Solar fireplace . It consists of a collector of solar radiation on a surface (it can be the ground) where the air is heated, allowing the heated air to ascend through a tower or chimney, due to the spontaneous effect of natural convection. Turbines, similar to those used by wind turbines, are placed inside the chimney , so that the rising air moves the turbines to generate electricity.
Summary
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- 1 History
- 2 New South Wales, Australia
- 3 La Campana Oasis, Chile
- 4 Perspective analysis
- 5 Sources
History
It is recognized that the first design of a solar fireplace was the one made by the Spanish Isidoro Cabanyes in 1903 . Later, in 1931, the German Hanns Gunther designed a power plant that used a solar chimney.
Figure. 1. Principle of operation of the solar chimney.
In 1975 , Roberto Lucier carried out important patents on the subject, and in 1982 , in Manzanares , Spain , the first power plant with a solar chimney of useful social power was built, with 50 kW of power, 195 m height, tower diameter 10 m and the solar energy collection area with a diameter of 240 m (Figure. 2). This facility is now dismantled after collapsing during a storm.
Figure. 2. Manzanares Station, Spain.
Fuente El Fresno, Spain In Fuente El Fresno (Ciudad Real), Spain , a project is being developed – which should have been completed in 2010 – of a power plant with a solar chimney, for a power of 40 MW, with a 750 m tower height and a solar energy collecting area 3 km in diameter. The tower structure constitutes the tallest human construction known (Figure. 3).
Figure. 3. Comparison of the Ciudad Real tower with other constructions.
Figures 4 and 5 show some illustrative elements of the project, including the idea of using the solar collector area as a greenhouse for crops.
Figure. 4. Representative drawing of the Ciudad Real station.
New South Wales, Australia
In New South Wales , Australia , work is underway on the design of an even more gigantic chimney with a height of 1,000 m, 150 m in diameter and a solar energy collecting area with a diameter of 5 km, with a capacity of 200 MW, using 32 6.25 MW turbines.
La Campana Oasis, Chile
In Chile , a project is developed, with the conception of a lying solar chimney, which consists of building the tower or chimney on the slope of an inclined elevation, which considerably reduces construction costs and offers greater protection against weather events, such as the one that happened in Manzanares . Although due to the steepness there is a relative decrease in electricity production, the project must ultimately reduce the cost of the electricity generated.
The large greenhouse that will form the solar collector will be free of frost and will be used to help the growth of Chilean palms and other native species.
The facility will have a 1,070 m long chimney, a vertical height of 320 m and a power of 20 MW, being located on the side of a hill located in the Oasis de La Campana Ecological Reserve .
Perspective analysis
The integral energy efficiency of installations with a solar chimney, taking into account the electrical power output and the solar irradiance input, is in the order of 2%. This value seems somewhat low, but considering that one works between a volume of heated air at about 45 oC, the Carnot efficiency is in the order of 6%, so 2% is not so low.
Its main advantages are in the use of a renewable source of energy and that the cost of the energy produced may be in the same order as the cost of the energy currently produced based on oil, as well as its projection for regions of little use of the soil, which in some cases can make it productive. Its fundamental disadvantages are in the necessary height of the tower and the technological difficulties that this entails, in addition to the environmental impact for the production of the materials to be used in the tower. There is still time to observe the development of this technology in the coming years.
