The SUNDISC cycle: A direct storage-charging dual-pressure air receiver cycle

Abstract A novel concentrating solar power cycle, the SUNDISC cycle, is proposed to address identified shortcomings of asynchronous combined cycles with a solarized gas turbine. The bottleneck in these cycles is the gas turbine because the mass flow through the pressurized air receiver system and, therefore, the amount of thermal energy that can be used in the bottoming cycle, is limited to the maximum throughput of the turbine. The enhancement in the SUNDISC cycle is an additional low-pressure air receiver system that is uncoupled from the gas turbine and directly feeds the storage system or steam generator. Different variations of the cycle with separated and hybrid receiver systems are presented and selected operating modes are shown. The asynchronous power cycles and separated receiver systems allow for project-specific plant layout and operation. Annual simulations with an hourly thermodynamic model returned the lowest levelized cost for a plant generating electricity during 87% of the year practically without co-firing. During almost all of this time, one of the two cycles operates at full load. The large storage capacity needed for this baseload plant is viable because of the low anticipated cost of the rock bed thermal energy storage technology. The calculated levelized cost of this plant is 25% lower than for a plant without a low-pressure receiver and is predicted to be on a par with a next-generation molten salt plant’s cost once medium-scale roll-out has commenced.