Nuclear scientists claim to have made a major breakthrough in fusion research.
Nuclear scientists claim to have made a major breakthrough in fusion research, with the energy return on energy invested reaching a new high of 154% — the previous record was 70%.
So what is nuclear fusion?
Fusion is the reaction that drives the energy production in the sun and indeed all stars in the universe. The basis of fusion is the conversion of mass into energy, much the same as nuclear fission. In fusion, two atomic nuclei merge to create a new element, and in the process shed some mass in the form of energy. In fission, one nucleus splits to create two new particles and also loses mass, which is released as energy.
It was Albert Einstein who first predicted that mass can be converted to energy, a discovery which led to nuclear weapons and nuclear power. The only problem is that it is extremely difficult to turn mass into energy. In some ways, this is just as well. If it was easy, all matter would quickly re-convert to energy and the universe could not exist.
Producing continuous energy from fission is a little easier than fusion, however. You need highly radioactive elements in close proximity and an initial trigger to start the reaction. This is what happens in a nuclear reactor. Fuel rods containing enriched uranium generate heat inside reactors for long periods.
Fission, however, also has its problems. In the first place, the uranium has to be mined and enriched. After the reaction is complete, the fuel rods contain large quantities of radioactive material that must be safely stored for several centuries. Nuclear waste is one reason that there is a strong anti-nuclear lobby. Nuclear power is a hazardous process with long-term environmental consequences.
Fusion, if it could be made to work, doesn’t share this problem. But fusion requires a temperature of at least 1-million degrees Kelvin (almost the same as Centigrade at this temperature). Generating such temperatures requires massive amounts of power and sophisticated engineering design. No materials can withstand such temperatures and the only way to contain a fusion reaction is for it to be suspended in space, surrounded only by electromagnetic radiation.
What is the new technological advance?
The new results have been achieved in the US National Ignition Facility in California. The facility uses a set of 192 giant X-ray lasers focused on a small gold cylinder containing deuterium and tritium, which are isotopes of hydrogen. The lasers instantly destroy the gold covering, heat up the deuterium/tritium mixture to about 3-million degrees Kelvin, and smash the atoms into each other, forming one atom of helium, releasing one neutron and generating a packet of energy.
The experiment in California released 3.15 megajoules (MJ) but required 2.05 MJ of laser power to drive the fusion reaction — hence the 54% net increase in energy. But this calculation ignores the 300 MJ required to warm up the lasers before the experiment could begin. If one includes this value, the equation is negative.
How excited should we get about this result?
We should not get excited in the least about the result. We have known in principle that fusion could be used to generate energy, otherwise there would be no sun and stars. Reproducing the conditions inside the sun on our little planet, however, is an almost impossible target. Yes, we can generate conditions of 5-million degrees Kelvin, and at a small scale with highly sophisticated equipment and a great deal of public funding, we can produce fusion reactions.
Scientists in this field are desperate to make some progress because the research is costing billions of dollars. So, announcements of this nature must be treated with some caution.
The other issue about nuclear energy research is that it has historically been an easy way to subsidise the development of nuclear weapons. The undisclosed agenda of superpowers in nuclear research has been bigger and better nuclear weapons, not necessarily abundant nuclear energy. Tackling the seemingly impossible, at a huge cost to the public purse, is more about the military strategy than it is about energy policy.
Public research budgets would be better spent on developing energy storage and renewable energy technologies, rather than on nuclear fusion. Seventy years of research on fusion has led to the unremarkable result that with a battery of high-powered X-ray lasers and 302.5 MJ of energy, it is possible to generate 3.15 MJ of heat, which must still be converted to electrical energy at a heat-to-electricity efficiency of perhaps 35%.
We should be using the abundance of energy already on the Earth’s surface in the form of waves, wind and solar, not dreaming of bringing the sun and the stars to us.