Oh well im fairly sure it burns MUCH quicker than wood and the use of coal is to boil water to create steam to turn rotary engines and motors at an industrial level. Its easy electricity if you want to generate . Wood is much cheaper than coal, but coal burns faster and gets the job done. Neither is environmentally friendly as they both extract resources and coal produces carbon pollutants. But time is money and coal gets the job done quicker and more efficiently. Thus more desirable.