One man's meat is another man's poison as the saying goes. And that's fine, but the trouble with biofuels is that very often that one man's biofuel is another man's supper and potentially a third man's chemical feedstock.
Although chemicals use only about 5% to 7% of the world's oil that is currently more than could be substituted with by biosources. Wandering around the archives of ICIS Chemical Business I came across this roundup on biofeedstocks for chemicals and fuels written in 1998.
It has a naturally, chemicals slant but is worth looking at.