What is nuclear fusion and why it shouldn’t help right now in the climate crisis – 11/17/2021 – The science

The next leap in human civilization may be in the stars. More specifically in the field of stellar energy: a nuclear fusion.

Fusion, for its ability to generate huge amounts of clean energy, brings hope that countries will no longer rely on it in the future Fossil fuels for power generation.

The problem in the previous paragraph is in one word: the future. Humanity cannot immediately rely – given the current technological stage, even in the medium term – on this energy source to deal with The current climate crisis on Earth.

Nuclear fusion occurs when two hydrogen nuclei fuse to form a helium atom. It is worth noting here: do not confuse integration nuclear fission, which is used in nuclear power plants and consists, as the name implies, from the collision of two atoms so that they “break”.

If a human is capable of ‘breaking down’, the fusion method should already be known, right?

right. The problem is with practice and control, on Earth, with the reactions that occur in the stars.

Fusion is only possible when the particles are at extremely high temperatures – to the point of forming plasma, the fourth state of matter, an ionized gas – under high pressure. This is because the protons (which are in the nucleus one wants to collide with) repel each other. To collect them and fuse them together, just under extreme conditions, like millions of degrees Celsius inside a fusion reactor.

But when the union works and helium is formed, large amounts of energy are produced, which in turn can serve the energy thirst of man.

Currently, we are able to produce fusion, but there are a number of issues that prevent it from being used for commercial energy production.

“The biggest problem is that you don’t generate more energy than you consume,” says Vinicius Njeim Duarte, a researcher in the Plasma Physics Laboratory at Princeton University in the US. In other words, the energy used to run fusion reactors is greater than the energy generated in the reaction.

In August of this year, scientists were able to fuse, producing 10 quadrillion watts, into a point the size of a human hair, for every 100 trillion milliseconds. To do this, they bombarded a hydrogen plate with more than a hundred lasers.

But Najim Duarte cautions that this specific initiative has no energy purpose. The purpose of the Lawrence Livermore National Laboratory at the National Ignition Facility in the United States is a military program, in search of new weapons.

But, returning to peaceful applications, another problem is the lack of time in which researchers can maintain reaction. For large-scale power generation, of course, it would be necessary for the process to be more permanent.

In June of this year, the East China Reactor (Experimental Advanced Superconducting Tokamak) announced that it had set a record: maintaining plasma flow for 101 seconds at 120 million degrees Celsius.

Besides the issue of time, there is also the problem of the raw material for plasma. Two isotopes of hydrogen are needed, deuterium and tritium.

Deuterium is an isotope that is widely available in Earth’s oceans. According to the researcher at Princeton University, the reservoir is almost inexhaustible. But tritium practically does not exist.

“There is no longer any tritium in nature, anywhere in the universe,” says Gustavo Canal, a University of the South Pacific researcher in the Plasma Physics Laboratory. The element is radioactive and has a half-life (generally, the time it takes for an amount of a substance to decay by half) of only 12 years.

To produce tritium, it is necessary to bombard lithium with neutrons, an additional step in energy production from fusion.

‘Very high’, ‘huge’, ‘millions’, ‘Quadlions’ stuff, nonexistent stuff. The descriptions give an idea of ​​the level of complexity of the process. And with the nuclear accidents that have characterized the past few decades, swear descriptions can also sound like a warning of the dangers.

But in addition to promising clean energy, the merger brings with it a guarantee of safety, experts say.

Any problem with the process, contrary to what one might imagine from experience with many superlatives, will only interrupt the complex interaction.

tokamak

Fusion is now typically developed in machines known as tokamak. It is where the heat and magnetic fields in the vacuum conduct a soup of deuterium and lithium, preventing the particles from colliding with the walls.

When fusion occurs, the neutrons are liberated, and yes, they must collide with walls. The energy in this shock is converted into heat, which heats the water, which in turn evaporates and turns the turbines, which then generate electrical energy – mechanisms already used in thermal power plants.

There are other machines with different tokamak settings, but the essence is the same.

The test, perhaps final, of the viability of fusion for energy production is almost ready in France, thanks to a group of more than 30 countries looking for the way. “The Way” in Latin: Iter.

NS Colossal Tokamak EaterAt a cost of about US$20 billion, it has big ambitions: to be the first in which fusion produces more energy than it consumes and the first to operate for long periods, two of the problems mentioned above.

Joint international action to implement the project, which began in the Cold War plans for cooperation between the United States and the Soviet Union, ends, in the current scenario, finding an echo in the global efforts of countries – which should at least happen – to contain the climate of crisis.

Logically, the tokamak structure also needs to withstand the hurdle of nuclear fusion. This is where another problem comes into play: developing materials that are sufficiently resistant.

Duarte compares the runner inside a fusion reactor to a spacecraft re-entering the atmosphere. “The shuttle’s nose is small and only needs to withstand the bombardment of particles for a few seconds. ITER has to withstand twice the bombardment per hour, and for years.”

It doesn’t stop there. During fusion, instabilities occur that generate filaments at the edges of the plasma, ELMs (Edge-Localized Mode). Canale, who studies this exact phenomenon and is looking for answers to the tokamak problem at the University of the South Pacific, says something similar would be solar eruptions.

If the bombardment inside the tokamak is already too intense in a normal fusion process, ELM can take the situation to unimaginable levels.

“We’re working with the maximum amount of materials that we know of,” Kanall says. “During ELM, the value of bombardment goes up exponentially, it’s an order of magnitude higher than what the material supports.”

ITER is already 75% ready, and the first plasmas should run through the device as early as 2025, if expectations hold.

Although all this technology looks like a distant future, the Princeton researcher notes that there is already enough private money being invested in the merger, suggesting that the strongest results may be closer than he imagines. Among the merged investors are Google, Bill Gates NS Jeff Bezos.

“Developed countries have realized that the future is integration,” the researcher from the University of the South Pacific continues, referring to the state’s investments in the region. The channel also says that, within Brazil, it is seeking partnerships with companies to support the national integration project.

“The field of fusion will be a milestone in civilization,” Duarte sums up, although clean energy, he reasoned, would not be enough to solve all of the world’s problems.