(286d) Design and Optimization of Solar Thermal Systems

Solar-thermal systems based on Concentrated Solar Power (CSP) are considered a promising method to generate electricity from solar energy. CSP systems have been considered for several decades and in recent years generate renewed interest in research, development and commercialization. Several difficulties associated with CSP systems have to be overcome before a successful wide-scale commercial adoption.
The focus of this talk is the design and optimization of CSP with a central receiver, in particular integrated with thermal energy storage. Such technologies are still at a research/development stage.

Central receiver systems are typically employed in flat land using dozens to thousands of heliostats for a single receiver. In the first part of the talk we describe a recent proposal to use hilly terrain [1,3]. Hilly terrain is often significantly cheaper than flat lands which is suitable for many uses. A tool for site selection is presented for both beam-up and beam-down configurations [1] and used to demonstrate the abundance of suitable hills. Additionally a computationally efficient tool for heliostat placement in both planar and hilly terrains is described and used to identify novel heliostat patterns that are significantly better than any of the existing ones [2].

An interdisciplinary team at MIT proposed a new concept, termed CSPonD, that collocates the receiver and storage system [3]. CSPonD has the potential to overcome some of the operational challenges of power towers and reduce capital cost of the receiver/storage system without compromising the efficiency. On the other hand, identifying an optimal design and operation is very challenging. The second part of the talk describes a methodology based on dynamic optimization [4,5,6]. Both single-purpose (electricity only) and dual-purpose plants (electricity and seawater desalination) are discussed. The effect of feed-in tariff (FIT) on optimal design and operation is demonstrated and the influence of seasonal variations on operability discussed. Finally, different energy storage systems (both conventional and novel) are compared in terms of thermodynamic efficiency and cost.

[1] C. J. Noone, A. Ghobeity, A. H. Slocum, G. Tzamtzis and A. Mitsos. Site Selection for Hillside Central Receiver Solar Thermal Plants, Solar Energy, 85 (5):839-848 2011.

[2] C. J. Noone and A. Mitsos, Heliostat Layout Optimization via Automatic Differentiation: Adjoints and Convex Relaxations. SIAM Computational Science and Engineering Conference, Reno, NV, 2011.

[3] A. H. Slocum, D. S. Codd, J. Buongiorno, C. Forsberg, T. McKrell, J.-C. Nave, C. N. Papanicolas, A. Ghobeity, C. J. Noone, S. Passerini, F. Rojas and A. Mitsos. Concentrated Solar Power on Demand, In Press: Solar Energy, April 11, 2011.

[4] A. Ghobeity and A. Mitsos, Optimal Use of Solar Thermal Energy for Combined Power Generation and Water Desalination (Plenary Talk, Paper #174), Nicosia, Cyprus. Conference on the Promotion of Distributed Renewable Energy Sources in the Mediterranean Region (DISTRES), 2009.

[5] A. Ghobeity and A. Mitsos. Optimal Operation of a Concentrated Solar Thermal Cogeneration Plant. 21st European Symposium on Computer Aided Process Engineering ESCAPE 21. Chalkidiki, Greece. 2011

[6] A. Ghobeity, E. Lizarraga-Garcia and A. Mitsos. Optimal Design and Operation of a Volumetric Solar-Thermal Energy Receiver and Storage. ECOS 2011, The 24th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, Novi Sad, Serbia, 2011.