The latest issue of Fortune magazine features an article on entrepreneurs Jeff Bezos, Peter Thiel, and Paul Allen and their efforts to succeed where government has failed in developing cost-effective nuclear fusion.

For more than half a century governments around the world have been trying to solve the challenge of nuclear fusion. In theory it could provide a cheap, clean, and almost boundless source of energy. Consider this: One tablespoon of liquid hydrogen fuel—a mix of deuterium and tritium—would produce the same energy as 28 tons of coal.

But smashing two hydrogen atoms together at 100 million degrees centigrade to create a fusion reaction has proved to be a costly and elusive endeavor. The ITER international project in France has been plagued by cost overruns—the original 5-billion-euro project is now budgeted at 13 billion euros (about $15 billion)—and its 23,000-ton ­Tokamak experimental reactor, three times heavier than the Eiffel Tower, is still many years from completion. In the U.S. the Department of Energy’s $4 billion Lawrence Livermore project, which uses lasers to smash atoms, is still deep in the experimental stage. Scientists are learning much from all this tinkering, but experts say these big projects—if they work—are at best decades away from commercialization.

That’s not soon enough if the world wants to mitigate the worst effects of climate change while providing cheap, clean energy to the poor—a point not lost on a handful of American billionaires including Jeff Bezos, Paul Allen, and Peter Thiel. These men are betting that fusion done on a small scale will be cheaper, less complex, and ready for market sooner than the big government projects. Some major corporations, such as Lockheed Martin and General Atomics, have the same idea and are working on their own versions of small-scale fusion.

America has six private-sector fusion projects underway, according to a new report by the research firm Third Way.