One of the issues that I have with fusion enthusiasts is that they obscure the truth about the fuel that they plan to use. When talking about the potential for fusion to supply the world’s energy needs, they often talk about using hydrogen and point out that it is the most abundant element on the planet.
My problem with that statement is that the fusion reactors that are currently being envisioned actually use two isotopes of hydrogen – deuterium and tritium – that are somewhat (please note the sarcasm) less abundant.
Deuterium is a stable isotope that makes up a fixed 0.015% (1 atom in 6500 atoms) of natural hydrogen. It is produced in a rather energy intensive industrial process normally located in areas with very inexpensive sources of power – generally large hydroelectric dams.
Tritium is a radioactive isotope with a half-life of 12.3 years that is produced in small quantities in the upper atmosphere due to interaction of cosmic radiation with water molecules. It can be artificially produced using several different techniques here on Earth, but its production is rather carefully controlled and monitored since it is a useful component in certain kinds of nuclear weapons.
Don’t get me wrong – I think that tritium is an exceedingly useful isotope with incredible commercial potential, but I would rather see it be used in small, distributed, high value energy applications.
As it decays at its steady and predictable rate, tritium releases low energy particles. In the nuclear lexicon, these particles are called “beta minus” particles, but an electrical engineer would call them electrons. In what is the realization of a long time dream – slowed over the years by some bureaucrats concerned about regulating the isotope – engineers have devised some ways to directly convert those particles into useful electricity.
BetaBatteries, described in detail on the Science Blog could be used in a number of exciting and profitable applications. Imagine the possibility of a laptop battery that could produce power for many years – after all, tritium takes 12.3 years of steady decay before its power output drops in half.