 
At the right, you are looking at a prototype of a solar tower power generating plant that was constructed and successfully operated in Spain. The tower operated for seven years, between 1982 and 1989, and consistently generated 50kW of pollution-free energy.What exactly is a 'solar tower'? Well, at the bottom is a huge greenhouse-like building, covering many acres, and open at the sides. As in all greenhouses, the air inside gets very hot. It wants to rise ... and it does, through the open tower in the middle. As it passes up the tower, it spins turbines just like in a hydro-electric plant, except it's the wind caused by all that hot air going up that spins the turbine blades. The turbine in turn powers an electrical generator ... and you get free electricity! Because the sides of the greenhouse are open, new air is constantly coming in to get heated and rise up the tower. EnviroMission is a company in Australia that plans to create a much bigger solar tower. This tower, constructed of reinforced high strength concrete, will be 990 metres tall, or almost a kilometre ... more than twice the height of the Petronas Towers, some of the largest buildings in the world. The greenhouse at its base, which will be one of the largest man-made structures, will be circular, with a diameter of 4 km and covering an area on the ground of about 13 square kilometres. The turbines in the tower will generate a huge 200 megawatts. All from hot air rising up the tower!    Looking sort of like a huge, upside-down golf tee, EnviroMissions's solar greenhouse with its upward-sloping roof, and the tall tower, would provide electricity to as many as 200,000 homes. The airflow inside the greenhouse will reach speeds of up to 50 km/h as it moves up towards the tower, where it will spin 32 wind turbines mounted about 40 m above ground level. The estimated cost to construct the structure will be around $342 million, costing about 70% more per megawatt than a similarly sized wind farm . But once in operation, it is likely to provide a more dependable source of power than wind. Australia is the perfect location for a solar thermal power station. It has the high solar radiation levels required to heat the air, and location isn't a problem, since the plant will be environmentally friendly. Each 200 MW solar thermal power station will help prevent 830,000 tonnes of CO2 gas from entering the atmosphere. EnviroMission’s solar thermal power station will generate electricity 24 hours a day, and will be at its most efficient on hot days, when energy is most needed, and peak prices are paid for electricity. Its design will enable the power station to store heat, and continue to generate energy during the night. This special feature will give it a big advantage over other forms of renewable energy. |