If we can get the technology right, nuclear fusion promises to give us all the clean energy we could want - which is why researchers across the world are racing to perfect the science to make this viable.
Nuclear fusion basically means replicating the Sun's chemical reactions here on Earth - or "bottling a star", as it's often called. That's no easy task, and the video above from Kurzgesagt - In a Nutshell explains both the incredible potential and massive challenges involved.
At the heart of nuclear fusion is a process where atoms become so hot, they're stripped of their electrons, leaving electrons and nuclei bouncing around freely in a plasma.
Once these nuclei reach a certain temperature - around 14,000,000°C (25,200,032°F) in the Sun's case - they fuse together, releasing the vast amounts of energy that power the Sun and could one day supply limitless amounts of energy on Earth.
The Sun manages this thermonuclear reaction thanks to its enormous mass, which leads to tremendous pressure and incredibly high temperatures inside its core. But how can we recreate the same pressure and temperature in a human-made reactor?
There are two main approaches. The first, magnetic confinement, uses magnetic fields to squeeze plasma inside a doughnut-shaped container – superconducting electromagnets are cooled with liquid helium to within a few degrees of absolute zero.
The ITER machine in France is an example of such a device.
The second approach, inertial confinement, uses super-powered lasers instead (you can see why nuclear fusion is expensive).
Pulses from these lasers are trained on fuel pellets, briefly making them hot and dense enough to fuse. The National Ignition Facility in the US is one place where these types of experiments are taking place.
Scientists are already seeing fusion happen in these complex machines - the problem is that the reactions need much more energy to create than they can produce, which isn't ideal for a future power source.
In fact, no one's sure that we'll ever be able to make a viable nuclear fusion reactor on Earth, but the possibility of virtually unlimited, environmentally friendly energy means we're going to keep trying for a while yet.
As the video explains, with nuclear fusion, a glass of seawater could provide as much energy as a barrel of oil, with hardly any waste. That's worth investigating.
Nuclear fusion doesn't create carbon dioxide emissions like fossil fuels do, and it only creates a very small amount of radioactive waste compared with nuclear fission. What's more, there's no chance of a meltdown with this type of reaction.
There's another issue though: we need special hydrogen isotopes called deuterium and tritium to power these reactions, and while deuterium is stable and abundant in seawater, tritium is radioactive and thought to be very rare.
Helium-3 is a possible replacement for tritium, and while it's also very rare on Earth, scientists think it can be found in large quantities on the Moon, thanks to deposits from millions of years of solar winds.
If we can collect it - a new Moon base, anyone? - it could power Earth along with deuterium for thousands of years.
It's a tantalising idea, and gives us a lot of hope for the future. We're counting on you, science.