There are two possible ways to address this situation. If the volume of each type of ethanol can be measured independently and precisely (for example, in a facility where the conversion of cellulosic feedstocks to ethanol occurs through separate equipment from that used to convert corn to ethanol), RINs can be generated separately for each type of ethanol with a unique Equivalence Value.
The same batch number (RIN code BBBBB) can be used to represent all the gallon-RINs generated, but the gallon-RINs representing the cellulosic ethanol will need to be listed separately from the gallon-RINs representing the corn-ethanol, since the two groups of RINs will have different RR codes (representing different Equivalence Values).
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.
Question and Answer was originally posted at: Questions and Answers on the Renewable Fuel Standard Program (PDF) (55 pp, 221 K, EPA420-F-07-041a, August 2007, About PDF)