Solar Tower is nearing approval

The Australian government has granted State Significant Development status to EnviroMission’s ‘Solar Tower’ power plant, a move that could lead to the construction of the world’s tallest engineered structure.

Construction of the world’s tallest man-made structure, the EnviroMission ‘Solar Tower’ power station destined for Tapio Station, Australia, has taken a significant step forward.

Australia’s Federal Industry Minister, Ian Macfarlane, has announced that the $800 million venture has been given State Significant Development status, which ensures federal government support including assistance through any necessary approval processes.

‘Now all we need is for the New South Wales (NSW) State Government to show the same faith and vision and things will really begin to hot up,’ said Mayor, Cr Don McKinnon.

The one kilometre tall Solar Tower power plant being developed by EnviroMission Limited will be the first solar powered conventional electricity generator to consistently supply 200 MW to Australia’s main grid. Excluding hydroelectric power, it will reportedly be the largest single renewable energy plant in the world.

The tower – originally developed in the early 1980s by Professor Jörg Schlaich – will generate electricity based on the use of the sun’s radiation to heat a large body of air within a glass collector roof, which then flows to a chimney in the middle of the roof and is drawn upwards. This upwind drives turbines installed at the base of the chimney, and these produce electricity.

Schlaich’s prototype, which successfully generated 50kW of electricity for 15,000 hours over seven years, had a collector roof 240m in diameter and a tower 197m high. The prototype was built in Manzanares in Spain to test the concept, and is now decommissioned.

The full-scale plant under evaluation by EnviroMission will be 5km across and 1km high to achieve 200MW of electricity generating capacity. This capacity can reportedly power 200,000 homes, which is equivalent to a city such as Hobart. The plant will cover an area of at least 20 square kilometres.

The 5km diameter collector system will have a slightly rising roof of semi-transparent glazed material, standing between two and twenty metres above the ground on steel supports at 6m intervals. The 4mm glass or plastic will be held by steel horizontal prop girders and transverse steel plates.

The tower will be constructed from reinforced concrete, 1m thick at the base, tapering to 25 cm thick at the top and will use a unique technique to counter the ovalisation that affects many tall cylindrical structures.

At six intervals inside the tower – 280m, 460m, 600m, 730m, 860m, 990m – a series of internal metal horizontal supports will be constructed to create added strength and also serve as platforms. The airflow loss from the supports will be no more than 2% and air speed is expected to be constant through the tower.

The original design proposed one large 90m diameter, 200 MW turbine with 12 blades made of light alloy metal, with the propeller set horizontally at the base of the tower. However, the EnviroMission plant will use 32 small 6.5 MW turbines set vertically in the transition area, where the collector system meets the tower.

EnviroMission’s Solar Tower power plant will compete directly with all othergenerators in Australia’s electricity market, either as a market generator selling into the electricity pool, or as a non-market generator selling its output locally; and it will compete with other renewable sources of power.

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