Solar Rising Tower (Solar Aerodynamic Power Plant)

Solar Ascending Tower — one of the types of solar power plants. The air is heated in a huge solar collector (similar to a greenhouse), rises and exits through a tall chimney tower. The moving air drives turbines to generate electricity. The pilot plant operated in Spain in the 1980s.

The sun and the wind are two inexhaustible sources of energy. Can they be forced to work on the same team? The first to answer this question was ... Leonardo da Vinci. As early as the 16th century, he designed a mechanical device powered by a miniature windmill. Its blades spin in a stream of rising air heated by the sun.

Spanish and German experts chose the La Mancha plain in the southeastern part of the New Castile plateau as a place to conduct a unique experiment. How can we not remember that it was here that the brave knight Don Quixote, the main character of the novel by Miguel de Cervantes, another outstanding creator of the Renaissance, fought the windmills.

In 1903Spanish colonel Isidoro Cabañez published a project for a solar tower. Between 1978 and 1981, these patents were issued in the US, Canada, Australia and Israel.

In 1982 near a Spanish town Manzanares It was built and tested 150 km south of Madrid demonstration model of a solar wind power plant, which realized one of Leonardo's many engineering ideas.

The installation contains three main blocks: a vertical pipe (tower, chimney), a solar collector located around its base, and a special turbine generator.

The principle of operation of a solar wind turbine is extremely simple. The collector, the role of which is performed by an overlap made of a polymer film, for example, a greenhouse, transmits solar radiation well.

At the same time, the film is opaque to infrared rays emitted by the heated earth's surface beneath it. As a result, as in any greenhouse, there is a greenhouse effect. At the same time, the main part of the solar radiation energy remains under the collector, heating the air layer between the ground and the floor.

The air in the collector has a significantly higher temperature than the surrounding atmosphere. As a result, a powerful updraft is generated in the tower, which, as in the case of the Leonardo windmill, turns the blades of the turbine generator.

Schematic of a solar wind power plant

The energy efficiency of a solar tower is indirectly dependent on two factors: the size of the collector and the height of the stack. With a large collector, a larger volume of air is heated, which causes a greater speed of its flow through the chimney.

The installation in the town of Manzanares is a very impressive structure.The height of the tower is 200 m, the diameter is 10 m, and the diameter of the solar collector is 250 m. Its design power is 50 kW.

The purpose of this research project was to conduct field measurements, to determine the characteristics of the installation in real engineering and meteorological conditions.

Installation tests were successful. The accuracy of the calculations, the efficiency and reliability of the blocks, the simplicity of the control of the technological process have been confirmed experimentally.

Another important conclusion was made: already with a capacity of 50 MW, a solar wind power plant becomes quite profitable. This is even more important because the cost of electricity generated by other types of solar power plants (tower, photovoltaic) is still 10 to 100 times higher than in thermal power plants.

This power plant in Manzanares operated satisfactorily for about 8 years and was destroyed by a hurricane in 1989.

Planned structures

Power plant «Ciudad Real Torre Solar» in Ciudad Real in Spain. The planned construction is to cover an area of ​​350 hectares, which in combination with a 750 meter high chimney will generate 40 MW of output power.

Burong Solar Tower. In early 2005, EnviroMission and SolarMission Technologies Inc. began collecting weather data around New South Wales, Australia to try to build a fully operational solar power plant in 2008. The maximum electrical output this project could develop was up to 200 MW.

Due to a lack of support from the Australian authorities, EnviroMission abandoned these plans and decided to build a tower in Arizona, USA.

The originally planned solar tower was supposed to have a height of 1 km, a base diameter of 7 km and an area of ​​38 km2.. In this way, the solar tower will extract about 0.5% of the solar energy (1 kW / m2) that is radiated at closed.

At a higher level of the flue, a greater pressure drop occurs, caused by the so-called chimney effect, which in turn causes a higher velocity of the passing air.

Increasing the height of the stack and the surface area of ​​the collector will increase the air flow through the turbines and therefore the amount of energy produced.

The heat can accumulate below the surface of the collector, where it will be used to power the tower off the sun by dissipating the heat into cool air, forcing it to circulate at night.

Water, which has a relatively high heat capacity, can fill the pipes located below the collector, increasing the amount of energy returned if necessary.

Wind turbines can be mounted horizontally in a collector-to-tower connection, similar to the Australian tower plans. In a prototype operating in Spain, the axis of the turbine coincides with the axis of the chimney.

Fantasy or reality

So, the solar aerodynamic installation combines the processes of converting solar energy into wind energy, and the latter into electricity.

At the same time, as the calculations show, it becomes possible to concentrate the energy of solar radiation from a huge area of ​​the earth's surface and to obtain large electrical energy in single installations without the use of high-temperature technologies.

The overheating of the air in the collector is only a few tens of degrees, which fundamentally distinguishes the solar wind power plant from thermal, nuclear and even tower solar power plants.

The indisputable advantages of solar-wind installations include the fact that even if implemented on a large scale, they will not have a harmful impact on the environment.

But the creation of such an exotic energy source is associated with a number of complex engineering problems. Suffice it to say that the diameter of the tower alone should be hundreds of meters, the height - about a kilometer, the area of ​​the solar collector - tens of square kilometers.

It is obvious that the more intense the solar radiation, the more power the installation develops. According to experts, it is most profitable to build solar wind power plants in areas located between 30 ° north and 30 ° south latitude on lands that are not very suitable for other purposes. The options for using the mountainous relief attract attention. This will drastically reduce construction costs.

However, another problem arises, to some extent characteristic of any solar power plant, but acquires a special urgency when creating large solar aerodynamic installations. Most often, promising areas for their construction are far from energy-intensive consumers. Also, as you know, solar energy arrives on Earth irregularly.

Small (low power) solar towers can be an interesting alternative to generate energy for developing countries, since their construction does not require expensive materials and equipment or highly skilled personnel during the operation of the structure.

In addition, the construction of a solar tower requires a large initial investment, which in turn is compensated by the low maintenance costs achieved by the absence of fuel costs.

Another disadvantage, however, is the lower efficiency of solar energy conversion than e.g in the mirror structures of solar power plants… This is due to the larger area occupied by the collector and the higher construction costs.

The solar tower is expected to require much less energy storage than wind farms or traditional solar power plants.

This is due to the accumulation of thermal energy that can be released at night, which will allow the tower to operate around the clock, which cannot be guaranteed by wind farms or photovoltaic cells, for which the energy system must have energy reserves in the form of traditional power plants.

This fact dictates the need to create energy storage units in tandem with such installations. Science does not yet know a better partner for such purposes than hydrogen. That is why experts consider it most expedient to use the electricity generated by the installation specifically for the production of hydrogen. In this case, the solar wind power plant becomes one of the main components of the future hydrogen energy.

So already next year, the world's first commercial-scale solid hydrogen energy storage project will be implemented in Australia. Excess solar energy will be converted into solid hydrogen called sodium borohydride (NaBH4).

This non-toxic solid material can absorb hydrogen like a sponge, store the gas until needed, and then release hydrogen using heat. The released hydrogen is then passed through a fuel cell to generate electricity. This system allows hydrogen to be stored cheaply at high density and low pressure without the need for energy-intensive compression or liquefaction.

In general, research and experiments make it possible to seriously question the place of solar wind power plants in the large energy industry in the near future.