>>7625344This is generally true.
The carbon content of coal is 60-90%, with anthracite being the highest. Let's call is 75%. So you have 750g of carbon. Assuming complete combustion (which you won't have), that will combine with 2 oxygen to produce 44 g of CO2 per 12 g of C.
750 * 44/12 = 2750.
So you're looking at about 2.75 kg of CO2.
This is all rough back of the envelope, of course, but it's a ballpark figure.
