If you think you are looking at something out of a Matrix movie… you’re sort of right.
Some exciting stuff has been happening in nuclear-energy-land lately with the completion of the Wendelstein 7X nuclear fusion generator.
Next month the German Stellarator fusion reactor will be turned on for the first time, which is expected to show some very interesting results hopefully putting nuclear fusion power within our reach.
Nuclear energy has been around in the form of nuclear fission, the splitting of atoms, for a few years now and giving us relatively clean energy by not producing CO2. But the side products are highly radioactive elements and the process is badly containable due to its explosive nature.
Nuclear fusion, the combining of atoms, on the other hand does not create highly radioactive byproducts which are hard to get rid of. The way the Wendelstein 7X works is the same way as our sun generates its energy by fusing hydrogen atoms into each other creating immense amounts of clean energy. The downside is: it is a pretty darn complex system. Therefore energy generation from nuclear fusion has been held as the holy grail of energy production for quite some years now.
There have been various experimental fusion reactors, but none have achieved real sustainable energy generation. After all these years of experimenting we have actually only recently been able to generate slightly more energy from fusion reaction than the energy required initiating and sustaining the fusion reaction with the help of a different system using lasers. The German scientists though, hope with this complex machine their system is actually able to turn into a self-sustained energy source.
The difference between and benefits of fusion vs. fission
The use of nuclear energy has been demonstrated since 1945 when the first nuclear explosion at the Trinity site took place.
The science behind the nuclear bombs have been put to use in energy plants in a more controlled manner, but in essence the nuclear power plants are still very slow explosions of nuclear bombs.
Both the bombs and power plants work according to the same principles of the splitting of the core of atoms called nuclear fission.
An element with a large amount of nucleons, like uranium 235, is used and shot at with a neutron. After absorbing this neutron the uranium will become highly unstable and break apart into two other elements and two more neutrons. The thing is that uranium 235 consists of not just one but a huge amount of atoms. Shooting a neutron at one atom core causes two more neutron’s to be freed, which will make those two neutron’s to break apart the next core and so on, causing a chain reaction and generating a whole lot of energy in the process.
This out of control chain reaction is fine while trying to blow up stuff, be rather not it being the roof of your power plant. To contain a nuclear reaction for the use of energy generation, shielding material is used to absorb the released neutrons. By varying the amount of coverage the reaction can be more or less controlled.
The way the reaction is turned into electricity is due to the fact that the reaction takes place under water and causes the water to warm and evaporate and drive a turbine which in its turn generates electrical power.
A very neat demonstration of our understanding of science, but the downside to nuclear fission is you are in essence still really just detonating a bomb. When for whatever reason you lose control over your reaction you are done. And apart from the instable nature of the reaction there are those instable side products that are generated with the reaction, releasing those pesky radioactive waves into our environment.
Nuclear fusion reaction
Nuclear fusion works the other way around. Here you don’t use an element with a large number of nucleons to break apart but an element with a low amount of nucleons, like hydrogen which has one nucleon, and fuse it together.
Nuclear fusion is a multi-step process, whereby firstly you will need two isotopes of hydrogen, deuterium and tritium. The core of deuterium consisting of one proton and neutron and tritium of one proton and two neutrons.
When those two elements are fused together they will form helium and free a neutron and a whole lot of energy in the process.
The new Wendelstein 7X generator is of the Stellarator type. A machine which is absolutely bonkers when it comes to the engineering of it! It has required more than 1.1 million man-hours to construct.
In this machine the deuterium and tritium are shot into a spiraling trajectory where 50 bizarrely twisted superconducting magnets will confine and accelerate the elements and turn them into a plasma. If sufficient temperature and pressure is reached, just like in our sun, the elements will start to slam into each other and fuse. The resulting products are the helium and a neuron. The neuron is not electrically charged and therefore will be launched out of the confined plasma. It is actually the energy released by neutron hitting the chamber wall which causes the reactor to generate power. The neutron slams into the chamber wall and causes it to heat up, this heat is transferred to water and steam is created to generate electricity using a turbine.
The amount of energy released in a fusion reaction is immense in comparison to a fission reaction, which means tiny amounts of material are needed to generate huge amounts of power. Also the reaction products of the fusion reaction are hardly radioactive and decay in a very short time. And as it is a multi step process it is impossible for the reaction to grow out of control.
Te generator is now facing some German regulatory processes before it is going to be turned on for the first time.
Let’s hope we are really going to manage this, we could do with a break and finally have a good and sustainable solution to climate change.