Why the nuclear fusion breakthrough won't prevent catastrophic climate change

A depiction of a target pellet inside a hohlraum capsule with laser beams entering through openings on either end.
A depiction of a target pellet inside a hohlraum capsule with laser beams entering through openings on either end. The beams compress and heat the target to achieve the necessary conditions for nuclear fusion to occur. (Lawrence Livermore National Laboratory via AP)

When the news leaked that the U.S. Department of Energy was planning to announce that a federal laboratory had conducted the first-ever experiment with contained nuclear fusion that produced a net energy gain, many observers rushed to extol the huge environmental benefits that applying the technology commercially would bring.

Since nuclear fusion produces no planet-warming greenhouse gas emissions, news outlets referred to fusion as “the ‘holy grail' of carbon-free, clean energy” and asserted as fact that “'Clean energy forever' [is] now just decades away.”

“This is going to change the world,” Harvard Law School instructor Alejandra Caraballo, wrote on Twitter. “Cheap unlimited energy with nearly no negative externalities is within reach.”

According to many climate scientists, however, these statements range from untrue to wildly optimistic. The experiment at Lawrence Livermore National Laboratory in California actually used 100 times as much energy as it produced, and the day when nuclear fusion can power your laptop is far off, if it ever comes.

Meanwhile, according to the Intergovernmental Panel on Climate Change, the world must cut greenhouse gas emissions in half by 2030 if it is to avoid warming to the point that irreversible and catastrophic climate change effects, such as glacier collapse, are virtually guaranteed.

“Given the massive technological challenges that would be required to actually utilize this technology in a reliable and affordable way of generating electricity for the grid, I think it has little to no relevance to the climate crisis,” said Edwin Lyman, a physicist who serves as director of nuclear power safety with the Union of Concerned Scientists, to Yahoo News. “The climate crisis has to be addressed imminently — really, within the next 10 to 15 years — and a technology that’s still going to take many decades of development is not going to play a role in that initial transition.”

The single most important technological drawback is the fact that the experiment did not create more energy than it used.

Researchers used a process called inertial confinement fusion, in which a pellet of hydrogen plasma is bombarded by the world’s biggest laser in order to achieve nuclear fusion. Nuclear fusion is when two light atomic nuclei combine to form a single heavier one and release massive amounts of energy. It’s essentially the more powerful inverse of nuclear fission, a process that is used in nuclear power plants.

A rendering of 192 laser beams as they reach the center of the target chamber at the Lawrence Livermore National Laboratory in Livermore, Calif.
A rendering of 192 laser beams as they reach the center of the target chamber at the Lawrence Livermore National Laboratory in Livermore, Calif. (Jake Long/Lawrence Livermore National Laboratory/Handout via Reuters)

The supposed gain in energy being touted was that 2.05 megajoules of energy went into the laser and 3.15 megajoules were produced. But, as Mark Herrmann, the Livermore laboratory’s program director for weapon physics and design, readily acknowledged in a panel discussion that followed Tuesday’s announcement, this scenario leaves out the huge amount of electricity used to power the laser.

“I want to be clear — ultimately this experiment drew about 300 megajoules from the grid,” Herrmann said. “The laser wasn’t designed to be efficient.” So the experiment produced only 1% of the energy it used.

“This laser was designed to give us as much juice as possible to make these incredible conditions happen in the laboratory,” Herrmann explained. “There are many, many steps that would have to be made to get to inertial fusion as an energy source.”

That 300 megajoules isn’t a comprehensive accounting of all the electricity used by the lab.

“It just counts the energy used to power the lasers,” Lyman said. “And about only about 1% of that energy ends up on the target, that’s the problem. If you look at the total energy balance of the system, you’re still putting a lot more energy into it than is produced. And that’s what’s relevant, of course, for generating electricity, is that it needs to produce power, not use more power than it’s producing.”

“Meeting that milestone of energy gain from the laser input isn’t like walking through a doorway to a new future,” Matthew McKinzie, senior director for planning and operations of the climate and clean energy program at the Natural Resources Defense Council, told Yahoo News. “It’s part of a very long-term, slow iteration of improvements.”

Laser energy is converted into X-rays inside the hohlraum, which then compress a fuel capsule until it implodes, creating a high-temperature, high-pressure plasma
Laser energy is converted into X-rays inside the hohlraum, which then compress a fuel capsule until it implodes, creating a high-temperature, high-pressure plasma. (John Jett and Jake Long/Lawrence Livermore National Laboratory/Handout via Reuters)

Also, it’s important to remember that the energy that comes out of this fusion isn’t electricity that can be sent back into the grid. The energy loss from turning that energy into electricity means you would need even more energy to be created for the whole process to produce more electricity than it requires.

“The energy you get is mostly heat, so to convert that to electricity you have to run it through some conversion process (e.g. steam cycle), which is only about 40% efficient,” Michael Mann, a professor of earth and environmental science at the University of Pennsylvania, told Yahoo News. “So … they’d need to boost the efficiency of the process by several orders of magnitude to generate as much electricity out as they’re providing in.”

The inefficiency of the existing laser isn’t the only limitation. “The laser was built to just fire once per day,” Brian Appelbe, a physicist at Imperial College London who has collaborated with the Livermore lab on fusion experiments, told the New Republic. To provide power at utility scale, you “would need a laser that fired about once per second.”

Even then, fusion doesn’t create energy in a steady stream. “You have a system that essentially pulses, and you have to figure out how to smooth those out,” Lyman said.

There are other unanswered questions about the practicality of using fusion to generate energy all over the country, including whether existing power plants can be retrofitted for that purpose, or if they will need to be in new locations requiring new transmission lines and grid upgrades.

Then there are the materials and components, which will need to withstand exceptionally high temperatures and levels of radiation.

A technician reviews an optic inside the preamplifier support structure at the Livermore lab
A technician reviews an optic inside the preamplifier support structure at the Livermore lab. (Damien Jemison/Lawrence Livermore National Laboratory via AP)

And while much has been made of the fact that fusion doesn’t produce long-lasting radioactive waste in the way that fission does, it relies on tritium, a radioactive isotope of hydrogen. Tritium exists in only trace amounts in the atmosphere, and while it can be produced artificially from lithium in a nuclear reactor, that is by no means a widespread and affordable process.

“These [fusion power] plants will have to breed their own tritium, and they just don’t have systems yet designed that can do that efficiently,” Lyman said.

It’s worth noting that, for all the discussion of clean energy around Tuesday’s announcement, the Livermore lab project actually exists primarily to study nuclear weapons. Fusion is the process used for thermonuclear weapons, also called hydrogen bombs, which are much more powerful than the first generation of atomic weapons, which used fission. In order to avoid carrying out dangerous test explosions, the federal government has built a lab that can contain fusion reactions in order to study them. But it’s not set up for solving all the problems with fusion as a source of civilian energy.

To be sure, the federal government could theoretically invest significantly more in fusion research directed toward energy production. As Vox’s Umair Irfan has pointed out, the DOE currently spends just $500 million per year on fusion, compared with around $1 billion on fossil fuel energy and $2.7 billion on renewables. And these sums are a small fraction of what goes annually to agencies such as NASA ($23 billion per year) and the Department of Defense ($700 billion).

Officials on Tuesday expressed optimism that private sector investment in fusion research and development will increase in the wake of this achievement.

“Private research is already booming,” said Secretary of Energy Jennifer Granholm. “It reached $3 billion last year alone. This is what it looks like for America to lead, and we’re just getting started.”

Secretary of Energy Jennifer Granholm
Secretary of Energy Jennifer Granholm discussing the new developments in fusion research on Tuesday. (J. Scott Applewhite/AP)

Meanwhile, other countries are pursuing varied approaches to developing fusion energy. In France, a multinational cooperative effort is attempting to create fusion energy through a process called magnetic confinement. The United Kingdom has announced a plan to build a fusion power plant that it hopes will be operational by 2040.

But while fusion might be worthy of investment and cautious optimism as a potential long-term solution to meeting the world’s ever-growing energy needs, climate experts say it is not the clean energy answer we need today.

“While it is important to continue to do this research, and fusion energy could play an important role in meeting societal energy needs decades in the future, I’m very wary of efforts to make it sound like this is some sort of panacea with regard to the climate crisis,” Mann said.

“The reality is that fusion energy will not be viable at scale anytime within the next decade, a time frame over which we must reduce carbon emissions by 50% to avoid catastrophic warming of more than 1.5°C. That task will only be achievable through the scaling up of existing clean energy — renewable sources such as wind and solar — along with energy storage capability and efficiency and conservation measures.”

During Tuesday’s press conference, reporters asked how long it would be until nuclear fusion is viable for electric utilities. They were met with vague answers from DOE officials about it being several decades away.

McKinzie said that reminded him of a joke about fusion popular among nuclear experts: “It’s 30 years in the future, and it always will be,” he said.