"The US is the world's leading consumer of oil. We use over 350,000,000 gallons of gasoline every day.
It's very important that the number of fossil BTUs that go into a gallon of fuel be significantly less than the number of renewable BTUs that come out of that gallon. If it's not -- let's not do it.
We have about 133,000 BTUs worth of energy in every gallon of biodiesel. When you add up all our inputs we need to end up being less than 133,000 BTUs, or we probably shouldn't be making that gallon. (1 BTU ~ the amount of energy in one wooden matchstick)."
Our main sources of energy are still petroleum, coal and natural gas. With global energy consumption predicted to increase 56 percent by 2040 the continued use of non-renewable fossil fuels comes at a great cost to the environment and to our health." QUEST: America's Energy Future
Infographic on composting courtesy of PBS's Nature