One famous anecdote: nuclear fusion is twenty years. Always will be in twenty years. The joke is now no longer funny, grew out of the optimism of scientists who in the 1950-ies (and in each subsequent decade) thought that nuclear fusion was only 20 years away. Now that is a joke seriously the startup comes from MIT (the Massachusetts Institute of technology), the highly respected and well known Institute are: Commonwealth Fusion Technologies. Startup promises to launch a working nuclear fusion reactor within 15 years. Promises cheap, clean and unlimited energy that will solve all the crises with fossil fuels and climate change. And I say “potentially inexhaustible and carbon-free energy”.
The only problem: we have heard it many times. This time different?
Another famous cliché applies to fusion energy. The idea is simple: you put sunshine in a bottle. You only have to build the bottle. Energy synthesis nourishes the stars, but it requires an extremely hot and dense conditions that the plasma is earned.
A huge amount of energy can be released when two light nuclei fuse together deuterium-tritium fusion, which is carried out in the experiment, ITER, emits 17.6 MeV per reaction a million times more energy per molecule than you get from the explosion of TNT projectile. But to release that energy, you need to overcome the powerful electrostatic repulsion between the nuclei of both are positively charged. The strong interaction at short distances leads to the synthesis that produces all of this energy, but the kernel must strike very close to femtometre. In the stars it turns out in itself because of the enormous gravitational pressure on the material, but on the Ground it is harder.
First you need to try to find materials which will remain alive after exposure to a temperature of hundreds of millions degrees Celsius.
Plasma consists of charged particles; matter and electrons are washed away. It can hold a magnetic field, which collapses the plasma in the circle. Manipulation of magnetic field allow the plasma to compress. In the 1950-ies and 1960-ies there appeared a whole generation of devices with exotic names: Stellarator, Perhapsatron, Z-Pinch, was developed for this purpose. But plasma, which they tried to hold was unstable. The plasma itself generates an electromagnetic field, it is possible to describe very complex theory of magnetohydrodynamics. Slight variations or defects on the surface of the plasma quickly got out of control. In short, the device did not work as planned.
The Soviet Union had developed the device “tokamak”, which offered significantly improved performance. At the same time was invented the laser, allowing for a new type of synthesis — a fusion with inertial confinement.
In this case, it is not necessary to keep the plasma burning in magnetic fields, you need to compress it with an explosion using lasers for a short time. But experiments with inertial confinement is also suffered from instabilities. They were carried out in the 1970-ies and perhaps one day get their way, but the biggest one to date — the national ignition laboratory in Livermore, California, and has not reached break-even point, when it will be produced more energy than it took in.
A large part of hopes are placed on ITER, the largest tokamak of fusion with magnetic confinement, which is still under construction.
The project developers hope to ignite the plasma for 20 minutes to produce 500 MW of power with a nominal input of 50 MW. The full synthesis is planned for 2035, but the problems with the international cooperation of the United States, the Soviet Union (then still), Japan and Europe have led to long delays and stretch the budget. The project is late for 12 years and worth $ 13 billion. It is not uncommon for projects that require the construction of huge installations.
According to the plan, the first ITER thermonuclear reactor of synthesis, which will work as power, lighting and maintaining the synthesis DEMO, should start operation in 2040 or even 2050. In other words, nuclear fusion… will be in twenty years. There is a trend of solving problems with instabilities due to the construction of all larger plants. ITER will be a larger JET, and the DEMO will be more ITER.
For many years many teams challenged the international collaboration, offering a smaller design. The question is not about speed but practicality. If the construction of the synthesis reactor is really going to cost billions of dollars and tens of years will it actually pay off? Who will pay for the construction? Maybe by the time when the working tokamak, a combination of solar panels and new batteries will provide us with energy that will be cheaper made on the tokamak. Some projects — even the notorious “cold fusion” — proved to be false or non-working.
Others deserve more attention. Startups with new designs for the fusion reactor — or, in some cases, revised versions of older attempts.
Tri Alpha expects to push the plasma cloud in design, reminiscent of the Large hadron Collider, and then keep synthesizing plasma in a magnetic field long enough to reach the breakeven point and produce energy. They were able to achieve the necessary temperature and confinement of the plasma in a few milliseconds, and attract more than $ 500 million in venture capital.
Team Lockheed Martin Skunk Works, known for its secret projects, has made a splash in 2013, announcing that it is working on a compact fusion reactor producing 100 MW and having a size of a jet engine. At that time they said that the prototype will be ready in five years. Of course, the details of the design, they didn’t. In 2016, it was confirmed that the project gets funded, but many have lost faith and gained skepticism.
And against the background of all this ugliness MIT scientists rush to the ring. Bob Mumgaard, CEO of Commonwealth Fusion Energy, said: “We are aiming to get the working station in time to fight climate change. We think science, the speed and scale of the project will require fifteen years.”
New MIT project adheres to the design of the tokamak, as it did in the past. The device has a SPARC to produce 100 MW of power in 10-second pulses of confinement. To obtain the energy of the pulses was already possible before, but the break-even point — that is what really attracts scientists.
The special sauce in this case is a new high-temperature superconducting magnets made of oxide of yttrium-barium-copper. Given that WTSM can create a more powerful magnetic field at the same temperature as conventional magnets, you may have to compress the plasma with a smaller input power, less magnetic device and reach of synthesis conditions in the device, which is 65 times less than ITER. That’s the plan, anyway. They hope to create superconducting magnets for the next three years.
Scientists are optimistic: “Our strategy is to use conservative physics, based on decades of work at MIT and elsewhere,” said Martin Greenwald, Director of the Center for the science of plasma and fusion at the Massachusetts Institute of technology. “If SPARC will reach the expected performance, my gut tells me that it can be scaled up to a real power plant”.
There are many other projects and startups that similarly promise to circumvent all sorts of tokamaks and budgets of international collaborations. It’s hard to say if any of them have a secret ingredient for the synthesis or ITER, with his weight in the scientific community and supported by the countries that will win. And it’s still difficult to say when and if fusion will be the best source of energy. The synthesis is difficult. So history shows.