Making gas‐CCS a commercial reality: The challenges of scaling up

Abstract

Significant reductions in CO 2 emissions are required to limit the global temperature rise to 2°C. Carbon capture and storage (CCS) is a key enabling technology that can be applied to power generation and industrial processes to lower their carbon intensity. There are, however, several challenges that such a method of decarbonization poses when used in the context of natural gas (gas-CCS), especially for solvent-based (predominantly amines) post-combustion capture. These are related to: (i) the low CO 2 partial pressure of the exhaust gases from gas-fired power plants (ß3-4%vol. CO 2 ), which substantially limits the driving force for the capture process; (ii) their high O 2 concentration (ß12-13%vol. O 2 ), which can degrade the capture media via oxidative solvent degradation; and (iii) their high volumetric flow rates, which means large capture plants are needed. Such post-combustion gas-CCS features unavoidably lead to increased CO 2 capture costs. This perspective aims to summarize the key technologies used to overcome these as a priority, including supplementary firing, humidified systems, exhaust gas recirculation and selective exhaust gas recirculation. These focus on the maximum CO 2 levels achievable for each, as well as the electrical efficiencies attainable when the capture penalty is taken into account. Oxy-turbine cycles are also discussed as an alternative to post-combustion gas-CCS, indicating the main advantages and limitations of these systems together with the expected electrical efficiencies. Furthermore, we consider the challenges for scaling-up and deployment of these technologies at a commercial level to enable gas-CCS to play a crucial role in a low-carbon future. C

Techno-economic analysis of a hybrid CO2 capture system for natural gas combined cycles with selective exhaust gas recirculation

“…A number of process modifications are being investigated to make the CO2 capture process in gas-fired power plants more economical by increasing the CO2 concentration (higher driving force) and reducing the flowrate of the flue gas entering the capture plant [9]. This is the case of natural gas combined cycle configurations that make use of exhaust gas recirculation (EGR) or selective exhaust gas recirculation (S-EGR) schemes, where a fraction of the inlet air is replaced by a chilled recycled gas flow.…”

“…This is the case of natural gas combined cycle configurations that make use of exhaust gas recirculation (EGR) or selective exhaust gas recirculation (S-EGR) schemes, where a fraction of the inlet air is replaced by a chilled recycled gas flow. As a result, a smaller flue gas flowrate with a higher CO2 concentration is generated [6,7,[9][10][11][12][13][14][15][16][17][18][19]. In the EGR process, this is achieved by taking a fraction of the flue gas exiting the heat recovery steam generator (HRSG) back to the inlet of the compressor, after passing through a cooling and a water knockout stage.…”

“…Therefore, the idea behind the S-EGR concept outlined in Figure 1 is to use the selective membrane only as a CO2 pre-concentrator, thus increasing the CO2 content of the flue gas sent to the post-combustion capture system using a limited energy input. This has potential efficiency and economic advantages for NGCC systems provided with postcombustion amine capture systems, as indicated above [9,13,19]. Two S-EGR configurations were proposed, which are referred as parallel and series S-EGR (Figures 1a and 1b, respectively) [13].…”

“…This is in addition to the use of more compact capture reactors (because of the higher driving force, and also because of the lower flowrates in the parallel scheme) and the expected lower oxidative degradation of the solvent (as a result of the reduced O2 content in the flue gas). Therefore, S-EGR has the potential to reduce both the capital and the operational costs of the associated amine capture plant systems for NGCCs [9,14,15,17,19]. The effects on the turbomachinery derived from the new composition of the working fluid in S-EGR schemes are still under discussion, and redesign might be necessary [14,16,28].…”

Application of Raman spectroscopy to real-time monitoring of CO2 capture at PACT pilot plant; Part 1: Plant operational data

“…Several research work is carried on developing and optimizing methods to remove CO2 from power plants and industrial sources using amine technology. Process modifications (Kang et al 2016;Jassim et al 2007;Le Moullec et al 2014;Madan et al 2013;Ahn et al 2013;Amrollahi et al 2011;Oh et al 2018;Diego et al 2017;Merkel et al 2013;Herraiz, 2016) and new solvents (Aronu et al 2010;Kumar et al 2014;Hakka 2007;Yuan and Rochelle, 2018;Wang et al 2015;Yang et al 2016;Kim et al 2013;Cheng et al 2013;Abu Zahra et al 2007) are being tested to minimise these issues. The process is complex and is greatly affected by process parameters.…”