Marco della Cava

USA TODAY

SAN FRANCISCO — Sustainable energy evangelist Elon Musk — whose Tesla brand is pushing to provide solar panels, home power storage and electric cars at affordable prices — once told a group of students that relying on fossil fuels to power the planet would inevitably lead to destruction on a cataclysmic scale.

Rex Tillerson, President Trump's newly confirmed Secretary of State, ran fossil fuel giant ExxonMobil for a decade.

Senate panel approves Rex Tillerson for secretary of State

You wouldn't think there would be much simpatico between these two figures, and yet Musk has tweeted his endorsement of Tillerson as the nation's top foreign envoy.

The reason: Tillerson, like Musk, has advocated for a carbon tax, a fee charged to a company based on how much carbon dioxide its fuel emits into the atmosphere. In 2009, Tillerson gave a speech in which he said his company, ExxonMobil, favored a carbon tax.

Late Tuesday, Musk tweeted: "Rex Tillerson supports a carbon tax. This is what is really needed to move the needle."

Last summer, Musk told reporters during a tour of his Nevada battery Gigafactory that a carbon tax on CO2 emissions was the only way to counter government subsidies that make U.S. gas station fill-ups significantly cheaper than those in Europe and Asia. Proponents say it's a market-based strategy to curb fossil fuel emissions that contribute to global warming.

"If you ask any economist, they will tell you that (a carbon tax) is the obvious thing to do, put the correct price on carbon because we currently have an error in the economy which mis-prices carbon at zero or something closer to zero," he said.

The outspoken tech entrepreneur's pro-Tillerson tweets began earlier in the day Tuesday, when he retweeted The Economist magazine saying that Tillerson could become "one of the most competent members of Donald Trump's cabinet."

Musk wrote: "This may sound surprising coming from me, but I agree with The Economist. Rex Tillerson has the potential to be an excellent Sec of State."

Spotting the surprising Musk approval, Bloomberg reporter Dana Hull (who had retweeted Musk's tweet with the addendum: "Excuse me while I pick my jaw up off the floor") then asked the Tesla and SpaceX CEO is he would elaborate.

Musk, who is a fan of Twitter as a mouthpiece but isn't known to engage with the media on the platform, tweeted back a response that would suggest a professional if not personal knowledge of Tillerson: "Rex is an exceptionally competent executive, understands geopolitics and knows how to win for his team. His team is now the USA."

Despite have been a career oilman, Tillerson is not the camp of outright climate change deniers. In fact, his stance clashes with that of his new boss, President Trump, who during the campaign alleged that the warming of the planet was a hoax being perpetrated by the Chinese.

In contrast, Tillerson has said the planet is changing, although he has not advocated strongly for clean energy solutions.

At his confirmation hearings earlier this month, Tillerson told lawmakers that “the increase in greenhouse gas in the atmosphere is having an effect," but added that "our ability to predict that effect is very limited."

Musk, on the other hand, was exceedingly clear about the repercussions of a continued global reliance on oil when he addressed students at the Sorbonne in Paris in 2015, when the world's leaders were meeting to agree on measures to slow climate change. During the presidential campaign, Trump stated that he would "cancel" the Paris Agreement.

"The question is when to we exit the (fossil fuel burning) era, and not if," Musk told the crowd.

The worst case of inaction, he said, would be "more displacement and destruction than all the wars in history combined. ... We would be talking about maybe two billion people being displaced and their homes being destroyed and their countries being gone. So I think we should take action."

While there's been a rash of speculation about Facebook boss Mark Zuckerberg one day running for political office, Musk is actually the technology entrepreneur who seems increasingly comfortable in the halls of power.

Specifically, Musk, who was born and raised in South Africa, was a prominent figure at a December meeting of tech CEOs called by then President-elect Trump at his New York tower, and then he agreed to be on the 45th president's business advisory council along with Uber CEO Travis Kalanick.

Follow USA TODAY tech reporter Marco della Cava on Twitter.