Now, as the world moves to phase out coal-fired power, fossil gas is being touted as a booming three-lettered climate hero.
But is it?
It is not, as the European Commission (EC) implied last week when it proposed classifying gas and nuclear energy as climate-friendly, a clean fuel.
True, gas has around 50% lower emissions than coal when producing electricity, but it has also proven to be the fastest growing source of planet-heating CO2 emissions over the last decade — a trajectory that's set to continue.
In the European Unionit's the second largest source of CO2 emissions after coal, and it makes up around 22% of global carbon output.
Yeah, oh. And that’s not all.
We're increasingly told that we need gas to "transition" to a clean energy future. The theory goes that because it is still cleaner than its fossil friends, gas can help make up the energy shortfall caused by a looming coal power phase-out.
But the reality is that as a fossil fuel, natural gas causes climate change — explaining why the European Green Party says it might take the EC to court over its push to classify some investments in gas as sustainable.
In short, gas is already being described as the "new coal."
And is it?
Natural gas is a combustible hydrocarbon mostly made up of methane — which is around 28 times more polluting than CO2 and is prone to leak from gas pipelines and infrastructure.
It's a non-renewable fossil fuel found deep in the ground amid shale and rock — and often close to petroleum. We use it to make energy but also as a chemical feedstock for plastics and fertilizers, and our current boundless appetite for the stuff means that natural gas reserves could run out in about 50 years.
So all this talk of using gas as a "bridging" fuel to a clean energy future is not long-term thinking. One day, not too far down the line, it will run out. Meanwhile, it's supposed to bring us energy security.
Is gas really that secure?
Gas is difficult to source, explaining why Europe still relies heavily on Russia for the fossil fuel.
As natural gas is pumped and shipped long distances, the massive infrastructure required adds to its cost — and carbon footprint.
Geopolitics is another problem: Just look at the delays getting the Nord Stream 2 Russia to Germany gas pipe connected amid escalating threats of war in Ukraine. It's ready to go but can't flow. Gas prices skyrocket as supply ebbs.
Germany itself is so reliant on gas for fuel and heating that it is open to supplies from the US, and has been planning to build big expensive new terminals to receive shipments in liquified natural gas (LNG) form.
The problem is that these imports would include fracked gas, which is extracted from rock and shale using poisonous chemicals in an environmentally-hazardous process.
Fracking, as it is known, also releases a lot of methane, making it potentially a bigger climate enemy than coal.
Many European countries, including Germany have banned the practice at home, but fracked US LNG might one day replace Putin's gas.
If gas is that bad, can’t we just leave it in the ground?
The EU reckons that down the track we can repurpose new and existing gas infrastructure for "low carbon" gases such as hydrogen and biogas. At least, that was the gist of a recent European Commission (EC) proposal to decarbonize gas markets.
It might sounds okay in theory, but a) it would mean burning a lot of the hydrocarbon in the short term, and b) clean gases like "green" hydrogen remain a pipe dream, partly because they can only be made with renewables that will be needed to power the energy transition.
Which is why critics say talk of the green gas transition is giving fossil fuel companies a pass to greenwash their climate-wrecking business.
"Natural gas is not a bridging fuel. It is a fossil fuel," said one climate analyst, adding that it must be treated like coal and phased out as quickly as possible.
What's the alternative?
Experts told us last year that solar energy was now the "cheapest ... electricity in history," and that by 2050, solar and wind could meet the world's energy demand 100 times over.
So we have alternatives. Yet Australia is talking up a "gas-fired recovery" from the pandemic, and Europe is pushing hard to build its "gas bridge" to our bright and clean energy tomorrow.
Some say all this gas boosterism is a recipe for a "carbon lock-in" that will only delay the energy transition.
Because all the capital and infrastructure that will go into a gas-fired energy transition means the fossil fuel will continue to be extracted to make good the investment.
Meanwhile, that same cash could have gone directly into the renewables that would directly decarbonize the energy supply.