100 facts about Solar at CSIRO: Part 2Posted: Tuesday, 9th October, 2012
To celebrate our 100th blog post, we’ve put together (in no particular order) a list of 100 things you may not know about solar research at CSIRO. Today: more about our high-temperature solar thermal fields including why we’re putting helicopter parts on our solar tower, and the strange animals and messages that occasionally crop up in our heliostat fields.
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- We call our heliostat design the ‘Spider’ due to its eight radial struts holding the mirror at the correct curvature. The design provides strength, rigidity and accuracy of focus.
- The mirrors are glued to the heliostat frames with the same material used in the manufacture of buses and caravans.
- The bonding glue on the mirrors is strong enough to withstand winds of over 200 km/hr – much higher than even the most extreme once-per-hundred-year wind conditions for the site.
- When each new heliostat is made we measure the curvature of the mirror surface at over 500 separate points to an accuracy of 10 millionths of a metre. Only if it meets our standards for focusing accuracy do we then install it in the field.
- We have used a ‘hail gun’ to test heliostats against hailstone impact. They passed.
- Each heliostat and its components are held together with 55 bolts – for a total 24,805 bolts in Solar Field 2 alone.
- The footings for the heliostats on the edges of the field are bigger than those in the middle. This is because the outermost heliostats will be exposed to higher winds than the sheltered, innermost ones.
- Solar Field 2’s mirrors have been used to spell out things like our organisation’s name, the year, and the Earth Hour logo. Despite journalists’ suggestions, we have never used them to spell ‘Don’t forget the milk’.
- Also despite journalists’ suggestions, the solar fields cannot be used as a ‘death ray’. This is because the combined reflections from the heliostats can’t be focussed anywhere but the top of our tower. (Rest easy, suburb of Mayfield; you remain safe.)
- Companies and research institutions from other countries have travelled to Australia to conduct experiments using CSIRO’s solar fields.
- There are unofficial reports that one of our solar engineers has personally signed several singe marks he’s left on the tower during experiments. His identity shall be kept anonymous for his own protection.
- CSIRO used to be home to several sets of solar troughs, but these were removed in 2010 to make way for the much larger Solar Field 2.
- The main experiment on Solar Field 2 is our Solar Air Turbine project. This uses just air and sunshine to generate electricity.
- The turbine is a modified helicopter engine, and is expected to be installed in the next few months.
- When the Solar Field 2 air turbine is fully operational, it’ll deliver about 150 kW of electricity to our site during the sunny hours of the day. Anything we don’t use ourselves can be sold on to the grid.
- Planning is under way for a thermal storage system to be added to Solar Field 2, making it able to store thermal energy for use after sundown.
- The Solar Field 2 tower is capable of supporting 15 tonnes – just in case we want to install some hefty experimental gear up there.
- Our tower and heliostats were manufactured locally, by a company on the NSW Central Coast.
- A CSIRO report has estimated that the cost of electricity from solar thermal power stations could drop to 13.5 c/kWh by 2020, with prices as low as 10 c/kWh technically feasible.
- CSIRO’s high temp materials laboratory in Newcastle can test new molten salt mixtures at temperatures up to 1000°C. Molten salts are used for storing solar thermal energy and have enabled the Gemasolar plant in Spain to generate energy 24 hours a day.
- SolarGas, which we make in Solar Field 1, contains 20% solar energy.
- Before CSIRO built its solar towers, we used a dish to carry out high-temperature solar thermal experiments. The dish was located at CSIRO’s Lucas Heights site.
- Our current tower-based solar receivers are ‘cavity receivers’ – that is, the area that’s heated up is inside a cavity. This means they have less heat loss compared to ‘external receivers’ such as used by other types of solar tower.
- For most of our experiments, we have more power available from the heliostats than is required. An automatic control system chooses which heliostats to use on the target and puts the spare ones in ‘stand-by’ positions close to (but missing) the receiver, where they sometimes make visible halos in the air. Stand-by heliostats can be brought on-sun if light cloud or haze develops and we need to maintain power levels.
- It’s cool to stand in an operating solar field – literally. The heliostats reflect most of the heat that would otherwise reach the ground.
- There’s a thriving local ecosystem in and around our solar fields. Regular visitors include lots of birds – magpies, corellas, herons, hawks, swamp hens and more – as well as less-welcome visitors like hares (that chew exposed cables) and the occasional reptile.