Madson said that If we used Sunspuds, a proprietary hybrid of sunflowers and Jerusalem artichoke tubers, we would need half the acerage that corn ethanol demands and would get the biofuel for the same price (see here). Another benefit is that the above-ground leaves and fibers would be about enough to burn in a boiler that would power the production process. This biomass could also be used for their cellulose to make ethanol. A 1994 article on Sunspuds in BioEnergyUpdate says that you could get 26 gallons of ethanol per ton of biomass, which comes to something like 652 to 775 gallons of ethanol per acre.
You can see Madson's slides in the gallery below and listen to his presentation here (26 min, download here):
[Source: Phil Madson, BioEnergyUpdate]
Our travel and lodging for this media event was provided by ACORE