Cellulose is an abundant bio renewable polymer derived from biomass and is composed of individual monomer glucose units chemically bound together. Glucose monomers (but not cellulose, itself) are a valuable resource for producing biofuels such as ethanol and other liquid transportation fuels. Glucose monomers also can be used to efficiently produce electricity in an alkaline fuel cell. In order to capitalize on the promise of glucose to produce transportation fuels and to generate electricity for commercial use, it is essential to produce individual glucose units from the complex cellulose biopolymer. There exists in the art, therefore, an abundant need to find alternative, efficient means for breaking natural polymeric materials derived from biomass into monomeric units.
Once monomeric glucose and other monomeric carbohydrates are obtained, they are used to produce ethanol by known industrial processes to meet the needs of the transportation sector and reduce the use of petroleum products for this purpose. Generation of electricity from bio renewable glucose via the above process will make electrical generation from biomass a feasible process.
Glucose is currently used on a large scale to produce ethanol as part of a strategy to reduce dependence on petroleum as a transportation fuel. Furan-based fuels derived from carbohydrates are also being investigated for the same purpose. Recent developments also have shown that carbohydrates can be used to efficiently generate electricity using alkaline fuel cells. The promise of using abundant biomass components to replace petroleum for transportation purposes and for the production of electricity is clearly important. However, current agricultural methods for producing glucose for the above processes will soon face serious availability problems, as glucose use for fuel and electricity will compete with glucose for food production.
The production of ethanol from glucose for use as a transportation fuel will reduce dependence on fossil fuel-derived products for transportation. The major use will be in the transportation sector. In addition, using glucose derived from renewable biomass for large-scale commercial electrical production using glucose fuel cells will minimize greenhouse gas production, which in turn will lower atmospheric pollution.
The long-term solution for energy production from carbohydrates lies in converting cellulose and hemicellulose from biomass into their substituent monomeric units, typically carbohydrates. Both cellulose and hemicellulose are abundant in biomass. The problem is that no economically feasible processes are presently available for cellulose and hemicellulose conversion into their substituent carbohydrates. In order to capitalize on the promise of using biomass components for energy production, new and economically feasible methods must be found for producing carbohydrate monomers from cellulose and hemicellulose derived from biomass.
The U.S. National Renewable Energy Laboratory (NREL) is involved in a variety of programs to produce glucose from cellulose. For the most part, these programs focus on physical methods (steam explosion, fine grinding, etc.) to produce glucose from the cellulose polymer. In addition, they employ harsh chemical treatments such as high temperature and high acid and base hydrolysis procedures. While these processes currently produce glucose in varying amounts, they are currently not economically competitive, they require harsh conditions and chemicals, and significant decomposition of the product glucose occurs.
Other processes use enzymes derived from fungi, bacteria and yeast to degrade cellulose to glucose but they are slow and expensive processes and are currently not economically viable. Thus, although chemical means to break the glycosidic bond have been investigated, there remains a need in the art to obtain alternative processes that that efficiently produce glucose and other monomeric units from biomass.