Reduced-order modelling of flexible CCS and assessment using short-term resource scheduling approach

CCS (Carbon Capture and Storage) can allow conventional fuels for electricity generation to be used while achieving deep reductions in GHG (Greenhouse Gas) emissions at the cost, though, of reduced efficiency and capacity relative to an electricity system without CCS. It has been proposed that the deployment of generating units with CCS that are flexible-in particular, that can moderate their CO2 recovery in response to market conditions-would mitigate some of the disbenefit associated with the technology. This paper uses the short-term resource scheduling approach to assess the value of flexible generating units with CCS (Carbon Capture and Storage); generating unit part-load performance, variability of CO2 recovery, and detailed operation of an electricity system including transmission and reliability constraints are considered simultaneously. A parametric study of the performance of a coal-fired generating unit with CCS is undertaken using an Aspen Plus® steady-state model and a reduced-order model representing the Pareto optimal frontier of the unit is developed using regression analysis. The base economic dispatch underlying the electricity system simulator is extended to accommodate flexible generating units with CCS. The flexible generating unit with CCS is added to the IEEE RTS'96 (Institute of Electrical and Electronics Engineers One-Area Reliability Test System-1996) and the operation of the modified IEEE RTS'96 is simulated for one week. The results are contrasted with results taken from Alie et al. (2015) for the base IEEE RTS'96 and an IEEE RTS'96 with “fixed” CCS. “Flexible” CCS is effective at reducing GHG emissions, though to a slightly lesser extent than was observed via “fixed” CCS. However, with GHG regulation in place, flexibility markedly increases the net energy benefit of the generating unit with CCS and this was achieved not through adjustment of CO2 recovery in order to moderate output but, rather, by increasing the generating unit's ability to successfully compete to provide reserve power. Performance metrics that do not consider the impact of GHG mitigation options on energy benefit may not correctly rank GHG mitigation options.