Benjamin Franklin flew a kite in a storm, in the movie Stardust you see a ship rigged to capture lightning. Obviously it's a helluva big discharge but perhaps our best scientists can spend a few dark and stormy nights doing some serious research. What do they say? There's enough energy in a single bolt of lightning to light up a whole city for a year?
My suggestion to get around the discharge issue, is that you immediately distribute from the lightning rod conductor into a capillary network of lines leading to a massive cellular structure of batteries. The object of the exercise is to conduct as much as possible, and store as much as possible. Hence you'll be needing ultrathick copper cables that unravel into hundreds of football field sized 'stations' filled with storage batteries.
That's the theory anyway. What has been done, in this field, is:
One strike has enough energy to light 150,000,000 light bulbs.
About 95 people die from lightning yearly in the U.S.
A single thunderstorm can release 470 million litres of water (that's the volume of 16 Washington Monuments).
One storm can discharge enough energy to supply the entire U.S. with electricity for 20 minutes
A large Midwestern cumulonimbus can tower 20-25 km (Mount Everest is 8.8 km high.)
There are approximately 2,000 thunderstorms at any given moment worldwide.
Or contact: Division for Electricity and Lightning Research, Uppsala University, Dept of Engineering Sciences