Fusion: A safer nuclear option

It is obvious that global efforts to combat climate change—that were agreed upon at the 21st Conference of Parties in Paris—have already gone off the rails. Subsequent conferences produced nothing but a long laundry list of unenforceable rules to cope with the rapidly changing climate that is forcing millions of people to lead cramped lives with other climate refugees in the slums of sweltering, shrinking continents.

Arguably, renewable energy is one of the most effective tools we have in the fight against climate change, and there is every reason to believe it will succeed, albeit partially only if we stop, or at least, cap fossil fuel emissions. Otherwise, we cannot simply bet on renewables to combat global warming.

Notwithstanding the remarkable growth due to technological advancements and huge cost improvements over the past decade, renewables, such as solar, wind, geothermal and tides, to name a few, are not available 24/7, year-round, everywhere. The sun does not shine at night or on cloudy or rainy days, and some days may be calm or less windy than others. Geothermal power plants cannot be built in places that do not have the right geological characteristics, while the energy carried by tidal surges can be utilised in coastal regions only, for a limited number of hours per day though.

That brings nuclear power, which generates huge amounts of electricity with zero emission of greenhouse gases, into the climate change equation. Yet, it is seen by many, and with good reason, as the misbegotten stepchild of nuclear weapon programmes.

What has given rise to our fears about nuclear power more than anything else are the accidents at Chernobyl in 1986 and Fukushima in 2011. The Fukushima disaster in particular has shattered the zero-risk myth of power reactors and heightened our concern about the invisibility of the added lethal component, nuclear radiation. These reactors entail substantial safety and security risks, waste disposal challenges and water requirements, too.

Nevertheless, scientists are reevaluating nuclear power as a possible solution to combat global warming. But they are not considering fission-based nuclear reactors that are used in power plants today. In fission reactions, a heavy nucleus, such as uranium, breaks up into two lighter fragments and two or three neutrons. The process is accompanied by the release of a large amount of energy.

Instead, scientists are actively engaged in developing safer nuclear power systems as one among several technologies that would not use the atmosphere as a waste basket. Specifically, they are focusing attention on nuclear fusion that would rekindle our trust in nuclear energy.

Nuclear fusion is a reaction in which two lighter nuclei, typically isotopes of hydrogen, combine together under conditions of extreme pressure and temperature to form a heavier nucleus, releasing energy in the process. Fusion has been powering the sun and stars since their formation. The energy released during fusion in the sun makes all life on earth possible.

The simplest way to replicate the primordial source of power on earth is via the fusion of deuterium and tritium. Deuterium is found aplenty in ocean water, enough to last for billions of years. Naturally occurring tritium is extremely rare, but it can be produced inside a reactor by neutron activation of lithium, found in brines, minerals and clays.

The appeal of fusion energy is enduring for several reasons. For equal mass, calculations indicate that fusing two nuclei in a controlled way would release nearly four million times more energy than burning fossil fuels and four times as much as nuclear fission reactions. Moreover, to run a 1,000 MW power plant with a fusion reactor, it is estimated that about 150kg of deuterium and three tonnes of lithium would be required per year, while the current fission reactors consume 25 to 30 tonnes of enriched uranium. A similar coal-fired power plant uses about three million tonnes of fuel. Clearly, gram for gram, fusion reactor wins the energy race hands down.

Unlike fission, fusion will have a low burden of radioactive waste. Fusion's by-product is helium, which is an inert, non-toxic, non-radioactive gas used to inflate balloons. In addition, a fusion power plant would not require transporting hazardous radioactive materials. Furthermore, because there is no "critical mass" required for fusion, the possibility of a "runaway" reaction that could result in a core meltdown—the most serious calamity possible in a fission reactor—is not an issue with fusion reactors.

Considerable amount of research on the development of reactors that would harness fusion energy is currently underway at several laboratories in the United States and around the world. However, the high cost of research and very expensive hardware limit most of the work to multinational consortia.

The 35-nation International Thermonuclear Experimental Reactor (ITER) project under construction at Cadarache in France is the world's largest fusion reactor. Launched in 2006, ITER has been beset with technical delays, labyrinthine decision-making and costs that have soared from an initial estimate of five billion euros to around 20 billion euros.

Despite the slow pace, construction of the project reached the halfway point last year. It is an important milestone for the multi-billion-euro facility, whose goal is to begin generating power on an experimental basis by 2025, although the technology to produce electricity commercially is likely many decades away.

Once fusion reactors become a reality, they would be an absolute game-changer in the sense that there will be a paradigm-shifting development in the global energy mix, thereby laying the groundwork for a clean energy revolution. As a source of non-hazardous, carbon-free energy, producing no long-lived radioactive waste, fusion will eventually make fossil-fuel-fired power plants and uranium-based nuclear facilities obsolete. More importantly, if we want to keep the lights on and the wheels of industries running while hardly producing greenhouse gases, nuclear fusion would provide sustainable energy on a nearly unlimited scale.

Finally, according to researchers at Columbia University in New York, in order to avoid disastrous effects of climate change, we have to reduce greenhouse gas emissions by at least six percent annually. They argue that "it's hard to see how we could conceivably accomplish this without nuclear."

Quamrul Haider is a Professor of Physics at Fordham University, New York. He is one of the authors of the book Nuclear Fusion ‒ One Noble Goal and a Variety of Scientific and Technological Challenges (IntechOpen, 2019, UK).

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