Following the hottest summer on record in the UK, London mayor, Ken Livingstone, offered a £100,000 (US$160,000) reward for the best idea to cool the London Underground, where temperatures regularly top 30ºC.
Among the ideas submitted is a scheme to use snow. Israeli firm IDE Technologies said that snow manufactured at street level can be pumped to the tunnels below. Air currents caused by the moving trains would help the cooler air to circulate.
Six US$6M machines would be needed to cool the 14km long Circle Line.
