The world is believed to be currently on the brink of an environmental and an energy crisis. Our dependency on non renewable and polluting energy sources has lead to a dramatic increase in carbon dioxide and sea levels. The world needs a solution to the problem, an energy source which can fill the gap of fossil fuels, whilst providing us with renewable and clean energy.
This has lead to the emergence of renewable energy sources, but these have so far been unable to stop our dependency on fossil fuels. The most common sources, wind and solar, simply are not efficient enough and are too expensive. There is however an alternative, which, should it be successful, would help us harness the power of the sun. Nuclear fusion is still in its infancy. However it has the enormous potential to change the world as we know it. It is clean- it emits no carbon dioxide, and leaves behind very little radioactive waste. It can dwarf all other power plants in its energy production.
Unfortunately, at the moment there are no commercial reactors, only ones built for research. There have been many false starts, as overconfident scientists claim fusion is only 40 years away, but so far, each claim has proven to be over-ambitious. During this economic crisis, it is not always easy to justify spending billions on research on fusion, when there have been so many failures.
What is nuclear fusion?
Nuclear fusion is ‘a reaction in which light atomic nuclei fuse to form a heavier nucleus, releasing much energy’. 1 The process which would take place in a fusion reactor involves the fusion of hydrogen, or more specifically with the isotopes deuterium and tritium. The reaction generates energy because of the difference in binding energy.
The binding energy is ‘equal to the energy needed to split the nucleus into its individual nucleons.’12 Binding energy is the difference in mass of the nucleus and of its constituent nucleons, because the mass of the separate nucleons is different to the mass of the total nucleus, which is known as the mass defect. This mass defect is equated to energy by the formula e=mc2, e being energy, m being the mass defect, and c being the speed of light. This is energy (which would be) released in forming the nucleus. As shown on the graph, 3
there are two directions from which energy can be obtained. This is by the disintegration of the nucleus, to make it smaller, which is nuclear fission, or by fusing nuclei together to form larger atoms, nuclear fusion. In both cases, the aim is to form nuclei which have a greater binding energy per nucleon, and therefore a mass transfer, and liberation of energy.
The different reactors
There are currently two main ways of producing fusion power. These are magnetic confinement and inertial confinement.4
4Magnetic confinement uses a strong magnetic field to pull the nuclei very close together and create a high temperature. Inside the reactor, there is deuterium-tritium plasma, which is confined by the magnetic field. These magnets slowly compress the hydrogen closer together, and a current is sent through the gas, heating it to enormously high temperatures of around 10,000,000°c, which is considerably higher than the temperature found on the surface of the sun.
Inertial confinement takes a different approach than magnetic confinement. Powerful lasers are aimed directly onto the surface of a deuterium-tritium pellet. The outer surface is heated up to enormously high temperatures, causing it to become ablated, and this material flies outwards. This then causes the pellet to compress inwards, due to Newton’s third law. The material becomes incredibly dense, around 1,000 times its liquid density, and it also heats the inner material due to the high pressure, and so conditions are created in which fusion can occur.
There are now several fusion power stations around the world. NIF (National Ignition Facility) works using the confinement technique. NIF was designed to produce net energy, and has recently passed this landmark 5 . Despite this success, NIF has highlighted some of the major problems with the project. The plant was completed in 2009, six years late, and the cost ballooned from $1 billion to $4 billion6 . JET (Joint European Torus) uses magnetic confinement. ITER, (the International Thermonuclear Experimental Reactor), which the target for completion is 2019, aims to generate 10 times the amount of energy than what is put into the reactor. DEMO and ARIES-AT are reactors which are planned to be built around 2030 and it is hoped they can nearly be competitive with fossil fuels, running at 5₵ per kilowatt-hour, and pave the way for commercial fusion power.
Are there better alternatives?
Renewable energy would, it would seem, be the perfect answer for many, to the question of which energy should become dominant, simply due to its zero carbon emissions, and the fact that their sources of energy will never run out (at least until our sun dies, but energy will be the least of our worries then.) However, market forces are currently stifling their use. It simply makes little economic sense to use solar panels, running at relatively high cost, when coal can run for much less. Furthermore, they are really quite inefficient. The most efficient solar panels are only 41% efficient, losing the rest through heat.
Of course, the science of renewables will improve. Solar panels will become more efficient, and new ingenious ideas will be brought forward, such as the snake-like Pelamis Offshore Wave Energy. More energy can thus be made from these renewables, but they are flawed. Most of the problem is that there’s only a certain amount of energy that can be taken from these resources. However efficient they may be, to generate all of the energy that the world would need, they would take up huge amounts of space in a world where there is becoming increasingly little of it. Therefore, I do not believe that renewables, and solar, are viable sources of energy for the future, largely for economic and practical reasons.
Can already well established fuels be the answer?
Nuclear fission, using uranium, is carbon neutral, and produces a large amount of energy, it is surely another competitor to fossil fuels. Uranium is in less danger of running out than coal and oil, and so certainly until fusion can be fully operational; it would seem to be an incredibly viable source of energy. However, like everything, it has flaws, and in fission’s case, they are quite major drawbacks. For a start, fissions’ radioactive waste is probably more dangerous than if it were to pump out carbon dioxide. Its radioactive waste will last for many millions of years, and will render the area it is in (and indeed the area around the power station) completely unusable. An example of this happening is America’s one nuclear waste site in New Mexico, which has been subject to two leaks, as recently as March 20147 , which shows that the waste disposal is not safe.
However, the major problem with fission is the devastation which it can cause if something is to go wrong. Whilst the safety at a reactor is quite good, a meltdown would cause far more destruction than it would if a coal powered station were to explode. Chernobyl is the obvious example of this. The explosion isn’t even the part which causes the most damage. The immediate explosion left 31 people dead, but the long term affects from cancer caused by high radiation levels, are thought to have led to around 4,000-30,000 deaths.
The Chernobyl disaster has left a devastating image of nuclear fission in the public’s conscious. Safety measures can and have been put in of course, to reduce the risk, but the recent Fukishima disaster showed that these methods are certainly not infallible, and so I believe that the risk still outweighs the benefits. Therefore, whilst nuclear fission can compete with fossil fuels, it seems unlikely to ever replace them fully due to the huge risk which is attached to them. They are therefore not viable as a source of energy for the future, not because of their economics, as they are quite competitive, but because of their inherent dangers, which outweigh financial gains.
Is fusion the answer then?
This brings us back to fusion. Fossil fuels will eventually run out, and it seems that renewable sources can never fully replace them. They are too inefficient to be truly economically viable, and they cause their own separate problems to outweigh the benefits of being carbon neutral. Nuclear fission is simply too dangerous to become the sole or major provider of our energy, and its waste, while not contributing to global warming, are a major hazard to all kinds of life.
Fusion would therefore be the answer. It is a clean, virtually limitless source of energy, with a high energy density. It has always seemed to be just around the corner, but now it seems that it is really the case. Fusion is entirely possible, being carried out in the stars, and has been achieved in the laboratories. With recent important milestones being reached, such as net energy being produced, real progress is seemingly being made. To fully answer my question however, fusion has to be economically viable, rather than just being possible. Whilst this is a question that I have realised can never be answered with 100% assuredness, I believe that this will happen. This will be due to energy prices continuing to rise, and the price of fusion energy being brought down thanks to refinements and perhaps even breakthroughs with technique. When this “crossover” point is reached, when fusion is more economically viable than other fuels, is also hard to judge. Science will always come along in leaps and bounds. However, at the current rate, this could be achieved before the mid century mark. DEMO is intended to be almost comparable with fossil fuels, and is intended to be finished by 20338 . Should DEMO work as hoped, it could lead to the widespread use of fusion.