Wes Stein

Design of the Heliostat Field of the CSIRO Solar Tower

A close-packed heliostat field of more than 800 m 2 reflector area has been installed by Solar Heat and Power for the CSIRO solar tower at the Energy Centre in Newcastle, Australia. The heliostat field has been designed with significantly greater field packing density than normally associated with heliostat fields. It can be shown that even though a heliostat field with a high ground coverage exhibits more blocking and shading, a higher annual performance can be achieved up to a certain point. The optimum ground coverage calculated for the CSIRO solar tower configuration is in the range of 53%. Other heliostat field designs usually have ground coverage below 30%. The annual optical performance of the CSIRO field per square meters of deflector is about 9% higher than a radial stagger field of 30% ground coverage for a research tower, which was optimized to have the highest perfor- mance for the time frame from 10 a.m. until 2 p.m.

Multi-objective thermodynamic optimisation of supercritical CO2 Brayton cycles integrated with solar central receivers

ABSTRACT In this paper, optimisation of the supercritical CO Brayton cycles integrated with a solar receiver, which provides heat input to the cycle, was performed. Four S-CO Brayton cycle configurations were analysed and optimum operating conditions were obtained by using a multi-objective thermodynamic optimisation. Four different sets, each including two objective parameters, were considered individually. The individual multi-objective optimisation was performed by using Non-dominated Sorting Genetic Algorithm. The effect of reheating, solar receiver pressure drop and cycle parameters on the overall exergy and cycle thermal efficiency was analysed. The results showed that, for all configurations, the overall exergy efficiency of the solarised systems achieved at maximum value between 700°C and 750°C and the optimum value is adversely affected by the solar receiver pressure drop. In addition, the optimum cycle high pressure was in the range of 24.2–25.9 MPa, depending on the configurations and reheat condition.

Solar Grid Parity and its Impact on the Grid

Market forces, rather than subsidies, will drive a much more diverse mix of PV-based prosumers. Further cost reductions for PV and its urban locational flexibility means its spread to commercial and industrial usages is likely to be particularly rapid, as it will be for urban fringe and remote rural regions where grid connection is uneconomic. For many prosumers in the commercial sector reliance on the grid will be limited, as daylight PV power generation matches power demand. However as renewables reach a critical proportion of energy generation, concentrated solar power or other solutions will be needed for system reliability. In the long run the uptake of corporate prosumers will be an increasingly important variable in grid management as will purchasing power agreements with utilities.

Collecting and Converting Photons for Thermal Processes

The concentration of the sun to drive thermal processes has wide application. The optics of concentration and collection are discussed in terms of impact and opportunity to improve the way in which we use the solar energy arriving on earth.