Boosting Fueling Confidence: Low Metals Grade of Biodiesel Approved by ASTM

ASTM International has recently granted approval for a new Low Metals (LM) grade of biodiesel within the D6751 specification, signifying a major development in fuel quality for government fleets. The approval comes considering updated biodiesel fuel quality data from top research institutions, highlighting the continuous improvement and adherence to quality standards in the biodiesel industry.

Throughout its 30-year history, the biodiesel industry, alongside Clean Fuels Alliance America (formerly known as the National Biodiesel Board), has been at the forefront of cooperative research projects with original equipment manufacturers (OEMs) and leading research institutions.

These efforts have aimed to assess the need to modify the ASTM specifications for B100 biodiesel, ensuring its reliable and effective performance in the face of evolving diesel fuel and diesel engine regulations.

Approving Low Metals Grade Biodiesel D6751

The most recent round of research, conducted in collaboration with Southwest Research Institute and the National Renewable Energy Laboratory, involved extensive testing to evaluate the long-term durability of diesel particulate filters in New Technology Diesel Engines (NTDEs).

These engines were equipped with modern Selective Catalytic Reduction (SCR) and Diesel Particulate Filter (DPF) aftertreatment and operated on B20 — a blend of 20% biodiesel and 80% Ultra-Low Sulfur Diesel (ULSD).

The comprehensive testing, spanning over 1,000 hours of accelerated aging, compared the effects of B20, with a lower metals content equivalent to B100 containing a maximum of 4 parts per million (PPM) total metals (sodium, potassium, calcium, and magnesium), to those of conventional ULSD.

The results revealed that biodiesel with a maximum of 4 PPM total metals demonstrated ash deposits and cleaning removal efficiency like ULSD. Furthermore, it did not harm DPF pressure drop or regeneration rates and exhibited no negative physical effects on the DPF substrate.

These significant research findings, presented at the SAE Congress in Detroit in April and published as SAE Papers 2023-01-0297 and 2023-01-0296, played a crucial role in the successful ballot for the approval of a new Low Metals (LM) grade of ASTM D6751 biodiesel by the ASTM D02 Fuels Committee.

This updated grade allows for a maximum of 4 PPM total metals, a notable reduction from the previous allowance of up to 10 PPM total metals.

Looking Back at Biodiesel Quality Data

Further supporting the need to modify ASTM specifications, the National Renewable Energy Laboratory (NREL) has published an annual report on biodiesel fuel quality for five consecutive years. This report details the biodiesel quality produced in the United States and Canada by BQ-9000 certified producers, accounting for over 90% of North American production.

The most recent report from June 2022 indicates that the average B100 total metals in the current marketplace are below 1 PPM total, well below the recently adopted 4 PPM specification in the new LM grade of biodiesel at ASTM.

Scott Fenwick, Clean Fuels Technical Director, highlighted the industry’s compliance with the new Low Metals grade, as evidenced by the annual BQ-9000 quality reports. He emphasized the ongoing investments made by soybean growers through the Soybean Checkoff Program in fuel quality and engine testing. These investments provide government fleets with increased confidence in biodiesel’s suitability for current and future diesel engines, ensuring positive impacts on performance and durability.

With the cooperative research efforts yielding positive results and the low level of metals observed in commercial production, the future holds promise for biodiesel use in the new Ultra-Low Emissions Diesel Engines (ULEDE) set to enter the market between 2027 and 2031.

Clean Fuels Alliance America remains committed to close collaboration with ASTM International, OEMs, and leading research institutions to ensure that B20 and higher biodiesel blends continue to serve as a reliable and sustainable decarbonization solution for government fleets in the years to come.

As ASTM International celebrates its 125th anniversary this year, the approval of the ASTM D6751 specification for biodiesel as a new Low Metals grade stands out as one of the organization’s Top 10 most influential standards ever produced.

Want more? Check out our sister publication, Work Truck's coverage of the new biodiesel specification!