Because I'm slow at work.. If we say the new generation iPhones have a 3,000mah battery, batteries are charged fully once per day, and that 100 million people

Because I'm slow at work.. If we say the new generation iPhones have a 3,000mah battery, batteries are charged fully once per day, and that 100 million people in the US have iPhones: 3,000mah x 3.8v = 11.4 watt-hours to fully charge a phone -- at $0.15/kWh, this equates to a daily expense of ~$0.002 to charge your phone. Annually, this is $0.62. If wireless charging were 50% efficient, it would still cost under a dollar annually to charge your phone. On a bigger scale: 11.4Wh * 365 days * 100M phones = 416 billion watt-hours annually to charge all the iPhones in the US. A 50% efficiency loss would equate to a difference of 208 billion Wh. Enercon makes a monster wind turbine called the E-126 that has a 7.6mW generator attached. With a modest 40% capacity factor, you would only need 8 additional wind turbines to make up for every iPhone user in the US switching to wireless charging.