0:01The fundamental currency of our Universe is energy. 0:05It lights our homes, 0:06grows our food, 0:08powers our computers. 0:10We can get it lots of ways: 0:12burning fossil fuels, 0:13splitting atoms 0:14or sunlight striking photovoltaics. 0:17But there's a downside to everything. 0:19Fossil fuels are extremely toxic, 0:22nuclear waste is... well, nuclear waste, 0:24and there are not enough batteries to store sunlight for cloudy days yet. 0:29And yet, the Sun seems to have virtually limitless, free energy. 0:34Is there a way we could build a sun on Earth? 0:37Can we bottle a star? 0:49The Sun shines beacuse of nuclear fusion. 0:51In a nutshell - fusion is a thermonuclear process, 0:55meaning that the ingredients have to be incredibly hot, so hot, 0:58that the atoms are stripped of their electrons, 1:00making a plasma where nuclei and electrons 1:03bounce around freely. 1:05Since nuclei are all positively charged, they repell each other. 1:10In order to overcome this repulsion 1:11the particles have to be going very, very fast. 1:15In this context, very fast means very hot: 1:18millions of degrees. 1:20Stars cheat to reach these temperatures. 1:23They are so massive, that the pressure in their cores 1:26generates the heat to squeeze the nuclei together 1:28until they merge and fuse, 1:30creating heavier nuclei and releasing energy in the process. 1:35It is this energy release 1:36that scientists hope to harness 1:38in a new generation of power plant: 1:41the fusion reactor. 1:42On Earth, it's not feasible to use this brute-force method 1:46to create fusion. 1:47So if we want to build a reactor that generates energy from fusion, 1:51we have to get clever. 1:53To date, scientists have invented two ways of making plasmas 1:56hot enough to fuse: 1:58The first type of reactor uses a magnetic field 2:01to squeeze a plasma in a donut-shaped chamber 2:04where the reactions take place. 2:06These magnetic confinement reactors, such as the ITER reactor in France, 2:11use superconducting electromagnets cooled with liquid helium 2:14to within a few degrees of absolute zero. 2:17Meaning they host some of the biggest temperature gradients in the known Universe. 2:21The second type, called inertial confinement, 2:24uses pulses from superpowered lasers 2:26to heat the surface of a pellet of fuel, 2:29imploding it, 2:29briefly making the fuel hot and dense enough to fuse. 2:33In fact, 2:34one of the most powerful lasers in the world 2:36is used for fusion experiments 2:38at the National Ignition Facility in the US. 2:41These experiments and others like them around the world 2:44are today just experiments. 2:46Scientists are still developing the technology. 2:50And although they can achieve fusion, 2:52right now, it costs more energy to do the experiment 2:55than they produce in fusion. 2:58The technology has a long way to go 3:00before it's commercially viable. 3:02And maybe it never will be. 3:04It might just be impossible to make a viable fusion reactor on Earth. 3:09But, if it gets there it will be so efficient, 3:12that a single glass of sea water 3:13could be used to produce as much energy as burning a barrel of oil, 3:17with no waste to speak of. 3:20This is because fusion reactors would use hydrogen or helium as fuel, 3:24and sea water is loaded with hydrogen. 3:27But not just any hydrogen will do: 3:29specific isotopes with extra neutrons, called deuterium and tritium, 3:34are needed to make the right reactions. 3:36Deuterium is stable and can be found in abundance in sea water, 3:40though, tritium is a bit trickier. 3:43It's radioactive and there may only be twenty kilograms 3:46of it in the world, mostly in nuclear warheads 3:49which makes it incredibly expensive. 3:51So, we may need another fusion body for deuterium instead of tritium. 3:56Helium-3, an isotope of helium, might be a great substitute. 4:00Unfortunately, 4:01it's also incedibly rare on Earth. 4:04But here the Moon might have the answer. 4:08Over billions of years, 4:10the solar wind may have built up huge deposits 4:12of helium-3 on the moon. 4:15Instead of making helium-3, we can mine it. 4:19If we can sift the lunar dust for helium, 4:21we'd have enough fuel to power the entire world 4:23for thousands of years. 4:25One more argument for establishing a moon base, 4:27if you weren't convinced already. 4:30Okay, maybe you think building a mini sun 4:33still sounds kind of dangerous. 4:37But they'd actually be much safer than most other types of power plant. 4:42A fusion reactor is not like a nuclear plant 4:45which can melt down catastrophically. 4:47If the confinement failed, 4:49then the plasma would expand and cool and the reaction would stop. 4:53Put simply, it's not a bomb. 4:57The release of radioactive fuel like tritium 5:00could pose a threat to the environment. 5:02Tritium could bond with oxygen, making radioactive water 5:05which could be dangerous as it seeps into the environment. 5:08Fortunately, there's no more than a few grams of tritium 5:12in use at a given time, 5:13so a leak would be quickly diluted. 5:16So we've just told you 5:17that there's nearly unlimited energy to be had, 5:19at no expense to the environment 5:21in something as simple as water. 5:23So, what's the catch? 5:26Cost. 5:27We simply don't know if fusion power will ever be commercially viable. 5:31Even if they work, they might be too expensive to ever build. 5:35The main drawback is that it's unproven technology. 5:38It's a ten billion dollar gamble. 5:40And that money might be better spent on other clean energy 5:43that's already proven itself. 5:46Maybe we should cut our losses. 5:48Or maybe, 5:49when the payoff is unlimited, clean energy for everyone, 5:53it might be worth a risk? 6:13Subtitles by the Amara.org community
