Cellulose and Biomass Conversion Technology and Its Application to Ethanol Production

.ansportation fuels are almost totally derived from petroleum and accounted for more than one-quarter of the total energy used in the U.S. in 1989, more than 81 quads.' Currently, almost 50 % of all petroleum used in the U.S. is imported, and im-ports have risen markedly over the last few years. ' Because OPEC con-trols about 75 % of tbe world's oil re-serves, and the U.S. has only about 5 % of that total, it is likely that petro-leum imports will continue to rise. Few substitutes exist for petro-leum-based transportation fuels, and the U.S. is extremely vulnerable strate-gically and economically to disrup-tions in its supply, as illustrated by our experience with Iraq's invasion of Kuwait. In addition, imported petro-leum contributed about 40 % of the balance-of-payments deficit for the U.S. in 1989' Evaporative losses during fuel-ing of automobiles, losses from the fuel system, and nitrogen oxides and unburned hydrocarbons from auto-motive exhaust contrihute [0 ozone formation in many cities, such as Los Angeles. ' High altitude cities, such ~IS Denver, experience excessive levels of c.ubon monoxide because uf in-complete comhllstion of carbon-con-iuining luels, Petroleum derived trans-porration fuels are rhe source of lip to two-i hirds ()I carhun monoxide and one-third to one-half of smog c:lu:iing MARCH/APRil J 993 SSF fermentation