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 integration costs of solar power. This study quantifies the economic benefits of an ISCC power plant relative to a stand-alone CSP with energy storage, and a NGCC plant. A combination of tools is used to estimate the levelized cost of electricity (LCOE) and the cost of carbon abatement (CoA) for CSP, NGCC and ISCC technologies under different natural gas prices, and at several locations experiencing different ambient temperatures and solar resources. Results show that an ISCC with up to 10-15% of nameplate capacity from solar energy can be cost effective as a dispatchable electricity generation resource. 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 fuel price reaches 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 an 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 component have great impact tilting the balance in the ISCC's favor.