Biomass, as fuel

Carbon dioxide is present in the atmosphere at about 0.03 vol.% and also in water as dissolved gas or carbonate. It is estimated that carbon dioxide follows a 350-year life cycle as it passes from air and water, into organic compounds, and then returns. The use of biomass as fuel will keep this carbon dioxide balance in check if the userreplacement ratio of biomass remains equally balanced. Burning fossil fuels, by comparison, does not provide the immediate opportunity or option for replacement. 

White, L.P. and Plaskett, L.G., Biomass as Fuel, Academic Press, London, 1981. 

Carbon capture refers to measures that at least temporarily remove carbon dioxide from the atmosphere or prevent its release to the atmosphere. One way in which net release of carbon dioxide to the atmosphere is prevented is the use of biomass for fuel and raw material in place of petroleum. When biomass is burned, carbon dioxide is released, but exactly the same amount of carbon dioxide was removed from the atmosphere for the photosynthetic production of the biomass. Therefore, on balance, using biomass as fuel does not add carbon dioxide to the atmosphere. If biomass is not burned or does not decay, its production amounts to a net loss of atmospheric carbon dioxide. 

A realistic assessment of biomass as an energy resource is made by calculating average surface areas needed to produce sufficient biomass at different aimual yields to meet certain percentages of fuel demand for a particular country (Table 2). These required areas are then compared with surface areas available. The conditions of biomass production and conversion used ia Table 2 are either within the range of 1993 technology and agricultural practice, or are beheved to be attainable ia the future. 

Sepa.ra.tlon, It maybe desirable to separate the feedstock into two or more components for different appHcations. Examples include separation of agricultural biomass into foodstuffs and residues that may serve as fuel or as a raw material for synfuel manufacture, separation of forest biomass into the darker bark-containing fractions and the pulpable components, separation of marine biomass to isolate various chemicals, and separation of urban... 

Still another possibiUty is a marine biomass plantation such as that envisaged for giant brown kelp grown off the California coast and conversion of the kelp to methane in a system similar to that shown in Figure 19. The location of the SNG plant could be either on a floating platform near the kelp growth area or located on shore, in which case the biomass or fuel transport requirements would be different. 

Another factor is the potential economic benefit that may be realized due to possible future environmental regulations from utilizing both waste and virgin biomass as energy resources. Carbon taxes imposed on the use of fossil fuels in the United States to help reduce undesirable automobile and power plant emissions to the atmosphere would provide additional economic incentives to stimulate development of new biomass energy systems. Certain tax credits and subsidies are already available for commercial use of specific types of biomass energy systems (93). 

H. F. Feldmann and co-workers, ia D. L. Klass, ed.. Biomass as a Nonfossil Fuel Source, ACS Symposium Series 144, American Chemical Society,... 

Refuse-Derived Fuel. Many processing faciUties divert a portion of the material that is not recovered for recycling to waste-to-energy plants, also referred to as resource recovery faciUties, where the material is employed as fuel. The processes involved in the production of refuse-derived fuel (RDF) are outlined in Figure 4 (23). Nine different RDFs have been defined, as Hsted in Table 3 (24). There are several ways to prepare RDF-3, which is perhaps the most popular form and is the feed used in the preparation of densified refuse-derived fuel (d-RDF). AH forms of RDF are part of the broader set of waste-derived fuels (WDF), which includes various waste biomass, eg, from silvaculture or agriculture (see Fuels frombiomass Fuels fromwaste). 

Electric power generation using biomass as a fuel is economic in situations where the cost of the fuel is competitive with that of fossil fuels. The cost of a commercially available biomass steam—electric power plant is about 1500/kW for a wood-fired facility. If wood can be obtained at a cost of 2.00/GJ ( 2.10 X 10 /Btu), the total cost of power for base-load operation would be about 0.05/kWh. If wood or agricultural wastes are available at... 

Biofuels are used to create a wide variety of energy sources. Ever since the harnessing of fire, biomass has been used for heating and conking. Residential burning of biomass continues to be a primary source of fuel in less industrialized nations, but also has been used as fuel for electricity generation, and converted to liquid transportation fuels. 

Hall, Carl W. Biomass as an Alternative Fuel. Government Institutes, Inc., Rockville, MD. 1981. 267 pp. 

In principle biomass is a useful fuel for fuel cells many of the technologies discussed above for using biomass as a fuel produce either methane or hydrogen directly and as highlighted below synthesis gas production from biomass for conversion to methanol is an attractive option. Cellulose-based material may be converted to a mixture of hydrogen (70% hydrogen content recovered), CO2 and methane by high-temperature treatment with a nickel catalyst. 

A bleached kraft pulp mill requires 15,140 to 45,420 L (4000 to 12,000 gal) of water and 8.56 to 12.22 million chu (14 to 20 million Btu) of energy per ton of pulp, of which ca. 4.44 to 5.56 million chu (8 to 10 million Btu) are typically derived from biomass-derived fuel from the pulping process itself.4 Across all facilities, the pulp, paper, and allied products industry is the largest consumer of process water and the third largest consumer of energy (after the chemicals and metals industries).5,6 The large amounts of water and energy used, as well as the chemical inputs, lead to a variety of environmental concerns. 

Develop methods to use biomass as a renewable fuel source. 

At Brookhaven National Laboratory in the 1980s, a two-step process was described for the coproduction of hydrogen and carbon, with methane being the intermediate see Steinberg.107108 In the first step, carbonaceous material is hydrogasified to methane with a subsequent thermal decomposition of the methane to hydrogen and carbon. In the process, water is also formed from the oxygen present in the fuel. A typical overall conversion of biomass, as reported by Milne et al.,5 would be... 

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