Green claims under fire

Britain has been importing “green” jet fuel from a United States producer since January 2025, and an investigation published on April 10, 2026 says some of the beef fat used to make that fuel can be traced to cattle linked to illegal clearing in the Amazon. The supplier is Diamond Green Diesel, a joint venture of Valero and Darling Ingredients. (unearthed.greenpeace.org) The fuel is sold as sustainable aviation fuel, which is meant to cut emissions over its full life compared with ordinary jet fuel. Diamond Green Diesel says its fuel can reduce lifecycle greenhouse gas emissions by 80% versus conventional jet fuel. (climatechangenews.com) The problem starts with the ingredient. One of the main feedstocks is tallow, which is industrial beef fat left over after slaughter and rendering, and investigators say Diamond Green Diesel bought Brazilian tallow from a rendering plant tied to a slaughterhouse operator named in multiple court cases over illegal deforestation. (unearthed.greenpeace.org) That gap matters because Britain’s rules treat this grade of tallow as a waste, and the certification system most widely used by the green fuel trade does not check whether the cattle behind that tallow were raised on illegally deforested land. A supply chain can therefore pass the paperwork test even if the ranching history is dirty. (unearthed.greenpeace.org) Britain has made this market bigger by law. Under the United Kingdom sustainable aviation fuel mandate, jet fuel supplied in 2025 must contain 2% sustainable aviation fuel, with the requirement rising to 10% in 2030 and 22% in 2040. (gov.uk) That mandate leans heavily on a production method called hydroprocessed esters and fatty acids, which is the refinery route that turns oils and fats into aviation fuel. A 2024 United States government industry report said this is the only commercially deployed pathway producing significant amounts of sustainable aviation fuel today. (osti.gov) So the industry has a scale problem as well as a traceability problem. The fastest way to make more “green” jet fuel right now is to buy more waste oils and animal fats, but those materials come from sprawling global supply chains that are much harder to audit farm by farm than a single oil well or refinery. (osti.gov) (unearthed.greenpeace.org) This is not the first warning around the same company. Reuters and Repórter Brasil reported in September 2025 that Diamond Green Diesel had already been buying cattle fat from Brazilian suppliers connected to illegally deforested Amazon land for fuel sold to United States airlines. (finance.yahoo.com) (reporterbrasil.org.br) Diamond Green Diesel says there is no suggestion the companies involved knew about deforestation at the farm level. But the April 2026 reporting shows how quickly a premium environmental claim can unravel when the chain of custody stops at “waste” and never reaches the ranch. (unearthed.greenpeace.org)