The price of Renewable Identification Numbers (RINs) continues to generate a lot of attention these days. We first reported on the big bull rally in RIN prices on 26 February and again on 25 March, when the Senate Committee on Energy and Natural Resources wrote a letter to the Environmental Protection Agency to inquire about RIN prices and gasoline. Last week, two noteworthy papers on RINs were published: one by Iowa State Professor Bruce Babcock and the other by Goldman Sachs. Both focused on the potential shortage of RINS for 2014, the result of reduced ethanol production in 2013 and a growing ethanol mandate.For a number of years, corn ethanol production has been running above the mandated level, and that has provided bankable RINs. Ho...