What’s next after the nuclear fusion breakthrough?

Earlier this week, the Lawrence Livermore National Laboratory (LLNL) announced a momentous breakthrough in harnessing controlled nuclear fusion. The LLNL’s National Ignition Facility (NIF) achieved “ignition” — a fusion experiment that produced more energy than consumed by the lasers needed to drive it. This piece of scientific news received significant publicity, even briefly capturing the front pages of major news outlets. What does it all mean?

Nuclear fusion powers our sun and all other stars. In it, light nuclei of hydrogen fuse into heavier nuclei of helium and generate tremendous amounts of energy. Hydrogen used in fusion is an incredibly dense energy source, holding more than 1 million times more energy in a unit of mass than natural gas. As hydrogen is easily produced from water, commercial nuclear fusion would effectively offer an unlimited source of energy with zero greenhouse gas emissions. Compared to its established relative, the nuclear fission — which is used in commercial nuclear power plants and functions by breaking up heavy nuclei — fusion’s radioactive waste would be shorter-lived and easier to handle.

But problems abound. One of the key ones is that fusion is difficult to kick-start, requiring high temperatures comparable to those in the sun, which create an unusual state of matter known as plasma. These temperatures are achieved by extremely powerful lasers, which typically consume more energy than the fusion generates. This is the crux of NIF’s announcement: For the first time, they produced 50 percent more energy in a fusion experiment than was consumed by the lasers powering it.

What does this mean for the role of fusion in our future energy supply? NIF’s discovery is undoubtedly significant, but much work remains. The amount of energy generated is still tiny, about 0.9 kilowatt-hours (kWh) from around 0.6 kWh input. In comparison, an average American home uses about 900 kWh per month. The obvious next task is to increase both the absolute output, and the ratio of output to input energy. This task will fall to the International Thermonuclear Experimental Reactor (ITER), currently under construction in the south of France (with the US as one of the three dozen partner countries) and scheduled to begin operation in 2025. By the end of the decade, ITER aims to produce a power of 500 MW, similar to the output of a mid-sized coal-fired power plant, using only 50 MW of laser power to kick-start the process.

However, even ITER is just a proof-of-concept: fusion will produce heat, not usable electricity delivered to the grid. Based on ITER’s expected insights, the new generation of even larger demonstration (DEMO) reactors will be built and use fusion to produce electricity. These DEMO reactors are scheduled for operation only in the late 2040s, making this limitless source of energy about two decades away. NIF’s announcement is on track with this timeline: It is progress, but is it enough?

Unfortunately, it may not be. Our energy landscape will need to modify quickly and dramatically to avoid the worst consequences of climate change. Nuclear fusion will most likely be late to the party, not entering commercial use in time to participate in this shift. Critics point out that we have a functioning, but underutilized fusion reactor already: the sun delivers enough energy to Earth in 90 minutes to satisfy all our annual energy needs — and yet the global utilization of solar power remains miniscule. If billions of dollars invested in fusion development were deployed to improve and subsidize solar panels, climate change woes may be solved much earlier.

The dream of developing controlled fusion maybe strikes at more than just the concerns about energy supply and climate change. Humans have developed many innovative technologies, replicating and improving upon nature’s ingenuity. But never have they come close to making their own sun — that remained firmly the domain of gods. Perhaps getting closer to that dream, of moving our knowledge beyond a long-impossible limit, is the true cause for celebration. Along the way, fusion-inspired advances in physics and material science will influence our world well beyond nuclear fusion.

Ognjen Miljanić is a professor of chemistry at the University of Houston, where he teaches on energy and sustainability. His is the author of “Introduction to Energy and Sustainability,” published by Wiley. Follow him on Twitter: @MiljanicGroup