The U.S. Environmental Protection Agency (EPA) has released the 2013 "renewable volume obligations" (RVOs) for 2013 under the Renewable Fuel Standard (RFS) with a surprisingly bullish cellulosic level and no waiver from the advanced biofuel levels. These are proposed levels, subject to a 45-day comment period, and thus could change in 60 days or so.Below is a closer look at EPA's math.Blend Wall: EPA calculates that the 16.55 billion-gallon mandate for total biofuel use would be 9.63 percent of the total motor fuel use on and off road adjusted for small refiners and Alaska, which opts out. The shortcut to the figure is based on the Energy Information Administration (EIA) data from the January 2013 Short-Term Energy Outlook (STEO). STEO da...