ANALYSIS OF THERMAL ENERGY STORAGE SOLUTIONS FOR A 1 MWe CSP-ORC POWER UNIT

asme-orc2015 Tracking Number 183

Organic Rankine Cycle (ORC) power generation blocks have been principally used in the past couple of decades to recover medium grade heat from sources such as geothermal steam, biomass boilers and the exhaust of a realm of different industrial processes. In the past few years, a new philosophy of integrating thermal solar energy to an organic Rankine cycle has been assessed, the purpose of which is to develop a compact, water free and decentralized solution that offers the advantages of solar thermal power with low intermittency and the possibility to extend power generation to the night time at a relatively reasonable cost. To achieve these objectives, a proper storage system that is thermodynamically fit to the heat profile captured by the solar collector and to that of the power cycle must be identified. This paper covers the selected criteria and the analysis done to identify the potential storage solutions adapted to a thermal solar – ORC system operating at temperature range between 170 C min and 300 °C max, while receiving energy in the form of sensible heat from the collector in order to eventually deliver it to a power organic Rankine cycle (ORC) that uses Cyclopentane as a working fluid. The system so developed will be integrated in the 1 MWe CSP-ORC facility based on Fresnel technology which is currently under construction at Iresen’s facilities in Morocco. The paper covers the optimisation process carried out to best match the characteristics of the thermal Energy storage system to the features of the ORC power block. Two alternative solutions are looked into: sensible heat storage and latent (phase-change) heat storage. A parallel analysis is presented from a multiple fold perspective (technical, economic…) showing that both technologies have particular advantages.