Red coal is a type of coal which was discovered in West Eghea in the years after The Pulse. At the time there were no trees left on the continent and without them the survivors of the cataclysm lacked a reliable fuel source. Regular coal was known prior to the Pulse so people began to search for coal deposits. During their search red coal was discovered. It appears to be a much purer form of coal which can burn a lot longer and with much less smoke.
Red coal is used for heating homes in the walled cities of West Eghea. Or atleast those cities who need heating in their homes. In Ishdal where the weather is below freezing point all year round a system of central heating was developed long ago. There homes are built in such a way that they have a basement specifically for heating the house. It is connected with pipes to the upper floors as well. So when fires are lit in the basement the air in there heats up and will warm up the floors and walls of the house. This gives a evenly dispersed warmth in every room of their houses and that without spreading smoke inside the house.
Red coal has also been used in cooking stoves since its discovery. Because it produces a lot less smoke than regular coal, and less of it is needed, it has remained popular. Since the discovery of Heatstone though the use of red coal for cooking has dwindled. Many able to afford a heatstone cooker will at some point make the switch and abandon their red coal stove. Ofcourse like with anything there are people who still prefer cooking on a red coal stove.
Cidale is by far the largest producer of red coal in West Eghea. They have access to several surface mines which speeds up their process of mining and leads to far less accidents. Mining red coal is hard work though and this shows in the hardened population of Cidale. In other locations red coal mines are often underground which brings more danger for the miners.
Cidale lies on the west coast of West Eghea between Tiham and Ishdal. It is the smallest of the walled cities and trives completely on their production of red coal. The city has cold winters which requires homes to be heated. During the summer months the weather is mild and some days temperatures can even rise up to 30°C.