For decades, the quest for nuclear fusion energy has been driven by giant government-led projects — with giant price tags to match.

Just as spaceflight companies such as SpaceX and Blue Origin have built upon NASA technology, a handful of fusion startups are building on government-funded fusion research, with the goal of firing up the first commercial fusion power plant as early as the 2020s.

"Fusion is poised for a “SpaceX moment,” says Christofer Mowry, CEO of General Fusion, a British Columbia-based firm that’s among the companies staking a claim in the fusion field. “We’re in a position today to combine new, enabling technologies to make something that was possible but not practical into something that’s commercially viable.”

A General Fusion team member installs magnetic field sensors on a machine known as PI3 during its construction in January 2019. General Fusion Inc

The rise of General Fusion and the other companies is “built on the decades of government research into fusion,” says Andrew Holland, executive director of the Fusion Industry Association, a Washington, D.C.-based group that represents 17 fusion companies. “Everything that the private companies have been able to do is built on the shoulders of giants.”

Power of the stars

Nuclear fusion power — harnessing the power of the stars here on Earth — has long been seen as the ultimate fix for Earth’s energy woes. And no wonder. The hydrogen fuel needed for fusion can be obtained in essentially limitless quantities from seawater. And while power plants that burn fossil fuels spew carbon dioxide and other greenhouse gases into the atmosphere, the only waste produced by fusion is helium — a commercially valuable gas.

“Fusion will have one of the smallest possible environmental footprints of any power source,” says Dennis Whyte, director of the Plasma Science and Fusion Center at the Massachusetts Institute of Technology. “It will be sustainable for the foreseeable future of mankind.”

Whyte and his colleagues have spun off their own company aimed at commercializing fusion, the Cambridge, Massachusetts-based Commonwealth Fusion Systems.

The challenge facing the startups is finding a way to achieve a sustained fusion reaction — something that’s never been done. Two government-led research facilities — the $438 million Joint European Torus (JET) facility near Oxford, England, has achieved only brief bursts of fusion energy. The even bigger International Thermonuclear Experimental Reactor (ITER) near Toulouse, France — with a price tag so far of about $14 billion — is still under construction.

The International Thermonuclear Experimental Reactor, under construction in France, is an experimental fusion facility designed to produce 500 megawatts of power for short intervals. The $14-billion project is funded by the European Union and six other counties, including the United States. ITER Organization

But General Fusion and the other fusion companies are betting on the proposition that smaller is better. While JET is about the size of a big-box store, and ITER is about the size of a mall, the companies aim to do the same with facilities a fraction of the cost and at a much smaller size — perhaps no bigger than a tennis court.

The downsizing is made possible by new materials, more powerful computers, new technologies such as 3D printing (which can make parts quickly and cheaply) and digital control systems that optimize reactor performance — none of which existed when those larger projects were designed.

One goal, multiple approaches

Nuclear fusion occurs when atomic nuclei fuse to form a heavier nucleus, an event that unleashes vast amounts of energy. This happens continuously inside the sun and other stars. There, high temperatures and pressures cause hydrogen nuclei to exist in a form of matter known as plasma, where the nuclei fuse to form atoms of helium and other heavier elements.

On Earth, it’s a bit harder. You won’t find plasmas occurring naturally, except inside a lightning bolt. Plasma can be created by applying an electric field to a gas until it’s so hot that it conducts electricity, but controlling the plasma once it’s created is very difficult. As one researcher put it, controlling plasma within a reactor vessel is like trying to control a cigarette’s smoke ring.

Fusion companies are trying several different approaches to controlling plasma. At MIT, Whyte and his colleagues are testing their approach at an experimental facility called SPARC, a compact fusion project designed to generate about 100 megawatts (converted to electricity, that would be enough to power 75,000 homes).

At SPARC, powerful magnetic fields created by an array of electromagnets will be used to control the plasma. That’s similar to the approach used at the JET and ITER projects, only instead of using house-size magnets like the ones at ITER, SPARC is taking advantage of new technologies that allow magnets the size of human beings to produce magnetic fields that are just as strong. The key breakthrough involves new kinds of superconductors (materials that carry current without internal resistance) that can function even in intense magnetic fields.

Aerial view of the ITER facility near Toulouse, France. ITER Organization

“Superconductors are the key to taking this to the next stage,” Whyte says.

General Fusion’s facility uses a different strategy: Instead of using magnetic fields, it heats the plasma by compressing it mechanically, in brief spurts, until it’s hot enough for fusion to occur.

At this point, it’s not clear which approach will work. But whichever technique prevails, Mowry sees fusion power as finally being within reach. “It’s absolutely different today than it was 10 years ago,” he says. What used to be a scientific question — Is fusion possible? — has become a question of engineering and of economics, he says.

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