It is said that when something is too good to be true, it often is. In the case of a new type of notebook battery touted to last decades, new technology promises to uproot all conventional energy storage, but just how practical is it?
Internet publication Next
Energy News ran a story earlier this week claiming a betavoltaic batteries are in development, and will run tomorrow's notebooks 30 years without replacement or recharging.
The betavoltaic battery works similarly to solar cells. However, instead of generating electricity when photons strike a substrate, betavolatic batteries generate power from using high-energy electrons generated by the decay of a
radioisotope, in this case reported to be tritium.
As the radioisotope decays, beta particles are emitted that
strike an interface layer between two layers of material generating a useful
electrical current. The power in the battery will decrease proportional to the
half-life of the radioisotope. While the battery uses radioactive materials, it
would produce no radiation and when exhausted would be an inert mass easily
disposed of.
Rupert Goodwins of ZDNET
UK says in short that the entire betavoltaic battery story is simply off
the mark. Goodwins says in his column, “One [problem] is that the sort of
atomic structures that generate power when bombarded with high energy electrons
are the sort that tend to fall apart when bombarded with high energy
electrons.”
Goodwins also says that while eventually the tritium battery
will turn into a safe lump of stuff, if you break the battery open during its
life all the radioactive, presumably toxic, materials will spill out. The Next
Energy News story says, “The reaction is non-thermal which means laptops and
other small devices like mobile phones will run much cooler than with
traditional lithium-ion power batteries.”
This particular claim is totally refuted by Goodwins
stating, “[Betavoltaic batteries] don’t have a great conversion efficiency.
Around 25 percent is the best you can get -- which is pretty good, but leaves 75
percent sloshing around as heat. That means a 25 Watt battery will get plenty
warm.”
Goodwins goes on to liken the heat output from a tritium battery to that
of a 60-watt light bulb. Certainly more heat than any person interested in
usable genitalia wants sitting on their laps.
Another big issue Goodwins says is that betavoltaic
batteries just don’t work that well, they can only output about 5-watts per
kilo, which means they would need to be 72 times heavier than the battery in
your notebook right now.
As good as betavoltaic batteries sounded in the
beginning, fuel cells are still more likely to replace batteries in our notebooks.