Waste biomass total

Several studies estimate the potential of available virgin and waste biomass as energy resources (Table 4) (10). In Table 4, the projected potential of the recoverable materials is about 25% of the theoretical maximum woody biomass is about 70% of the total recoverable potential. These estimates of biomass energy potential are based on existing, sustainable biomass production and do not iaclude new, dedicated biomass energy plantations that might be developed. 

If the particle size of the biomass fuel or feedstock is not predetermined by its history, as is the case for sawdusts, nutshells, and a few other waste biomass materials, size reduction is usually carried out with one or more units that make up the front end of the total processing system. Many different kinds of machines are employed. Generally, the size of the feed is reduced by grinding, cutting, or impact mechanisms. Not all of the designs are suitable for biomass energy applications because the equipment is customized for certain uses or the cost of size reduction is excessive. Agricultural crops and woody biomass are also usually processed by different types of machines. A brief review of the basic types of machines that are or have been used for biomass follows to illustrate the variety of size-reduction equipment and their biomass applications. 

A total of 288,000 tons of waste/biomass - corresponding to 10 wt% of the annual coal consumption - is foreseen to be contracted, although a larger amount will be possible. The solid fuels will be blended with the raw coal and pulverised in the existing pulverisers, although the use of a separate milling system for some of the biomass products is also considered. The fluids will be stored in bins and pumped to the boilers. In both units fluid burners are mounted in two of the four burner boxes. 

Many of these processes cannot compete with the chemical routes used today. If total environmental costs of global warming, natural resource depletion, waste disposal, and such were included, more of them would be practical today. Research continues to reduce their costs by increasing yields, starting with waste biomass where both five-and six-carbon sugars must be utilized and so forth. 

Secondary consumers eat the primary consumers and produce feces waste, biomass, and cellular respiratory products. Respiration totally degrades the biomass, usually producing water and carbon dioxide. These compounds cannot be further exploited for their energy values and so are the ultimate energy sink for an ecosystem. 

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... 

At the low end is the United States, where biomass energy accounted for only about 3 percent (2.7 quadrillion Btus) of the total energy consumption in 1997. However, biomass use had been rising over the previous five years at an average rate of about 1 to 2 percent per year, but fell in 1997 due to a warmer-than-average heating season. Bioenergy produced in the United States is primarily from wood and wood waste and municipal solid waste. 

Economics for generating electricity from biogas can be favorable. Landfill gas from municipal solid waste can supply about 4 percent of the energy consumed in the United States. In 1997, a total of 90 trillion Btus were generated by landfill gas, about 3 percent of total biomass energy consumption. 

Generating hydrogen from such waste materials may turn out to be one of the least expensive methods of producing hydrogen since this resource is quite extensive. It has been estimated that in the U.S., roughly 14 quads of the annual 64 quad total energy requirement could be met from renewable biomass sources, which is about 20% of our total energy needs. 

There is an apparent upper limit to the strength of waste a biological system ean handle in a liquid system. In some cases the constraint is oxygen transfer. In other eases it is the solids concentration in the mixed liquor and the shear whieh is neeessary to keep it in suspension. Recent work with membranes replaeing the elarifiers have indicated that the upper limit to solids is between 2% and 4% total solids, but not all of that is active biomass. The solids retention time in the system is often well over 40 days. The apparent upper limit on waste expressed as BOD is about 600mg/l -800 mg/1. Stronger wastes ean be treated, but they comprise a portion of the total flow and in effect are diluted. 

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