JOHANNESBURG — "Clean coal" is a centerpiece of the Trump administration's energy policy to revive the industry, but there are signs that researchers here may have moved ahead of their American counterparts in the race to refine and commercialize the technology.
Experiments at Johannesburg's leading university suggest that South Africa is taking the lead in achieving the dream of clean coal rather than just capturing the smoke and emissions.
Professor Rosemary Falcon heads the sustainable coal research group at the University of the Witwatersrand. Known locally as "Wits," it's the school where Nelson Mandela studied law in the 1950s.
Ms. Falcon leads a team of nine academics along with 20 master's and doctoral students who say they have proved conclusively that clean coal is not only feasible, but is also among the cheapest ways to generate electricity on a continent where more than 600 million people live without power. The key insight: Not all lumps of coal are created equal.
"Coal varies enormously," Ms. Falcon said in an interview. "Each region has a different composition of minerals and fossil matter, and if you give me a lump of coal out of the U.S., India or Colombia, I can probably tell you where it's from."
Coal from Europe and North America, she said, burned cooler and more quickly than the South African product, and each type needed a specific oven to make a cleaner burn.
South Africa is facing the same energy debates that the U.S. and other industrial economies are facing: trying to determine the best mix of fuel sources in a rapidly shifting environmental and financial landscape.
The South African Energy Department's 2016 Integrated Resources Plan projected that coal, now the country's dominant fuel source, would fall to fifth among the country's power-generating sources by 2050, behind wind power, gas turbines, nuclear power and solar power.
Working with Ms. Falcon is Nandi Malumbazo, who earned a Ph.D. in chemical engineering at Wits. Africa, she said, was going to continue to rely on coal for decades to come, and it was incumbent on science to minimize the impact on the environment.
"In Africa, the use of coal is growing, and that's something we have to deal with," she said. "The challenge is to burn it more cleanly, and this starts at the mine with techniques we've developed to separate poor-quality coal from the better stuff that is already less toxic.
"You then crush it and remove elements that will not contribute to a good burn. Like unleaded petrol, you're starting from a better place. Less ash, less fumes, more heat and a longer burn."
She said her team has conducted experiments and written peer-reviewed research to make the case that "we can use [coal] way cleaner than in most countries."
South Africa gets more than 90 percent of its power from coal. In Botswana, the share is 100 percent, while Kenya and Tanzania are building coal-fired generators to meet Africa's surging power needs.
Samson Bada of Nigeria and Jacob Masiala from Congo have joined the Wits research team, which also includes postgraduate staff and students from Zimbabwe, Botswana and Mozambique.
"If we mix pulverized coal with bamboo, something that grows well in Africa, we take emission levels down even further," said Mr. Masiala. "Of course, a bamboo plantation also gives you carbon credits, and we can grow it on old mine sites to rehabilitate the ground. It's a winner on so many fronts."
In Washington, Barry K. Worthington, executive director of the United States Energy Association, said the South African research was "vital in the move to a cleaner and better use of coal."
It was tempting, he said, "to believe the answers always come from Europe or America, when others may be ahead of us in the field."
Former White House energy adviser George David Banks said it was time to unite those working on clean coal across six continents. "The world is not going to stop using fossil fuel anytime soon, but we can do it so much better," he said.
For all its groundbreaking work, South Africa's clean coal push is in trouble.
"Funding has been difficult," said Ms. Falcon. "We have to scrape and beg for every cent. We are passionate about the work, and there's still a lot to do, but the money is not always there."
The use of coal to generate electricity in Africa is at a record high, with new plants in Kenya, Tanzania, Botswana, Mozambique and South Africa. Mr. Bada said he has little time for those who condemn the trend.
"I am tired of being lectured by people in rich countries who have never lived a day without electricity," he said. "Maybe they should just go home and turn off their fridge, hot water, their laptops and lights. Then live like that for a month and tell us, who have suffered for years, not to burn coal."
Mr. Masiala agrees. "Aid groups come to Africa and give out solar lamps the size of a pumpkin," he said. "But no one in London or Los Angeles would be willing to make do with that. We need power for cities, factories, mines and to run schools and hospitals."
Africa, he said, is urbanizing faster than anywhere else on the planet.
"Our youth are on the same Facebook and WhatsApp as kids in Chicago," he said. "They watch the same 'Big Bang Theory' on TV and have the same aspirations, but many have no work."
The lack of industry, he said, is linked to electricity.
Mr. Bada said the thousands of power stations around the world pumping out emissions from coal could operate in a much cleaner, greener fashion.
"What holds up the process is not a lack of knowledge, but funding and political will," he said. "And every day that we live with the status quo, people are forced to breathe dirty air. That is tantamount to a crime against humanity if we have the science but do nothing."
African countries, he said, need a massive jump in the amount of power they generate. "Tanzania, for example, has around 70 percent of its people still short of electricity while it sits on 4 billion tons of coal. And we have activists from wealthy countries who chant, 'Leave it in the ground.'"
The Johannesburg researchers angrily reject the notion that clean coal is a myth invented by President Trump and his allies in business.
Mr. Falcon said critics of coal are either in denial or unaware of the truth.
"Not that long ago, there was no such thing as fat-free yogurt or painless dentistry," she said. "But there is now, and there is also clean coal, provable and peer-reviewed."
Her team, she said, would be happy to help colleges in the U.S. replicate the experiments.