1129th General Monthly Meeting
Low Cost Solar Thermal Electricity
Dr David Mills, Head of the Solar Energy Group, School of Physics, University of Sydney
Date: Wednesday, 1st September 2004
Time: 7:00 pm
Venue: Lecture Room 3, Institute Building,
University of Sydney (building adjacent to Darlington Centre, City Road)
The first stage of a 39 MW solar thermal electricity plant has been constructed and is being tested prior to expansion and connection to an existing coal-fired plant at Liddell in NSW. The plant will eventually consist of 135,000 m2 of reflector, and will be the largest solar plant built anywhere in the world since 1990, yielding three times the peak power of all the photovoltaic solar power installed in Australia.
Design efforts are beginning to move toward very large stand-alone solar plants incorporating storage. Calculations for a 240 MW plant are being developed for an Australian generating utility, and the first proposed site is being monitored for solar beam radiation. Preliminary costings suggest the technology has the potential to be competitive with coal generation in some areas.
Enquiries: Prof. P.A. Williams
email: P.Williams@uws.edu.au
or phone the Society - details on Introduction page.
David Mills obtained his Doctorate in Physics at UNSW in 1980. He developed asymmetrical non-imaging optics theory and invented the prism PV concentrator, several concentrator designs for evacuated absorber tubes, and the first solar steam cooker with storage.
He worked on a solar selective coating between 1983 and 1995 which is commercialised on a large scale in China and developed two solar hot water designs, one commercialized and the other still under development.
David was President of the International Solar Energy Society 1997 - 99, and a finalist in the World Technology Awards 2002. He is current Chair of the Steering Committee of the International Solar City Initiative (ISCI) and is Chairman of Solar Heat and Power Pty Ltd which is building a large scale solar thermal plant for production of steam for electricity generation in New South Wales.
Report on the General Monthly Meeting
The 1129th September General Meeting was held at the Sydney University in Lecture Room 3, Institute Building. The Guest Speaker was Dr David Mills, Head Solar Energy Group, School of Physics, University of Sydney and Chairman of Solar Heat and Power Pty Ltd.
Dr Mills addressed a capacity audience on the latest developments in Solar Thermal Electricity. He explained that Solar Thermal (unlike photovoltaics) produces steam to generate electricity just like coal, gas, or nuclear plants. The heat is collected by solar collectors and provides steam to turn turbines just as it does in conventional power plants.
The concept of producing steam from solar energy is not new. In fact, in 1866 a French scientist called Mouchot produced the first known solar collector which was displayed to the King of France. We also learned that many collector projects have been built since then including a major array in Egypt in 1913.
While many of these arrays have been technically successful, producing steam reliably, the problem has been that burning fossil fuels was cheaper.
David Mills and Peter Le Lievres CLFR (Compact Linear Fresnel Reflector) array is much cheaper to make than the trough design usually used by Solar Thermal plants. This is because the glass used is almost flat, there are no moving joints, the array heats water rather than oil, the supporting structure costs are lower and it uses less than half the ground area. These factors bring the cost of the array down by a staggering 35%.
Such an array is being built as an adjunct to the Liddell coal power station for Australias largest electricity generator, Macquarie Generation. 1,350 m2 has so far been built but the final array is planned to cover 135,000 m2 and will produce 39 megawatts of peak electric power to the station. All of the photovoltaic cell arrays already installed around Australia only produce 13 megawatts of electricity so this project represents a tripling of solar electricity capacity.
Dr Mills then showed us the "microclimates" around Moree and Bourke where they enjoy an average of 9 hours of sunlight every day. These areas are also blessed with grid lines which supply the local communities with electricity generated in the Hunter Valley. But these grids could also work in reverse, supplying the energy-hungry cities with abundant power generated where solar energy is abundant.
With this in mind, Dr Mills and his colleagues are talking to Macquarie Generation about a 240 Megawatt station at Moree which would require 4.4 square kilometres of array and occupy 6.1 square kilometres of land. The plan is that such a plant would provide peak electricity by using storage in the form of a steel-lined cavern dug a couple of hundred metres below the surface. Pressurised water contained by the surrounding rock would hold the heat generated during the day and allow electricity to be supplied when it is needed, not just when the sun is shining. By adding storage, Solar Electricity becomes a serious contender in the competition to supply our energy needs. And of course it does so without producing greenhouse emissions.
Most interesting of all, Dr Mills' costings for his arrays were almost unbelievably low. He claims that the system is comparable in price to coal, when the handling of coal costs are taken into account and when a similar sized turbine is used. Solar Thermal seems to be cost-competitive for the first time in its history. And if the size of the audience attracted by the talk is anything to go by, the interest in using this non-polluting energy source is already here.