Fusion Energy: Present and Future

 

What is the source of energy of this vast, dynamic universe in which such enormous activity is taking place — billions of galaxies racing through space at tremendous speed, billions of stars within each galaxy, black holes, planets and moons revolving around stars — all held together by the invisible force of gravity? Where does this enormous amount of energy come from? By what process is this energy produced? If the answer must be given in one word, that answer is — fusion.

The universe runs on the energy continuously produced by fusion processes inside stars. In our solar system, the primary source of energy for all the planets is our Sun. Every second, the Sun radiates 3.8 × 10²⁶ joules of energy into space. Only about one two-billionth of that reaches the Earth. Is that small fraction enough for our planet? Let us do a simple calculation. At present, the total energy demand of the Earth is about 6.1 × 10²⁰ joules per year. The energy that reaches Earth from the Sun is about 1.7 × 10¹⁷ joules per second, which amounts to 6.12 × 10²⁰ joules in one hour. We can see that the amount of energy required to run all human activities on Earth for an entire year reaches our planet from the Sun in just one hour.

Then where does all the energy that reaches Earth from the Sun throughout the year go? About 30 percent of the energy absorbed by Earth is radiated back into space. The remaining 70 percent is consumed in driving natural processes. Energy is needed to sustain gravitational forces, to circulate the vast oceans, to produce clouds, rain, storms, cyclones and typhoons. All the phenomena that we call “natural processes” are powered by energy we receive from our star.

But what about the energy required for the daily activities of the eight billion humans and the countless (10²¹) other living beings on Earth — where does that energy come from? Stars produce energy through fusion. But planets do not generate such energy on their own. The inhabitants of a planet must obtain that energy by themselves. So far, no evidence of life has been found on any planet other than Earth. Therefore, leaving aside all other planets, let us focus on Earth — what is our energy demand, and how is it currently being met?

Before the age of science and technology began, humans and other living beings depended entirely on nature for their energy needs. Except for humans and some domesticated animals, all other animals are still completely dependent on nature. But as humans advance in science and technology, their energy demand keeps increasing, and to meet this demand they continue to invent newer methods of energy production.

At present, about 6 × 10²⁰ joules of energy are required each year to meet the needs of the Earth’s eight billion people. By 2050, this energy demand is expected to double. Currently, about 30 percent of this demand is met by liquid fuels (such as petroleum), 25 percent by coal, 25 percent by natural gas, and the remaining 20 percent by nuclear and other sources (such as solar, wind, and hydro power).

It is evident that 80 percent of total energy demand is being met by fossil fuels. However, fossil fuel reserves on Earth are rapidly declining and will eventually be exhausted. Not only that, but the pollution also caused by fossil fuels is seriously altering the Earth’s environment. Therefore, for many years now, there has been an ongoing search for alternative energy sources — sources that can provide enormous amounts of energy without causing pollution.

The acceptability of an energy source is mainly judged by five parameters: dependence on weather, amount of carbon dioxide emissions, availability of supply, amount of waste produced, and cost of production. Energy produced from fossil fuels — oil, gas, and coal — is not dependent on weather, but it produces large amounts of carbon dioxide, its supply is not unlimited, it generates a great deal of waste, and its production cost is also high.

The greatest weakness of fossil fuels is that by emitting large amounts of carbon dioxide, they cause severe environmental pollution. Therefore, efforts to find alternatives to fossil fuels have been underway for a long time, and electricity generation from alternative sources has been gradually increasing.

Among the alternative sources currently used to generate electricity are nuclear power, solar power, wind power, and hydro power. Although these do not emit carbon dioxide, their supply is not unlimited, and in many cases their production costs are quite high. Solar and wind power are completely weather-dependent. The greatest weaknesses of nuclear power are its high production cost and the complexity of managing radioactive waste.

In contrast to all of these, fusion energy alone can satisfy all the parameters of an acceptable energy source — if commercial production of fusion energy can be achieved with appropriate technology.

Producing fusion energy commercially — the same energy that powers the stars — is equivalent to creating a small artificial Sun. Remarkably, scientists have already made significant progress toward this goal. It is hoped that by around 2040, commercial production of fusion energy will be possible, at least on a limited scale.

Let us now look at the different stages of fusion energy production. As mentioned earlier, the process of producing fusion energy is like the process by which energy is produced inside the Sun. Let us first examine the fusion process that is continuously taking place in the Sun.

At the centre of the Sun, where fusion occurs, the temperature is about 15 million degrees Celsius. At such extremely high temperatures, all matter exists in the form of plasma. Within this plasma, one proton can combine with another proton. We should remember that in an environment of about fifteen million degrees Celsius, Coulomb’s law does not effectively prevent fusion — that is, like charges do not strongly repel each other — and therefore one proton can join with another proton.

A proton is a hydrogen nucleus, which contains no neutron. When two protons combine, one of the protons transforms into a neutron, and a positron and an electron neutrino are emitted. The hydrogen nucleus then contains one proton and one neutron. This isotope of hydrogen is called deuterium. The nucleus of deuterium is called a deuteron.

Next, in the continuing fusion process, this deuteron combines with another proton (hydrogen nucleus). As a result, the nucleus now contains two protons and one neutron, which is the isotope helium-3. Two such helium-3 isotopes then combine to form a helium-4 atom and release two protons (hydrogen nuclei). This proton–proton chain reaction continues continuously. Each time, about 12.9 million electron-volts (MeV) of energy is produced. Since fusion occurs billions upon billions of times simultaneously, an enormous amount of energy is generated every second.

Fusion is essentially a nuclear reaction. The energy is produced according to Einstein’s equation E = mc². When two nuclei fuse to form a new nucleus, the atomic mass of the new nucleus is slightly less than the sum of the individual masses of the original two nuclei. Although this mass difference is very small, when it is multiplied by the square of the speed of light, the resulting energy is enormous.

Fusion can occur in different ways with different nuclei. Some examples, along with the amount of energy produced in each reaction, are given below:

Fusion reaction	Energy produced
Deuterium + Deuterium → Tritium + Hydrogen	4.04 MeV
Deuterium + Deuterium → Helium-3 + Neutron	3.27 MeV
Deuterium + Tritium → Helium-4 + Neutron	17.6 MeV
Helium-3 + Helium-3 → Helium-4 + 2 Protons	12.9 MeV
Helium-3 + Lithium-6 → Hydrogen + 2 Helium-4	16.88 MeV

The fusion reaction between deuterium (D) and tritium (T) produces the largest amount of energy. Therefore, in artificial fusion, the D–T reaction is considered the most practical and advantageous to use.

The greatest challenge in producing fusion energy on Earth — in other words, creating an artificial Sun — is to reproduce in a laboratory or nuclear reactor the extreme conditions under which fusion occurs in the Sun.

Fusion Reactor:

A fusion reactor is designed in such a way that the nuclei of light atomic elements combine through nuclear fusion to form relatively heavier nuclei, producing fusion energy as a by-product of the process.

In the Sun, fusion reactions occur in plasma at temperatures of 15 million to 20 million degrees Celsius. However, maintaining continuous fusion at such temperatures on Earth is not possible. This is because the Sun’s enormous mass generates gravitational pressure billions of times higher than that on Earth, allowing plasma to form at relatively lower temperatures (15–20 million °C). On Earth, due to much lower atmospheric pressure, plasma suitable for fusion requires temperatures at least ten times higher than the Sun’s, i.e., around 100–150 million °C. Fusion reactors must be able to withstand such extreme temperatures.

Therefore, the first requirement for a fusion reactor is a large containment vessel made of materials capable of withstanding 100–150 million °C, where plasma can be confined for fusion reactions.

The reactor is supplied with deuterium–tritium plasma fuel. Deuterium is an isotope of hydrogen, naturally found in seawater — one deuterium atom occurs per roughly 6,500 hydrogen atoms. Deuterium is extracted from seawater as heavy water (deuterium oxide) via electrolysis. Tritium, however, is not naturally abundant and must be produced artificially. Fusion reactors generate tritium in situ using a lithium breeding blanket surrounding the plasma chamber. When fusion begins in the initial deuterium–tritium plasma, the neutrons produced as by-products react with lithium in the blanket, creating helium-4 nuclei and tritium, which then participates in subsequent fusion reactions with deuterium.

Another major technical challenge is containing the ultra-hot plasma and the energetic neutrons inside the fusion vessel. This challenge is primarily addressed in three ways:

1. Magnetic Confinement Fusion (MCF)
2. Inertial Confinement Fusion (ICF)
3. Magneto-Inertial Fusion (MIF)

In MCF reactors, plasma is confined using extremely strong magnetic fields. This method is particularly effective for deuterium–tritium fusion, and most large commercial fusion energy projects currently use this technique.

In ICF reactors, extremely powerful lasers or particle beams are used to compress and confine fusion fuel. Within nanoseconds, the plasma reaches temperatures exceeding 100 million °C. The fusion events caused by lasers at this scale can be compared to microscopic nuclear explosions. While this can be achieved on a small scale in the laboratory, large-scale implementation has not yet been realized.

MIF is essentially a hybrid of MCF and ICF, using magnetic fields to confine plasma while rapidly compressing it to create fusion conditions similar to ICF.

Fusion reactors also require the creation of ultra-strong magnetic fields, achievable using high-temperature superconducting magnets. This is challenging because magnetic strength decreases at high temperatures.

Raising the plasma temperature to 100 million °C and maintaining it is extremely difficult. Efforts include using high-frequency electromagnetic waves to create resonance inside plasma particles and using high-energy neutron flux to transfer energy to plasma as heat. However, producing temperatures ten times higher than the Sun and maintaining them is not easy. Experiments have successfully raised plasma temperatures to 100–200 million °C in test reactors, but the challenge remains to sustain these temperatures for longer durations.

Once plasma is heated and maintained, the next step is to confine the high-energy, fast-moving neutrons produced by fusion reactions. The inner walls of the reactor are lined with lithium breeding blankets, which serve dual purposes: they absorb the high-speed neutrons and react with them to produce tritium, which serves as fuel for the reactor.

Unwanted by-products and excess heat from fusion are removed and managed through divertors.

The superconducting magnets used to confine plasma must be kept at extremely low temperatures to remain functional. If the magnet temperature exceeds 4 K (−269 °C), superconductivity is lost. These magnets are isolated from the 100 million °C plasma using cryostats.

The energy generated by fusion is released primarily as heat, which is transferred via steam of water, helium, or carbon dioxide to large turbines, which then rotate to produce electricity.

Fusion Reactor – Tokamak

Although scientists have worked on several fusion reactor designs, the most effective and successful fusion reactor to date is the Tokamak. Tokamak was invented by scientists in the Soviet Union in the late 1950s. The original Russian word “Tokamak” stands for “Toroidal Chamber with Magnetic Coils.” In such reactors, plasma circulates in a donut-shaped (toroidal) path and is confined by magnetic fields, which is why these reactors are called Tokamaks.

In a Tokamak reactor, plasma is created by heating hydrogen gas. It is impossible to construct a metallic container that can hold plasma at 100 million °C. Therefore, the plasma is confined using high-strength magnetic fields. Most current and future fusion energy projects use Tokamak-type reactors.

 

Current and Future Fusion Energy Projects

ITER (International Thermonuclear Experimental Reactor)

The largest and most promising ongoing fusion energy project is the ITER. It is the world’s biggest fusion energy research project, involving many influential countries. The European Union, United States, Russia, China, India, Japan, and South Korea are funding ITER. The budget for planning, research, and construction is approximately €25 billion (~350,000 crore INR), though actual costs may be higher.

ITER is not a power plant — the electricity it generates will not be connected to any grid. The primary aim is to acquire the scientific knowledge and technical expertise needed for commercial fusion energy production. If successful, larger projects will follow to build the first generation of demo power plants.

Construction of ITER’s reactor in southern France began in 2000. By 2020, the main structural construction was completed. Installation of high-performance magnets, vacuum vessels, and cryostat support systems is ongoing. It is expected that within the next few years (2026–2028), the first plasma using pure deuterium will be created. By 2030–2035, the role of plasma in engineering-scale hydrogen–deuterium reactions will be tested. The target is to achieve deuterium–tritium fusion, tritium breeding, lithium blankets, and heat absorption experiments by 2040. Once ITER meets its objectives, the plan is to build a commercial demo fusion reactor between 2045 and 2050.

 

JET (Joint European Torus)

The JET project began in the late 1970s by a European fusion research team, aiming to create a large-scale deuterium–tritium Tokamak reactor. Construction started in the UK in 1983, and at that time, it was the largest fusion reactor project in the world. The first deuterium–tritium experiments took place in 1991, marking the first use of D–T fuel. Between 1990 and 2000, multiple experiments contributed significantly to plasma physics and the scientific and technological development of fusion reactors. Since 2009, fusion energy has been generated at a research scale at JET. The scientific data from JET continues to guide the design and progress of subsequent projects.

Apart from international and EU projects, Japan, China, and South Korea have launched their own projects. Japan started the JET-60 project in 1985, upgraded it in 2000 in collaboration with the EU as JET-60SA, testing high-performance plasma for commercial reactors. In the 1990s, South Korea launched the K-STAR (Korea Superconducting Tokamak Advanced Research) project, and in 2006, China initiated the EAST (Experimental Advanced Superconducting Tokamak), modelled after K-STAR. These projects test all aspects of reactor operations for fusion energy production.

Several private companies in the USA and Canada are also pursuing fusion energy projects. Many countries and organizations are moving forward to build demo fusion plants. For example:

• Canada’s General Fusion Plant plans a Magnetized Target Fusion Plant by 2030.
• China is developing the Chinese Fusion Engineering Demo Reactor (CFEDR) to serve as a technical bridge between experimental and commercial plants.
• EU’s DEMO project aims to produce 300–500 MW of fusion electricity.
• Germany’s Focused Energy is building a laser-controlled inertial fusion plant – Lighthouse.
• Israel is developing a compact modular fusion system producing 10–20 MW.
• Japan is building Fusion by Advanced Superconducting Tokamak (FAST) producing 50–100 MW.
• South Korea, Sweden, the UK, and Russia also have multiple fusion projects underway.

Given the rapid pace of research and engineering, commercial fusion energy production is expected to begin around 2050, providing virtually limitless, environmentally friendly energy. Humanity is essentially creating small artificial stars on Earth, bringing the power of the Sundown to the ground.

 

References:

1. Amir Shahzad (Ed.), Fusion Energy, Intech Open, London, 2020.
2. IAEA, World Fusion Outlook, Vienna, 2023, 2024, 2025.
3. Alain Becoulet, Star Power, MIT Press, 2021.
4. Bringing Fusion to the US Grid, National Academy Press, Washington DC, 2021.
5. iter.org
6. Professor Lucy Green, Fifteen Million Degrees, Penguin Books, 2017.