Nuclear fusion energy: A few more miles to go

Experiments have been successful in achieving a break-even in fusion reaction, charting a path to commercialise the technology, writes B K Singh

Scientists have been working in labs for decades to develop nuclear fusion reactors. When fusion energy is available, the burning of fossil fuels will stop. Generating clean energy through nuclear fusion reactors, which is safe, abundant and free from radioactive risk, has been a pipedream until now.

California-based Lawrence Livermore National Laboratory (LLNL) has observed “net energy gain” in fusion experiments, according to a study published recently in Physical Review Letters. For the first time, there is a technology to help nuclear fusion reactions produce more energy than they consume to maintain temperature and pressure.

Nuclear fusion and fission are nuclear reactions in which the binding energy of protons and neutrons in atomic nuclei is utilised, and an enormous amount of energy is released. In fission reactions, a heavier and unstable nucleus splits into two smaller nuclei, while in fusion reactions, two lighter nuclei combine to form a heavier one.

Thus, nuclear fusion is a reaction in which two or more atomic nuclei, usually deuterium and tritium (both isotopes of hydrogen), combine to form one or more atomic nuclei, neutron and proton. The difference in mass between reactants and products is manifested in the absorption/ release of energy, also called nuclear binding energy. When deuterium and tritium nuclei fuse, helium is formed, and a tremendous amount of binding energy is released. Fusion reaction has been powering the sun and stars for billions of years.

For nearly three-quarters of a century, power has been commercially generated from fission-based power plants. Nearly 10% of the world’s power is generated from nearly 440 reactors in 50 countries.

India has several nuclear power plants that contribute substantially to the power grid. India’s share of power from nuclear fission reactors is 2%. More than 30% of global nuclear power is generated in the United States. Power generated from fission-related power plants is also carbon-free, but it carries radioactive risk. India currently generates 7500 MW of nuclear power.

The isotope of Uranium (U235), when bombarded by neutron radiation, splits in Barium (Ba), Krypton (Kr) and more neutron radiation, which has the potential to excite the isotope of Uranium and continue the chain reaction. Enormous energy is released in each reaction. 235 is the mass number of the isotope of Uranium—the sum of the number of protons and neutrons in its nucleus. The energy released from fission reactions is utilised to boil water and generate steam, which helps run the turbine and generate electricity.

The radioactive isotopes of Barium, Krypton, and Uranium, byproducts of fission reactions, need special disposal facilities and can remain radioactive for thousands of years. Any accident can release radioactive materials into the environment, causing human health hazards. In a densely populated country like India, the establishment of nuclear fission reactors is questioned by the masses, fearing accidents from nuclear waste.

Scientists have had the challenge of generating and maintaining the high pressure and temperature required for fusion reactions. Now, scientists have succeeded in gaining net energy through fusion reactions. When the operation is commercialised, carbon-free electricity will be generated.

Unlike fission reactors that can be located at the source of radioactive substances such as Uranium, Thorium etc, fusion reactors can be located anywhere. The other advantage of fusion reactors is that we will be free from radioactive risk.

Though LLNL uses high temperatures of millions of degrees Celsius, some electrochemists have attempted fusion at room temperature, which yielded byproducts like neutrons and tritium with electrolysis of heavy water on the surface of the Palladium electrode. But we have yet to achieve this at room temperature.

However, LLNL pursued the concept for over two decades by building a series of laser systems in an area equivalent to the size of a sports field. This led to the creation of the National Ignition Facility (NIF), which generates powerful laser beams that create temperature and pressure like those in the cores of stars and exploding nuclear weapons.

The nuclear fusion race among scientists is also becoming competitive. Instead of using laser technology, scientists working in Oxford have deployed magnets strong enough to lift an aircraft carrier to control streams of plasma flow. In 2021, they generated a record-breaking amount of sustained energy for five seconds. Plasma can tear and escape the machine’s powerful magnetic field. Princeton’s Plasma Physics laboratory has found a way to use artificial intelligence to fix this instability.

Nevertheless, fusion technology has attracted investments from sovereign wealth funds, national development banks, venture capitals, and business houses like Jeff Bezos, Bill Gates, Peter Thiel, etc. Though the fusion industry attracted $2 billion in the last decade, last year’s investment alone was $2.8 billion.

Private players to run the show

In India state-run Nuclear Power Corporation of India Ltd (NPCIL) is pursuing private investors like Tata Power Adani Power Vedanta Reliance Industries etc for an investment of Rs 44000 crore in the sector for an additional 11000 MW capacities by 2040. Under Indian laws the right to build and run these plants vests with NPCIL but creating infrastructure outside the reactor premise and selling electricity would be done by private entities and NPCIL would manage the plant for a fee.

(The author is a retired Principal Chief Conservator of Forests (Head of Forest Force), Karnataka and a physics post-graduate)