Biodiesel is a renewable fuel made from vegetable oils (such as soybeans or waste cooking oils) and animal fats. It can be used in most unmodified diesel engines. B20 (20% biodiesel, 80% diesel) is the most common biodiesel blend for fleet use.
Biodiesel is nontoxic and biodegradable. The production and use of biodiesel results in a 78.5% reduction in carbon dioxide emissions compared with petroleum diesel (US DOE). Biodiesel has a positive energy balance; for every unit of energy needed to produce one gallon of biodiesel, 3.24 units of energy or more are gained. Biodiesel has positive performance attributes such as increased cetane, high fuel lubricity, and high oxygen content. Locally biodiesel is produced commercially by Pacific Biodiesel on Oahu, Maui, and soon on the Big Island.