According to the energy historian Vaclav Smil, every gallon of gasoline represents roughly one hundred tons of marine biomass, principally algae or phytoplankton, that has gone through an inconceivably long crushing, cooking, and curing process deep underground. One way to visualize a tank of gas is to imagine a mass of ancient plant matter weighing as much as fifteen blue whales crammed into a tank next to your spare tire, just behind your child’s car seat.