There is a growing demand from remote communities in Australia to increase the amount of decentralised renewable energy in their energy supply mix in order to decrease their fuel costs. In contrast to large scale concentrated solar power (CSP) plants, small solar-hybrid gas turbine systems promise a way to decentralise electricity generation at power levels in the range of 0.1-10MW e , and reduce to cost of energy production for off-grid, isolated communities. Thermal storage provides such CSP systems with an advantage over photovoltaic (PV) technology as this would be potentially cheaper than adding batteries to PV systems or providing stand-by back-up systems such as diesel fuelled generators. Hybrid operation with conventional fuels and solar thermal collection and storage ensures the availability of power even if short term solar radiation is not sufficient or the thermal storage is empty. This paper presents initial modelling results of a centrifugal receiver (CentRec) system, using hourly weather data of regional Australia for a 100kW e microturbine as well as a more efficient and cost effective 4.6MW e unit. The simulations involve calculation and optimisation of the heliostat field, by calculating heliostat by heliostat annual performance. This is combined with a model of the receiver efficiency based on experimental figures and a model of the particle storage system and turbine performance data. The optimized design for 15 hours of thermal storage capacity results in a tower height of 35m and a solar field size of 2100m 2 for the 100kW e turbine, and a tower height of 115m and solar field size of 50 000m 2 for the 4.6MW e turbine. The solar field provides a greater portion of the operational energy requirement for the 100kWe turbine, as the TIT of the 4.6MW e turbine (1150°C) is greater than what the solar system can provide. System evaluations of the two particle receiver systems, with a selection of cost assumptions, are then compared to the current conventional means of supplying energy in such remote locations.

Coal power stations have been hybridised with concentrated solar thermal (CST) fields which produce feedwater or with turbine bleed steam (TBS) heating from direct linear Fresnel to steam technology. This paper assesses solar hybridisation of boiler based steam power plants, which preheat boiler combustion air with a novel high temperature CST system based on a solid particle receiver (SPR). This new method of preheating has the potential to increase the solar share of the overall system, improve fuel saving and therefore produce a higher solar to electric conversion efficiency. These benefits result from the SPR solar systems higher operating temperature and integrated thermal storage. The integrated thermal storage also allows a buffered response time for handling transients in the intermittent solar resource. Analysis indicates that air-solarisation of coal plants can result in significantly higher solar to electric conversion efficiency than existing solar hybridisation options. Solarisation by TBS decreases power cycle efficiency due to bleed steam reduction, while solarisation by air-preheating increases the power system efficiency, primarily due to enhanced boiler efficiency brought about by reduced stack losses.The air solarisation option proposed in this paper has been compared to current TBS with Fresnel based technology. The comparison was conducted by modelling both systems and analysing the thermodynamic heat and mass balance of the steam cycle and boiler using EBSILON®Professional software. Annual simulation tools, which calculate the performance of the solar field, receiver, storage (when applicable) and other system components, were used to model the output of the solar technologies. These tools, coupled with available economic data and cost models for the newly developed solar components, were used to calculate the levelized cost of energy of the compared hybridisation options. It was calculated that the levelized cost of the solar electricity produced by the SPR system was approximately 59% the electricity produced by the Fresnel hybridisation.

No abstract

No abstract