A team of scientists at the Lawrence Livermore National Laboratory in California announced Wednesday that they have reached a key milestone in the development of nuclear fusion. Nuclear fusion is the process of atomic nuclei fusing to form a larger atom, which is how the sun emits heat and light.

Writing in the journal Nature, the scientists declared that for the first time ever they had yielded more energy out of fusion than what was needed to create the reaction. They "used 192 lasers to compress a pellet of fuel and generate a reaction in which more energy came out of the fuel core than went into it," Joel Achenbach at The Washington Post explains.

But the goal of "ignition" — which is when more energy is yielded than was consumed in the entire process — remains distant.

"We're closer than anyone's gotten before," said (the fantastically named) Omar Hurricane, the lead author of the study. "It does show there's promise."

He’s absolutely right, and this is a big breakthrough for achieving the dream of cheap, clean, and abundant fusion energy. However, even ignition is not enough. The final frontier for nuclear fusion is not scientific, but economic — meaning, when it can compete price-wise with the alternatives. And humans already have lots of energy options for the future.

In the short term, the most economical energy option remains fossil fuels — coal, oil, natural gas, etc. These, of course, are finite resources. At current rates of usage, extractable reserves are likely to be extinguished as early as within the next hundred years, and at most within the next millennium. And while a millennium may sound like a lot, in the context of six million years of human history (sorry, Ken Ham), it is not really a long time at all.

The twilight of the fossil fuel age is being spent developing renewable forms of energy. Some are inherently small-scale in nature, like wind and hydroelectric power. The two larger-scale ones are non-renewable fissionable fuels, like uranium and plutonium found in rocks in the Earth’s crust, and our own fusion power plant, the Sun, which each year casts down much greater quantities of energy onto the Earth than the total amount of fossil fuel beneath its surface.

For photovoltaic energy, we have already passed the threshold of "ignition," with solar panels capturing more energy than it takes to produce them. Furthermore, solar energy’s prices are falling so rapidly that it is becoming competitive with fossil fuels.

Now, in the future, nuclear fusion may have some benefits over photovoltaic solar energy, irrespective of nuclear fusion's efficiency. While it makes sense to cover unused space like deserts and the roofs of buildings with solar panels, people will want to use land for other purposes than energy capture. And for places that don’t see much sunlight — deep space, the ocean depths, underground facilities, etc. — nuclear fusion reactors are obviously superior for energy generation. When we develop interstellar spacecraft to explore the universe, nuclear fusion would be the ideal power source.

But for most purposes, it all comes down to efficiency. We still don’t know how efficient nuclear fusion reactors will be in practice. Right now, we do know that solar energy is already viable.

Editor's note: This article has been revised since it was first published in order to more clearly include proper attribution to source material.