International Journal of Greenhouse Gas Control 24 (2014) 43–53 Contents lists available at ScienceDirect International Journal of Greenhouse Gas Control j ourna l h o mepage: www.elsevier.com/locate/ijggc NGCC post-combustion CO 2 capture with Ca/carbonate looping: Efficiency dependency on sorbent properties, capture unit performance and process configuration David Berstad a,∗ , Rahul Anantharaman a , Richard Blom b , Kristin Jordal a , Bjørnar Arstad b a SINTEF Energy Research, 7465 Trondheim, Norway b SINTEF Materials and Chemistry, P.O. Box 124 Blindern, 0314 Oslo, Norway a r t i c l e i n f o Article history: Received 2 December 2013 Received in revised form 20 February 2014 Accepted 25 February 2014 Available online 22 March 2014 Keywords: Post-combustion CO2 capture Solid sorbents Carbonate looping NGCC Process simulations a b s t r a c t This paper evaluates the potential of post-combustion CO 2 capture from a natural gas combined cycle (NGCC) through the use of solid sorbents at high temperatures. Experimental deactivation and residual sorption capacity parameters for various sorbents reported in the literature, as well as from own lab, are reviewed and the performance of three different Ca-based sorbents is studied in more detail: natural CaCO 3 , natural dolomite and synthetic CaO. Results from steady-state simulations of the Ca/carbonate looping unit show how the energy requirement for sorbent regeneration varies with sorbent properties, sorbent make-up ratio, internal heat recuperation and CO 2 recirculation temperature. Net electric effi- ciency for a reference NGCC power plant without CO 2 capture is 58.1% on a lower heating value basis and 49.5% for 90% CO 2 capture rate with MEA. In comparison, an NGCC combined with looping of syn- thetic CaO sorbent and an advanced secondary steam cycle reaches a net electric efficiency of 53.1% for a capture rate above 90%. It is concluded that in addition to improved sorbent capacity and stability, heat recuperation in the solid streams between the carbonator and calciner as well as high CO 2 recycle temperature are important for obtaining the high overall power plant efficiency. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Post-combustion capture is one of three principal capture routes for reducing CO 2 emissions from power generation. Although the main part of fossil fuel-based power generation capacity is based on coal, natural gas combined cycles (NGCC) with post-combustion CO 2 capture can have a benefit in a next-generation power system with a high share of wind and solar power. The inherently vari- able power output form these renewable sources should be a good combination with the rapid load-changing capability of the NGCC. Within the field of post-combustion capture, the use of amine- based solvents has received most attention and is beginning to reach commercial-scale implementation, for instance at the Bound- ary Dam project in Saskatchewan, Canada. In parallel with this project there is extensive on-going research and development aimed at finding improved liquid solvents with reduced energy consumption. This development has been reviewed for instance ∗ Corresponding author. Tel.: +47 930 02 784; fax: +47 735 93 950. E-mail address: david.berstad@sintef.no (D. Berstad). by Wang et al., 2011. As an alternative to reactive liquid solvents, Ca/carbonate looping (CaL) was first proposed by Shimizu et al., 1999. This work has later been followed up by several studies for instance by Abanades et al., 2005, Li et al., 2008, Romeo et al., 2008 and Martínez et al., 2012. Whereas these works focused on coal as primary energy source, NGCC was recently investigated in the study preceding this paper (Berstad et al., 2012) where natural limestone (CaCO 3 ) was investigated as solid sorbent for CO 2 capture from NGCC. However, no advantage in process efficiency relative to post-combustion capture with MEA absorption was found in this work, in spite of a high degree of heat recuperation between the solid streams and adoption of super-critical steam parameters. The case with highest net electric efficiency was 1.4%-points lower than that with MEA-based CO 2 capture. As an extension to this work other possible sorbent formulations have been studied in order to point out what performance levels solid sorbents should pos- sess to be considered as a relevant option for CO 2 capture from NGCC power plants. The work investigates both the use of sorbents with a higher capacity than natural CaCO 3 , and also further devel- opment of the integration of solid sorbent looping into the NGCC process. http://dx.doi.org/10.1016/j.ijggc.2014.02.015 1750-5836/© 2014 Elsevier Ltd. All rights reserved.