ASI funded Solar Thermal Storage and Steam Programs at the CSIRO and ANU

The use of concentrated solar thermal energy for the production of electricity has been achieved commercially with the generation of steam in trough or tower concentrating systems. More recently, solar power stations such as the AndaSol 1 have also included 1,010 MW·h of heat storage, enough to run the turbine for about 7.5 hours at full-load. The thermal storage in the AnderSol 1 solar power station is a molten salt mixture of 60% sodium nitrate and 40% potassium nitrate that is stored in large insulated tanks at temperatures up to 380 o C. These first generation commercial systems have some limitations in their operation when compared to state of the art fossil fuelled generators; the most significant of these is the temperature and pressure of the resultant steam that is generated and the types of steam turbines that can be utilised. Other major limitations are the ability of the solar system to produce a consistent steam quality required for operation of a steam turbine, and the upper temperature limit that molten salt can be safely stored before it begins to decompose. The CSIRO and Australian National University (ANU) have recently begun two Australian Solar Institute (ASI) funded projects, one looking at development of high temperature thermal storage systems, and a second investigating techniques for the generation of high pressure and temperature steam. These projects will be undertaken over the next three years. The high temperature thermal storage project will examine a wide range of techniques, fluids, materials and process designs that will enable the storage of solar thermal heat at temperatures beyond the limitations of the salts used in current solar power generation facilities. The advanced steam generation project will address the challenges of producing steam at the conditions required to couple solar thermal with state of the art power generation turbines, and through the use of storage technologies enable production of reliable, consistent and high quality steam. This paper outlines the research directions and the areas of focus of the two projects.