Zipping down the open highway in your clunker of a car, you look at the gas tank meter and see that it’s close to empty. What to do? You futilely wish the car didn’t have to run on gasoline—you could buy an electric car, but they’re still too expensive. So you resolve to figure out how you can live a life less dependent on petroleum in general, and luckily, you see a gas station just off the road.
