Feedstock testing becomes critical as U.S. biofuel output surges

As U.S. biofuel makers ramp up production to meet federal Renewable Fuel Standard volumes, one analytical chemistry expert says feedstock authentication is becoming essential to protect yields, equipment and compliance value. R.W. Heiden Associates is promoting deeper testing as producers take on new suppliers and more uncertain input streams.

Why it matters: - U.S. biodiesel, renewable diesel and sustainable aviation fuel producers are pushing more feedstock through plants after running far below capacity for several years. - New suppliers and aggregator-sourced material can bring hidden impurities, unclear origins and quality risks. - Feedstock problems can reduce yields, foul equipment, hurt cold-flow performance and put RIN or tax credit eligibility at risk.

What happened: - R.W. Heiden Associates says advanced feedstock testing is needed as biofuel production rises to meet aggressive federal Renewable Fuel Standard volumes for this year and next. - Richard Heiden, founder, president and chief science and technology officer of R.W. Heiden Associates, is urging producers to verify feedstock authenticity before scaling up. - Heiden discussed the issue in a newly published article in the Winter 2026 print edition of Biobased Diesel®.

The details: - Feedstocks for biofuel production can contain foreign substances that interfere with conversion reactions or lower output. - Common screening tests can still label contaminated material as suitable for use, which can create false confidence in suppliers. - R.W. Heiden Associates uses a modified gas chromatography approach to generate impurity scans for low-volatility feedstock samples. - The company says the method has been used for nearly 10 years to track yield-reducing impurities at biodiesel plants. - When needed, the lab follows up with mass spectrometry or other hyphenated analytical tools to identify suspicious components. - The testing can fingerprint material down to 0.1% and help determine whether a feedstock fits a producer’s process. - Sampling programs are tailored to each biofuel producer’s concerns. - Most biobased diesel producers need triglycerides, diglycerides and monoglycerides in their feedstock. - Enzymatic biodiesel systems can also process free fatty acids. - Enzymatic production is more vulnerable to impurities than standard transesterification. - Renewable diesel and SAF producers also face concern about catalyst poisons in feedstock that can damage hydrotreatment catalysts. - Waste materials such as used cooking oil and animal fats are common targets for composition testing. - Even refined, bleached and deodorized soybean oil can warrant closer inspection when the supplier is new or untested. - Feedstock variation can affect cold-flow performance, especially as winter approaches. - Impurities that are less noticeable in warm weather can become a problem in colder conditions for soybean and rapeseed oil. - Heiden says he was among the earliest researchers to study low-solubility impurities such as sterol glucosides in blended biodiesel from soybean oil. - Heiden began that work in the early 2000s, when U.S. commercial biodiesel production was expanding quickly. - Heiden has spent more than 20 years studying contaminants that affect biofuel production and performance. - His research has been presented at ASTM and AOCS meetings since 2007 and published in scientific journals.

Between the lines: - The pitch is not just about quality control. It is also about supplier vetting and risk management in a market that is scaling faster than some producers’ current input networks. - The warning is broader than waste oil. Even cleaner-looking virgin oils can vary enough to affect process performance and winter operability. - The analytical argument is that simple pass-fail screening can miss the chemistry that matters most to production economics.

What's next: - Producers are expected to lean more on advanced testing as feedstock sourcing widens and winter creates tighter operating conditions. - R.W. Heiden Associates is positioning customized sampling and impurity fingerprinting as a way to identify reliable vendors before material enters production. - More information is available in Heiden’s article in Biobased Diesel®.