Performance assessment of USC power plants integrated with CCS and concentrating solar collectors

CAU, GIORGIO;COCCO, DANIELE;TOLA, VITTORIO

2014-01-01

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Abstract

This paper focuses on the evaluation of the potential benefits arising from the integration of Ultra Super Critical (USC) steam power plants with Carbon Capture and Storage (CCS) and concentrating solar systems. In particular, it reports on a comparative performance analysis of different integrating approaches, based on the design of the solar field to produce low-pressure saturated steam for the CCS solvent regeneration process and intermediate-pressure saturated and superheated steam for the introduction in the steam cycle. For the two different technical solutions, the comparative study calculates the increase in the annual energy production and net efficiency due to the solar energy contribution as a function of solar field size and for two different CO2 removal efficiencies. The study demonstrates that the integration of concentrating solar collectors can partially offset the efficiency penalties due to CO2 removal in USC power plants and that the most efficient approach is based on the production of superheated steam while lesser benefits can be achieved by producing low-pressure saturated steam for the solvent regeneration process. It also demonstrates that the introduction of the steam produced by the solar field greatly affects the performance of the power plant that operates in an "off design" mode. For this reason, to avoid an excessive increase in the turbine steam mass flow, the solar energy contribution to the annual electricity production cannot exceed 2-3%. Overall, integration with the solar section can improve the efficiency of the USC-CCS power plant by about 1 percentage point. Finally, the results of a preliminary economic analysis show that the solar assisted USC-CCS configuration may be able to operate with competitive solar energy production costs, especially with reduced solar field costs. In particular, the marginal levelized energy production cost of the most efficient solar assisted USC-CCS configuration is lower than that of the reference USC-CCS power plant for solar field costs lower than 110-115 €/m2.