OREANDA-NEWS. December 12, 2014. Chinese negotiators attending this week’s climate change talks in Lima have come armed with a long and detailed list of measures to rein in the coal use that creates smog at home and climate change worries abroad.

Early this month President Xi Jinping unveiled an estimate that China’s greenhouse gases would stop climbing in about 2030, thanks to policies restricting coal use around big cities in the east.

But there’s a wild card in the carefully tabulated spreadsheets of boilers to be shut and pipes to be laid. Emissions from an industry that transforms coal into gas or liquid fuel are proving difficult to measure and could undermine the country’s greenhouse gas projections.

Plants that transform coal into automotive fuel, chemicals or gas – by steaming the fossil fuel under pressure – are mushrooming in the grasslands along the edge of the Gobi desert and in ethnically divided towns in northern Xinjiang.

Nobody knows how many may ultimately be built, nor how much emissions they will produce. But what is clear is that they guzzle water, a scarce commodity, and produce clouds of greenhouse gases. By some estimates, emissions from the coal-to-chemicals plants in the pipeline could add up to between 4 per cent and 11 per cent of China’s current emissions.

Giving the green light to powerful state-owned energy firms to invest in these large and expensive projects in the frontier has made it easier for Beijing to win support for coal use restrictions in the east. Senior advisers are divided over the wisdom of that trade-off.

Coal-to-gas projects’ heavy toll on water and coal resources means “it is not the way to go, in my opinion,” Du Xiangwan, one of the senior scientists who help shape Chinese policy, said at a recent conference, shooting a pointed look at coal conversion backers in the rows of honoured guests.

The role of these projects is key. China uses half the world’s coal and accurate projections of its consumption are essential to understanding how much more carbon humans are likely to pump into the atmosphere.

China’s announcement that emissions are likely to reach their highest point in about 2030 leaves open the likelihood that coal use will grow steeply in some regions while it gradually eases off in others. As Li Shuo, climate and energy policy campaigner for Greenpeace, puts it: “We know when we will see the summit, but we don’t know what the contours of this mountain will be.”

Greenpeace estimates that 18 coal-to-gas projects are under construction or in advanced planning, out of a total 54 on the drawing board which may or may not come to fruition. They would contribute nearly 400m tonnes of carbon to the atmosphere every year, equivalent to 4 per cent of China’s total carbon emissions in 2013.