Many of the most important scientific achievements throughout history seem obvious in retrospect. It is easy to overlook how much time and effort went into developing a scientific discovery before someone finally found a way to make it work. Of course, there were many times when an inventor or scientist spent years trying to find a solution that was never discovered.
The quest for fusion energy is one such example. Scientists have been working on developing fusion energy for more than 60 years, and it is only in the past few years that they have made significant progress. So what is fusion energy, and why has it been so difficult to achieve?
Fusion energy is created when two lighter atomic nuclei collide and fuse together to create a heavier nucleus. This process releases a tremendous amount of energy, which is why fusion is seen as a potential source of clean and sustainable energy. The problem is that fusion reactions are very difficult to achieve, and scientists have yet to find a way to do it in a controlled setting.
Progress has been made in recent years, however, and it is possible that the first commercially available fusion energy systems will be available in 10 to 20 years. To better understand what options scientists are pursuing, it is helpful to consider how fusion energy works.
Hydrogen Fusion
Scientists believe that achieving fusion requires heating gas to high temperatures so that its atoms collide with enough force and at fast enough speeds for them to fuse together. The easiest atom to collide in this way is hydrogen since it only has one proton and therefore only needs to overcome the electromagnetic force that tries to push protons apart.
Hydrogen fusion requires a tremendous amount of energy in order to work because each atom carries an electric charge and needs extra energy to push it close enough to another atom so that they can fuse. This is why heating the fuel to high temperatures is such a challenge.
The simplest way to heat hydrogen atoms is by using very high voltages to accelerate them and collide them with atoms in a metal target, creating an electric current. The problem with this method of fusion is that it takes as much energy to push the ions through the electric grid as it does to heat them up and allow them to fuse.
Another method of heating hydrogen is to use a laser aimed at a solid target or a beam of high-energy electrons, but these approaches also seem unlikely to lead to commercially available fusion energy systems in the near future. Scientists are now focusing more of their efforts on a method called inertial confinement fusion, which involves heating hydrogen atoms to very high temperatures with powerful lasers.
Inertial Confinement Fusion
In order to generate fusion energy from lasers, scientists have to create a target that is evaporated by the beam in a process known as ablation. In this case, a laser would heat hydrogen atoms in a pellet to the point where they would fuse together.
The problem with this approach is that there are many different pellets made from different materials, each of which will react differently when heated. Scientists believe they can overcome this problem by heating all of the pellets at the same time, making it more likely that some pellets will reach the required temperature for fusion to take place.
Another challenge is that the lasers need to be very precise in order to heat the pellets evenly. If the laser is too powerful, it will blow the pellet apart before fusion can take place. If it is not powerful enough, the pellet will not reach the required temperature.
Scientists are still working on this approach, but they have been able to create fusion using inertial confinement techniques. In 2008 for example, a laser at the Lawrence Livermore National Laboratory in California fused two pellets together . However, these experiments had very little success with actually creating a self-sustaining fusion reaction that continues indefinitely.
As a result, scientists are still trying to find a way to create a fusion reaction that is both efficient and self-sustaining. While there are many challenges that still need to be overcome, the potential for fusion energy to provide a clean and sustainable source of power is very high.