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ABSTRACT: a b s t r a c t Using sustainably-grown biomass as the sole fuel, or co-fired with coal, is an effective way of reducing the net CO 2 emissions from a combustion power plant. There may be a reduction in efficiency from the use of biomass, mainly as a result of its relatively high moisture content, and the system economics may also be adversely affected. The economic cost of reducing CO 2 emissions through the replacement of coal with biomass can be identified by analysing the system when fuelled solely by biomass, solely by coal and when a coal-bio-mass mixture is used. The technical feasibility of burning biomass or certain wastes with pulverised coal in utility boilers has been well established. Cofiring had also been found to have little effect on efficiency or flame stability, and pilot plant studies had shown that cofiring could reduce NO x and SO x emissions. Several technologies could be applied to the co-combustion of biomass or waste and coal. The assess-ment studies here examine the potential for co-combustion of (a) a 600 MWe pulverised fuel (PF) power plant, (i) cofiring coal with straw and sewage sludge and (ii) using straw derived fuel gas as return fuel; (b) a 350 MWe pressurised fluidised bed combustion (PFBC) system cofiring coal with sewage sludge; (c) 250 and 125 MWe circulating fluidised bed combustion (CFBC) plants cofiring coal with straw and sew-age sludge; (d) 25 MWe CFBC systems cofiring low and high sulphur content coal with straw, wood and woody matter pressed from olive stones (WPOS); and (e) 12 MWe CFBC cofiring low and high sulphur content coal with straw. The technical, environmental and economic analysis of such technologies, using the ECLIPSE suite of pro-cess simulation software, is the subject of this study. System efficiencies for generating electricity are eval-uated and compared for the different technologies and system scales. The capital costs of systems are estimated for coal-firing and also any additional costs introduced when biomass is used. The Break-even electricity selling price is calculated for each technology, taking into account the system scale and fuel used. Since net CO 2 emissions are reduced when biomass is used, the effect of the use of biomass on the elec-tricity selling price can be found and the premium required for emissions reduction assessed. Consideration is also given to the level of subvention required, either as a Carbon dioxide Credit or as a Renewable Credit, to make the systems using biomass competitive with those fuelled only with coal. It would appear that a Renewable Credit (RC) is a more transparent and cost-effective mechanism to sup-port the use of biomass in such power plants than a Carbon dioxide Credit (CC).
10/2010;
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Developments in Chemical Engineering and Mineral Processing. 01/2008; 11:55-66.
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International Journal of Ambient Energy 01/2007; 28(3):143-150.
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ABSTRACT: Using sustainably-grown biomass as the sole fuel, or co-fired with coal, is an effective way of reducing the net CO2 emissions from a combustion power plant. There may be a reduction in efficiency from the use of biomass, mainly as a result of its relatively high moisture content, and the system economics may also be adversely affected.The economic cost of reducing CO2 emissions through the replacement of coal with biomass can be identified by analysing the system when fuelled solely by biomass, solely by coal and when a coal-biomass mixture is used.The technical feasibility of burning biomass or certain wastes with pulverised coal in utility boilers has been well established. Cofiring had also been found to have little effect on efficiency or flame stability, and pilot plant studies had shown that cofiring could reduce NOx and SOx emissions.Several technologies could be applied to the co-combustion of biomass or waste and coal. The assessment studies here examine the potential for co-combustion of (a) a 600 MWe pulverised fuel (PF) power plant, (i) cofiring coal with straw and sewage sludge and (ii) using straw derived fuel gas as return fuel; (b) a 350 MWe pressurised fluidised bed combustion (PFBC) system cofiring coal with sewage sludge; (c) 250 and 125 MWe circulating fluidised bed combustion (CFBC) plants cofiring coal with straw and sewage sludge; (d) 25 MWe CFBC systems cofiring low and high sulphur content coal with straw, wood and woody matter pressed from olive stones (WPOS); and (e) 12 MWe CFBC cofiring low and high sulphur content coal with straw.The technical, environmental and economic analysis of such technologies, using the ECLIPSE suite of process simulation software, is the subject of this study. System efficiencies for generating electricity are evaluated and compared for the different technologies and system scales. The capital costs of systems are estimated for coal-firing and also any additional costs introduced when biomass is used. The Break-even electricity selling price is calculated for each technology, taking into account the system scale and fuel used.Since net CO2 emissions are reduced when biomass is used, the effect of the use of biomass on the electricity selling price can be found and the premium required for emissions reduction assessed. Consideration is also given to the level of subvention required, either as a Carbon dioxide Credit or as a Renewable Credit, to make the systems using biomass competitive with those fuelled only with coal.It would appear that a Renewable Credit (RC) is a more transparent and cost-effective mechanism to support the use of biomass in such power plants than a Carbon dioxide Credit (CC).
Fuel.
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ABSTRACT: Experimental tests have been carried out to evaluate the performance and gaseous emission characteristics of a diesel engine when fuelled with vegetable oil and its blends of 25%, 50%, and 75% of vegetable oil with ordinary diesel fuel separately. Tests on ordinary diesel fuel have also been carried out for comparison purposes.A series of tests are conducted and repeated six times for each of the test fuels. The engine works at a fixed speed of 1500 rpm, but at different loads respectively, i.e. 0%, 25%, 50%, 75% and 100% of engine full loads. The performance and the emission characteristics of exhaust gases of the engine are analyzed and compared.The experimental results show that the basic engine performance – power output and fuel consumption are comparable to diesel when fueled with vegetable oil and its blends. The emission of nitrogen oxides (NOx) from vegetable oil and its blends are lower than that of pure diesel fuel. This emission character found in the tests to some extent is of significance for the practical application of vegetable oil to replace ordinary diesel fuel.The results for the other emissions are also shown in the figures and tables.
Applied Thermal Engineering.
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ABSTRACT: Many buildings require simultaneous electricity, heating and cooling. Biomass is one of the renewable energy sources which is not intermittent, location-dependent or very difficult to store. If grown sustainably, biomass can be considered to be CO2 neutral. A trigeneration system consisting of an internal combustion (IC) engine integrated with biomass gasification may offer a combination for delivering heat, electricity and cooling cleanly and economically. The producer gas generated by the gasifier is used to provide electricity for building use via the IC engine. The waste heat is recovered from the engine cooling system and exhaust gases to supply hot water to space heating, excess heat is also used to drive an absorption cooling system. The proposed system is designed to meet the energy requirements for selected commercial buildings and district heating/cooling applications. This work focuses on the modeling and simulation of a commercial building scale trigeneration plant fuelled by a biomass downdraft gasifier. In order to use both energy and financial resources most efficiently, technical and economic analyses were carried out, using the ECLIPSE process simulation package. The study also looks at the impact of different biomass feedstock (willow, rice husk and miscanthus) on the performance of a trigeneration plant.Highlights► We model a commercial building scale biomass fuelled trigeneration plant. ► It is economically feasible to use willow chips, miscanthus and rice husk as the fuel to operate the trigeneration system. ► The efficiency of TG is much higher than that of PO, but is lower than that of the combined heat and power (CHP) configuration. ► The breakeven electricity selling price (BESP) of the TG system is better than that of the PO option with the CHP option producing the cheapest electricity.
Energy Conversion and Management 52(6):2448-2454. · 2.22 Impact Factor
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ABSTRACT: A parallel approach for fabricating nanocrystal-based semiconductor–insulator–metal tunnel diodes is presented. The devices consisted of a Au electrode, a monolayer of 38 Å CdSe nanocrystals, an insulating bilayer of eicosanoic acid (C19H39CO2H), and an Al electrode. Each device was approximately 100 µm^2. Conductance measurements at 77 K reveal strong diode behavior and evidence of Coulomb blockade and staircase structure. A single barrier model was found to reproduce the electronic characteristics of these devices.
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ABSTRACT: Nitrogen oxides (NOx) is one of the harmful emissions from power plants. Efforts are made to reduce NOx emissions by researchers and engineers all the times. NOx emissions are from three resources during the combustion: prompt NO, fuel NO and thermal NO. The last one – thermal NO, which is described by ‘Zeldovich-mechanism’, is the main source for NOx emissions. The thermal NO emission mainly results from the high combustion temperature in the combustion process. In order to control the NO formation, the control of peak combustion temperature is the key factor, as well as the oxygen concentration in the combustion areas. Flameless oxidation (FLOX) and continuous staged air combustion (COSTAIR) are two relatively new technologies to control the combustion temperature and the reaction rate and consequently to control the NOx emissions.In this study both FLOX and COSTAIR technologies are assessed based on a 12 MWe, coal-fired, circulating fluidised bed combustion (CFBC) power plant by using ECLIPSE simulation software, together with a circulating fluidised bed gasification (CFBG) plus normal burner plant. Two different fuels – coal and biomass (straw) are used for the simulation. The technical results from the study show that the application of FLOX technology to the plant may reduce NOx emissions by 90% and the application of COSTAIR technology can reduce NOx emissions by 80–85% from the power plant. The emissions from the straw-fuelled plants are all lower than that of coal-fuelled ones although with less plant efficiencies.
Fuel.
