Forbes Ethan Siegel AUG 27, 2015
The ability to not only utilize but, at will, to create fire — a source of heat, light and energy that could be applied to a variety of purposes — was perhaps the key development that led humankind to dominate the plant and animal world, and eventually, all of Earth itself. By harnessing and controlling a rapidly releasable form of energy that stemmed from an abundant, accessible, freely available source — plant matter — we became capable of doing something no other living creature had ever done before.
As time went on, we were able to move to more efficient and scalable technologies.
Instead of burning wood for energy, we were able to find fuel sources that packed a greater amount of energy release into smaller masses and volumes: coal, oil, and gas. But these are still all chemical-based energy sources, where energy is liberated by changing the bonding configurations of electrons in atoms and molecules. While this can certainly release a lot of energy — up to tens of electron-Volts for every electron that gets rearranged — it poses three problems:
- The resources for it are finite: there’s a limited amount of fossil fuels on our world.
- There’s an environmental cost: even in the best case scenarios, burning these fuels pollutes our air and water with unwanted, harmful chemicals.
- And, in the end, it’s not really that much more energy-efficient than our original solution of burning plant matter.
In the 20th century, we discovered the secrets of harnessing the energy inside the atomic nucleus, allowing us to split the heaviest elements through the process of nuclear fission.
While an uncontrolled chain reaction would lead to a catastrophic nuclear bomb, a controlled reaction could provide a steady release of power that was much, much more efficient. Instead of releasing tens of electron-Volts for every atom or molecule of fuel inside, a nuclear fission reactions would release millions. And yet, nuclear fission has problems as well:
- The resources are still finite, and in this case, incredibly rare. Materials containing fissile uranium or thorium are very hard to come by, particularly in large quantities.
- Both the waste products and the reactants are radioactive: severe precautions must be taken not to contaminate the air, water or surrounding plant and animal life.
- And finally, the risk of an environmental disaster — such as through a plant meltdown — carries with it Chernobyl-level consequences.
But there’s a different way of harnessing the power of the nucleus that circumvents all three of these risks: nuclear fusion.
This is the same process at play in the Sun: by combining abundant, light elements into heavier ones (like hydrogen into helium), we can release even more energy than with nuclear fission, about three-to-ten times as much on average. In addition, the resources are incredibly common, as these light elements are among the most common on Earth, in our atmosphere and in the Universe in general. There’s no radioactivity to speak of, and the environmental risks are nil. In short, it’s the ultimate form of clean, green energy, offering the potential to meet all of humanity’s on-demand energy needs for hundreds of millions of years.
The only problem is we haven’t yet figured out how to reach the breakeven energy point in nuclear fusion — where we get out as much energy as we put in — without instigating the runaway explosion of a hydrogen bomb. But right now, three different types of efforts are underway.
1.) Inertial Confinement Fusion. We take a pellet of hydrogen — the fuel for this fusion reaction — and compress it using many lasers that surround the pellet. The compression causes the hydrogen nuclei to fuse into heavier elements like helium, and releases a burst of energy. We still have not yet reached that all-important breakeven point, as it takes much more energy to operate the lasers than we’ve been able to get out of any fusion reaction we’ve created. But we’ve recently created a laser capable of emitting pulses of 2 quadrillion Watts of power, which could potentially be enough, with the right application, to create more energy via fusion than it costs in input energy. Stay tuned.
2.) Magnetic Confinement Fusion. Instead of using mechanical compression, why not let the electromagnetic force do the confining work? Magnetic fields confine a superheated plasma of fusible material, and nuclear fusion reactions occur inside this Tokamak-style reactor. This concept was first used to fuse elements beginning in the 1950s, and since that time, Magnetic Confinement and Inertial Confinement have gone back-and-forth as each one inches closer to the breakeven point, where the fusion energy out will exceed the input energy. While that point hasn’t yet been reached, a recent new advance by a small fusion company deserves a bit of attention: they’ve figured out an inexpensive way to increase the density, temperature and confinement time of a plasma to make nuclear fusion via this method an intriguing possibility.
It’s definitely worth following the potential developments on this front. And finally, there’s one more option at play.
3.) Magnetized Target Fusion. In MTF, a superheated plasma is created and confined magnetically, but pistons surrounding it compress the fuel inside, creating a burst of nuclear fusion in the interior. This clever hybrid approach was developed by Michel Laberge, and is one of the only other approaches besides the two mainstream ones to successfully fuse hydrogen atoms into helium. Unfortunately, it hasn’t overtaken either ICF or MCF as the closest candidate to the breakeven point, and progress on this method has not moved forward in approximately five years.
Naysayers love to claim that nuclear fusion is always decades away — and always will be — but the reality is we’ve moved ever closer to the breakeven point and solved a large number of technical challenges over the past twenty years. Nuclear fusion, if we ever achieve it on a large scale, will usher in a new era for humanity: one where energy conservation is a thing of the past, as the fuel for our heart’s desires will literally be without limits.
Ethan Siegel is the writer and founder of Starts With A Bang, a NASA columnist and professor at Lewis & Clark College. Follow him on Twitter, Facebook, Google+, and support his Patreon.