Regular diesel fuel
is made from crude oil. It is a fuel that is highly polluting in that it produces a large amount of greenhouse gasses. Biodiesel is made from organic substances such as used cooking oil and corn and is blended with regular diesel to reduce greenhouse gas emissions. Renewable diesel is made entirely from organic materials and can be used in place of regular diesel without blending and is often referred to as a drop-in
fuel for that reason. The pathways for manufacturing both biodiesel and renewable diesel fuels are carefully monitored and must be approved by the EPA.