Coal
While in years past, coal was a more common heating agent in U.S. homes, today the fossil fuel has been pushed aside by oil, gas, and other heating methods. Perhaps, the major reason for this shift is that coal doesn’t burn clean enough. (Efforts to develop better methods and so-called “clean coal” still suffer from sufficient enough gaps to limit any broader applications. None of this means that other countries such as China are not taking advantage of this heating solution in substantial numbers. (For those who use coal-burning furnaces, it does come with an inexpensive price tag, if you live in a coal abundant region, such as Pennsylvania.)
There are some other drawbacks that have hindered the use of coal heating. First, it is a serious pollutant. The smoke given off by burning coal distributes carbon dioxide into the air, a serious greenhouse gas. The ecological impact of coal burning can lead to air pollution as well as damage to wildlife and vegetation. The other factor is that coal has a limited shelf life since it is classified as a fossil fuel. Some estimates suggest that there is about 150 years worth of useable coal in the world.
There is good news however. Research is being conducted that could neutralize the polluting effects of coal. Other programs are looking at ways to extend the supplies of coal. Such success could make coal a viable heating solution again.