Vegetable oil and U.S. farmers started planting large areas that spring. Canola oil is lower in saturated fats, and higher in monounsaturates and is a better source of omega-3 fats than other popular oils. Canola is very thin (unlike corn oil) and flavorless (unlike olive oil), so it largely succeeds by displacing soy oil, just as soy oil largely succeeded by displacing cottonseed oil. A large quantity of used vegetable oil is produced and recycled, mainly from industrial deep fryers in potato processing plants, snack food factories and fast food restaurants. Recycled oil has numerous uses, including use as a direct fuel,
Butter sauce with meat and vegetables. In antiquity, butter was used for fuel in lamps as a substitute for oil. The "Butter Tower" of Rouen Cathedral was erected in the early 16th century when Archbishop Georges d'Amboise authorized the burning of butter instead of oil, which was scarce at the time, during Lent. Across northern Europe, butter was sometimes treated in a manner unheard-of today: it was packed into barrels (firkins) and buried in peat bogs, perhaps for years. Such "bog butter" would develop a strong flavor as it aged, but remain edible, in large part because of the unique cool,