Is Ethanol Dirtier Than Tar Sands Oil?

The Environmental Working Group thinks so:

Last year, corn ethanol producers churned out 14 billion gallons, about 13.4 billion gallons of which were blended into the 135 billion gallons of gasoline the nation’s drivers used.
Extracting tar sands and turning them into oil is more energy-intensive than traditional drilling for petroleum. According to the Natural Resources Defense Council, dirty oil transmitted from Alberta, Canada, to the Gulf Coast by the Keystone Pipeline would emit 24 million tons of carbon per year. But our calculations show that last year’s production and use of 14 billion gallons of corn ethanol resulted in 27 million tons more carbon emissions than if Americans had used straight gasoline in their vehicles. That’s worse than Keystone’s projected emissions. It’s the equivalent of emissions from seven coal-fired power plants.¹So far the federal corn ethanol mandate has resulted in a massive influx of dirty corn ethanol, which is bad for the climate and bad for consumers. The only interest it benefits is the ethanol industry.1. Calculated by comparing the emissions from 14.3 billion gallons of gasoline (using 2014 baseline) EPA’s estimate of corn ethanol emissions. Coal plant emissions use an estimate that a typical coal plant emits 3.5 million tons of CO₂per year

I'm not going to get down in the weeds and argue against the idea that ethanol fuel isn't a bad, and market warping, idea.