Investigation through government tracking data, interviews with relevant parties, and witness testimonies reveals that a Texas refinery supplying green fuel to American airlines has been purchasing animal fat extracted from cattle raised on illegally cleared Amazon rainforest land.

Diamond Green Diesel, headquartered in Louisiana, is a joint venture between biofuel producer Darling Ingredients and oil refining company Valero Energy. The company has invested hundreds of millions of dollars in a refinery in Port Arthur, Texas, which can convert beef tallow into cleaner fuel as an alternative to petroleum-based aviation fuel and diesel.

Diamond Green Diesel is a major participant in the U.S. sustainable fuel market. Documents show that since 2022, the company has received over $3 billion in U.S. tax credits for producing biofuels.

However, interviews and related documents indicate that since 2023, at least two Brazilian factories that have supplied tens of thousands of tons of beef tallow to Diamond Green Diesel have been sourcing raw materials from slaughterhouses that purchase cattle from ranches established on illegally deforested Amazon rainforest land.

Airlines including JetBlue and Southwest Airlines have reached agreements with Valero Energy to use this "green" aviation fuel. Since Diamond Green Diesel's facilities are certified under a United Nations program called the "Carbon Offsetting and Reduction Scheme for International Aviation" (CORSIA), which aims to control the aviation industry's climate impact, these airlines can claim emissions reduction achievements.

Currently, the global sustainable aviation fuel market is relatively small: according to analysis firm SkyQuest Technology Group, the market size in 2025 is approximately $2.9 billion, while the global conventional aviation fuel market reaches $239 billion. However, government incentive policies are expected to drive exponential growth in the sustainable aviation fuel market, which will inject more resources into Brazil's cattle industry – the primary driver of Amazon rainforest destruction.

Pedro Piris-Cabezas, an economist at the nonprofit Environmental Defense Fund, stated that any additional demand for cattle-related products "could lead to herd expansion and directly or indirectly drive deforestation and forest degradation."

This behavior may also violate Brazilian law. Brazilian federal prosecutor Ricardo Negrini, who has initiated multiple government investigations into the cattle industry, pointed out: "If companies obtain raw materials from supply chains involving deforestation and profit from them, they must also bear responsibility for these illegal activities."

Diamond Green Diesel, Darling Ingredients, Valero Energy, Southwest Airlines, and JetBlue have not responded to multiple requests for comment, including detailed inquiries about the Brazilian beef tallow supply chain.

To track the flow of beef tallow from Amazon illegal deforestation ranches to Diamond Green Diesel, cooperation was established with nonprofit investigative organization Reporter Brasil. The organization helped organize court documents, corporate filings, trade data, and government cattle tracking records that link slaughterhouses with tallow factories.

Interviews were conducted with more than ten people across various segments of the beef tallow supply chain, including traders, truck drivers, prosecutors, auditors, and regulatory officials.

Diamond Green Diesel's beef tallow procurement involves multiple countries, and it's currently impossible to determine how much comes from ranches on illegally cleared Amazon rainforest land.

**The Flow of "Problem Cattle"**

In 2022, Darling Ingredients CEO Randall Stuewe announced the acquisition of multiple Brazilian factories for $557 million, including four facilities in the Amazon region. According to the statement released at the time, these factories would supply "waste fats for the production of renewable diesel and sustainable aviation fuel."

Investigation revealed that one of these rendering plants is located in Para state, named Araguaia. In May 2025, Brazilian federal prosecutors conducted audits of multiple meat processing plants and found that at least five plants failed audits for slaughtering 20,000 head of cattle from illegal deforestation areas – and the Araguaia plant's beef tallow originated from these five facilities.

Trade data from import data platform Import Genius shows that in 2023, the Araguaia plant exported $4.4 million worth of beef tallow from the Amazon region to Diamond Green Diesel.

In June this year, a truck bearing the Araguaia plant's logo was observed at the Sao Francisco slaughterhouse. This slaughterhouse had previously failed audits for purchasing cattle from farms on illegally deforested land.

A truck driver, speaking anonymously, revealed that for two years he had been responsible for loading livestock carcasses from the Sao Francisco slaughterhouse and transporting them to the Araguaia plant. Two other drivers and two Sao Francisco slaughterhouse employees confirmed that the slaughterhouse is one of Araguaia plant's suppliers.

The Sao Francisco slaughterhouse neither confirmed nor denied supplying raw materials to the Araguaia plant, only stating that it has been cooperating with federal prosecutor investigations since 2018 and has hired external companies to monitor its supply chain.

Information from Brazil's environmental protection agency (Ibama) shows that some cattle from the Sao Francisco slaughterhouse indirectly originated from "Vale do Paraiso" ranch. This ranch has been prohibited from grazing since 2006 due to illegally cutting down 15 square miles (approximately 38.85 square kilometers) of trees. Cattle tracking data shows these cattle were first transferred from Vale do Paraiso ranch to another "clean record" farm before being transported to the slaughterhouse.

Last year, a Brazilian court ruled that the statute of limitations for this case had expired, and Brazil's environmental protection agency therefore lifted the ban on Vale do Paraiso ranch. However, government documents show that ranch owner Antonio Lucena Barros still needs to pay over $3 million in fines for previous deforestation activities.

Barros' lawyer Calebe Rocha stated in a declaration that his client is legally contesting these fines and has obtained an injunction to suspend fine payments. He also claimed that the areas within Vale do Paraiso ranch prohibited from use by Brazil's environmental protection agency due to deforestation have never sold any livestock externally.

Another Darling Ingredients factory sources beef tallow raw materials from a slaughterhouse. This slaughterhouse confirmed that between 2022 and 2023, it purchased hundreds of cattle from rancher Bruno Heller. Brazilian federal police described Heller in a 2023 investigation as potentially "the largest deforester in the Amazon region."

Heller's lawyer Vinicius Segatto stated that Brazil's environmental laws are "overly strict" and that criminal cases against his client are still under review.

**From Fat to Fuel Conversion**

To achieve the aviation industry's goal of net-zero emissions by 2050, airlines face pressure to procure more green aviation fuel – currently production of such fuel remains extremely low.

Supporters of using beef tallow as biofuel argue that demand for beef tallow alone is unlikely to encourage ranchers to clear rainforest to expand ranches, as beef tallow's economic value accounts for less than 3% of slaughterhouses' total revenue per head of cattle.

Beef tallow imported by Diamond Green Diesel from Brazil has received sustainability certification from the International Sustainability and Carbon Certification (ISCC) – this third-party certification body also provides CORSIA certification qualifications for Diamond Green Diesel's facilities.

To qualify for certification, biomass raw materials used in fuel must not originate from land deforested after 2008 or from protected areas. However, ISCC told investigators that it has not conducted investigations into Diamond Green Diesel's supply chain because under the CORSIA framework, the organization considers beef tallow a "by-product" of the cattle industry.

Three experts who participated in designing the CORSIA plan revealed that the plan allows producers to exclude carbon emissions and deforestation-related data from the Amazon rainforest, because it assumes that demand for beef tallow will not encourage ranchers to expand herd sizes.

When asked whether it believes deforestation activities in the beef tallow supply chain violate its sustainability standards, the International Civil Aviation Organization (ICAO) declined to comment.

However, the organization stated it is "continuously monitoring" compliance of third-party organizations responsible for certifying sustainable aviation fuel producers and welcomes information from all parties regarding "any potential violations" for further evaluation.