Words Alia Fawaz
Meeting the world’s energy demands is one of the major challenges of our time. Our overdependence on fossil fuels to meet our energy needs (nearly 80 percent of global energy comes from them) has significantly contributed to global warming and climate change. Today the use of renewable energy sources (such as solar and wind) is on the rise, but the cost, infrastructure, and technology has still not come close to enabling such energy to power the world. Nuclear fission still remains unpopular because of its radioactive waste and potential dangers (as in Chernobyl and Fukushima). One hope is for scientists to make fusion energy a reality: a pollution-free, cheap source of energy that would potentially power human development infinitely.
The Sun is 93 million miles away, yet we can see this ball of fire and feel its immense energy every day. How does this happen? The Sun shines because it is able to convert energy from gravity into light. The hydrogen gas in the core of the Sun gets squeezed together so tightly that four hydrogen nuclei combine to form one helium atom. This is called nuclear fusion. In the process, some of the mass of the hydrogen atoms is converted into energy in the form of light. In fact, scientists have been attempting to replicate this and turn nuclear fusion into a viable energy source since the 1950s. The idea is to create a giant star to replicate the chemical reaction that occurs naturally on the Sun to produce energy here on Earth. Scientists believe that it is worth trying to design and build a fusion power station, and currently there are numerous research and development fusion projects around the world with this same goal in mind.
Of course, the real challenge is harnessing the power of the Sun in a laboratory setting, because we don’t have the gravity of the Sun. One way to achieve fusion is to use powerful magnets to contain an extremely hot gas of electrically-charged deuterium and tritium nuclei and electrons. This hot charged gas is called plasma. In fact the plasma must be so hot – more than 100 million degrees Celsius – that the positively-charged nuclei move fast enough to overcome their electrical repulsion and fuse. When the nuclei fuse, they form two energetic particles – an alpha particle (the nucleus of the helium atom) and a neutron.
Heating the plasma to such a high temperature requires a lot of energy – which must be put into the reactor before fusion can begin. But once it gets going, fusion has the potential to generate enough energy to maintain its own heat, enabling us to draw off excess heat that can be converted into steam to drive turbines and put power onto the electricity grid.
Making wishful thinking a reality
Human-engineered fusion has already been demonstrated on a small scale. However, the major challenges facing the engineering community are to find ways to scale up the fusion process to commercial proportions, in an efficient and economical way.
One high-profile fusion research facility project is ITER (International Thermonuclear Experimental Reactor). Once completed, this fusion plant will weigh 23,000 tons and it will be as big as 60 football fields. ITER is currently being built in the south of France by a group of countries including the US, China, Russia, Japan and the EU. ITER employs the design known as the tokamak*. It involves donut-shaped plasma, confined in a very strong magnetic field, which is partly created by electrical current that flows in the plasma itself. This ambitious project, which is expected to cost more than 20 billion euros, is a testament to the commitment to and the need for fusion energy.
In terms of scale, the energy potential of the fusion reaction is superior to all other energy sources known on Earth. Fusing atoms together in a controlled way releases nearly four million times more energy than a chemical reaction such as the burning of coal, oil or gas and four times more than nuclear fission. Fusion doesn’t produce runaway chain reactions in the way that fission can (meaning that there is no need to worry about meltdowns), nor does it produce the large amounts of dangerous radioactive waste of fission reactions. That’s why it’s such a desirable source of energy.
If we can successfully harness the clean and limitless energy from fusion we will have hit the green energy jackpot. While small technical advances are constantly being made in this highly promising technology, it still remains elusive. The big question remains: Will it become a reality in our lifetime?
*The tokamak, which is a donut shape, is the most developed magnetic confinement system and is the basis for the design of future fusion reactors. It was invented in the Soviet Union during the 1960s and has been adopted by researchers around the world. Another method of confining thermonuclear plasmas involves stellarators, which are used in other fusion projects. This design has five-fold symmetry, like the middle of a pentagon.