Has anybody heard of this concept? http://www.sciencedaily.com/releases/2009/03/090311162807.htm Somebody seems to have now actually shown one in practice. A magnetic 'spin battery'. Can anyone tell me if this thing is supposed to be capable of greater energy storage density than a conventional chemical battery? Is it capable of even having greater energy storage density than a chemical fuel cell? What kind of energy density should it have, in Wh?