Integrated Solar Combined Cycle Power Plants: Paving the way for thermal solar

Abstract

Integrated Solar Combined Cycle Power Plants (ISCCs), composed of a Concentrated Solar Power (CSP) plant and a Natural Gas-Fired Combined Cycle (NGCC) power plant, have been recently introduced in the power generation sector as a technology with the potential to simultaneously reduce fossil fuel usage and the costs of integrating solar power in an electricity system. This study quantifies the economic and environmental benefits of an ISCC power plant relative to a stand-alone CSP with energy storage, and a NGCC plant. The corresponding levelized cost of electricity (LCOE) and the Cost of Carbon Abatement (CoA) are estimated by simulating hourly operations for five U.S. locations with different solar resources and ambient temperature, under varying assumptions regarding natural gas prices, tax incentives, capacity factors, and capital costs. Results show that integrating the CSP into an ISCC reduces the LCOE of solar-generated electricity by 35-40% relative to a stand-alone CSP plant, and provides the additional benefit of dispatchability. An ISCC also outperforms a CSP with energy storage in terms of LCOE and CoA. The current LCOE of an ISCC is lower than that of a stand-alone NGCC when natural gas prices reach 13.5 $/MMBtu, while its CoA is lower at a fuel price of 8.5 $/MMBtu. Although, under low to moderate natural gas price conditions, a NGCC generates electricity and abates carbon emissions at a lower cost than an ISCC; small changes in the capacity factor of an ISCC relative to the NGCC, or capital cost reductions for the CSP components significantly tilt the balance in the ISCC's favor. Hence, this technology should be seriously considered as a cost-effective baseload electricity generation alternative to speed up the transition to sustainable energy systems.