"Our credits function like money, but they’re not backed by gold or silver. They’re backed by energy, human and other sorts, and our basic unit of value is the calorie. So a product is valued by how much energy goes into its production, in terms of labor and fuel and materials that themselves require energy to produce. And part of that accounting is how much energy it takes to to replace a resource that is used. Something that works with solar or wind power becomes very cheap. Anything requiring irreplaceable fossil fuels is generally too expensive to think about [...]"See more here.