The United States gets 81% of its total energy from oil, coal, and natural gas, all of which are fossil fuels. We depend on those fuels to heat our homes, run our vehicles, power industry and manufacturing, and provide us with electricity. Eventually, the degree to which we depend on fossil fuels will have to decline as the planet’s known supplies diminish, the difficulty and cost of tapping remaining reserves increase, and the effect of their continued use on our planet grows more critical. But shifting to new energy sources will take time. In the meantime, how do we use fossil fuels in the most efficient and environmentally responsible way possible?