Whale oil

Whale oil is a fuel type used in the 31st century, since petroleum oil doesn't exist anymore. When Earth's oil reserves ran out in 2038, humanity started using whale oil instead, but was later replaced by Dark Matter. After all Dark Matter became useless as fuel in 3009, spaceships started using whale oil again.

Trivia

 * The name Mobil Dick spoofs the gasoline company Mobil and the famous whale Moby Dick.