The most common blend is B5, a mix of 5% biodiesel and 95% petroleum-based diesel. Likewise, B20 equals 20% biodiesel content, B30 equals 30% biodiesel and so on. B100 represents pure biodiesel.

The discussion usually revolves around changing the common blend level from 10 percent ethanol (E10) to 15-percent ethanol content (E15). In late June, the US Supreme Court blocked an effort to ...