ABSTRACT
Alkenes .................................................................................................................... 624 12.6 Biohydrogen ........................................................................................................................ 625 12.7 Concluding Remarks on Bioeconomy ............................................................................. 625
12.7.1 Economics of Bioethanol ....................................................................................... 626 12.7.2 Economics of Biobutanol ....................................................................................... 628
12.8 Fermentative Biofuels: Prospects for Practical Applications ....................................... 629 References ..................................................................................................................................... 629
12.1.1 Rationale for Biofuels
In June, 2008, the Goldman Sachs Group predicted that crude oil prices could reach U.S. $200 per barrel by 2012. Within weeks of this assessment, the price of crude oil exceeded U.S. $140 per barrel, raising concerns that the unprecedented price of U.S. $200 per barrel may be reached well before 2012. Although the current economic downturn has resulted in lower crude oil prices, the global economy is expected to resurge in 2-3 years, and, with this, oil prices will again increase. Reserves of easy-to-reach, inexpensive oil (oil that was on land, near the surface, under pressure, light and “sweet”—meaning low sulfur content-and therefore easy to re‚ne) are more or less depleted. The remaining oil reserves are offshore in deep waters, or in oil-sands, and of lower quality (i.e., high sulfur content). It therefore takes ever more money and energy to extract, re‚ne, and transport. Under these conditions, the rate of production inevitably drops. Furthermore, all oil ‚elds eventually reach a point where they become economically, and energetically, no longer viable (Kleykamp 2008; Rhodes 2008).
