Development of a CST system based on a solid particle receiver, optimised for commercialisation in the Australian market

This thesis explores a recently developed concentrated solar thermal (CST) central receiver technology, known as the solid particle receiver (SPR). Calculations of long and near term thermo-economic competitiveness for promising potential applications were preformed, for the first time within the Australian context. With these results, the most suitable SPR technology configurations and technical developments, required to reach the commercial potential, were identified. An innovative simulation tool which included a variety of different thermodynamic and economic models, was developed to compute the annual performance of solar SPR systems. This simulation tool was then applied to design and to optimise CST SPR tower systems based on hourly simulations utilising meteorological data, the NREL Solar Position Algorithm, solar field efficiency matrices generated by DLR software HFLCAL, as well as a mathematical SPR model for calculating receiver efficiency. The SPR model was calibrated using results from DLR receiver prototype tests. To allow economic assessment of the entire SPR system, a financial model was implemented within the tool and detailed CST component costs were generated. The optimisation process utilised in the CST tower system design is more detailed than typical for a research project, since it adds a new degree of freedom when optimising the receiver and solar field. By decoupling the connection between solar field and receiver, the energy delivered from the solar field relative to the design receiver power becomes an additional optimisation variable. Applications of SPR systems for electricity production and industrial process heat generation have been identified for the Australian market. Promising heat supply uses of SPR technology examined in this thesis were: thermal enhanced oil recovery, preheating scrap metal during steel production, and solar augmentation of coal-fired steam power stations. Before this project, there were no detailed investigations on utilising SPR based CST power plants in Australia. This thesis has identified several potential applications, the required sub-components and system integration methods which should be further developed for commercialisation of this solar technology in the Australian market

Solar gas turbine systems with centrifugal particle receivers, for remote power generation

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- 10 MWe, 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 100 kWe microturbine as well as a more efficient and cost effective 4.6 MWe 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 35 m and a solar field size of 2100 m² for the 100 kWe turbine, and a tower height of 115 m and solar field size of 50 000 m² for the 4.6 MWe turbine. The solar field provides a greater portion of the operational energy requirement for the 100 kWe turbine, as the TIT of the 4.6 MWe 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

Hybrid Solar and Coal-Fired Steam Power Plant with Air Preheating Using a Solid Particle Receiver

Fuel reduction has been achieved for coal power stations by hybridisation with solar thermal systems. Current technology uses feedwater or turbine bleed steam (TBS) heating with linear Fresnel based concentrated solar power (CSP) fields. The low temperature heat produced by these systems results in low solar to power conversion efficiency and very low annual solar shares. In this paper the technical advantages of solarising coal fired power plants using preheated air by a novel CSP system based on a solid particle receiver (SPR) are examined. This system is compared to the current deployed state-of-the-art coal plant solarisation by modelling the systems and analysing the thermodynamic heat and mass balance of the steam cycle and coal boiler using EBSILON®Professional software. Annual performance simulation tools are also used to calculate the performance of the solarisation technologies. Solarisation using SPR technology for preheating air in solar-coal hybrid power stations has the potential to considerably increase the solar share of the energy input by 28% points at design point and improve the annual fuel reduction from 0.7% fuel saved to 20% over the year. This is a significant reduction in fossil fuel requirements and resulting emissions. These benefits are a result of SPR solar system’s higher operating temperature and integrated thermal storage, which also allow a buffered response time for handling transients in the intermittent solar resource. Analysis indicates air-solarisation of coal plants can enable 81% higher solar to electric conversion efficiency than currently existing solar hybridisation option. Thus, the cost of the thermal energy generated by Fresnel based TBS solarisation must be up to 38% lower than thermal energy generation of secondary air preheating SPR system for economic parity between the options. Initial calculations indicate that the required thermal energy cost levels for SPR systems for this application are already achievable