Biofuel

Biodiesel (FAME) is a renewable fuel that is made by transesterification of vegetable oils or animal fat with methanol. Several different types of oils could be used, the most common are soybean oil, rapeseed oil, and palm oil [66]. The most widely used transesterification process for commercial biodiesel is alkali-catalyzed [67]. This process typically uses NaOH or KOH as a catalyst. Although the biodiesel is purified, residual amounts of Na or K can remain in the biodiesel [68]. Current standard is Na H- K 5 ppm for 100 % biodiesel (BlOO). Biodiesel also contains phosphorus that originates from phospholipids. The current standard is P 4 ppm for BlOO. 

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D. Tillman, E. Hughes, and B. Gold, "Cofiring of Biofuels in Coal Eked Boilers Results of Case Study Analysis," Proceedings First Biomass Conference... 

The percentage of energy demand that could be satisfied by particular nonfossil energy resources can be estimated by examination of the potential amounts of energy and biofuels that can be produced from renewable carbon resources and comparison of these amounts with fossil fuel demands. 

Gross heating value of biomass or methane. Conversion of biomass or methane to another biofuel requires that the process conversion efficiency be used to reduce the potential energy available. These figures do not include additional biomass from dedicated energy plantations. 

U.S. capacity for producing biofuels manufactured by biological or thermal conversion of biomass must be dramatically increased to approach the potential contributions based on biomass availabiUty. For example, an incremental EJ per year of methane requires about 210 times the biological methane production capacity that now exists, and an incremental EJ per year of fuel ethanol requires about 14 times existing ethanol fermentation plant capacity. 

Includes fuelwood, charcoal bagasse, and animal, crop, pulp, paper, and municipal soHd wastes, but does not include derived biofuels. Sums of individual figures may not equal totals because of rounding. 

Less than Table 5 value of 2.954 EJ for the United States because does not include biofuels from biomass. 

The need to meet environmental regulations can affect processing costs. Undesirable air emissions may have to be eliminated and Hquid effluents and soHd residues treated and disposed of by incineration or/and landfilling. It is possible for biomass conversion processes that utilize waste feedstocks to combine waste disposal and treatment with energy and/or biofuel production so that credits can be taken for negative feedstock costs and tipping or receiving fees. 

Alternatively, short-rotation hybrid poplar and selected grasses can be multicropped on an energy plantation in the U.S. Northwest and harvested for conversion to Hquid transportation fuels and cogenerated power for on-site use in a centrally located conversion plant. The salable products are Hquid biofuels and surplus steam and electric power. This type of design may be especially useful for larger land-based systems. 

Table 32. Biofuels Utilization and Production and Biomass-Fueled Electric Power Plant Capacities in the United States ...

Ref. 2. The indicated biofuels consumption and capacity figures are the estimated values for various time periods since 1985 and do not refer to a specific year. 

Municipal Solid Waste. In the eady 1990s, the need to dispose of municipal soHd waste (MSW) ia U.S. cities has created a biofuels industry because there is Htde or no other recourse (107). Landfills and garbage dumps are being phased out ia many communities. Combustion of MSW, ie, mass-bum systems, and RDF, ie, refuse-derived fuel, has become an estabhshed waste disposal—energy recovery industry. 

Table 35. Installed Nonutility Electricity Generation Capacity and Generation by Biofuel, 1986 ...

Biofuel Cogeneration Small power producers Total ... 

Capacity Limitations and Biofuels Markets. Large biofuels markets exist (130—133), eg, production of fermentation ethanol for use as a gasoline extender (see Alcohol fuels). Even with existing (1987) and planned additions to ethanol plant capacities, less than 10% of gasoline sales could be satisfied with ethanol—gasoline blends of 10 vol % ethanol the maximum volumetric displacement of gasoline possible is about 1%. The same condition apphes to methanol and alcohol derivatives, ie, methyl-/-butyl ether [1634-04-4] and ethyl-/-butyl ether. 

The Energy PoHcy Act of 1992 (H.R. 776) has Hberalized the rules concerning biofuels and provides tax incentives for increased usage. Many states also have gasohol fuel tax exemptions in place, and some have enacted legislation that requites use of oxygenated fuels under certain conditions. Most of these laws impact favorably on biofuels usage. 

Biofuels Technical Information Guide, SERI/SP-220-3366, Solar Energy Research Institute, Golden, Colo., Apr. 1989, 198 pp. 

Physical Properties. Physical properties of waste as fuels are defined in accordance with the specific materials under consideration. The greatest degree of definition exists for wood and related biofuels. The least degree of definition exists for MSW, related RDF products, and the broad array of ha2ardous wastes. Table 3 compares the physical property data of some representative combustible wastes with the traditional fossil fuel bituminous coal. The soHd organic wastes typically have specific gravities or bulk densities much lower than those associated with coal and lignite. 

Table 8. Trace Metal Concentrations in Ash from Agricultural Biofuels and Wood-Fired Boilers, mg/kg...

In the United States, up to about 4 x 10 Btu/yr of biofuels ate consumed for electricity generation, raising process heat, and domestic heat. Eurthermore, much of the energy needs of many nations are met by biofuels, including wood and wood waste, spent pulping fiquors, bagasse, and municipal waste. Some use is also made of dried com cobs, rice hulls, and a wide variety of agricultural wastes used in niche appfications. 

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