"During the Second World War and immediate post-war years amid rationing in the United Kingdom, only two types of margarine were available: a premium brand and a budget brand with whale oil being used in its manufacture."

...The alternative to Coal being Whales.

> producing edible fats by oxidizing synthetic paraffin wax made from coal… edible fats were obtained … which were reacted with glycerol such as that synthesized from propylene. Margarine made from them was found to be nutritious and of agreeable taste, and it was incorporated into diets contributing as much as 700 calories per day. The process required at least 60 kilograms of coal per kilogram of synthetic butter.

Yummm