"There are four major types (or “ranks”) of coal. Rank refers to steps in a slow, natural process called “coalification,” during which buried plant matter changes into an ever denser, drier, more carbon rich, and harder material. The four ranks are:
The U.S. Department of Energy's visualization of annual energy production in each state allows you to explore how much and what type of energy each of America's states produced in 2012, from Rhode Island with 2.8 trillion Btu energy produced, to Texas with 14,201 trillion Btu. The visualization is interactive and allows users to view the breakdown of energy production by type and state.