SM, Hills T, Brandl P, Gazzani M, Cuellar-Franca R, Fennell P, Sutter D, Bui M, Scholes C, Dowson G, Gibbins J, Joss L, Maitland G, Brandani S, Garcia-Gutierrez P, Zhang Y, Muller C, Jackson G, Ocone R, Joos L, Bell R, Graham Ret al., 2016, Modelling - from molecules to megascale: general discussion, Faraday Discussions, Vol: 192, Pages: 493-509, ISSN: 1359-6640

Journal article

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