In November 2017, the PFI Standards Program was updated to include the testing of the same metals that are referenced in the international pellet specifications published under ISO 17225-2, and referenced in wood pellet quality certification schemes.
In November 2017, the PFI Standards Program was updated to include the testing of metals. The minimum requirements are to conduct a metals test at least annually, using a recently published ISO test method (ISO 16968), and to test for eight specific metals: arsenic, cadmium, chromium, copper, lead, mercury, nickel and zinc. These are the same metals that are referenced in the international pellet specifications published under ISO 17225-2, and referenced in wood pellet quality certification schemes ENplus, CANplus and DINplus. The new metals testing provisions are being implemented in 2018, and have resulted in many questions, including: Why test for these specific metals? What are the baseline levels for these metals in wood? What type of instances could lead to a failure of the metals testing, and why are we adopting ISO test methods? In this column, I will try to answer these questions.
The original list of metals and the test method itself was developed by a European initiative to develop standards for solid biofuels, in the early 2000s. The European Committee for Standardization (CEN) created Technical Committee 335 to spearhead this work, and as part of the initiative, two research projects were funded (BioNorm I and BioNorm II), to answer technical questions about biomass and the appropriateness of various testing methodologies available at that time. The result was information that allowed technical experts to develop specifications and test methods specific to solid biofuels. These were originally published as European National (EN) standards between 2000 and 2008, but subsequently moved to ISO to allow for their development into ISO standards, and to facilitate global adoption. It was this research that led to the adoption of the current testing method, and the focus on the eight metals listed above.