It's a very interesting substance, petroleum, rather hydrocarbons themselves. The fat of the land is not an unwise moniker. Hydrocarbons/Fat/Oil has twice as much energy as carbohydrates or protein, only alcohols come close to hydrocarbons, but hydrocarbons have other wonderful properties, like the ability to polymerize, whereas alcohols/naptha are solvents. Everything we use is built with polymerized hydrocarbons. Even your body.