When the government introduced the mandates for ethanol and related biofuels, they needed a way in which companies could verify that they were complying with the Energy Independence & Security Act of 2007. For whatever reason, the decided mechanism would require that companies purchase credits to demonstrate that they had complied with the mandate: a renewable identification number (RIN).
Each RIN is theoretically tied to a gallon of ethanol, biodiesel, or similar renewable fuel. However, because the RINs can be sold and traded similar to stock, in practice the pairing of a RIN with a particular gallon of fuel is somewhat superficial.
Unfortunately, this government created market in RINs has created an opportunity for criminally-minded entrepreneurs to scam the companies who are attempting to comply with the law by creating fake RINs and selling them in the marketplace. Note that these oil companies are required by law to purchase these credits, and its often difficult to verify that they are genuine, leading oil companies to often completely bypass small producers and only purchase biofuels and credits from larger, recognizable producers, a somewhat unique barrier to entry for small firms (suspicion of fraud). The latest case in fraudulent RINs surfaced late last month involved the sale of 60 million credits worth roughly $84 million, the third big bust in recent years