How much coal does it take to charge an iphone?

This may help, I don’t know about the facts behind it, although it does cite this which may help to.

Hope this helps, it’s certainly an interesting topic :)

Takes only about half a pound, but I have to keep stoking it which is a pain.

I just use electricity to charge mine. It’s so much easier!!!

@AstroChuck lol

The energy density of coal is about 30 MJ/kg. A 60 watt bulb running for one hours is 60W x 3600 seconds = 216,000 joules or 0.22 MJ. So it would take 0.22/30 = .007 kg of coal if the system was perfectly efficient. Let’s figure 50% efficiency at the power plant and 50% efficiency in the lines to your house.
That will make it ~0.007kg x 4 = 28 grams of coal to power a 60 Watt light bulb for one hour with typical efficiencies.