Scott Morrison's plan for a gas-led economic recovery has brought the Coalition's climate and energy policies back into focus.

But the emphasis on natural gas — a fossil fuel mostly made up of methane — has alarmed some scientists and political figures, who say such an approach would only add to the challenge of tackling climate change.

In a September 23 tweet, Greens leader Adam Bandt said coal and gas must be kept in the ground "to have any chance of stopping runaway global warming".

"Gas is as dirty as coal," Mr Bandt said.

Is it correct that gas is as "dirty" as coal? 

The methane contained in natural gas is significantly more potent than carbon dioxide in terms of its impact in warming the atmosphere.

However, the debate in Australia has primarily focused on using gas to generate power, particularly to back up — or "firm" — intermittent renewable energy.

For electricity generation, gas is, on average, less emissions-intensive than coal, even after factoring in "fugitive emissions" lost in the transportation of gas, as well as other "upstream" and "downstream" sources of emissions linked to power generation.

How much less depends on the type of technology used.

Fact Check analysed 2018-19 emissions data for 82 gas and coal-fired plants.

On average, and weighted by the volume of power generated, gas generators were found to be significantly less emissions intensive than those fired by coal.

This was the case across various different types of power generation technologies.

The averages, however, masked significant variations in the performance of individual plants.

For example, Australia's "dirtiest" gas plant, Barcaldine in central Queensland, produces almost double the emissions per kilowatt hour of electricity generated than Australia's dirtiest brown-coal fired plant, Victoria's Yallourn power station.

In other words, gas is not always cleaner than coal for power generation.

Moreover, the analysis is clouded by scientific uncertainty relating to fugitive (and deliberately released) emissions linked to the extraction, processing, storage and transportation of gas.

The verdict: Mr Bandt's claim is oversimplified