Ethanol from Waste Sweet Potatoes in Canada

I would love to see a net energy balance study on this one -- looks quite promising. This could make Sweet Potatoes a perfect replacement crop for tobacco.
Sweet potato alliance pushing ahead with ethanol project -- Tillsonburg News:
by Jeff Helsdon -- August 5, 2005

...Tillsonburg, ON -- Traditionally with sweet potatoes, there is a 40 to 50 per cent waste rate of product that never makes it to market. The proposal is to use the waste to produce ethanol at a plant built in either Tillsonburg, Aylmer or in Norfolk County.
Murray cited figures that show the crop will produce 6,000 litres of ethanol per acre, as compared to the 1,420 produced by corn. The end result is the farmer can net $1,500-plus per acre, dependent on his/her growing skills and the market...