They skeptics here are right to be skeptical.
An average keyboard key takes 55g of downward force to press and has 4mm of travel. Say you can sustain a rate of 30 wpm for an hour–that’s 9,000 keystrokes per hour. I’ll let Mashable’s very smart readers do the math on their own (Wolfram|Alpha helps), but that comes out to 0.00052 watts your fingers are transferring to the keys. For comparison, the 11″ MacBook Air draws 35 watts from its battery. In order to match that you’d have to type more than two million words, or nearly four copies of War and Peace, every minute.