New Low Metals Grade of Biodiesel Approved by ASTM International

In a recent development, ASTM International has approved a new Low Metals (LM) grade of biodiesel following the D6751 specification. This new performance standard brings increased confidence to original equipment manufacturers (OEMs) and fleets, highlighting the reliability and effectiveness of biodiesel fuel.

The approval comes after compelling biodiesel fuel quality data from leading research institutions showcased its high quality and continual improvement, meeting robust standards, according to a release from Clean Fuels.

Teaming Up to Clean the Air

The biodiesel industry and Clean Fuels Alliance America (formerly known as the National Biodiesel Board) have been actively involved in cooperative research projects with OEMs and research institutions over the past 30 years.

The aim has been to assess whether modifications to the ASTM specifications for B100 are necessary to ensure the consistent performance of biodiesel blends, particularly in response to changing diesel fuel or diesel engine regulations.

In a recent multi-year cooperative program conducted with Southwest Research Institute and the National Renewable Energy Laboratory, extensive testing was carried out to determine the impacts of B20 — a blend of 20% biodiesel and 80% Ultra-Low Sulfur Diesel (ULSD) — on the long-term durability of diesel particulate filters in New Technology Diesel Engines (NTDEs) equipped with modern selective catalytic reduction (SCR) and diesel particulate filter (DPF) aftertreatment.

The research, which involved over 1,000 hours of accelerated aging, compared the effects of NTDEs running on B20 with a lower level of metals (equivalent to B100 containing a total of 4 parts per million [PPM] for sodium, potassium, calcium, and magnesium) to the impacts of conventional ULSD.

The research results showed that biodiesel containing a maximum of 4 PPM total metals had ash deposits and cleaning removal efficiency like ULSD. It did not adversely affect DPF pressure drop or regeneration rates and exhibited no harmful physical effects on the DPF substrate.

This research, presented at the SAE Congress in Detroit in April and published as SAE Papers 2023-01-0297 and 2023-01-0296, played a pivotal role in the approval of a new Low Metals (LM) grade of ASTM D6751 biodiesel by the ASTM D02 Fuels Committee. The new grade allows a maximum of 4 PPM total metals, a significant reduction from the previous allowance of up to 10 PPM total metals.

Understanding the Quality of Biodiesel

Further strengthening the case for modifying ASTM specifications, the National Renewable Energy Lab (NREL) has published an annual biodiesel fuel quality report for five years. The report documents the biodiesel quality produced in the United States and Canada by BQ-9000 certified producers, representing over 90% of North American production.

The latest report from June 2022 reveals that the current average of B100 total metals in the market is below 1 PPM total, well below the 4 PPM specification recently adopted in the new LM grade of biodiesel at ASTM.

Scott Fenwick, Clean Fuels Technical Director, emphasized the industry's compliance with the new Low Metals grade, as demonstrated by the annual BQ-9000 quality reports. He highlighted soybean growers' ongoing investments in fuel quality and engine testing through the Soybean Checkoff Program. These efforts provide increased confidence to engine manufacturers and fleets regarding the suitability of biodiesel in both current and future diesel engines, promising positive impacts on performance and durability.

With the rigorous cooperative research efforts and positive results obtained, along with the low level of metals in commercial production, the future looks promising for biodiesel use in the new Ultra-Low Emissions Diesel Engines (ULEDE) scheduled to enter the market between 2027 and 2031.

Clean Fuels Alliance America remains committed to working closely with ASTM International, OEMs, and research institutions to ensure that B20 and higher biodiesel blends continue to serve as an easy, reliable, and sustainable decarbonization solution for fleets in the coming decades.

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

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