It's generally a good idea to use "Thunder Dragon"'s effect as soon as you draw it. Your opponent will know what two of the cards in your hand are, but you don't risk drawing another "Thunder Dragon" on a later turn, effectively wasting both the draw and "Thunder Dragon"'s effect.
Running 3 of this card is useful in a "Batteryman" Deck, as they thin out the deck so you are more likely to draw the all important OTK cards you need. They are also good fodder for the effect of "Batteryman Industrial Strength".
Use this card to Special Summon "Lightray Grepher" from the hand, and use the second Thunder dragon to banish a monster from the deck.