Carbon Intensity by the Numbers
In California the Air Resources Board (ARB) has a Fuels Evaluation section that is responsible for accessing and developing transportation fuels for the California Low Carbon Fuel Standard (LCFS) as well as conducting lifecycle analysis of Greenhouse Gas (GHG) emissions. When they compare fuels they assign a Carbon Intensity (CI) number which measures the average emission rate of a given pollutant. As of 2014 these CI numbers are:
Petroleum Gasoline = 97.47
Petroleum Diesel = 96.56
Biodiesel from Used Cooking Oil = 11.76-15.80
Renewable Diesel from Tallow = 19.65-39.33
So you can see that renewable fuels made from recycled products from renderers are a much kinder to the environment than standard petroleum fuels.