It’s one of the biggest international events of the year for solar thermal experts and for the first time it was held in Australia!
The SolarPACES (Solar Power and Chemical Energy Systems) executive committee meeting and conference enticed experts from countries including USA, Spain, Germany, France and China. During the event they discussed important solar thermal issues and all the latest developments in the technology, markets and the future of the technology.
CSIRO’s Wes Stein told us, ‘We’re hearing from the experts about their experiences in their different countries, not only around research and technology programs, but also around the measures that have made advancements possible in their country.’
This is important stuff for the future of solar thermal research and technology – to help get this technology operating efficiently and make it more affordable.
CSIRO’s two solar towers were operating for the visitors during the event as working examples of the technology.
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.
We’re making solar thermal heliostats and receivers cheaper and work better.
As you may have read in a previous post, a bunch of solar projects were recently given the green light by the Australian Renewable Energy Agency (ARENA). We’re going to run a series of posts on the CSIRO-led projects so you know exactly what some of our scientists will be working on for the next few years. First up… ‘Optimisation of central receivers for advanced power cycles’.
Let’s call this the ‘Lego’ project. We’re pulling apart the most important Lego bricks that make up concentrated solar power (CSP) technology and making them cheaper and work better: the heliostats and the receiver.
Heliostats (or mirrors) make up the ‘solar field’, they concentrate the sunshine and reflect it onto a receiver (check out the process here).
Our field in Newcastle has 450 heliostats, however some fields have thousands. As you can imagine it is a major cost for a solar power plant and there are still many improvements to be made around field layout, heliostat size, performance and lifecycle. This project will investigate all of these areas to help develop the next generation of ultra low-cost heliostats and field design.
After we reduce the price of heliostats, we move to the receivers. Our receivers need to work efficiently at temperatures exceeding 800 degrees Celsius (that’s about as hot as lava spewing from a volcano), so this is a challenge. We also need to work out the best type of receiver system for the various solar field layouts.
If we can improve the efficiency with which the heliostats and receiver work together, we can reduce the cost of supplying heat to the turbine, which reduces the cost of solar power.
It’s a big job. The project is worth $3.2 million and we’ll be working with Graphite Energy in Australia plus the U.S. Department of Energy’s national laboratories. Hopefully they’re good at playing with Lego.
For more Lego fun, check out CSIRO’s new ship, the Investigator, made of Lego.
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.
Click on an icon below to download the image as a desktop wallpaper for your screen size.
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.
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.