I did about 10 minutes of google research, whatever that is worth, and came up with the following numbers....
The carbon dioxide lbs / 1,000,000 btu's of heat from anthracite coal is 227. Surprisingly, other types of coal have less CO2 emissionshttp://www.eia.doe.gov/cneaf/coal/quart ... e/co2.html
Assuming 138,700 btu / gallon of oil, there is 22.384 lbs of carbon dioxide per gallon which translates to 161 lbs of CO2 per 1,000,000 btus.http://www.earthlab.com/carbon-calculator.html
This link is broken, either the page no longer exists or there is some other issue like a typo.
I don't know the assumptions made to get to these numbers. I guess the most accurate comparison would be to see how many gallons of fuel oil / propane we would typically burn vs. how many tons of coal and see how the CO2 compares. Of course, that does not take into consideration the energy expended to get the fuel to your furnace. Drilling, transportation, processing and final delivery of oil uses more energy than it takes to get local coal to our doorsteps. It also does not take into consideration other emissions, just CO2.
Anyway, I've got my 5+ tons of coal (about 3 years worth) and I'm not giving it back!!