Royal Dutch Shell recently began selling gasoline blended with cellulosic ethanol
for a 30-day period. The E10 (1o% ethanol, 90% gasoline) fuel currently available only at its designated service station in Ottawa, Ontario in Canada was made in association with Iogen as a pilot program.
Cellulosic ethanol is a second-generation ethanol production technology which uses plant biomass as feedstock. The four main groups of plant biomass are, wood residues, tall woody grasses, agricultural residues and municipal paper wastes. The Shell-Iogen biofuel was made from agricultural residues (wheat straw).
There are potential benefits to the use of agricultural residues such as wheat straw in the production of biofuels. For example, there is the freedom from food-fuels crises (the wheat grains are used for food while the residual straw is used for ethanol production) which plagued the corn-based program. It optimizes crop acreage (the same acreage is used simultaneously for both food and fuel) and utilizes in the main, existing crop and acreage infrastructure. Depending on the type of residue, it can be used for auxiliary power generation (as is the case with sugarcane bagasse in Brazil).
Ethanol production from lignocellulosic biomass (tall, fast-growing woody grasses) like miscanthus (Miscanthus x giganteus), also holds potential benefits. These include very high ethanol productivity (see Table 1), viability on marginal soils (and so does not compete for acreage with food crops or use much resources such as water and fertilizer) and auxiliary power generation.
Inherent problems associated with corn-based ethanol in the United states had led to the proclamation by a strident opposition that bioethanol technology, especially for use in the liquid fuels transportation industry was a failure. On the contrary, Brazil with a sugarcane-based program has been a model of excellence and even with recent crude oil discoveries which rival the North Sea in size and importance, has vowed to retain her ethanol program.
The production economics for various cellulosic ethanol feedstock need to be evaluated. For example, production from a feedstock of agricultural residues has the advantage of utilizing already existing infrastructure (crop, acreage, etc) but the yield may be less than that from lignocellulosic feedstock, for which infrastructure is currently less well developed.
Success of the U.S. biofuels program will depend largely on the viability of advanced biofuels (those utilising cellulosic feedstock among others). Not a few therefore, will be evaluating with keen interest, the Shell-Iogen test run.