CSP-PT gas plant using air as Heat Transfer Fluid with a packed-bed storage section

Concentrated Solar Power technologies represent an important alternative able to replace in a medium/long term fossil fuel sources. Current technology has several drawbacks which prevent a large diffusion: the principal one is the choice of the Heat Transfer Fluid which involves a certain complexity, including the heat storage section. Conventional plants in operation, consider diathermic oil and, more recently, molten salts. The potential of gases as working fluid has been underestimated till now and its use has not still fully exploited. Using gas would determinate a simpler conversion section increasing reliability. The gas, as proposed by the authors, can expand directly in a series of inter-reheated turbines after a series of intercooled compressions, reaching an acceptable overall global efficiency of the conversion section. The paper describes the optimum choice for the thermodynamic cycle which approaches an Ericsson cycle, integrating it with a comprehensive mathematical model for the heating section of the gas inside the solar receiver. A Thermal Energy Storage section based on the use of a packed bed of rocks has been considered, merged at the plant to insure production continuity. The overall software platform for the plant can be used as design tool in order to set up most important alternatives related to the plant characteristics and specific parameters.