A Texas refinery touted as a leader in sustainable aviation fuel is under scrutiny for sourcing animal fat linked to Amazon deforestation. Diamond Green Diesel, a joint venture between Darling Ingredients and Valero Energy, operates a $500+ million refinery in Port Arthur that converts cattle fat (tallow) into renewable diesel and jet fuel. The company has already secured over $3 billion in U.S. tax credits since 2022 for producing biofuels.

Investigations by Reuters and Reporter Brasil reveal that some Brazilian suppliers of tallow to Diamond Green Diesel source from slaughterhouses tied to illegally deforested ranches in the Amazon. Despite certification under CORSIA, a UN aviation emissions program, loopholes allow tallow to be considered a byproduct shielding it from deeper scrutiny.

Airlines including JetBlue and Southwest have embraced this “green” fuel, promoting emissions reductions, yet critics warn that growing demand for tallow could indirectly expand cattle herds and accelerate Amazon destruction. Brazil’s prosecutors argue that companies profiting from deforestation-linked supply chains may share legal liability.

With the sustainable aviation fuel market projected to surge from $2.9 billion in 2025, pressure is mounting for stronger safeguards to ensure climate-friendly fuels don’t come at the rainforest’s expense.