US scientists trying to harness the power of the sun have made a 2nd major breakthrough for the future of sustainable, green energy

• Scientists replicated their breakthrough December 2022 nuclear fusion experiment.
• But this time, they produced even more energy from the experiment than the first time.

In a second successful experiment, US scientists say they produced a nuclear fusion reaction that yields more energy than they put into it.

After decades of trying, this is only the second time in history scientists have achieved such a feat, and it could usher in a future age of cleaner, sustainable energy, unlike anything we've ever seen.

Why nuclear fusion is so important for global energy needs

We see the colossal power of nuclear fusion in action every day — the sun.

At the sun's core, immense heat and gravity cause the fusion of hydrogen into helium, generating enough energy per hour to power 2,880 trillion light bulbs for a lifetime, per Solar Reviews.

Creating that same force that powers the sun here on Earth is a challenge, but worth the effort if we're going to solve the ongoing global energy crisis.

Experts expect global electricity consumption to continue to grow through 2050, according to the International Energy Agency. Increasing oil prices and attempts to curb greenhouse gas emissions are driving demand for renewable and greener energy.

Fusion can provide both.

Fusion generates between 20 million to 100 million times more energy per kilogram of fuel compared to fossil fuels. About a gram of fuel for nuclear fusion is the equivalent of 2,400 gallons of oil, according to the Department of Energy.

The sources of fuel for nuclear fusion, seawater and lithium, are also abundant and produce carbon-free energy. Meaning that unlike fossil fuels, nuclear fusion doesn't contribute to greenhouse gases in the atmosphere that are driving climate change.

"This milestone moves us one significant step closer to the possibility of zero carbon abundant fusion energy powering our society," Secretary of Energy Jennifer Granholm said after the December 2022 breakthrough experiment.

2 major breakthroughs in nuclear fusion

In December 2022, US scientists generated 3.15 megajoules of energy from a nuclear fusion experiment — 1.1 megajoules more than the 2.05 megajoules used to power the reaction.

It was a major breakthrough and the first time a fusion experiment had ever generated an energy surplus. But the breakthrough was recently usurped. The most recent reaction performed better than the original, according to early reports.

Both experiments took place at the National Ignition Facility, part of the Lawrence Livermore National Laboratory.

The early results from the July 30 experiment showed an output greater than 3.5 megajoules, the Financial Times reported.

That's almost 1 kilowatt hour. To put that in perspective, many Energy Star clothes washers use about 100 kWh each year, so 1 kWh is enough to power one of those washers for about three loads.

The experiment's success, however, requires additional analysis before the scientists are ready to release more details and publish their results in a peer-reviewed scientific journal.

"As is our standard practice, we plan on reporting those results at upcoming scientific conferences and in peer-reviewed publications," Paul Rhien, a public rep with the laboratory, said in an emailed statement.

Why nuclear fusion beats nuclear fission

Current nuclear power plants use fission to make energy. Unlike fusion, which joins atoms together to generate energy, fission splits atoms apart.

Fission is actually what powers atomic bombs, which were first developed out of the Manhattan Project run by J. Robert Oppenheimer. Eventually, scientists learned to harness fission in reactors to generate energy.

For some, the ultimate goal, however, is not fission, but fusion reactors.

Both fusion and fission release large amounts of energy. But joining two hydrogen nuclei to form helium doesn't generate the same long-lived nuclear waste products that breaking apart uranium and plutonium does.

While fission creates a chain reaction, nuclear fusion reactors of the future would not, avoiding the risk of a meltdown.

Fusion can also create four times as much energy as fission, according to the International Atomic Energy Agency.

Scientists still have a few challenges ahead before the nuclear fusion revolution

While NIF seems to be on its way to repeatedly generating extra energy from its nuclear experiments, there are several obstacles still ahead before the world runs on fusion reactors, experts have said.

To start, the NIF method requires radioactive materials. It uses a tiny capsule of deuterium and tritium, two hydrogen isotopes, and 192 lasers. Tritium is radioactive, and Arjun Makhijani, president of the Institute for Energy and Environmental Research, has argued that many of its health effects are under-studied.

Moreover, Daniel Jassby, a physicist formerly with the Princeton Plasma Physics Laboratory, wrote in 2017 that fusion reactors would still generate radioactive material that would have to be buried. The waste's level of radioactivity would be lower, but there would be more of it, Jassby wrote.

It also took a large amount of energy to power the NIF's lasers, a problem that scientists need to solve before scaling up the process to provide electricity to a grid. The yield would have to be much higher and the operation much quicker, according to a recent report in Energy Policy.

Even with the new breakthroughs, it could take decades for the technology to be competitive with current methods of energy production. But it is another promising step to a clean energy future.