The ABC has unearthed previously unreported evidence that shows Adani plans to export a low-quality coal product to India — coal with a high ash content that could cause deadly air pollution.

Key points: Supporters say Adani's coal would improve air quality, lower greenhouse gases

Supporters say Adani's coal would improve air quality, lower greenhouse gases But report says Carmichael mine would produce "two coal products"

But report says Carmichael mine would produce "two coal products" Coal bound for India could be a low-grade product

Supporters of the Indian conglomerate's planned giant coal mine in Queensland claim it will improve air quality and lower greenhouse gases, because it would supply India with "high quality" Australian coal.

The Minister for Resources, Matthew Canavan, recently said if Australia did not supply India with coal from Queensland, "they will get that coal elsewhere — which they are doing right now".

"Generally speaking that coal is of lower quality than what we have in Queensland," he said.

But whether the coal from Adani's Carmichael mine would be better quality has not been made clear.

According to sworn evidence to the Land Court in Queensland, Adani plans to ship polluting, low-energy coal to India.

A report to the court made on its behalf said the Carmichael mine would produce "two coal products".

"Product one, a low ash/moderate energy product most suitable for Asian premium markets," the report said.

"And product two, a high ash/lower energy product most suitable for non-premium markets, particularly India."

So the coal bound for India could be a fairly low-grade product.

Mr Canavan said while it might not be the highest quality coal in Australia, "it's still much much higher than the coal quality in India".

When asked about whether he was aware of the plan to produce two different coal quality products, Mr Canavan said "different coal companies create different products for different circumstances".

"There is also the opportunity to blend and then officiate that coal at the other end. That's a commercial decision for themselves," he said.

Mr Canavan said it was not just the Government who thought it would be better for the environment if India used Australian coal.

"The Queensland Supreme Court itself also made the point that the Adani Carmichael coal mine itself won't increase greenhouse gas emissions, if it displaces coal from other sources," he said.

"That's exactly what it will do, because India will get coal from somewhere, [and] as I say, their own coal is generally lower quality than ours."

'Poor quality coal' at Galilee Basin

Associate Professor Gavin Mudd, from RMIT University, has mapped the quality of coal deposits across Australia.

"If you look at the Galilee Basin coal, there's a reason why it hasn't been developed — it's poorer quality coal, compared to other places of Australia," Dr Mudd said.

"It's certainly not as bad as brown coal from an energy point of view, but from an ash point of view it's almost 10 times more ash content."

The average energy content of coal at Adani's planned mine is about 18 per cent below benchmark Australian coal.

Adani conceded in court the ash content was about 26 per cent, roughly double the Australian benchmark.

Keep in mind the best coal from the mine will not go to India — it will get unwashed, high-ash coal.

Associate Professor Mudd said that raised serious health concerns.

"Major issues with respiratory illness — so asthma and all sorts of related things, heart disease increases in things like lung cancer and so on as well," he said.

"So we need to make sure that when we're using such quality coal we have really rigorous pollution control."

India's air quality rivals China as the worst in the world, with air pollution accounting for more than one million deaths a year.

Carmichael mine will reduce Indian plants' carbon footprint: Adani

Despite the sworn court evidence, Adani has publicly maintained that coal exports from the Carmichael mine will cut greenhouse gas emissions.

"The thing about Carmichael is, it will reduce the carbon footprint of existing [Indian] plants, which are using Indonesian or Indian coal today, by say 30 to 40 per cent," Adani Australia's CEO Jeyakumar Janakara told a forum in Brisbane last week.

Adani has repeatedly declined requests by the ABC for an interview about the Carmichael mine and the company's corporate structure in Australia.