Nuclear Vision

For decades, physicists have been working to produce a cheap, clean source of energy.

In this time, it has become increasingly clear that the fuels chosen by the majority of the human race to power us into a bright new age have, in reality, created a dark future.

Hydrocarbons, whether in the form of oil, gas, or coal, harm our home planet of Earth in potentially catastrophic and irreversible ways.

The climate does go through phases of cooling, and then warming, but the after-effects of the industrial revolution have seen to it that, as a species, we have a problem.

The evidence is almost irrefutable. If temperatures rise by as little as 2 degrees Celsius (as predicted in a recent UN report), sea levels could rise by just under a metre by the end of the century; make it 3 metres by 2300. The consequences of this could be disastrous.

Fortunate, then, that someone thought of funding research into alternatives. Each, however, has flaws. Solar panels,

Members of the NIF
Ed Moses (Left), and other members of the National Ignition Facility (Credit: Steve Jurvetson)

whilst effective and (relatively) cheap, are not enough on their own. Wind turbines are generally viewed as noisy and ugly by those that live near them, resulting in the added cost of placing them in the sea (whilst I am not in favour of using the term ‘NIMBY’ – Not In My Back Yard – to describe other people, I appreciate the sentiment).

Geothermal vents are only usable in the very few places that are on top of a fault line, such as Iceland. Nuclear power has seemingly always been contentious, given the large amount of potentially lethal radioactive waste. It has also taken major hits, due to incidents at Sellafield, Chernobyl and, most recently, Fukushima. Whilst the energy produced is great, the risks are arguably greater.

At this point, I would like to make clear a distinction. Nuclear power, as much of the world knows it, involves splitting atoms (usually uranium), causing a controllable chain reaction. This produces heat, which turns water to steam, driving turbines linked to a generator. The process of splitting atoms is called Fission. This is not, however, what happens in much of the rest of the universe.

In stars, hydrogen atoms are fused, under enormous pressure, to eventually form helium. As a result, this produces large amounts of energy, resulting in the heat and light upon which we, along with most life on the planet, depend. This is a process called, unsurprisingly, fusion.

Nuclear physicists have been trying to replicate this process. Unfortunately, it is very hard to do this. The fuel, hydrogen, must be heated to around 100 million degrees, by which time it has transformed from a gas to a different state, plasma.

This plasma must be controlled by the creation of a magnetic field, to prevent collisions with the walls of the reactor. A toroidal (doughnut) shape is often used for the reaction, in a machine called a Tokomak. Using these machines, physicists have achieved fusion, although not the self-sustaining ‘ignition’ that is required for wide-scale energy use.

Other means of achieving fusion are available though, researchers at the National Ignition Facility, Livermore, California, have developed a means of achieving nuclear fusion without the Tokomaks. They use the world’s most powerful laser, split into 192 beams, to heat a small amount of hydrogen to the point where fusion will occur.

Just last month, they achieved the feat of releasing more energy in the reaction than was being absorbed by the fuel. This is not ignition; the energy of the lasers exceeds that produced by the reaction, due to inefficiencies in the system. But it is an important step. Inefficiencies can be ironed out, or at least lessened. Domestic energy from nuclear fusion might yet be possible.

And the benefits are clear. Once perfected, fusion could easily satisfy the population’s demand for energy. It would not contribute to the greenhouse effect. Fuel is not exactly in short supply, either; hydrogen is the most abundant element in the universe. Out-of-control reactions cannot happen, and a malfunction would cause a quick shutdown of the reactor.

Some pieces of equipment used in the reactor would become radioactive, and the amounts of waste are similar to fission reactors, but the long-term radiation levels from the waste would be much lower; less waste would have to be stored for the long periods that fission has been so criticised for.

Funding continues in the shape of ITER, a tokomak currently being built in Cadarache, France. Yet to physicists around the world, for funding to continue in current economic circumstances, and to continue the difficult steps towards the ultimate goal, one thing remains clear:

They must believe.

All pictures from Flickr, used under the Creative Commons license found at http://creativecommons.org/licenses/by/4.0/legalcode

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