Does this achievement bring us nearer to deciphering the secret of this pristine energy?
Just a few days prior, the Korea Superconducting Tokamak Advanced Research (KSTAR) in South Korea shattered its own fusion record. The organization managed to maintain a temperature of 100 million degrees Celsius for an impressive 48 seconds! To put that into perspective, that’s 17,857 times more scorching than the Sun’s surface and almost 7 times hotter than the Sun’s core! KSTAR topped their previous 2021 achievement, where they held the same temperature, but only for 31 seconds. This represents a notable step forward. The lingering question, however, is, does this progression lead us nearer to tapping into the ultimate renewable energy source, nuclear fusion? The answer is a resounding yes; allow me to clarify.
Understanding fusion begins with recognizing its potential game-changing capabilities.
The energy source that fuels our Sun is none other than nuclear fusion. Within the Sun’s heart, the elevated pressures and extreme temperatures give hydrogen atoms the necessary kinetic energy to surmount the repulsive forces keeping them apart. Once they collide, they combine to form a larger helium atom. Interestingly, the helium atom weighs a little less than the sum of two hydrogen atoms. The leftover mass transforms into subatomic particles, which can’t exist independently and therefore convert into energy and disperse. If you recall Einstein’s iconic formula E=MC² from your physics lessons, you’ll understand that a minuscule amount of matter can result in a staggering amount of energy!
Hence, a single kilogram of hydrogen can yield a whopping 177,717 MWh of energy via fusion. This is 7.9 times more than what a kilogram of uranium-235 can generate through fission, and 14.8 million times more than a kilogram of gasoline can produce through combustion! However, unlike uranium or gasoline, fusion does not result in the production of radioactive waste or harmful emissions that contribute to climate change. The sole by-product is non-radioactive helium gas, which in itself holds value.
Picture this: if we successfully mimic the Sun, we could power the globe using immense quantities of readily available, carbon-neutral energy, generated from a few hundred tonnes of hydrogen annually.
However, it’s not as simple as it sounds. The complex fusion reactors we’ve developed so far consume more energy to spur fusion than they produce, making them ineffective energy sources.
Introducing KSTAR, a tokamak-style fusion reactor. It consists of a doughnut-shaped reaction chamber, roughly the size of a large automobile, encased by superconducting electromagnets. Hydrogen plasma is introduced into the chamber where it reacts to the magnetic fields. These magnets then heat up the plasma through induction (akin to how an induction stove warms pots) and compress it. But these magnets cannot replicate the intense pressure at the Sun’s core. Therefore, to achieve the kinetic energy required for fusion, the plasma temperature must far surpass that of the Sun’s core.
Managing plasma at such extreme temperatures in a limited space is an immensely challenging task. If not managed properly, plasma can inflict severe damage to the reactor shell and cause substantial energy loss through instability and turbulence. This could lead to a rapid cooling of the plasma, making it impossible to achieve a net energy gain.
So what’s the secret behind KSTAR’s breakthrough in achieving a fusion duration record? Over time, they have perfected their method of managing plasma and recently upgraded the reactor. The older carbon “divertors” were replaced with tungsten ones. Their role is crucial as they extract excess heat and unwanted byproducts from the reaction room. The tungsten divertors are more efficient than their carbon counterparts, helping to reduce heat on the reactor walls and extend the duration of the reactions without inflicting damage.
So, why is this significant?
KSTAR, in itself, will never generate a surplus of energy. Its size and power aren’t sufficient to create a “burning plasma” state, where one fusion reaction’s energy is maintained by the plasma, spurring further fusion reactions in a domino effect. This burning plasma state is crucial for these machines to yield a larger amount of energy per unit of energy invested. Nonetheless, KSTAR serves as a testing ground for ITER, which is currently being built in France and slated to become the world’s largest and most potent tokamak by a considerable margin. This enormous size and power potential could enable ITER to generate ten times more fusion energy than what’s required to operate it, thus making ITER a feasible energy source. To achieve this, however, it needs to sustain its reaction pulses for a sufficient time, and the recent achievements at KSTAR could bring ITER closer to becoming the first practical fusion power plant in the world.
However, the scientists at KSTAR are not done yet. They aim to maintain the reactor temperatures at 100 million Celsius for 300 seconds by 2026. Besides, ITER won’t begin full fusion operations until 2035. Therefore, it’s likely that we will witness more significant strides from KSTAR in the coming years, but the implications of these advancements on the fusion energy scene may not be understood for at least another decade.
