Contents lists available at ScienceDirect Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser Harnessing flexibility potential of flexible carbon capture power plants for future low carbon power systems: Review Abdirahman M. Abdilahi ⁎ , Mohd Wazir Mustafa, Saleh Y. Abujarad, Mamunu Mustapha Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia ARTICLE INFO Keywords: Power system flexibility Carbon Capture and Storage Power system operations Flexible operation of CCS ABSTRACT Fossil-fired power plants retrofitted with Carbon Capture and Storage (CCS) may have operational benefits for future low carbon power systems. This paper aims to review state of the art literature with the objective to identify whether carbon capture power plants would bring flexibility within future lower carbon power systems. To achieve this objective, at first, the work investigates flexible operation of CCS technology. In particular, flexibility enabling mechanisms and factors that affect the flexible operation of CCS are reviewed. Flexibility requirements and provision assessment tools/metrics for future low carbon power systems are reviewed with the aim to identify the favourite properties required for future low carbon technologies. The work then presents how flexible CCS might improve the conventional power plant flexibility properties. Moreover, the paper presents the value of flexible operation of CCS for different stakeholders while it also identifies different influencing factors of optimal plant operation and profitability. The different power system services that the CCS-equipped plants might serve are also presented. 1. Introduction Global projections on primary energy demand by fuel source show increases in global fossil fuels use over the coming decades. For instance, the International Energy Agency (IEA) predicts that fossil fuel use is expected to contribute 74% of global primary energy demand by the year 2040 [1]. Additionally, proved reserves of fossil fuels are estimated at 6 trillion barrels of oil equivalent with a reserve to production ratio of 75 years [2]. With all these fossil fuel demand growth coupled with robust reserve availability for fuel use, fossil fuels usage is expected to continue at least in the foreseeable future. On the other hand, the Intergovernmental Panel on Climate Change (IPCC) projections indicate that avoiding the most serious impacts of climate change demands to limit the increase in global average temperature at 2 °C. This sets a global “carbon budget” that has to be met and puts constraint on global fossil fuel use because of their inherent CO 2 emission. Because of this carbon budget, the electricity industry, which accounts more than 42% of global CO 2 emissions, is subjected to shift to a low-carbon future [3]. Following the landmark climate conference, Paris Agreement, most of the leading developed countries have established or are in the processing of establishing legally binding emission reduction targets [4,5]. For this reason, policy makers should carefully choose the right mix of the future power system generation portfolio that will achieve the de-carbonization targets at the least cost possible. The transitions to low-carbon power systems, in global scale, demands a shift to low-carbon technologies such as renewable tech- nologies, nuclear power and fossil-fuel generators with Carbon Capture and Storage (CCS) [6]. The acceleration of CCS as a mitigation option for CO 2 is even more pronounced, especially within the recently developed context of a more challenging mitigation goal of 1.5 °C compared to the pre-COP21 (Conference of Parties) baseline of 2 °C [7]. Different jurisdictions need to reform power generation so that most optimal pathway of decarbonisation is proportionately decided. On this note, global policy makers consider a pool of genuine measures to combat the emissions of the power generation while maintaining the global economic growth at the least cost situation. Fig. 1 shows the projected estimations of CO 2 reductions expected to be contributed by the different low carbon technologies that are deployable at the moment [8]. Carbon capture power plants (CCPPs) which result from retrofitting existing fossil-fired power plants with CCS technologies is at the forefront of these http://dx.doi.org/10.1016/j.rser.2017.08.085 Received 7 July 2016; Received in revised form 6 July 2017; Accepted 22 August 2017 ⁎ Corresponding author. E-mail address: abdirahmaan11@gmail.com (A.M. Abdilahi). Abbreviations: ASU, Air separation unit; CC, Combined cycle; CCPP, Carbon capture power plants; CCS, Carbon Capture and Storage; CO 2 , Carbon dioxide; COP21, 21st Conference of Parties; GT, Gas turbine; GW, Giga Watt; HRSG, Heat recovery steam generator; IEA, International Energy Agency; IGCC, Integrated Gasification Combined Cycle; INDCs, Intended Nationally Determined Contributions; IPCC, Intergovernmental Panel on Climate Change; LCPS, Lower carbon power system; Mtpa, Million tonnes per annum; MW, Mega Watt; NGCC, Natural gas combined cycle; NPO, Net power output; ROI, Return on investment; UK, United Kingdom; USA, United States of America; USC PC, Ultra-Super-Critical Pulverised Coal Renewable and Sustainable Energy Reviews 81 (2018) 3101–3110 Available online 05 September 2017 1364-0321/ © 2017 Elsevier Ltd. All rights reserved. MARK