CARB issues alert for fuel additives under alternative diesel regulation

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The California Air Resources Board (CARB) has recently issued a product alert for fuel additives under the Alternative Diesel Fuels (ADF) Regulation.

The alert was issued following emissions testing by CARB, which showed that tested additives failed to effectively mitigate to the regulatory standards. These results have raised significant questions, both as to the specific additives addressed by the testing, as well as how best to ensure appropriate performance of additives under the ADF regulation in the future.

The emissions testing, which was conducted at the University of California, Riverside, was designed to determine that additives certified pursuant to the ADF regulation are effective at mitigating biodiesel nitrogen oxide (NOx) emissions to equivalence with CARB diesel. Testing showed that the additives failed to effectively mitigate to the regulatory standard.

According to CARB, it now intends to propose modifications to the ADF regulation that will ensure that additives perform consistently with all regulatory requirements. These amendments could require additional testing of currently certified additives, for example, as well as other steps to ensure conformance.

As part of the amendment process, CARB may consider approving blends of renewable diesel with biodiesel (approximately R80/B20) for use by any blender to meet the NOx control requirements, in case additive availability is limited due to the regulatory changes.

Biodiesel producers, importers and blenders are allowed to continue using CARB-certified NOx mitigation additives pending further notice, in order to comply with the ADF regulation.

The product alert does not affect biodiesel blend B5 or lower, which represents around 70% of the biodiesel market in California, as no mitigation is required for those blends. Moreover, exempted fleets and stations do not need to take additional action, as no additives are required by them.