Greeting the sun and a lovely rosy dawn, our heliostats in formation for Earth Hour (8.30pm, Saturday 23 March).
Want some practical energy saving tips? Our energy efficiency expert, Glenn Platt, blogged with The Newcastle Herald recently and answered all your ‘hot’ questions including saving money on your power bills and electric cars for the future.
Visited our CSIRO Facebook page recently? Solar Field 2, here at our Newcastle site, is currently featured in the banner image on our Facebook site. We promise we won’t let the glamour of being a cover model go to our heads… too much.
If you ♥ science like we do, visit us on Facebook for fun and interesting updates on what CSIRO is up to. After all, our organisation does much more than solar – our areas of interest range from nanomaterials to deep space, and include much of what’s in between – so there’s always something interesting going on. Friend us or like us, and show your support for Australian science that’s making a positive impact on all our lives.
This photo shows CSIRO’s Solar Field 2, a one megawatt-thermal solar central receiver system, in operation at CSIRO Energy Centre, Newcastle.
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To celebrate our 100th blog post (did you see our custom solar cell?), we’ve put together (in no particular order) a list of 100 things you may not know about solar research at CSIRO. Today: our high-temperature solar fields, the connection they have with solar companies that were operating before Europeans settled Australia, some stories about stuff we’ve melted, and how a vacation student’s work is embodied in over 600 heliostats.
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- CSIRO’s two high-temperature solar tower facilities go by the practical and descriptive names of CSIRO Solar Field 1 and CSIRO Solar Field 2. Despite what you might think, they’re not necessarily the most unimaginative titles in solar research tower history.
- Solar Field 1 was opened in 2005 and is primarily used for SolarGas research, and Solar Field 2, which will make electricity using an air turbine cycle, was opened in 2011.
- We also had several rows of solar parabolic concentrators or ‘solar troughs’. Four of these units were originally developed by ANU. Two additional units were later installed for testing on behalf of a client.
- The Energy Centre at Newcastle only opened in 2003, but concentrating solar thermal research at CSIRO goes back to the 1980s using small dish and trough units. Concentrating solar power itself goes back much further – the first commercial trough system was in Egypt in 1913, and operating systems were being exhibited as far back as the 18th and 19th centuries.
- CSIRO Solar Field 2 is bigger than Field 1, and collects about two and a half times as much energy.
- Solar Field 2 has been designed to be ‘peaky’ – that is, the layout of the heliostats maximises the peak field output at the expense of the overall annual energy capture. This is to extend the field’s research capabilities.
- Our solar fields can have several different experiments mounted on the towers at any given time. Currently Solar Field 2 hosts an air turbine receiver, a SolarGas experiment, and a high-temperature testing rig.
- The two solar fields are most commonly used to run processes at temperatures from 800 to 1000°C.
- The highest temperature we’re aware of having generated was around 1700°C with Solar Field 1, when we melted a piece of ceramic. We don’t actually know what the maximum temperature we’d be able to reach is, as it would depend on the receiver material and conditions.
- There are 621 heliostats installed in total at the Newcastle site. Laid side by side, the mirrors would make a reflecting surface large enough to cover four tennis courts.
- Due to their excellent focusing, even a single CSIRO heliostat can generate temperatures high enough to melt aluminium – which has a melting point of 660°C.
- The reflectivity of our mirrors is about 92%. For comparison, the mirrors you have in your bathroom are likely to be about 84% reflective.
- Our mirrors use low-iron glass, which transmits more infra-red energy than normal glass. This makes the glass more see-through at wavelengths we can’t see – but which our solar receiver can use.
- Dust and dirt on the mirrors can reduce their reflectivity by a few percent. For our purposes we only need to clean them occasionally, usually just before experiments requiring ultra-high temperatures. That’s when lucky Brendo gets handed the mop and squeegee.
- When our solar fields are operating, the mirrors look like they’re standing still – but each heliostat is actually changing its orientation by a tiny amount several times a minute to keep up with the sun as it moves across the sky.
- The mirrors in our heliostats also look like they’re flat, but in reality each one is very slightly (and precisely) curved in a dish-like shape so as to focus the reflected light.
- Because the different mirrors in our solar fields have different distances from the receiver, they need to be built with different focal lengths. We have four different focal lengths for Solar Field 2 and five for Field 1.
- The company that supplies our mirrors has been making components for concentrating solar thermal systems for over 240 years – dating back to before Europeans first settled in Australia.
- A vacation student made integral contributions to the design and engineering of CSIRO’s heliostats. The results of his work are now present in over 600 heliostats. Vacation studentships are periodically advertised on CSIRO’s website here.
- Our heliostat frames are ‘steel origami’: the mirror support struts are made by folding laser-cut sheets of stainless steel. This simplifies assembly, keeps the structure strong and lightweight, and helps keep material and fabrication costs down.
There’s a new experimental rig on top of Solar Tower 2 – and it gives CSIRO the ability to do something unique.
This slot-shaped device, shown above, is a way for us to test new components for use in solar receivers. We can install a component for testing into the insulated cavity, illuminate it with concentrated solar energy using our heliostat field, and take accurate measurements of how well the new component operates.
We gave it its first field test a few weeks ago and it performed well. We brought the temperature of the tube we were testing up to 1000°C in a controlled way, monitored the way it transferred heat to air passing through it, and then let it cool again.
Why is this so great? It’s because now we have a facility that can test components or materials at very high temperatures under very controlled conditions. Few other solar fields – or indeed any other type of facility – in the world can do this.
The reason we’ve been able to is because our heliostats can focus more tightly than most, and because our computer control system has smart and accurate control over where the mirrors point. This allows our mirrors to ‘paint’ onto the object a given pattern of light as requested by the experimenters.
How our Australian solar field can be linked to a Las Vegas casino
Previously, to carry out experiments like ours, researchers have had to find some other way to mimic the heating effect of hundreds or thousands of ‘suns’ – no mean feat. There are two types of approach to this problem.
The first is to build a ‘solar simulator’ – a collection of (usually) xenon arc lamps whose light is focused into a super intense beam by mirrors. (Xenon lamps are the type used to make the tower of light at the Luxor Casino in Las Vegas, which draws nearly 280 kW of power.) A solar simulator can deliver a high intensity of radiation, with a spectral distribution similar to the sun, over a small area. The German Aerospace Agency DLR, for example, has one about a quarter the power of the Luxor Sky Beam that can deliver about 5000 suns’ intensity over an area the size of a post-it note, and the Paul Scherrer Institute (PSI) in Switzerland has a bigger one that uses half the power of Luxor’s.
The second approach is to use the sun itself as the laboratory – as we have. Usually, though, high-temperature testing with tightly-focused light is carried out in special concentrators called solar furnaces. (DLR and PSI have their own solar furnaces, too, which have been used for a range of things including satellite testing.)
Our new tower-based high-temperature test rig will initially be used for our own receiver component and materials testing. In the future, though, it’ll find use for many more and varied experiments.
It’s been a busy month here at the Solar Energy Centre with a couple of new experiments being installed and operated.
One of the big additions we made to the tower was to add a new level: a mezzanine platform that was lifted up by crane. On it we’ve installed components for a new type of SolarGas reactor. This is one of our new projects that’s taking shape rapidly. Look for more information and updates over the coming months.
Photos: S Morgan and T Ritchie
Exactly one year ago Solar Field 2, CSIRO’s newest concentrating solar thermal facility, was opened by Prime Minister Julia Gillard. In the twelve months since, we’ve achieved a lot including successful operation of a new high-temperature receiver and demonstration of our improved heliostat design.
The next year is going to be a productive one, too, with no less than three new projects already underway for future installation on the tower – a new type of SolarGas reactor, an air turbine to be coupled to the existing receiver, and a new receiver for experiments and testing.
To celebrate the anniversary, I’ve put together a slideshow of images from the field’s construction, opening and first year. Click below to start.