Almost $1tn of investment in new coal-fired power stations could be wasted if growing concerns about climate change and air pollution leave the plants unused, according to a new report. About 1,500 new coal plants are in construction or planning stages around the world but electricity generation from the fossil fuel has fallen in recent years, the detailed report from the Sierra Club, Greenpeace and CoalSwarm found. In China, existing plants are now used just 50% of the time, coal use is falling and new permits and construction have been halted in half of the nation’s provinces, affecting about 250 plants. A second new report has found that China, India, Indonesia and Vietnam - seen as big growth areas by the coal industry - are likely to build far less than half of their planned coal plants. However, 84GW of plants (about 85 stations) were built in 2015 and new plants are being commissioned at five times the rate that old plants, such as those in the UK, are being retired.