In deserts, the sun is almost always the same – they are ideal locations for solar power plants. However, the harsh conditions in the stemson are increasing by the high-tech installations. That is why the Ticino Company Airtight Energy has set itself the goal of developing a simpler and more favorable construction for solar power plants. For almost two years, she has been operating a pilot plant near Air Baca near the Moroccan port of Acadia. “An ideal place to test the technology and bring it to market maturity,” says project manager Giuseppe Lo Valdo in safety vest.
The Ticino pioneers have deliberately opted for a so-called solar thermal plant, because it is particularly suitable for hot sites – better than photovoltaic plants. These gain electrical current from sunlight, but lose their effect dramatically at high temperatures. In addition, the generated current can only be stored poorly.
This is different for solar thermal systems, which use energy from the sun’s heat radiation. In the case of so-called parabolic trough power plants, which are already commercially used, this works according to the following principle: Curved mirrors concentrate the solar radiation onto a centrally mounted pipe in which a carrier liquid circulates – for example, oil. This heats up, is passed to a heat exchanger and there brings water to evaporate. The steam drives a turbine. This type of power generation is not only good for use in the warm climate; it also allows storing excess heat for the night.
Low-tech and local materials
Such a parabolic trough power station, according to traditional construction, was recently opened in the Moroccan desert town. The Ticino Company Aright Energy uses the same principle in its new plant, but it goes one step further. It has optimized the process and improved the technology with new materials to make them more efficient, cheaper and more sustainable. The three collectors of the Air Baca power station are each 200 meters long and over 10 meters high. They are not made of expensive steel and transported from far away, but have been poured from cement on site. The collectors are covered with a transparent protective film which protects them from sand and dust.
The mirrors, which combine solar radiation with conventional solar thermal systems, have been replaced by a reflective heat transfer film in the new pilot plant. This is filled with air so that its pressure and thus its curvature can be regulated. This means that it can always be arranged in such a way that it optimally bundles the incoming solar radiation. The focal point is directed at hoses that connect two tubes positioned one above the other. The air flowing in the hoses is thus heated up to 600 degrees Celsius and rises from the lower to the upper tube.
The hot air can be used in two ways: one part flows directly into the furnace of a nearby cement plant. This does not have to be heated with fossil fuels – gas or oil – and emits less climate-damaging greenhouse gases. The remaining part of the hot air operates a turbine and thus generates electricity. If, however, no one is needed, the air is first directed into a heat accumulator. This is also simply constructed: a coarse gravel-filled underground container. There the heat can be stored for up to eight hours.
The concept is so impressive that the low-tech solar power station was nominated for the Innovate Prize in London in early February. It did not win, but Aright Energy sees a great future for its technology. By the summer of 2016 the pilot plant in Air Baca will be checked by external company workers in safety clothing. In the case of future tenders for Moroccan solar power plants, Aright Energy intends to be part of the electricity market. The location of Morocco is not only ideal for climatic reasons, as project leader Giuseppe Lo Valdo emphasizes. Thanks to its ambitious solar plan, the country offers a growing market for technology developers.