See : http://www.sciencedaily.com/releases/2001/05/010524062508.htm
"Associate Professor Kathleen Danna of the molecular, cellular and
developmental biology department and her research team created a new
technique they expect to produce large amounts of low-cost, highly
effective enzymes vital for the conversion of plant cellulose into
ethanol. Successfully producing large quantities of the enzymes could
significantly lower costs for the processing of renewable fuels from
plant biomass, said Danna.
Although the ethanol currently used as a fuel additive in America is
derived from cornstarch rather than cellulose via biomass conversion,
cornstarch as a source of raw material would not be able to meet the
demand if ethanol were to become a major transportation fuel, she said.
While there is a competing use for cornstarch -- food -- the supply of
plant biomass is so large it often has a "negative cost" in that
households, industry and government often must pay for its disposal,
Danna said. "
It remains to be seen whether this process will have a net EROI in spite
of "negative cost" for one of its inputs.