Divestment from coal mining in the US as a financial sanction seems a bit like closing the stable door after the horse has bolted (Michael Sean Winters, “Making money morally”, 19 September), since coal has now been largely superseded by the methane from shale gas. At the same time, there is little prospect that coal consumption in developing countries will fall in the near future.Is it really “making money morally” to invest in wind power? These constructions are crucially dependent on the rare-earth element neodymium to form magnets that are far lighter and stronger than used to be possible. The separation, isolation and purification of neodymium requires huge volumes of radioactive tailings and chemical waste. Such processes under modern environmental practice w