Coal breaker remaining. The sorting by size is particularly important for anthracite coal. In order to burn efficiently, air must flow evenly around anthracite. Subsequently, most anthracite coal is sold in uniform sizes. In the 1910s, there were six commercial sizes of coal (with the smallest size having three subsets): Coal pieces smaller than in size were considered "culm," and unable to be separated from the impurities (and thus useless). The grade of coal ranged from a low of 5 percent impurities for steam or broken coal to a high of 15 percent for pea-size coal and its subsets. Coal breakers were
Coal in Australia of production was exported (389 Mt out of 503 Mt total). Coal mining in Australia has been criticized by members of the environmental movement, due to carbon dioxide emissions during combustion. This criticism is primarily directed at thermal coal, for its connection to coal-fired power stations as a major source of carbon dioxide emissions, and the link to climate change and the effects of global warming on Australia. The burning of coal for electricity produces 29% of Australia's total greenhouse gas emissions, based on 2013-2014 Clean Energy Regulator data. The Carbon Pollution Reduction Scheme, which followed the draft report in