Diesel or iesel fuel (IPA: /ˈdiːzəl/) in general is any fuel used in diesel engines. Production costs are 25-35% less than that of regular gasoline, due to the fact that diesel is less refined than normal gasoline. However, the price of diesel fuel at the pump is generally higher, since diesel fuel has high demand in the industrial world. The most common is a specific fractional distillate of petroleum fuel oil, but alternatives that are not derived from petroleum, such as biodiesel, biomass to liquid (BTL) or gas to liquid (GTL) diesel, are increasingly being developed and adopted. To distinguish these types, petroleum-derived diesel is increasingly called petrodiesel. Ultra-low sulfur diesel (ULSD) is a term used to describe a standard for defining diesel fuel with substantially lowered sulfur contents. As of 2007, almost every diesel fuel available in America and Europe are ULSD type.