Combined-cycle solarised gas turbine with steam, organic and CO2 bottoming cycles

Dish concentrators permit the collection of very high-temperature heat, at temperatures limited only by the properties of the containment vessel material. Using this heat efficiently is a major challenge in the design of energy conversion systems for dish concentrators: the heat must be used either immediately on the dish, or else transported, with losses, to a remote energy conversion device. This paper presents a study of the technical feasibility a solarised combined-cycle gas turbines with a dish concentrator, with several different possible Rankine-cycle working fluids considered: carbon dioxide, toluene, ammonia and water. Carbon dioxide is found to be unsuitable for the bottoming cycle, but options toluene, water and ammonia are all found to be similar at ~46% efficiency. The toluene cycle shows promise because of its suitability for thermal storage.