One man's green energy is another man's child abuse: New York Times suggests that during a power outage, you have your kids turn a hand-crank twice per second for two hours (over 14,000 turns) to charge your iPhone 25%

Charging Up (Slowly) After the Next Big Storm - NYTimes.com

Assuming clear weather after a storm (which is a good bet for hurricanes, less so for blizzards), it will take one of the small solar chargers six to eight hours of sunlight to provide a 25 percent charge to an iPhone, the study found. The crank models don’t require sunlight, of course, just strong wrists. Very strong wrists, it turns out, capable of turning the crank at two rotations per second for long periods.

“A typical person will have to crank for 120 to 150 minutes at a steady pace to get a 25 percent charge on the iPhone,’’ the study found. “This may be a great option to keep the kids busy.’’ (It took five or six minutes for each 1 percent of charge, the researchers found.)