For a supposedly clean-burning gasoline additive, ethanol always has carried a full load of environmental compromises.The problem of volatility is a longstanding example. It's why ethanol promoters focus on tailpipe emissions of ozone precursors and ignore evaporative emissions. Generally, ethanol improves the former but aggravates the latter.And it turns out that ethanol from corn—most of the ethanol burned as fuel in the US—doesn't live up to its press notices as a way to combat global warming. To sweep this one under the rug, ethanol promoters want everyone to ignore the forests displaced by fuel-crop agriculture.New to the list of questions about ethanol's environmental go...