Two claims that practical power from nuclear fusion is nearly here have been made in the past week. While one is a lot more credible than the other, it remains hard to tell hype from reality.

In theory, fusion power would be a possible solution to global power shortage problems. Fusion is the force that drives the sun, as well as hydrogen bombs. The fuel is available in sea water, and there is no waste other 0than the walls of the containment vessel becoming somewhat radioactive. Depending on the methodology used, the risk of Fukushima-type accidents is anticipated to be low as well.

Even a 13 year old has succeeded in fusing atoms, but getting more power out than you put in is a much harder challenge. The line that “practical fusion is 20 years away and has been for 20 years” gets bandied about, but is out of date. It's now almost 60 years since people started saying fusion power would be replacing fossil fuels in 20 years.

Now, however, defense contractor Lockheed Martin has shortened the timeline. They claim they will have viable reactors by 2024 and they will  fit on the back of a truck. As Lockheed Martin's website notes, “The smaller the size of the device, the easier it is to build up momentum and develop it faster. Instead of taking five years to design and build a concept, it takes only a few months.” Prototypes will be appearing within five years, the giant company claims, but the statement is notably light on detail.

Several different methods to achieve nuclear fusion have been attempted, but Lockheed Martin are using the most popular, holding hydrogen atoms within what they call a “magnetic bottle”. The atoms are forced together to the point where four fuse to become a single helium atom. Since the mass of helium is slightly less than four times that of hydrogen, a little is left over, which according to E=mc²  turns to heat.

Any solid container would be blown apart, but the magnetic fields can hold the process in place, maintaining a steady supply of energy.

Net energy from controlled fusion is certainly possible, but economics is a different matter. While the fuel and running costs will be negligible, the same is true for solar and wind. The question is whether the capital costs will be low enough to allow the product to compete.

Cold fusion, in which huge quantities of energy are not required to force the hydrogen atoms together, would be very cheap, if only it existed. The claim that the E-Cat cold fusion device has been independently verified has been circulating online recently. Rather than being something that would sit on the back of a truck, the E-Cat could fit on a bicycle.

However, previous “verifications” of the E-cat turned out to be greatly flawed, just like previous claims for cold fusion technology, and the supposed mechanism contradicts well established physics.