Abstract
Thermal energy storage (TES) increases concentrating solar power (CSP) plant capacity factors, but more important, improves dispatchability; therefore, reducing the capital cost of TES systems is very important to reduce cost of energy and serve as an enabler for commercial solar power plants. After presenting the concept of a novel cascade PCM configuration of CSP and demonstrating it energy efficiency, it is needed to develop a thoughtful economic evaluation of the concept. The goal of this paper was to investigate this system through annual modelling, engineering procurement company price quotes, and levelized cost metric comparison with a baseline case, the commercial two-tank molten salt storage system. Simulation results show that this new PCM concept decrease levelized costs of storage. The baseline of using shell and tube heat exchangers for PCM storage offers a reduction in capital and levelized cost, but this paper also shows that there are further cost reduction possibilities, as shown in the scenarios presented here, such as thermal conductivity enhancement, encapsulation of the PCM, or modification of the material to improve its thermal properties. Therefore, although the basic shell and tube PCM system has been shown to offer a cost savings, the 1.8% reduction in LCOE may not be worth the risk of further development. The shell and tube system should be a jumping off point to more appropriate technologies. The variants studied are likely to yield cost reductions in cost performance quotient (CPQ) as high at 80% and in LCOE as high as 10%, representing an unprecedented and valuable avenue of CSP plant cost reduction.
Highlights
Commercial concentrated solar power (CSP) is more accommodating to energy storage than other solar technologies
The development of reliable, flexible and cost-efficient molten salt storage system has recently been acknowledged by the CSP community as a potential major enabler of a better integration of CSP with other cheap variable renewables, by potentially facilitating smart control of co-located assets through smoothening the fast variations from PV and/or wind
This study considered a Thermal en ergy storage (TES) capacity of 6 equivalent full load hours (EFLH) of indirect storage since this is representative of systems currently commercially considered
Summary
Commercial concentrated solar power (CSP) is more accommodating to energy storage than other solar technologies. Many PCM sizing models were generated to model both PCM TES systems [9,10,11] These models focus on calcu lating a cost per kWh of thermal energy storage. While the latter method is considerably more accurate, it still relies on a generalization of the TES performance over the course of a whole year This modelling method is suspect due to the inability of simple performance models to capture the realistic response of passive TES systems to transient energy flows observed in a CSP plant. Indirect 2-tank molten salt 6 equivalent full load hours (864 MWhe_gross) 3 hot/3 cold Binary salt (60% NaNO3, 40%KNO3) 66,613 metric tons 386 ◦C 295 ◦C overcome in some cases with experimental work These experiments reinforced the low capitol cost potential of PCM TES systems. The goal of this paper was to investigate this system through annual modelling, engi neering procurement company price quotes, and levelized cost metric comparison with a baseline case, the commercial two-tank molten salt storage system
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