In-situ gasification chemical looping combustion (iG-CLC), which has been tested on pilot plant level, is regarded as an advanced carbon capture and storage (CCS) technology for reducing CO2 emissions. A life cycle global warming impact (GWI) analysis is performed to consider the lifetime emissions of the lowcarbon iG-CLC technology. Herein, the capacity is considered to be 610 MWe using natural ilmenite as oxygen carrier and steam as gasification agent. At the condition of operational pressure of 15 atm and air reactor temperature of 1050
C, the net power efficiency of 37.7% for achieving 93.5% inherent CO2 capture is obtained in simulations with thermodynamically optimum condition. The life cycle GWI is calculated equal to be 160.3 kg CO2-equivalent/MW h. The effects of several essential parameters, including steam to carbon ratio (S/C), oxygen carrier to fuel ratio (ф), different oxygen carriers and lifetime of oxygen carriers, on the lifecycle GWI have been analyzed and discussed to meet the potential possibility for further reducing greenhouse gas (GHG) emissions. To obtain sufficient carbon capture efficiency, the S/C ratio and ф are suggested to be 1.3 and 1.2 in this study, respectively. The life cycle GWI is heavily dependent on lifetime of ferrum (Fe) when it is less than 2000 h, beyond that range, the GWI is decreasing, but very slowly.

Introduction

Increasing concerns associated with irreversible climate change have led policy-makers to design climate policies to reduce the anthropogenic Greenhouse gas (GHG) emissions. For example, the Chinese government committed to reduce its CO2 emissions per unit of GDP by 40%e45% of 2005 levels by 2020 (Yi et al., 2011). Significant R&D efforts are underway worldwide to mitigate GHG emissions, including (1) switching to low-carbon fossil fuels, such as biofuels, natural gas or hydrogen; (2) decarbonisation of fuel or flue gas and then carbon sequestration, i.e. carbon capture and storage (CCS); (3) accelerating the use of renewable energy (such as bioenergy, direct solar and wind energy). The share of low-carbon electricity supply (including renewable energy, nuclear and CCS) is expected to be increased from currently 30% (2014) to more than 80% by 2050 (IPCC, 2014). Yet still in a very early stage of technical demonstration, the cost of renewable energy is not currently competitive; the current CCS technology incorporating into a power plant has also not reached large-scale commercial maturity owing to the efficiency losses (e.g. CO2 capture by amine scrubbing reduces the power output by 20e30% for a typical coal-fired power plant) as well as cost enhancement on CCS. Though numerous power plants can be incorporated with CCS activity, very limited demonstration plants have gained any measure of acceptance from an industrial viewpoint as more than 20 large-scale CCS projects have been cancelled in 2010e2016 owing to the sharply fluctuated policy and financial support (IEA, 2016). Up-to-date information related to CCS can be found elsewhere (Boot-Handford et al., 2014; Macdowell et al., 2010).