"Give me a break - who coined 'clean coal' and why did we let that happen.

"Natural gas should and must play a key role in addressing climate change and we must step up."

The term "clean coal" is used by coal industry mostly in reference to the carbon capture and storage of emissions underground.

Big oil companies have become more vocal opponents of coal in recent years as they have stepped up production of natural gas, which is cleaner to burn than oil and gas.

Gas production overtook oil at Shell in 2013 while Total began producing more gas than oil last year. Gas production at US giant ExxonMobil reached just under half of total output last year.

That the promotion of the environmental advantages of gas over coal has emerged as the key theme of the World Gas Conference should not come as a surprise given it is six months before more than 200 nations attempt to reach an agreement to curb carbon emissions at a United Nations climate change meeting in Paris.

The major European oil companies including Shell and BP sent a joint letter to the UN last week indicating their support for a global pricing system for carbon that would push up the cost of burning coal, which remains the cheapest fuel for electricity generation.

Mr Coleman argued that coal's impact on air pollution was arguably a greater problem than its impact on global warning in India, which has 13 of the world's most polluted cities.


Quoting a World Health Organisation report that found air pollution caused seven million premature deaths worldwide in 2012 - and described smog as the world's "largest single environmental health risk" - Mr Coleman said cleaner-burning gas was the logical successor to coal in base electricity generation.

"The major cause of air pollution is well-known - burning coal for power generation and the use of gasoline-powered vehicles are very key contributors," he said.

"Natural gas can and needs to be part of a cleaner air solution."

Mr Coleman said burning natural gas produced only "trace" quantities of microscopic particulates that make up smog and half as much carbon dioxide per energy unit as coal.

"We also know that for every tonne of greenhouse gas emitted in the production of LNG produced in Australia, at least four tonnes of greenhouse gas emissions in customer countries are avoided when LNG is used to displace coal-fired power generation."