There are very few sources of truly clean energy out there. Coal, oil, natural gas, etc. all expel tremendous amounts of carbon dioxide into the atmosphere, something we know we need to stop doing very soon if we want our planet to be habitable to humans for very much longer. Biofuels, while not as harmful as fossil fuels, still emit tremendous amounts of carbon dioxide, and are not a long-term solution. Modern nuclear power produces low amounts of carbon dioxide, but significant amounts of radioactive waste, which isn’t good for anybody! Even hydroelectric power has disastrous environmental consequences, destroying entire river ecosystems downstream of wherever the dams are built.
But there is an abundant source of power that is free to all and free of pollution. I refer, of course, to the Sun. The Sun bombards the Earth with visible light, infrared heat and ultraviolet radiation continuously, providing us with a constant and tremendous source of energy.
If we could create this same energy source here on Earth, we would have virtually limitless, pollution-free energy. Let’s look into how it works. The Sun is a giant ball of (mostly Hydrogen) gas. For that matter, so are the four largest planets in the Solar System. What’s the major difference between the Sun and Jupiter, Saturn, Uranus, and Neptune?
Size. The Sun is 750 times as massive as those four gas giants combined. The pressure generated at its center is incredible — about 250 billion times what the pressure is on Earth, or about two billion tonnes per square inch.
The pressure is so great at the center that it can cause nuclear fusion, the reaction that takes protons, neutrons, and light nuclei, and combines them into heavier elements, giving off a tremendous amount of energy in the process. The most energetic bombs in the world — H-bombs — rely on nuclear fusion.
But bombs are completely uncontrolled; there is no way to harness that energy to make it useful and usable for energy purposes. So how can we build a safe, efficient, but usable energy-producing mini-star on Earth? The National Ignition Facility in California has taken an old idea and is running with it: use lasers to compress a pellet of fuse-able materials!
The lasers they’re using simply send out a short pulse of energy, compressing this pellet. There isn’t even that much energy involved: 10 million Joules. That’s about as much energy as you’ll find in a very large, fatty (e.g., Waffle House) breakfast. Why is this so impressive? Because the energy is put out over a miniscule timescale, only 20 nanoseconds. If you convert that into “power”, then for those 20 nanoseconds, you spend 500 trillion Watts, or 500,000,000,000,000 Watts! This is enough pressure, at the atomic level, to fuse the hydrogen isotopes inside into helium.
Each atomic fusion reaction releases a tiny amount of energy: about 2.8 trillionths of a Joule. But there are so many atoms in there — around Avogadro’s Number — that you can get out even more energy than you put in! It’s like making your own miniature star for a teeny-tiny amount of time.
The fusion that results is exciting because this will get us past the break-even point for the very first time using this method! This means we get more energy out than we put in! The products of this reaction? Helium and Hydrogen gas: completely benign. So not only is it possible to build your own star — however briefly — but this may also be the long-term solution to our energy problems! Now, if only we can figure out how to take the energy from these mini-explosions and put them to good use…