There is nothing quite like a massive coal rail to demonstrate China's loyalty to the dirtiest of fossil fuels.

Almost a decade in the making, the nearly $30 billion Haoji Railway will start this month and eventually haul as much as 200 million tons from key producing regions in the north to consumers in the south. That is more than Japan uses in a year and could cut China's domestic seaborne coal trade by 10 percent in the long run, Fenwei Energy Information Services Co. forecasts.

In a world where governments and businesses are under pressure to leave fossil fuels in the ground, the new rail is decidedly old-fashioned. China has pumped more money into renewable energy than any other country and is battling pollution by urging its population to burn gas instead. Yet it continues to mine and burn half the world's coal.