For such a bulk product, any improvements, especially in its major fermentation technologies, will be economically very attractive. In practice, the R&D in ethanol fermentation, especially using lignocellulosic biomass to replace current sugar and starch feedstocks, has never been interrupted since the shock of the crude oil crisis in the 1970s, except for a slowdown in the 1980s and 1990s when the price of crude oil was lower, and the economic prospect of fuel ethanol seemed to be less promising.