What a stunning turnaround. The man who lost the leadership by fighting to introduce a carbon price is now railing against renewable energy.

In 2010, Malcolm Turnbull believed that Australia needed to move to a "a situation where all or almost all of our energy comes from zero or very near zero-emission sources" to avoid the risks, laid out in the science, of catastrophic climate change.

Now politicians who advocate positions that Mr Turnbull once held firmly are, he says, "drunk on left ideology on energy" and threatening peoples' livelihoods.

In Parliament yesterday, Mr Turnbull led the charge as minister after minister accused Labor of an "ideological" obsession with renewable energy at the expense of "energy security", blaming wind farms for another blackout in South Australia.

Never mind that the truth was in fact much more complicated.

As wedge politics, it may prove to be a winner: driving a schism between Labor's urban supporters, concerned about climate change, from its traditional working-class base.

In the past, Malcolm Turnbull accepted the extensive body of work by engineers and scientists that shows it is possible to supply all, or most, of our electricity from renewable sources and still have reliable supply.

Now, he's talking about "unrealistic" renewable energy targets, and leading a Government that argues Australia needs more, not less, coal-fired electricity generation.

Never mind that "clean coal" is, in fact, not that clean.

Even the best of the new-generation coal power plants emit huge quantities of greenhouse gases that, on the overwhelming evidence from climate science, risk frying the planet.

And the reduction in carbon emissions is minor when high quality black coal is the fuel source, as it in most coal-fired power stations in Australia: about 700 tonnes of CO2 per megawatt hour from the new-style plants compared to about 800 tonnes per megawatt hour.

Only in the case of very low quality brown coal burned in the dirtiest of power stations — such as the soon-to-close Hazelwood in Victoria — would there be a substantial reduction in emissions, but we're still talking about far more than double the carbon emissions of modern gas-fired power plants.

The weight of evidence is for renewables, not 'clean coal'

Never mind either that relying on "clean coal" won't achieve even the modest short-term target for reducing carbon emissions that Australia has set, experts say.

Never mind that it would lock Australia into a technology that emits very large quantities of greenhouse gases for 30 to 40 years, the typical life of a new power plant, at a time when many other western nations are moving to phase out coal-fired power to avoid the risk of catastrophic climate change — once the Prime Minister's driving motivation.

The new Malcolm is all for it.

Never mind, either, that clean coal won't push down power prices: electricity costs for consumers could double, not fall, if new coal-fired power stations are built, energy experts say.

And never mind that the Government's enthusiasm for coal-fired power has baffled just about everybody in the real world of energy policy.

"While lower emissions coal-fired power stations could be considered theoretically, there is no current investment appetite to develop new coal-fired power in Australia," the Australian Energy Council said in statement last week.

Energy Council CEO Matthew Warren said: "The industry's investment focus has shifted to a combination of lower emission gas generation, renewables and enabling technologies like storage."

The Australian Industry Group, representing heavy industry, also pooh-poohed the idea.

"Right now 'clean coal' doesn't look like it's got a place in the Australian energy mix," its chief executive Innes Willox, a former Liberal Party staffer, told the ABC.

Greenhouse gas emissions from coal-fired power stations, the price of coal-fired power (which is becoming uncompetitive against renewables) and political risks about climate change policy, all make new projects "unbankable", he said.

But never mind that.

The new Malcolm Turnbull is so enamoured with "clean coal", his Government is talking about throwing public money at it.

A stunning turnaround.