One hour of sunlight has enough strength to supply Earth with energy for a full year. Why is the sun's light so powerful? Because it stems from a reaction called nuclear fusion.
This process, which has the potential to generate eternal energy, is considered to be the sacred city of the energy industry, and several world's brightest minds must develop it.
In an interview with the BBC in late 2016, the famous British physicist Stephen Havking, who died last March, said the technology that allows the generation of nuclear fusion is the most dangerous for humanity.
"I would like to see the development of fusion energy"he replied, advising on the idea that can most transform our society.
"Nuclear fusion would be a source of practical energy that would give us an inexhaustible amount of energy without pollution or global warming," he said.
Unlike traditional nuclear energy, which is generated by the separation of atoms – a process known as fission – this new source of energy is created by fusion – that is, by connecting – atoms.
More specifically, it connects hydrogen to the production of helium, a reaction that releases huge amounts of energy, just as it happens on the Sun.
The idea is essentially creating a "micro" on Earth.
The race to reach the Holy Grail
Today they have them more than 25 private ventures dedicated to this goal, several of them were funded by some of the most famous entrepreneurs on the planet, such as Bill Gates (Microsoft), Jeff Bezos (Amazon) and Peter Thiel (PaiPal).
The first private project was Tri-Alpha Energi (or TAE Technologies), headquartered in California, USA, which has been in existence for two decades.
One of his most famous investors was Microsoft's co-founder, Paul Allen, who died last October.
Difficulties in this sector are Commonwealth Fusion Systems, a startup founded by six professors from the prestigious Massachusetts Institute of Technology (MIT).
Although it was created just a year ago, it is considered to be one of the most ambitious projects as it aims to create a reactor prototype for 2025.
Gates and Bezos are two of those who fund this venture, along with other renowned entrepreneurs like Richard Branson and Michael Bloomberg.
Too some oil companies are beginning to lap in the future without fossil fuels. According to the Bloomberg agency, Italian Eni SpA led a group that invested $ 50 million in Commonwealth Fusion Systems in March.
But some experts believe that a project that most likely goes ahead is not in the private sector.
It's a call International Thermonuclear Experimental Reactor (ITER, for its acronym in English), which was built in Cadarache, in the south of France, with a budget of $ 23,000 million.
In this scientific experiment, 35 countries collaborated, which began more than three decades ago.
Those who are responsible for estimating ITER that by 2050 will be ready a large-scale reactor.
Some countries are also developing their own initiatives. Last April, the BBC could access facilities in Anhui Province, China, where scientists from that country claim to be more advanced than their peers in the USA, the European Union (EU), Japan, South Korea and Brazil.
But all of these projects are facing the same problem, which is an unusual way of achieving nuclear fusion.
It's a big challenge how to generate more energy than it is spent in the process.
The fusion is based on heat substances at very high temperatures, which exceed hundreds of millions of degrees. In this state, matter is called plasma.
Unlike the Sun, the Earth has no conditions to keep the plasma warm. In order to achieve this, plasma must be isolated from other materials. For this, some special ring shaped camerasawith Tokamak.
Tokamak They use powerful magnets to create a magnetic field that maintains plasma isolation. The problem is that today these cameras consume more energy than they can produce.
The solutions that companies have highlighted, such as Commonwealth Fusion Systems, is using a better magnet, but the truth is that no one has managed to overcome this big obstacle.
Some like Tesla's creator, Elon Muska, believe that it would be necessary to invest in creating better solar panels and batteries to catch the Sun's energy, instead of wasting money trying to reproduce our star.
However, the IP Group Plc investor told Bloomerg that although the fusion energy lasts longer than it wants to develop, many innovations created for this industry They are proving to be very lucrative.
"Research companies patented many of their creations, from software that simulates plasma burning to 150 million degrees Celsius to a new type of magnet that has medical applications," reports Bloomberg.
In the meantime, we will have to wait to know if Professor Havking's desire for unlimited and clean energy can be achieved.