DUBAI, UNITED ARAB EMIRATES — Amid the unprecedented hoopla of the COP28 climate summit over the past two weeks, the geekiest of new energy technologies made a first-time splash appearance.

Nuclear fusion is so nascent an energy business it doesn’t yet exist on Earth. But there on an expansive stage at COP28 were a globally renowned fashion designer and one of the world’s top scientists raving over it, having been introduced with thundering plaudits by United States climate envoy John Kerry.

Uruguayan designer Gabriela Hearst wore a dress adorned with the blueprint of a nuclear fusion reactor and explained why, as chief creative director at luxury brand Chloé, she produced an entire fashion show in Paris last year around the concept of crushing atoms together, the essence of nuclear fusion.

“It’s become my holy grail,” she said, not the first time a fusion advocate used this metaphor of the ultimate mythical treasure to describe the technology.

Ernest Moniz, the mop-haired MIT brainiac and former U.S. energy secretary, nodded in agreement at the opposite end of the same panel. Other nuclear fusion events, promotions and photo-ops popped up elsewhere at COP28, including among the investments highlighted by Bill Gates’ Breakthrough Energy Ventures. (Breakthrough Energy Ventures is a program of Breakthrough Energy, which provides support for Cipher).

Nuclear fusion differs from the dominant nuclear energy in the world today, which is nuclear fission. Fission got plenty of attention at this COP, as well, with 22 countries pledging to triple the capacity of the technology, which produces no global warming gases.

Fission plants — the hulking towers that have rarely, but at times spectacularly, struggled with safety issues in the three-quarters of a century they’ve been around — unleash massive amounts of energy by splitting atoms apart. This creates radioactive waste and requires controls to avoid the sort of runaway chain reaction that melted down the infamous Chernobyl facility in the former Soviet Union in 1986.

Nuclear fusion, on the other hand, forces multiple atoms together into one. This also unleashes vast amounts of energy but leaves behind plain water as the main byproduct and carries no risk of an uncontrolled reaction. It is, as advocates love to say, the energy that powers the stars and created all matter in the universe, including life on earth.

“If you want to know if it works, just go outside and look up,” said Ralf Kaiser, an official at the International Centre for Theoretical Physics and the former head of the physics section of the International Atomic Energy Agency.

At the COP28 event hosted by the Atlantic Council, Kerry announced an international research and development effort aimed at accelerating the timeline for fusion to become a commercial source of power.

U.S. Climate Envoy John Kerry talks about fusion at an Atlantic Council event at COP28. Photo courtesy of the Atlantic Council.

The universal fanfare over nuclear fusion was a counterpoint to often frustrated clashes at COP over the role of fossil fuels in the energy transition. Its long timeline of the early 2030s at best also contrasted with urgent calls for moving to triple already available renewable sources such as solar and wind — which are producing substantial clean power today and are growing fast.

Heightening the excitement over fusion, a U.S. defense research laboratory effort achieved a critical nuclear fusion threshold twice over the past year, a feat requiring the generation of almost fantastical amounts of heat and pressure. Using lasers, scientists at the Lawrence Livermore Laboratories joined two light-weight atoms into a denser one, releasing more energy from their union than was used to join them.

The U.S. Department of Energy called the result “a major scientific breakthrough decades in the making.”

But as much as nuclear fusion advocates tout the future potential of fusion — “It is inevitable that eventually fusion will power everything,” Kaiser told one audience at COP28— the industry is working equally hard to convince potential investors, government funders and anyone else who will listen that the technology is on the cusp of becoming a commercial reality.

Several companies aim to generate commercial electricity by 2035 and are building small-scale demonstration projects. More than 40 private companies globally are pursuing fusion as a practical power source. Fusion has its own industry association, based in Washington D.C., which has helped successfully lobby in the U.S. for a regulatory approach acknowledging the technology as qualitatively different from nuclear fission reactors. Those have frequently been delayed by years or even decades while undergoing regulatory reviews.

In China, the government is massively funding fusion projects. An international consortium including China, Europe, Japan, the U.S., South Korea and Russia have poured tens of billions of dollars into a joint research effort known as the International Thermonuclear Experimental Reactor, or ITER, that is building a massive array of magnets designed to support nuclear fusion.

The rise of private companies in recent years, seeded with a total of what experts at COP28 estimated to be $6 billion in private capital, are getting much of the attention today. Their goal is to “turn a physics experiment into a practical, bottom line” business, said Michel Laberge, founder and CEO of General Fusion.

“That’s much harder to do,” he told an audience at COP28.

The Vancouver, Canada-based company is attempting to use mechanical pressure to lower the cost and make the fusion reaction repeatable and sustainable — both core challenges the technology presents.

Meanwhile, about a half-hour by car outside Boston, Commonwealth Fusion Systems, another private fusion effort that grew out of research at the Massachusetts Institute of Technology, is building its own demonstration plant.

The company, one of four that Breakthrough Energy Ventures is backing in the nuclear fusion arena, is using electromagnets to create and contain the fusion reaction. The machine it is building now, dubbed SPARC, represents an interim step before building a full-scale power-generating machine slated to be up and running in the early 2030s, said Bob Mumgaard, CEO and co-founder of the company, on the sidelines of COP28.

If it works, he said after delivering a presentation in an amphitheater that included an indoor waterfall, “that’s a machine we would make many of,” he said.

Editor’s note: Commonwealth Fusion investors include Breakthrough Energy Ventures, a program of Breakthrough Energy, which also supports Cipher.

Correction: An earlier version of this story misspelled Ernest Moniz’s name.