“Our desire for progress has side effects and smog is one of them,” says the Dutch inventor Daan Roosegaard, who was inspired to look for a solution after visiting Beijing in 2013. Three years later, his seven metre-high ‘Smog Free Tower’, supported by the Chinese Ministry of Environmental Protection, opened in Beijing’s 751 D Park in September 2016.
It is a giant, outdoor air purifier. In much the same way that static electricity can make loose hairs stick to a comb, airborne particles are sucked into the tower where they receive a positive charge. The particles are then captured by a negatively charged dust-removal plate and clean air is blown out of the other end.
“We're working now on the calculation: how many towers do we actually need to place in a city like Beijing to get a pollution reduction of 20-40%? It shouldn't be thousands of towers, it should be hundreds. We can make larger versions as well, the size of buildings.”
As for what to do with the collected PM waste, he currently has a side-line selling the compacted substance as jewellery. Prince Charles owns a set of “smog free” cufflinks. If collected on at a sufficient scale, Roosegaarde believes it could even be used as a building material.
Berlin-based architect Allison Dring, director of Elegant Embellishments, has an alternative solution... She is now making a building material out of biochar, a charcoal-like substance made by burning agricultural crop by-product or tree clippings in a pyrolysis kiln, which chemically decomposes organic materials by heating them in the absence of oxygen. “It means that you are actually taking carbon out of the sky, converting it into a material, and then using it to build,” says Dring.
http://www.bbc.com/future/story/20170112-how-the-worlds-biggest-cities-are-fighting-smog
... Badly!
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