Various people have mentioned various possible fuels. As a rough guide the heat value of 1 pound of fuel is: Coal - 10,000 to 15,000 BTU Coke - 12,000 Peat - 8,000 Wood - 6,000 if dry Tan bark - 4,300 Sawdust - 7,000 Bagasse - 8,300 Straw - 5,000 Tar - 15,000