The batches of each type of ethanol (cellulosic or corn) should be measured independently and precisely, according to the separate processes used to produce them in the plant. Once separate batch numbers are created and RINs are generated, the producer can combine the mixed volumes (cellulosic with corn) in a common tank. As product leaves the common tank, the producer may assign whatever valid RINs they wish to assign that outgoing product.
The total number of RINs that could potentially be assigned to product leaving the tank would be the sum of the RINs generated for the different types of ethanol added to the tank. However, up to 1.5 RINs per gallon of the cellulosic ethanol produced and added to the tank may be retained as an unassigned RIN with a K code of 2. It should be highlighted that due to changes that will result from passage of the Energy Independence and Security Act, certain aspects of this approach are likely to change in future regulations.
Alternatively, we have created a regulatory mechanism through which the producer may submit a petition to the Agency describing the renewable fuel, its feedstock and production process, and the calculation of its Equivalence Value. See regulation Section 80.1115. This petition process can be used to identify an appropriate Equivalence Value for mixtures of renewable fuels.
This Question and Answer was originally posted at: Questions and Answers on the Renewable Fuel Standard Program (PDF) (59 pp, 228 K, EPA420-F-08-006, April 2008, About PDF)