ITER: Pursuing the Sun on Earth. The challenge of nuclear fusion
The Sun, that incandescent star shining in our skies, is the beating heart of our existence. Its energy is the fundamental pillar that allows life to thrive on our planet. From the growth of the plants that nourish us to the regulation of the climate that shelters us, its influence is omnipresent and vital, ensuring the balance and diversity of terrestrial and marine ecosystems.
Have you ever wondered how much energy we receive from the Sun in a day?
Every square meter of land bathed in its light receives an irradiation of 1.36 kilowatts (kW). At first glance, it seems astonishing, but it is merely a tiny fraction of the colossal energy the Sun releases per square meter — an astounding 6400 kW. There lies our challenge: to unveil the mystery behind the prodigious source of solar energy and replicate it here on Earth.
But where does the energy the Sun emits with such intensity come from?
The Sun is primarily composed of hydrogen and helium. Inside, temperatures reach astounding levels, causing hydrogen atoms to lose their electrons and transform into a state of matter called plasma. In this frenetic stage, electrons and protons move energetically and unrestricted through space.
But here comes the wonder: these hydrogen nuclei engage in a cosmic ballet, fusing together to form new helium atoms. This magical process releases a tremendous amount of energy, the same light and heat that reach us. Every second, the Sun astonishingly transforms approximately 564 million tons of hydrogen into 560 million tons of helium. It’s like a fabulous stellar factory converting matter into energy on an inconceivable scale!
In fact, nearly four million tons of matter are converted into solar energy every second. And the incredible thing is that only a small fraction of this energy reaches our planet.
With hydrogen so abundant and helium so harmless here on Earth: Can we imitate the stars and recreate a similar source of energy on Earth?
The conditions inside the Sun are incredibly complex to replicate on Earth, requiring high pressure and temperature. But there is a way to achieve plasma hot enough to undergo fusion, and this is what the International Thermonuclear Experimental Reactor (ITER) in Cadarache, France, is striving to do.
ITER — an acronym that also means “the way” in Latin — is not intended to generate electricity but to demonstrate the viability of fusion. The goal is to surpass the threshold where a reactor releases as much energy through fusion as it needs to heat the plasma.
10 Times Hotter Than the Sun
In the Sun, nuclear fusion is driven by immense gravitational force. However, in the ITER, the aim is to demonstrate that it is possible to confine atomic nuclei using magnetic fields and force them to fuse.
To achieve this, a donut-shaped device called a tokamak is employed, injecting a few grams of the two necessary ingredients: tritium and deuterium, both isotopes of hydrogen. These atoms are accelerated by magnetic fields until they become plasma, separating from the electrons and reaching an astounding temperature of up to 150 million degrees Celsius. The high temperature enables the fusion of the nuclei. During this process, helium atoms are generated, and a tremendous amount of energy is released, which is used to heat water and rotate a turbine, ultimately generating electricity.
A Global Project
ITER is an unparalleled project that has brought together 35 countries, including the European Union, China, the United States, Russia, India, Japan, and South Korea, in a historic collaboration. This unity of efforts is crucial, as nuclear fusion is a challenge that demands scientific, human, technical, industrial, and financial resources on an unprecedented scale.
Fusion or fission?
It is essential to differentiate fusion energy from the fission that occurs in nuclear power plants using radioactive uranium or plutonium. Fusion is a completely safe and clean reaction. The main risk lies in the possibility of a tritium leak, a radioactive element with a half-life of 12.3 years, much shorter than the waste from conventional fission plants. To ensure the containment of tritium, various physical barriers and auxiliary techniques are employed.
The challenge of nuclear fusion
ITER is extraordinary but not without its drawbacks. Its construction is expensive, slow, difficult, and with no guarantees of success. The project has been underway since 1980 and has cost 20 billion euros, with the schedule to test first plasma in 2025 and full fusion in 2035.
Its success could revolutionize our approach to obtaining energy and provide a sustainable solution to future energy challenges. Just like the historic Apollo lunar mission, ITER symbolizes the transformative potential of science and technology when combined with political and social commitment. It is a powerful reminder that, as a society, we must unite to address global issues and achieve a brighter and more sustainable energy future for generations to come.