By Emma Davies – Chemistry World  – Published January 2011
Last October, China started building the world’s biggest off-shore wind farm in Bohai Bay, a few hours from Beijing. The country is constructing wind farms on an unprecedented scale – surely good news given its insatiable appetite for coal. But each megawatt of power a wind turbine generates requires up to one tonne of rare earth permanent magnets. The elements used in the magnets – neodymium, dysprosium and terbium – are in short supply and the west is in danger of losing access to them as China’s domestic needs soar.