Substitution, biomass

Reducing CO2 emissions by substituting biomass for fossil foels, Energy, 20. pp. 

With all components in the ideal gas state, the standard enthalpy of the process is exothermic by —165 kJ (—39.4 kcal) per mole of methane formed. Biomass can serve as the original source of hydrogen, which then effectively acts as an energy carrier from the biomass to carbon dioxide, to produce substitute (or synthetic) natural gas (SNG) (see Euels, synthetic). 

X 10 Btu/short ton), the solar energy trapped in 17.9 x 10 t of biomass, or about 8 x 10 t of biomass carbon, would be equivalent to the world s fossil fuel consumption in 1990 of 286 x 10 J. It is estimated that 77 x 10 t of carbon, or 171 x 10 t of biomass equivalent, most of it wild and not controlled, is fixed on the earth each year. Biomass should therefore be considered as a raw material for conversion to large suppHes of renewable substitute fossil fuels. Under controlled conditions dedicated biomass crops could be grown specifically for energy appHcations. 

Table 2. Potential Substitute Natural Gas in United States from Biomass at Different Crop Yields...

There has been considerable research into the production of substitute natural gas (SNG) from fractions of cmde oil, coal, or biomass (see Euels SYNTHETIC, Euels frombiomass Euels fromwaste). The process involves partial oxidation of the feedstock to produce a synthesis gas containing carbon... 

The selling price of the SCP must be the same as or less than competing food and feedstuffs The price of conventional competing protein feeds is 0.80 per kg protein. The price of conventional competing high-protein food additives is 155 per kg proton. For a meat substitute, the SCP can be priced at 1.05 per kg biomass. 

To produce Fusarium sp. for meat substitutes the aseptic system must be operated with recovery by filtration followed by deep-freezing. The cost is thus 0.649 + 0.04 + 0.001 + 0.04 = 0.730 per kg biomass. 

With meat substitutes at 1.05 per kg, and Fusarium sp. at 0,730 per kg biomass, this product would make a profit of 1.050 - 0.730 = 0.32 per kg. This would be the most profitable product. 

Substituting values into (E.2.2), the maximum biomass production is calculated as follows ... 

A Monod rate model is used to demonstrate the rate of biomass generation. We neglect the cell death rate. Let us denote the ratio of biomass rate of generation to biomass concentration, rJX, that is the specific growth rate /a also denotes the dilution rate D is defined as number of tank volumes passed through per unit time, FIV. After substitution of D and /a into (6.8.1), the following equation is obtained ... 

Coal used in power stations has the potential to be partly replaced by fuels derived from pre-treated plastics and paper waste, reducing both dependency on fossil fuels and reliance on landfill. APME reports on a project in the Netherlands which it co-sponsored to develop a substitute fuel from plastics. The environmental assessment of the project compared the environmental impacts of coal substitution with other plastics recovery methods, including gasification in feedstock recycling and energy recovery from plastics waste in cement kilns. The study also compared coal substitution with the generation of power from burning biomass. 

Because of limits on the amount of land accordingly available for growing plants that can be used for energy, bioenergy cannot be viewed globally as the sole replacement or substitute for fossil fuels, but rather as one element in a broader portfolio of renewable energy sources [1]. In rural locations in developing countries without current access to electricity, however, biomass can provide a transformative local power source. 

Being on-farm emissions (from cultivation and animals breeding) the most important source of GHG in food life cycle, numerous studies have tried to reduce them. Ahlgren [55] has used LCA to evaluate the use of biofuels in tractors and the substitution of mineral nitrogen fertilizers. This implied that 3-6% of a farm s available land was needed to produce the required biomass (to produce biofuels and fertilizer). 

A fundamental requirement for using a sewer as a treatment system followed by subsequent physicochemical or mechanical treatment is often the installment of aerators. Contrary to what has been proposed by a number of authors, the limitation in using the sewer as a treatment system is normally not the biomass. Addition (circulation) of activated sludge is, therefore — except for cases with excessive aeration — in general, of no interest. Substitution of oxygen with nitrate as electron acceptor is possible, but a reduced rate of transformation is expected. 

Methanol, which is also known as wood alcohol, is a colorless and odorless liquid alcohol fuel that can be made from biomass, natural gas, or coal. It is the simplest alcohol chemically and it may be used as an automobile fuel in its pure form (Ml 00), as a gasoline blend of typically 85% methane to 15% unleaded gasoline (M85). It is also used as a feedstock for reformulated gasoline. M100 or pure methanol may be used as a substitute for diesel. In M85, the gasoline is added to color the flame of burning fuel for safety reasons and to improve starting in cold weather. 

Biomass can provide substitutes for fossil fuels as well as electricity and heat. Its resource base is varied. Arid land, wetlands, forest, and agricultural lands can provide a variety of plants and organic matter for biomass feedstock. 

The potential of biomass to make a large contribution towards replacing conventional fuels is constrained by land availability and competition with other end-use sectors. In particular, the potential for oil seeds to generate FAME is limited. Generally, yields of biofuels from purpose-grown crops depend on the species, soil type and climate.22 At a global level, it is estimated that biofuels could substitute up... 

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