Smokeless Coal

Smokeless coal is a fuel that emits roughly less than 5 grams per hour of smoke when burnt. This equates to 80% less smoke and 25% less carbon dioxide than standard fuels. ... Not only does smokeless fuel function far better than some other fuel alternatives and is better for the enviroment. 

Smokeless fuels can give up to a third more heat than normal house coal and can also burn for up to 40% longer. This means that they can burn hotter for longer, meaning you need to refuel your appliance less often. Less refuelling also means that smokeless fuels can be more cost effective than your normal house coal.