Yeah, the first attempts to harness lightning weren't too successful, they were like the predecessor to the capacitor, it was called the layden jar, now if you could build one that was large enough, sure, you could possibly do it.
The layden jar is just what it say, it's a jar, on the inside are two pieces of foil surrounded by a thick insulator, when the foil had stored enough electricity in it, and the two contacts were touched to a conductor, BOOM! it would release them, however, if the insulator was too thick, and the jar charged to full capacity, it could easily jump the insulator, and hit you while you were carrying it.
This method is not a good idea.
So far there have been no good ideas on how to harness lightning, and there probably won't be any for several hundred years simply because it is difficult to contain that kind of raw power without being injured.