Solar Tower Power Plant and Green Technology
Solar Tower Power Plant and Green Technology
The Solar Tower Technology also known as solar updraft tower is a proposed type of renewable-energy power plant. Air is heated in a very large circular greenhouse-like structure, and the resulting convection causes the air to rise and escape through a tall tower. The moving air drives turbines, which produce electricity. A research prototype operated in Spain in the 1980s.
Solar Tower of Power Finds Home
The quest for a new form of green energy has taken a significant step with the purchase of a 25,000-acre sheep farm in the Australian outback. The huge alternative energy project isn’t driven by manure, but by a 1-kilometer-high thermal power station called the Solar Tower.
Schematic presentation of a Solar updraft tower is shown in the figure.
Description: Solar Tower Power Plant
The generating ability of a solar updraft power plant depends primarily on two factors: the size of the collector area and chimney height. With a larger collector area, more volume of air is warmed up to flow up the chimney; collector areas as large as 7 km in diameter have been considered. With a larger chimney height, the pressure difference increases the stack effect; chimneys as tall as 1000 m have been considered. Further, a combined increase of the collector area and the chimney height leads to massively larger productivity of the power plant.
Heat can be stored inside the collector area greenhouse, to be used to warm the air later on. Water, with its relatively high specific heat capacity, can be filled in tubes placed under the collector increasing the energy storage as needed.[3]
Turbines can be installed in a ring around the base of the tower, with a horizontal axis, as planned for the Australian project and seen in the diagram above; or—as in the prototype in Spain—a single vertical axis turbine can be installed inside the chimney.
Carbon dioxide is emitted only negligibly while operating, but is emitted more significantly during manufacture of its construction materials, particularly cement. Net energy payback is estimated to be 2-3 years.[3]
A solar updraft tower power station would consume a significant area of land if it were designed to generate as much electricity as is produced by modern power stations using conventional technology. Construction would be most likely in hot areas with large amounts of very low-value land, such as deserts, or otherwise degraded land.
A small-scale solar updraft tower may be an attractive option for remote regions in developing countries.[3] The relatively low-tech approach could allow local resources and labour to be used for its construction and maintenance.
Announced several years ago, the 3,280-foot Solar Tower is one of the most ambitious alternative energy projects on the planet: a renewable energy plant that pumps out the same power as a small reactor but is totally safe. If built, it will be nearly double the height of the world’s tallest structure, the CN Tower in Canada.
The Solar Tower is hollow in the middle like a chimney. At its base is a solar collector — a 25,000-acre, transparent circular skirt. The air under the collector is heated by the sun and funneled up the chimney by convection — hot air rises. As it rises, the air accelerates to 35 mph, driving 32 wind turbines inside the tower, which generate electricity much like conventional wind farms.
But the Solar Tower has a major advantage over wind farms and solar generators: It can operate with no wind, and 24 hours a day. Thanks to banks of solar cells, the tower stores heat during the day, allowing it to produce electricity continuously.
Originally slated to be operational this year, construction of the massive project won’t begin until 2006 at the earliest, said Roger Davey, chairman of EnviroMission Limited, the Melbourne, Australia, company behind the venture.
Videos for Solar Tower Power Technology
Video-1
Solar Tower in Green Technology
Video-2
How Solar Tower Works?
But the purchase of the farm, which cost $1 million, near Mildura, Victoria, is a “very big step” in getting the project built, Davey said.
So far, the main impediment to building the tower has been the cost, with estimates ranging from $500 million to $750 million. Davey won’t say how much the project will ultimately cost but said the company is considering two new engineering innovations that will reduce construction costs and improve efficiency.
“It will make the project a totally different business case,” Davey said.
The timing couldn’t be better. With the price of oil topping $50 a barrel, many countries are looking for cheap energy and to cut greenhouse gas emissions.
“The time is now here,” Davey said. “The world is looking for a major renewable energy source.”
It’s estimated the Solar Tower will generate 200 megawatts, enough electricity to power 200,000 homes, and will keep 830,000 tons of greenhouse gases out of the atmosphere annually.
“Solar chimneys (towers) have become a hot area of research recently,” said S.A. Sherif, a professor of mechanical and aerospace engineering at the University of Florida, who wrote several papers on the technology in the early 1990s and is the technical editor of the Solar Energy journal.
by Stephen Leahy
Frequently Asked Questions about Solar Tower Technology
Who is EnviroMission?
What is Solar Tower Technology?
What will a Solar Tower power station look like?
What materials will be used?
How many hours in a day will it generate electricity?
Where will the world’s first Solar Tower power station be built?
What factors are critical to site determination?
Can it be built?
Why hasn’t Solar Tower technology been developed before now?
Will power from Solar Towers be competitive?
Who is EnviroMission?
Melbourne based EnviroMission is a newly formed green energy public company that listed on the ASX on 6 August 2001. The company owns an exclusive licence to innovative Solar Tower technology. We aim to commercialise the first 200MW Solar Tower power station in Australia by before 2008.
What is Solar Tower Technology?
Solar Tower technology is not simply solar energy. Solar Tower technology is created when the sun’s radiation is used to heat a large body of air, which is then forced by the laws of physics (hot air rises) to move as a hot wind through large turbines to generate electricity. A solar thermal power station using Solar Tower technology will create the conditions to cause hot wind to flow continuously through its turbines to generate electricity.
What will a Solar Tower power station look like?
The power station will be based on German designed Solar Tower technology. It will look like an enormous greenhouse canopy with a very tall hollow ventilation Tower located at its centre.
The sun’s radiation will be collected and trapped under the transparent canopy, creating a massive force of air heated to around 35°C greater than the ambient temperature. The laws of physics will make this air move at 15 metres per second towards the cold air at the top of the Tower located in centre of the canopy. The powerful updraft will force the rising air to pass through large turbines positioned at the base of the Tower. The movement of the hot wind through the turbines will generate up to 200MW of clean, emission free electricity – enough electricity for 200,000 typical Australian homes.
What materials will be used?
A Solar Tower has three major components: the collector zone (greenhouse), Solar Tower (chimney) and turbines.
The large roof of the collector zone will be covered translucent heat enhancing properties materials including glass, polycarbonate and polymer. The Tower will be constructed from reinforced high strength concrete. The large-scale turbines will be purpose designed and constructed from lightweight alloy materials like those used in aircraft manufacture.
How many hours in a day will it generate electricity?
EnviroMission’s Solar Tower is proposed to generate electricity 24-hours a day. The power station will be at its most efficient on the hottest days when energy is most needed and peak prices are paid for electricity.
Re-radiation of heat present in the ground under the collector zone will provide the energy source during the night. This special feature enhances the commercial viability of the power station and gives EnviroMission a consistent competitive advantage over other forms of renewable energy generation.
Where will the world’s first power station be built?
After an extensive search, EnviroMission has selected the site for the world’s first Solar Tower power station in the Buronga district of the Wentworth Shire in NSW and 25km north east of Mildura in Victoria. The proposed site confirms EnviroMission’s commitment to the Sunraysia Region of NSW and Victoria.
The project will need to meet the necessary planning approval codes, regulations and legislation of the Commonwealth, State and Local Government.
What factors are critical to site determination?
EnviroMission evaluated site suitability against the following criteria:
* Commerciality
* Access to Regional Infrastructure
* Solar radiation levels
* Weather patterns
* Geological stability
* Access to the electricity grid and transmission centres
* Geographic features
* Current land use and access to change of land use
* Environmental factors
* Federal Government support
* State Government support
* Local Government/regional support
Can it be built?
Prior to listing on the Australian Stock Exchange a technical review report prepared by Sinclair Knight Merz, one of Australia’s leading engineering specialists, independently assessed the Solar Tower’s design concepts and construction methods were well proven and it could be built in Australia.
A 50kW prototype Solar Tower plant was constructed and successfully operated in Manzanares, Spain, with involvement of the designer Professor Jörg Schlaich, and the Spanish Government in 1982. The prototype operated for seven years and conclusively proved the concept works. Data obtained from the prototype provided the basis for a scaled up 200MW generation plant.
Why hasn’t Solar Tower technology been developed before now?
Formerly referred to as Solar Chimney technology in academic literature - it is now marketed without the reference to chimney (to avoid confusion with the pollution associated with chimneys - this technology is emission free) - the Solar Tower has had in excess of A$35 million and twenty years of research and development invested in it. Now, more than ever before, the time is ideal to apply this technology.
For more than 100 years it has been relatively cheap, environmentally unaccountable and simple to dig up coal as a fuel source to produce electricity.
Enormous shifts in community values and understanding about the relationship between energy generation and its impact on the environment have evolved around the world. Combined with growing concerns about the relationship between energy generation with global warming and air quality a demand has evolved for alternative methods of electricity generation increasingly over the last 20 years.
Community concern about Australia’s over reliance on coal-based ‘black’ and ‘brown’ energy and the negative impact on the environment has helped to drive political change. There is now a legislated market for clean, green renewable energy, legislated as a Mandated Renewable Energy Target (9500 gWh annual renewable energy target by 2010) has opened the way for investment in new approaches to renewable energy generation. This recent incentive is important to the growth of renewable energy development including Solar Tower technology.
A further political incentive in the form of the Renewable Energy Credit (REC) developed by the Federal Government in 2001 has been developed to encourage new investment in renewable energy development, with the purpose of reducing greenhouse gases and increasing the amount of renewable energy output.
New materials, construction methods and government policy are now available to the extent that there is environmental, social and commercial advantage in the development of Solar Tower technology.
Will power from Solar Towers be competitive?
The selling price of Solar Tower renewable energy will be based on the average peak pool electricity price paid to generators plus an additional renewable energy credit incentive paid by retailers.
Further value is expected to be added to the internal rate of return through the emerging synthetic carbon trading instrument, where a premium is paid for a tradeable unit that represents a carbon abatement value - this form of trading will off-set carbon producing activity of companies needing to balance their carbon ledgers.
References
1. http://www.wired.com
2. http://www.enviromission.com.au/
3. wikipedia - Solar Tower
4. Youtube video service
