The first LNG shipments from the east coast will be heading out through the Great Barrier Reef shortly, pushing Australia towards world's biggest gas exporter by 2018.

For resource sector buffs and government treasuries that day can't come soon enough. The mining industry stalwarts of iron ore and thermal coal are in serious price decline as export demand falters, and that means royalties, tax collections, new investment and jobs are in trouble too. In the case of thermal coal, many think the decline is more structural than cyclical – it may be terminal.

Many Australians will, however, be less enthusiastic about the dawn of the new gas boom. Not just environmentalists, but also many farmers defending the integrity of agricultural lands and water tables from coal seam gas wells. The wells that have to be drilled to feed the three new east coast LNG export terminals.

With domestic gas prices now moving to align with international markets, consumers get slugged as well with a doubling or even tripling of their bills by 2020. Manufacturing sector business owners reliant on gas are caught already in a price squeeze. So are residential consumers who’ve chosen gas for hot water, heating and cooking.

If you need a crash course in how hard global energy market forecasting really is, look no further than gas. If you need to be updated on how outside of Australia the threat of climate change is forcing an energy transformation, Greenlight suggests you also look no further than gas.

A decade ago, the US was aiming to build large LNG receiving terminals along their coastlines to import gas as domestic prices soared. Perhaps luckily, local coastal residents fought hard to block such facilities. Then the extraordinary shale gas boom started and now the US is more likely to be building LNG export terminals.

A decade ago it was fashionable to see natural gas as a 'transition fuel', with a carbon emission profile about half that of coal, which would play a vital role in the market moving in a timely and efficient way towards a low-carbon economy. Gas sector giants like BP and Shell globally, and Origin Energy in Australia, were even lauded as sustainability leaders.

Skip to the present day and much has changed. Onetime sustainability leaders are now fossil fuel pariahs. Gas-fired power stations built a decade ago are being mothballed because the fuel costs too much.

Far from being green-hyped as a transition fuel, gas is now lucky to get even grudging respect on the sustainability side as a 'bridging fuel', which to most now means a relatively short-term role as back-up to renewables. And very short-term unless carbon capture and storage (CCS) is perfected and implemented for gas-fired electricity generation.

When it comes to CCS, a 'deliver results or get out of the way' tipping point is shaping up for gas and coal alike.

BHP Billiton boss Andrew Mackenzie has just signalled that the world's biggest miner may have to get out of coal altogether if a global 'Green Horizon' trend continues and his company's experimentation with CCS fails to deliver results. The challenge of making burning fossil fuels cheaper and cleaner than wind and solar is daunting, however much the federal government tries to undermine renewables and reinvigorate the fossil fuel sector.

Gas dependent co-generation and tri-generation, once bright spots for green building, now may be priced out of the market altogether as solar photo voltaic gets cheaper and covers more and more structures and surfaces. Unless biogas can crack through the waste-to-energy barriers it faces to deliver a less expensive, on-the-spot and greener gas alternative.

Just as the 'oils ain't oils' advertisement said, 'gas isn't gas' either. First there was natural gas mixed with oil in large onshore deposits like Moomba in Central Australia, and Bass Strait off Victoria, all of which was fed into the domestic market. Then came the big offshore gas discoveries off Western Australia, and the first onshore LNG export terminals. Now we’re moving to FLNG, floating LNG terminals.

Then there's landfill gas, the possibility of more biogas from metropolitan and farm wastes, and a growing list of other 'unconventional gases'.

Behind the coal seam gas expansion on the eastern states, and the controversy it has stirred, Australia also is being tipped as the next big thing for shale gas after the US. The reserves in vast underground basins, mainly below the red-hued landscapes of outback Australia, are enormous. Extracting the gas, however, is unlikely to be cheap, technically easy or controversy-free.

What does Greenlight predict for gas? Domestic prices will go up because gas should flow to energy-needy economies like China, Japan and Korea that can and will pay for cleaner fuels than coal to generate electricity.

Piping gas to Australian suburbia will be priced out altogether, as will much of the gas use for the manufacturing industry. So demand for electricity will rise, and from an environmental and economic perspective it is vital that in Australia this demand is met by renewables not rebooted coal.

By Greenlight, a regular columnist on affiliated publication WME.