Renewable diesel from oils and animal fat waste: implications of feedstock, technology, co-products and ILUC on life cycle GWP

•Rendering plant fats can be converted to renewable diesel to meet renewable energy policies.•Renewable diesel from soybean oil can reduce GHG emissions significantly in spite of ILUC.•Ab initio methods used to simulate thermodynamic data on reaction chemistry.•Thermodynamic calculations used to build prospective LCI models. We investigate the use of rendered poultry fat, beef tallow, and soybean oil as ready sources of free fatty acids (FFAs) and triglycerides (TG) for conversion to renewable diesel. Laboratory scale saponification and decarboxylation experiments using trilaurin, lauric acid, protein, and water as a model compound representing rendered animal fat are reported and combined with chemical process simulations, and thermodynamic and kinematics equations to build energy and material balances where Ab Initio methods are used for estimating missing data to build a life cycle inventory model. Life cycle greenhouse gas (GHG) emissions for producing renewable diesel from soybean oil, poultry fat, and beef tallow fall between −8.7 and 47.2 g CO2 equivalent/MJ even considering induced land use change when soybean oil is used as feedstock. Emissions vary depending on co-products and allocation rules used, which can affect compliance with energy policies. [Display omitted]