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.
It has been a good week for CSIRO’s SolarGas™ reactor. The reactor – which was recently down in our workshop here at CSIRO Newcastle – was reintroduced to concentrated sunlight in Solar Field 1 on Thursday morning, and it’s been passing its start-up tests with flying colours. When I was down in the field this morning it was being held steady at just under 600°C while engineers continue the process of recommissioning it to its usual operating conditions of 800°C and above.
The reactor is now operating with several improvements including a new and better temperature monitoring system.
Don’t know what SolarGas is? Read this previous blog post for a description of how it works and why it’s useful.
This illustration shows a solar thermal ‘power tower’ similar to CSIRO’s Solar Field 1.
Click on an icon below to download the image as a desktop wallpaper for your screen size.
Thanks to everyone who’s visited the solar blog this year, and all the CSIRO folk behind the scenes who have given time to make this grand experiment happen. Enjoy our pop-up CSIRO Solar Field 1 card, and see you in 2012!
Michael Rae is an Experimental Scientist with the solar thermal research group at CSIRO. In between writing software, working at heights and spending time as the unofficial CSIRO Solar Facility tour guide, he found time to answer some questions about himself for the solar blog.
How would you briefly describe your work? I take care of all the industrial control systems and instrumentation for our solar facility. What does this mean? Well, all our experimental rigs need to be operated and monitored remotely. I’m responsible for designing and implementing all our automation systems to allow this to happen safely. Plus various software work, plant design, plant operation and giving the occasional guided tour.
How does your work impact on the ‘real world’? Being able to successfully automate these plants is vital as they scale up to commercial size. In a large plant with multiple towers the ultimate goal would be for an operator or team of operators to be able to run the entire facility from a central control room in a supervisory role. To do this we need systems that allow operators to know exactly what is happening in the plant so they can respond to changing conditions or problems.
“Everything starts out as an idea over coffee and a sketch on a whiteboard then actually seeing that built and working is a fantastic feeling.”
Describe a typical day at work for you. I spend a lot of time in my office doing design work, sourcing equipment and writing software. The fun part is getting out in the field and actually making this stuff work. This can involve anything from diagnosing equipment that isn’t doing what we want, to commissioning and operating the field and plants.
What is the most exciting thing about your job? Being able to see something you’ve been designing for ages actually working. Everything starts out as an idea over coffee and a sketch on a whiteboard then actually seeing that built and working is a fantastic feeling. Also, being able to get up the tower and do some field work on a nice warm sunny day after being trapped in the office for ages is great.
What is the worst thing about your job? Having to get up the tower to do field work to meet a deadline when it’s freezing cold.
At what age did you realise you were interested in science / engineering? Why did it interest you? I always enjoyed pulling things apart. Eventually they started going back together.
What’s your educational background? I graduated in Computer Science at the University of Newcastle with a mixture of Software Engineering, Electrical Engineering and Computer Science studies under my belt. Given the chance to change things I’d probably have dropped some of the big software development studies and taken up some more heavy engineering courses in Electrical or Chemical Engineering.
“I always enjoyed pulling things apart. Eventually they started going back together.”
How did you end up in the field of solar energy? I was working at CSIRO doing computer simulation of airborne emissions and the opportunity came up to do a few odds and ends for the solar team. That slowly became more and more industrial control and plant engineering work until I was full time solar. Since then I’ve played a part in almost every project on the solar towers.
What is the strangest thing you’ve found yourself doing as part of your science/engineering career? Releasing weather balloons off a carpark roof at the crack of dawn to identify local wind patterns as part of an air quality measurement campaign.
What do you like getting up to on your weekends? I’m a revhead at heart and have owned, raced, broken and spent far too much time under old Toyotas. Love the outdoors, hopping in the ute and finding that camping spot with no-one around for miles.
What else do readers of the CSIRO Solar Blog need to know about you and your work? I’ve never owned a lab coat, or ever plan to.
It’s corella breeding season and flocks of birds are hanging out in our solar field. They’re beautiful, social white birds that always look like they’re having a good time. It’s nice to watch them larking about on the heliostats, but we’re keeping an eye on them – we’d prefer to keep admiring their antics rather than having to patch up any damage they might do with their sharp beaks. If it comes to that, though, the next step might be to put a fake hawk on the tower to scare them away.
Addendum: thanks to twitter user @pattyjansen who alerted us to a novel way of scaring away birds:
you may have to install ‘aliens’ as protector against cockatoo damage, like
Intrigued, I got in touch with the Canberra Deep Space Communication Complex at Tidbinbilla to find out where we could get aliens of our own. It turns out that it actually refers to a bird deterrent system they have on the main antenna. They’ve found that the most effective system for preventing cockatoos from from roosting there is to install electronic bells that go off morning and evening to irritate the birds.
Why ‘aliens’? According to Glen Nagle, CSIRO’s Communications manager at the CDSCC:
When people are here and they hear the electronic bells go off on the dish, they ask “What’s that noise?” and we often jokingly reply “Oh, that’s the aliens calling us again.”
It’s a clear spring day in this photo of Solar Field 1 at our Newcastle site. There’s obviously plenty of sunshine to power solar panels or solar turbines. But in this case there’s more going on than meets the eye. Even after the sun has set we’ll still have a supply of solar energy, thanks to what’s in the small shed circled below.
In the shed is a group of gas cylinders. They’re holding the product of a process that CSIRO has developed to near commercial demonstration that captures and stores solar energy for later use. Because the added solar energy is stored in the chemical bonds of a gas, we call the product SolarGas™.
SolarGas isn’t just a way of storing solar energy. It’s also a way to add solar energy to fuels like natural gas, and it can even be used in production of many liquid fuels and fine chemicals which currently rely on finite fossil fuel feedstocks. It’s been one of the main areas of research and development for our solar thermal team over the last decade, and that’s because we think it’s a really versatile product that’s well suited for Australian resources and needs.
I get asked questions about SolarGas all the time from people ranging from school students to scientists. For people who don’t work in process industries (that’s most of you, I’m guessing) I’ve realised that to really get across why SolarGas has so much potential, it’s necessary to take a bit of time to start at the beginning and explain the concepts involved. Unlike a system that produces electricity – which we can all relate to, because we use it to power our kitchen blenders and so on – SolarGas applications are more varied and perhaps might seem a bit further from home (related more closely to, say, the industrial manufacture of hydrogen rather than lighting our houses at night). Nonetheless, it has the potential to have huge benefits that are worth understanding. That’s why I’ve chosen to spread this article over two sections, and why I’m going to write it for the sort of reader who prefers to call a fire ‘hot’ rather than ‘exothermic’. No apologies.
How it’s made
To make SolarGas, we use mirrors to focus solar energy onto a series of metal pipes, which creates temperatures of around 800°C inside them. Through these pipes we flow a stream of natural gas mixed with something else. This ‘something else’ can be steam or carbon dioxide – both pretty common ingredients, suited to different situations.
These metal pipes form our SolarGas Reactor, and they have been carefully designed so that inside them the conditions are right for a chemical reaction to occur. This reaction converts the natural gas and steam (or carbon dioxide) to a new mix of gases, and in the process ‘sucks up’ a whole lot of solar energy into the new gas molecules in what is called an endothermic reaction. If you could touch the pipes where the reaction is going on (and we wouldn’t recommend it) you’d feel that they’re actually cooled as energy transfers from solar heat to chemical bonds – thus changing it into a form that, unlike the energy in sunlight, can be stored in bottles or pumped from place to place.
It’s interesting to note that steam and carbon dioxide are the products of normal combustion. So here, where we’re using them as the reactants, we’re in essence turning the usual reaction around using energy from the sun. That’s neat.
So, the result is that we’ve produced a new gas that has more energy than the gas we started with – and this extra energy came from the sun. The video below gives an overview of the process. In this example, the more common steam version of the reaction is shown.
You might have noticed that the video shows what SolarGas is. It’s made up of hydrogen and carbon monoxide – specifically, three units of hydrogen gas for every molecule of carbon monoxide gas. This mixture makes the gas very useful in a number of ways.
But that’s a topic that deserves a post of its own. Next: Part II – how it can be used.
The new Solar Field 2 has been given most of the limelight on this blog up until now. But as its name suggests, it’s not the only concentrating solar thermal power facility at our site.
Solar Field 1, shown below, was Australia’s first ‘power tower’ when it was opened in 2006. Even though it has a newer sibling beside it, it’s still an important research facility here at the National Solar Energy Centre.
This solar tower was one of the first few in the world to be constructed since the 1980s, when energy concerns caused a handful of central receiver research facilities to spring up in Europe, the USA, Japan and Israel. Although most of these first-generation towers were decommissioned after their testing programmes were complete, some are still in operation today. These include the SSPS-CRS and CESA-1 towers in Spain, Sandia’s Central Receiver Test Facility in Albuquerque, USA, the Weizmann Institute solar facility in Israel, and Themis in France. In recent years several new central receiver facilities have been constructed for both research and commercial purposes. You can read more about the ones that generate electricity for the grid at the SolarPACES Database of Concentrating Solar Power Projects.
CSIRO’s interest in solar towers was due to their ability to generate very high temperatures inside a fixed-place receiver. The temperature can be much higher than solar troughs or linear Fresnel, which can operate up to about 500°C. One advantage of higher temperatures is that processes which use the heat can be more efficient, which gives the potential for cheaper electricity generation. Higher temperatures also open up new uses for the thermal energy.
The first task of CSIRO Solar Field 1 was to demonstrate one of these new uses, which was the production of SolarGas™ at temperatures over 800°C. This process – which you can read more about at our SolarGas website – uses concentrated solar energy to convert natural gas into a product that stores solar energy in chemical form. So far, the field has been used to test two different CSIRO reactors for SolarGas™ production.
But SolarGas™ isn’t the only project for which Solar Field 1 has been used. International research organisations have used it to test solar components they’ve developed, such as new heliostats and receivers. It was used to demonstrate the first stage of solar water splitting at over 1500°C on behalf of another organisation. It’s also given CSIRO a lot of experience in solar field operation, development of control software, and heliostat design – knowledge that we put to use when designing Solar Field 2.
Newcastle’s two solar ‘power towers’ have been featured in Climate Spectator. In the same week as CSIRO’s Solar Cooling project was featured (see blog post), an article has been published in which Robbie McNaughton, the engineering manager here at the National Solar Energy Centre, answers questions about our high-temperature solar thermal facilities. He explains the basics of our SolarGas research (running in Solar Field 1) and our Brayton Cycle project (in Solar Field 2) and discusses how the technologies will be used.
From the article:
A new solar array at the CSIRO’s energy research centre in Newcastle is the world’s largest demonstration of a new technology that uses concentrated solar energy to heat air rather than liquids. In many ways it works the same as a gas turbine: compressed air is heated, and then the air expands through a turbine to create power. “We’ve just eliminated the combustor,” said Robbie McNaughton, the engineering manager at the National Solar Energy Center, during a visit to the centre last week.
The technology is known as a solar air turbine, but its official name is a Solar Brayton Cycle. And because it needs no water, it is uniquely suited to Australian conditions, where the best solar radiation often coincides with the least amount of available water. And because it lacks the complexity of rival technologies, and can operate as a modular, stand-alone system, it is also suitable for remote locations such as mine sites.
Today CSIRO staff had a spectacular new view out their windows, with both of our solar towers being lit up by focused sunlight at the same time. This is the first time both systems have been in operation simultaneously.
Solar Field 1, shown at left, was being run to produce SolarGas — a gaseous fuel which stores solar energy in its chemical bonds. It was achieving temperatures over 800°C and delivering around 300 kW of thermal energy to the reactor on top of the tower.
The new Solar Field 2 was being used to calibrate heliostats. As described in the previous post, a camera in the field was monitoring the focused spots of light on the target plates, checking that they were pointing accurately. This process ensures that the mirrors track the sun very precisely throughout the day.