(707d) The Value of Chemical Looping Combustion in Future Electricity Systems

Power generation via Chemical Looping Combustion (CLC) is inherently low in carbon dioxide emissions while maintaining the advantages of conventional thermal power plants such as dispatchability, flexibility, or firmness of capacity. The energy penalty incurred by the carbon dioxide removal process is performed at a fraction of other carbon capture techniques [1], such as post-combustion capture using amine solvents.

In this work, we quantify the role and value of three different CLC technologies and their integration into the future electricity system; CLC with natural gas coupled to a combined cycle (NGCC-CLC), integrated gasification combined cycle with CLC (IGCC-CLC) and CLC with in situ gasification and combustion of solid fuel (iG-CLC). We develop a national-scale capacity expansion and unit commitment model based on a mixed-integer linear program (MILP), minimising total system cost while limiting carbon emission, and maintaining security, and operability requirements [2]. Detailed operational constraints (e.g., start-up, ramp rates, minimum stable generation) on an hourly time discretisation enable the analysis of individual power plant performance characteristics and an assessment of their system-level impact.

We investigate the effects of the integration of CLC power plants into a 2030 and 2050 electricity system of the United Kingdom on the optimal capacity mix, the operational and system cost, and dispatch patterns. All three CLC power generation technologies prove valuable to the electricity system, as their deployment reduces system-wide investment and operational cost. Power generation from intermittent renewables becomes less economical as CLC technologies become available. Consequently, the requirements for carbon-intense reserve capacity, energy storage and overseas electric interconnection reduces. NGCC-CLC operating at virtually zero-carbon dioxide emission and moderate operation cost compares most favourably to IGCC-CLC and iG-CLC. The most cost-effective operational strategy for CLC power plants is in a steady manner, however, their ability for flexible operation can complement intermittent renewable power generation.

Additionally, we present the sensitivities to capital and operating expenditure and efficiency. A reduction in the efficiency of NGCC-CLC power plants from 46 % to 42 % reduces their annual average utilisation rate by only 1 %. For iG-CLC, the sensitivity to the cost of the oxygen carrier material is small; a variation of -50 % to +70 % causes a deviation in the average utilisation factor of -2 % to 3 %. For iG-CLC and IGCC-CLC, a 20-40 % increase in capital cost can reduce optimal capacity deployment levels considerably. NGCC-CLC deployment is more robust against investment cost increase. The results emphasises the high value of CLC power generation in a carbon-constrained system and can indicate and guide a prioritisation of future research efforts.

[1] C. Ekstrom, F. Schwendig, O. Biede, F. Franco, and G. Haupt. Technoeconomic evaluations and benchmarking of pre-combustion CO₂ capture and oxy-fuel processes developed in the European ENCAP project. Energy Procedia, 1(1):4233-4240, 2009.
[2] C. F. Heuberger, I. Staffell, N. Shah, and N. Mac Dowell. Levelised Value of Electricity - A Systemic Approach to Technology Valuation. In 26^th European Symposium on Computer Aided Process Engineering, volume 38, pages 721-726, 2016.