A Dummy’s Guide: Fuel from Fusion

Impact cuts through the jargon to give you all you need to know about the science that matters. 

On the 3rd of February at 2.39pm(GMT) the German Chancellor Angela Merkel pushed the switch to turn on the billion euro Wendelstien 7-X Stellarator. This contraption is a huge metal doughnut of superconducting magnets which can successfully sustain a gooey centre of hydrogen plasma. This liquid makes up our own sun and is the key ingredient to the nuclear process known as fusion.

Fusion is where atoms are fused together under immense heat, pressure and an effect known as quantum tunnelling to form heavier elements and with it create large amounts of energy. In fact, a deuterium tritium (2 isotopes of Hydrogen) fusion reaction creates 24,000 times more energy than coal power for the same mass, and is four times more efficient than current reactions in nuclear power plants.

Where does this energy come from?

Every time one of these reactions happen, a bit of mass is lost to form the products and thanks to our old friend Einstein, we know it is converted into energy. In fact we can work out how much energy is created using arguably the most famous equation in the world: E=mc². For example, we can calculate that the mass of the cup of tea on your desk (225g) is equivalent to 20,000 terajoules, enough energy to power the United Kingdom for roughly 10 years. It is clear why people want to harness this effect and indeed they have, but for far more sinister reasons. It has been estimated that a mere 700 milligrams of mass was necessary to cause the destructive power of ‘Little Boy’ the bomb dropped on Hiroshima in 1945, which is about a 5th of the mass of a 1p coin.  

“The mass of a cup of tea is equivalent to 20,000 terajoules, enough energy to power the United Kingdom for 10 years” 

Only four times more efficient? What’s the big deal?

Well fusion has been described as being a ‘clean’ energy. Unlike oil, coal and nuclear fuel, which are infamous for pollution and general destruction of the planet, the by-product of fusion is helium, the harmless and hilarious, balloon floating, voice changing chemical we all know and love. It does however produce some radioactive waste but it typically has a half life of about 100 years, a fleeting moment compared to the 210,000 year half-life of nuclear fission waste. Furthermore, hydrogen is the most abundant element in the universe and can be isolated through many chemical reactions (such as electrolysis of water) here on earth, making it an almost unlimited source.  

“The only by-product of this process is helium, the harmless and hilarious voice changing chemical we all know and love” 

What’s the catch?

Here we have an energy source more powerful than any other, that basically runs off water and which can supply the world with energy whilst simultaneously supplying kids’ parties with floating balloons. It’s almost too good to be true! And for the time being, it is. In order to induce fusion, the reaction has to be hot. Not a mere gas mark 4, think more the temperature at the centre of a star. The Wendelstien 7-X itself heats the plasma to temperatures of 130 million degrees Celsius and to create these conditions on earth takes a vast amount of energy. In fact so much energy is needed that we can only get out a fraction of what we put in. The most efficient machine we have so far is the Joint European Tokomak (JET) in the UK which has managed to salvage 70% of the energy input but with the necessary output of a functioning power plant being 10 times the input. Therefore, it’s unlikely to be hooked up to the national grid any time soon. It is safe to say that we are far from the verdant shores of unlimited clean energy, but with every new model and iteration the gap is closing. The Wedelstein’s sleek design and superior technology moves us ever closer, and maybe in the hopefully not so distant future, the benefits will be within our grasp. 

John Norrie 

Image by NASA via Flickr

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Science editor for the University of Nottingham student magazine IMPACT

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