Whilst present future-energy discussions are consumed by a locked-in back and forth between proponents of “renewables” and “fossil fuels,” nuclear energy has faded into the background. This is unfortunate as one of the most promising energy developments, nuclear fusion, is being consistently overlooked or dismissed as too far-flung and fanciful.
Nuclear fission is the process utilized at contemporary nuclear facilities whether LWRs or HWRs, fast-breeders or graphite moderated, wherein a uranium atom is split, releasing a tremendous amount of energy and a significant amount of nuclear by-product which decays slowly. In contradistinction to fission, nuclear fusion merges hydrogen atoms together into helium atoms and generates larger amounts of energy than fission and also generates a large amount of by-product which decays rapidly. Fusion is the process by which stars (such as our sun) generate energy. Whilst fusion is easy in a solar body as massive as the sun, due to the extreme pressure and heat, it is very difficult to recreate on earth.
Some of the most promising means of recreating the internal conditions of a star were achieved via the creation and utilization of tokamak reactors (the word “tokamak” comes from a Russian science abbreviation). Tokamak reactors differ markedly from traditional nuclear fission reactors in terms of their design which features a doughnut shaped apparatus (torus) that houses deuterium and tritium (heavy and super-heavy hydrogen isotopes) which are then meant to be heated to 100+ million degrees Celsius via electric currents within the apparatus. At such high temperatures the electrons are stripped off of the atoms and generate charged hydrogen plasma. Magnets within the tokamak reactor constrain the plasma to a small area which both keeps it from melting the machine-interior (because no known material can withstand such high temperatures) and increases the chances of hydrogen ions fusing and giving off more energy. The energy generated by this process can then be used to turn water to steam and power turbines to generate electricity.
One of the most well known tokamak reactors in the world is China’s EAST (Experimental Advanced Superconducting Tokamak), located in Hefei; the first reactor in the world to utilize super-conducting toroidal (parallel to lines of latitude) and poloidal (towards the poles) magnets. EAST has been able to achieve temperatures of 50 million Celsius for 102 seconds, the device was also able to sustain plasma for over 100 seconds (a world record at the time of achievement in 2017). Later, the EAST reactor was able to achieve temperatures of 100 million Celsius, the ideal temperature range for the technology.
EAST’s success is the culmination of over 12 years of intensive research and planning as researchers from China’s Hefei Institute of Physical Science have been attempting to achieve nuclear fusion since 2006.
A large collaborative project (of which China is a member) known as the ITER (International Thermonuclear Experimental Reactor) is slated for testing 2027 in the south of France and is designed and expected to produce 10 times the number of energy utilized to power it which, if successful, will be the very first tokamak reactor to output more power than was put into the system.
Whilst even the most impressive tokamaks, such as EAST, to date, cannot output more energy than is put into them, the fact that they can generate charged plasma and increasing densities is extremely promising. However, tokamak reactors are not the only configurations being developed in the pursuit of nuclear fusion. Another promising reactor design purposed for nuclear fusion are known as stellarators (from the latin for star) and were first envisioned by the American theoretical physicist Lyman S. Spitzer Jr. Unlike tokamaks, stellarator reactors feature a modified torus which allows for better sustained plasma via the utilization of computationally modeled magnetic fields (to better direct and contain the plasma). One of the world’s most advanced stellarators is the Wendelstein 7-X of the Max Plank Institute For Plasma Physics of Greifswald, Germany. The Wendelstein has been able to sustain plasma for up to 26 seconds which is quite impressive given that a few years ago the public was astounded when plasma was sustain for less than a second. The rate of advancement in system enhancement bodes well.
Another vector of research is laser fusion wherein extremely short bursts of high powered lasers are used to achieve the high-temperature and pressure scenarios required for fusion via the hyper-compression of hydrogen isotopes which then fuses into helium and releases high-energy neutrons. A vexing consequence of this process (when utilizing deuterium and tritium) is the creation of neutron radiation. A alternative laser fusion method at the University of South Wales utilizes normal hydrogen protons and boron 11. Hydrogen-boron (HB11) fusion is fascinating because it produces very, very low levels of radioactivity; in fact the radioactivity levels are lower even than those generated by coal production. That’s extremely promising. But then the obvious question: How far away are any of these technologies from a fully functional, generously outputting fusion reactor?
According to ITER Director General Bernard Bigot, “The ITER project is very much on track. By the second half of this century this fusion technology will be available.” Others say development will take slightly longer, others, sooner. No one knows precisely, but what everyone can say for certain is that the technologies are progressing rapidly as both EAST and 7-X aptly demonstrate. In place of a “green” future we should be angling – championing – for a future far brighter, wherein the stars are not only ours to own, but ours to emulate and control.
- A. Dinklage. (2018) Magnetic configuration effects on the Wendelstein 7-X stellarator. Nature.
- Alex Epstein. (2016) Why Green Energy Means No Energy. Forbes.
- V. Gulati. (2018) How Far Are We From Commercial Fusion Energy? Yahoo News.
- WNN. (2018) Renewables experience could benefit US SMR deployment. World Nuclear News.