Did you know that the fossil fuels oil and coal provide almost half of the energy used around the world? Humans have been using coal as an energy source for thousands of years. As our energy needs grow, scientists and other innovators are seeking energy sources and methods that are efficient, sustainable, and environmentally friendly. In this book, you'll examine oil and coal, weigh their benefits and costs, and see both how we are using these fuels now and how oil and coal might fit into our energy future.