US scientists have released details of an experiment in nuclear fusion conducted in California that give hope for the possibility of almost limitless clean energy.

Researchers involved in the Nuclear Ignition Facility (NIF) at the Lawrence Livermore National Laboratory said that they have used 192 laser beams to compress a tiny fuel pellet less than half the diameter of a human hair in such a way that it triggered the net release of energy by nuclear fusion.

While welcoming the achievement, the body that represents the conventional nuclear power industry says perspective must be maintained, as the technology is at an early stage and nuclear fission should still be viewed as a true means of ensuring carbon emissions are effectively contained.
Nuclear fusion

While keen to point out that they represent the nuclear fission, rather than nuclear fusion industry, a World Nuclear Association spokesperson told Power Engineering International the world needed to maintain its focus on nuclear fission to ensure a low-carbon economy.

Dr Jonathan Cobb said, “The announcement is a positive next step for fusion. It is important to pursue research in all potential future energy technologies. But supplying electricity from fusion is still some way off and we need to make significant changes to our generation mix in the near term, using the full range of low carbon options we have available now, including nuclear fission.”

It is the latest in a 60-year series of studies aimed at harnessing the nuclear reactions that power the Sun, scientists say that they have for the first time managed to release more energy from their nuclear fusion experiment than they put into it, which marks a critical threshold in eventually achieving the goal of a self-sustaining nuclear-fusion reaction.

The ultimate goal – to produce more energy than the whole experiment consumes, which would later be used in nuclear fusion reactors – remains a long way off, but the feat has nonetheless raised hopes that after decades of setbacks, firm progress is finally being made.

The FT reports that fusion energy has the potential to become a radical alternative power source, with zero carbon emissions during operation and minimal waste, but the technical difficulties in demonstrating fusion in the laboratory have so far proved overwhelming. While existing nuclear reactors generate energy by splitting atoms into lighter particles, fusion reactors combine light atomic nuclei into heavier particles.

A spokesperson said that the latest improvement came by controlling the implosion of spherical pellets involved in the process more carefully. In previous experiments, the pellet distorted as it was crushed, which seemed to reduce the efficiency of the process.

Ultimately researchers need to get a hundred times more energy from the fusion reactions before the process can run itself, and more for it to deliver an overall surplus of energy.

The experimental fusion reactor Iter, which is being built in France, is expected to be the first plant to produce more energy than it consumes. The project has faced delays of more than two years and overrun budgets, but is still an international flagship for fusion research.

Nuclear fusion uses a fuel source derived from water and produces none of the more dangerous and long-lasting isotopes, such as enriched uranium and plutonium, that result from conventional nuclear power plants, which rely on the fission or splitting of atoms rather than their fusion.

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