BBC News: Molten metal batteries for the grid

[Mike O'Dell]

most places with huge supermagnets actually
put the power back into the grid if they have
to shut the magnets down. the Heavy Ion Spectrometer
at LBL (eons ago now) had a big supermagnet and
whenever they did a shutdown, they put the power
back into grid.  It also had a "shunt" however.
if the magnet started to quench (aka "go normal")
the closed circuit of the magnet was broken
and shorted into a very large block of pig iron
which functioned as the load resistor to dump
the stored energy as heat. The guy I knew who
worked there said that their calculations indicated
that the block of iron would go white-hot almost
instantly, and that probably half of the iron block would
sublimate before it disappated enough energy
to start cooling down. They wanted to be nowhere
near that if it happened!

     -mo