1.1 Natural Resource Limitation and Economic Security

Although the potential adverse environmental effects of CO2 emission is a major factor pressuring governments to steer their energy policy away from fossil fuels, the global decline of fossil fuel reserves is also a major driver for public and private organizations around the world to develop technologies to use renewable energy sources. Various estimates exist for the current proved reserves (Rp), and the Rp:consumption ratio (Rp:c), with units of years. For example, the global Rp:c of coal, oil, and natural gas have been estimated as 140, 40, and 60 [3, 13]. Using the widely-recognized global energy database provided in the British Petroleum (BP) energy report [14], we calculated Rp:c for coal, oil and natural gas as 133, 35, and 60, respectively. For coal and natural gas, the Rp:c value is similar to the previ­ously published estimates and indicates that issues may arise later in this century. However, for oil, our Rp:c value of 35 (years) is even less than that published pre­viously, indicating a serious situation with near-term pressure building to replace oil reserves either with new discoveries (perhaps some, but unlikely to be major) or with new alternatives (biofuels can play a role).

The earliest fuel ethanol production from lignocellulose biomass began in Germany, in 1920s [15], using sulfuric acid to hydrolyze wood. The ethanol yield was low at approximately 75-130 L (20-34 gallons) of ethanol per ton of wood hydrolyzed. From 1945 to1960s, several acid-hydrolysis ethanol plants were built in Europe, the USA, and the former Soviet Union. The capacities of these plants ranged from 10,000 to 45,000 tons of wood materials a year. Ethanol yield reached 190-200 L (50-53 gallons) per ton of wood. Subsequently, almost all of these wood — based ethanol plants were closed due to competition from the rapid development of the petroleum industry and relatively inexpensive crude oil feedstock.

The first gasification of biomass can be dated back to the 1800s, when wood was gasified to generate “town gas” for lighting and cooking. Although there are around 140 large gasification facilities in operation around the world today [16], these gasifiers are basically used to generate heat and/or electricity from coal (55% of total 140 large gasification facilities), oil, or natural gas, with a few plants using residues from the wood/pulp industry. The current main products generated from gasifier syngas are power (18%), chemicals (44%), and FT fuel (38%) [16]. To — date, there are no commercial scale gasification or pyrolysis facilities dedicated for biofuels production from lignocellulosic biomass. However, many research units have been built to investigate the mechanism, kinetics, and economical feasibility of biofuel production via syngas from biomass gasification.