Coke
Coke is a fuel formed from coal. In coking coal specialise plants, located near coal mines in different parts of Poland. Coke transported in containers is formed due to high temperature of around 1000 degrees. Thanks to high temperature all other particles, like water, sulphur, or air, are released. Coke formed this way is much more calorific than ordinary coal because it contains 90-98% of pure carbon.
It is also lighter than coal and it burns slower but amount of energy is much bigger than any other coal has. There are many kinds of coke, blast furnace coke is used in smelting plants or stabilised coke which differs from others with size of its lumps.