During the same time period that the cost of crude petroleum rose 150%, from January 2001 to 2005, the total number of bioethanol refineries in the USA increased from 56 to 81, with total production capacity increasing from 6.6 bil­lion L/year to 13.8 billion L/year. Within the last year, from January 2005 to 2006, the total number of refineries increased to 95 and output further increased to 14.3 billion L/year, a 1500% increase since 2001. Total world production in 2005 was 46 billion L, with the USA and Brazil representing a combined 70% of the world’s production. It should be further noted that by the end of 2005, 29 ethanol refineries and nine expansions of existing refineries were under con­struction, with a combined annual capacity of 5.7 billion L. If you consider all of the US ethanol production capacity currently on-line, under expansion, and under construction, then the projected capacity is approximately 24 billion L — approximately 85% of that required by the RFS by 2012 [43].

In the USA, the raw material of choice for bioethanol production is corn. Approximately 13% of the US corn crop is dedicated to ethanol production,

third only to livestock feed and exports [43]. In Brazil, however, the raw ma­terial of choice is sugarcane. With over 100 countries producing sugarcane, no one has yet to match Brazil’s cost structure and supply chain. In mid-2005, the sugar production costs in the three lowest countries were estimated to be $145/metric ton in Brazil, $185/metric ton in Australia, and $195/metric ton in Thailand. About 25% of worldwide sugar production is at $200-250/metric ton, above which the figure escalates to $400/metric ton and higher. Sugar­cane is a highly efficient crop for producing biomass, representing the highest biomass per growing area of any major commercial crop, including corn. This is a result of sugarcane’s ability to incorporate C3 and C4 compounds in its photosynthetic pathway, while most plants only incorporate C3 compounds. Brazilian ethanol is most likely the cheapest in the world, with an estimated production cost of between $0.19 and $0.21/L in 2005. For this reason Brazil is not only looking to expand its ethanol production capacity, but to further expand into biorefineries [54].

Brazil’s sugarcane production is unique, and not representative of the gen­eral challenge almost all other nations face when determining which raw ma­terial source is preferred. Raw material utilization for bioethanol and biotech­nology processes in general represents a significant challenge and opportu­nity for research and development. The US Department of Agriculture and Department of Energy estimate that the resources exist to produce over 1 bil­lion tonnes of biomass annually, representing approximately 30% displace­ment of current fossil fuel usage (302 billion L) [55]. Biomass is composed of cellulose (40-50%), hemicellulose (25-35%) and lignin (15-20%) [56]. Significant effort in the fields of non-food agricultural engineering, enzyme catalysis of cellulose and hemicellulose, and hexose and pentose fermentation will be required to extrapolate the full energetic value of lignocellulose.

Figure 2 schematically shows how research in the aforementioned areas is integrated into bioethanol process development, specifically focusing on the secondary pretreatment of feedstocks and microbial metabolic engineer­ing. In both examples, the application of systems biology to the metabolic engineering framework can yield improved products, either in the form of enzymes or microbial platforms. We will further explore how scientific and technical achievements in the fields of metabolic engineering and systems bi­ology as applied to the afore mentioned areas and others, driven by industrial biotechnology and demand for bioethanol, will improve bioethanol process development.

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