Coal engineer José Manuel Pérez Rodriguez can only laugh when he recalls what his university taught him about renewables. 

"My teacher said, well, we are going to teach you that but it's going to be of minor use," he says. "It's not profitable, it's very expensive. Just centre on coal."

Twenty years on, he works in Spain's last full-time coal-fired power plant in the coal mining province of Asturias. His job is to plan its conversion into a green hydrogen plant. 

As head of hydrogen conversion for the power company EDP, Mr Pérez Rodriguez still marvels at how quickly coal is vanishing from the energy landscape.

"Everything is changing dramatically every year," he says. "We expect that the next year is going to be greener, but it's always greener than we expect. This is exponential."

Three years ago, Spain's Socialist Workers' Party government signed an agreement with trade unions and energy companies to shut down the entire coal industry in return for early retirement and investment in replacement industries.

Known as Transicion Justa, or "Just Transition", it's become the model for rapid transition from fossil fuel production. There is now only one mine still operating in Spain and it's due to close in December.

Foreign Correspondent travelled to Asturias on the eve of the United Nations' landmark IPCC climate report, which has hardened calls to end investment in fossil fuels. 

Unlike Australia, where lobby groups have pushed to expand coal production, Spanish corporations have embraced the change. Angeles Santamaria, CEO of the energy giant Iberdrola, says there is not a single coal project in the world she would invest in.

When I pointed out that Australia still makes billions of dollars from coal, she smiled.

"In Spanish, we have an expression: 'Those days are numbered'. There isn't much future there," she says. 

Spain has long had pressing economic reasons to switch to renewables. Rather than reaping billions from coal exports, it had spent billions subsidising unprofitable mines.

Successive governments had been fighting unions to close mines since the 1990s. The Paris climate agreement of 2015, coupled with the EU's decision to phase out coal subsidies, made the end inevitable.

Australia insists coal will remain profitable for decades, even with major trading partners embracing net zero emissions targets. But in Spain, that's seen as magical thinking. 

Mr Pérez Rodriguez predicts Australia will soon face carbon tariffs if it doesn't transition.

"This trend will come to Australia some way, because otherwise, you won't be able to compete against the countries that are already implementing these measures because the people and the politicians will be demanding this from us," he says. 

"I think that every single part of the world will be copying what we are doing in Europe right now."

The workers left behind

The transition may be supported by business but the final death knell for coal has been a psychological blow for mining communities. 

Asturias, on Spain's north-west coast, is famous for its Celtic traditions of bagpipes and folk dancing based on centuries of trade with the British Isles. It's also well known for its cider, which is poured into glasses from hands raised high to aerate the beverage.

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But its people take just as much pride in having powered Spain's industrialisation through two centuries of coal mining.

As he pours us glasses of cider, Lluques Díaz Rozada, who's in his early 30s, tells us his entire family worked in the mines.

"All my family: my father, my brother, my uncle, my grandfather, my grand grandfather, everybody in my family," Rozada says. "Now I'm an electrician. There are no mines anymore."

His is the first generation with no prospect of following the family tradition. Some of his friends are still working for the state mining company Hunosa doing mine restoration rather than coal extraction. 

In the Just Transition deal, older miners were offered early retirement with relatively comfortable pensions, an average of $3,700 a month for life. But Mr Rozada worries about what's going to happen to his generation.

"The only thing I see every day are friends leaving, highly skilled people with studies, very prepared, professionally prepared, with much experience and at the end of the day they have to leave," he says. 

"What will come next, what will happen to our future?"

Hundreds of kilometres away in Madrid, Spain's Secretary of State for Energy Sara Aagesen is urging patience. She's responsible for ensuring energy supply and the success of the Just Transition. 

Born in 1976, she's of a different generation to the energy bureaucrats who once decorated the boardroom table with lumps of coal. She makes no secret of wishing an early death to the global coal industry.

"I think the planet is giving us lots of signals that we need to stop this. The sooner, the better."

She realises the outcome of Spain's Just Transition could influence how quickly that happens, as other countries consider negotiating similar agreements. Ms Aagesen insists investment is coming through to transform Asturias's economy.

"Probably people feel that they don't have the answer at adequate speed, but I think this is going to be good," she says. "And we are going to provide what we want. It's that we don't leave anyone behind.

"One of the goals is zero impact in employment. We will fulfil that. Yes, I think we can do it."

Successive governments have learned the hard way to fear the wrath of coal communities.

At a former mine, Pozo Soton, a choir of retired miners meets to sing the union anthem, Santa Barbara. This was a rallying call for decades of industrial action to fight the closure of state-run mines.

In 2012, Asturian miners fought pitched battles with police, even firing rockets at police lines, after the government cut subsidies. Ten thousand miners and supporters marched on Madrid to try to force a backdown. 

Unions only agreed to Just Transition after the government guaranteed both early retirement and massive investment to create alternative jobs.

As the choir enjoys ciders after their weekly practice, they share misgivings about what's in store for young people. Soloist Javier Toral says politicians have been promising to create new industries in Asturias for decades. 

"They didn't create anything else, they didn't do anything else," he says.

His accompanist, Mario Coto, says past programs to give grants for new enterprises were stolen by unscrupulous businessmen.

"The only thing they did was to take advantage of the grants they received to set up the company and then, in that same moment, they closed up the company, left with the grant money, they took it, and then, no money nor company," says Mr Coto.

But not everyone is complaining. Javier Toral's son Angel, one of Spain's last coal miners, says he's looking forward to retiring this year at the age of 44.

"Not having to work anymore, well, there is nothing more positive than that," he says.

The switch to renewables

While government grants have had mixed success in creating new enterprises, the renewables industry is booming. In May, renewables provided over 50 per cent of Spain's electricity and the government has set a target of 74 per cent green electricity by 2030.

At the same time it negotiated the Just Transition deal, the new Socialist government scrapped the so-called "sun tax" forcing households with solar panels to pay 7 per cent tax to stay connected to the grid. The result was a massive uptake of solar energy.

Asturias hasn't benefited as much as sunnier parts of Spain. Its Celtic traditions are matched by a Celtic climate of cool summers and misty rain. 

But investors see huge potential for green hydrogen, where electrolysers powered by wind or solar split hydrogen fuel from water.

"We already have the electric connections; we already have the water; we are next to the sea, next to the port to make exports of the hydrogen produced and we have renewable sources not very far from here," says José Manuel Pérez Rodriguez.

"So we think it makes a lot of sense."

Wind power is a key part of Spain's transition away from fossil fuels to renewable energy sources. The country currently ranks second among European nations for wind energy production and has plans to double that in the next 10 years.

Iberdrola has just built a series of giant wind farms across Asturias and says it will spend up to a quarter of a trillion dollars on renewable energy by 2030. The company's CEO Angeles Santamaria says clean energy is far more cost-effective than fossil fuels.

"The big change in renewables is that there has been a rupture in costs and technology," says Ms Santamaria.

"If 15 years ago producing photovoltaic energy was more expensive than producing it in gas plants, today, producing photovoltaic energy in many of the places where we operate is the most competitive and cheap way of producing electricity."

One of the main reasons renewables are so much cheaper is that carbon has a hefty price. In 2005, the EU began the world's first international emissions trading scheme. 

In May, largely thanks to Europe's ambitious climate targets, the carbon price nearly doubled. Electricity prices soared.

"The main cost of producing electricity with coal is the CO2," says Mr Pérez Rodriguez. "So there are market reasons and environmental reasons that are linked. And of course, the investors are demanding that we make this change."

Australia has shielded its domestic industry from such pressure by scrapping the carbon pricing scheme in 2014. But seven years later, pressure is building from outside our borders.

For all the challenges of transition, Spain sees itself as being on the right side of history. It's hoping the UN Climate Conference in Glasgow in November will make life easier for countries embracing a green future - and harder for countries clinging to Old King Coal.

Watch Foreign Correspondent's Old King Coal tonight on ABCTV and iview, and streaming live on YouTube and Facebook.