【正文】 M costs were conservatively estimated at $5/MWhth. . Gasification cofiring In the analysis of the gasification cofiring option, a generation loss of % was taken, thus reducing the plant capacity factor to %. The product gas produced by the gasifier can cause problems in the backpass of the boiler with increased tube corrosion/fouling. This would lead to a slight increase in time for boiler maintenance and repairs, and hence the lower capacity factor. The capital cost of the gasification cofiring option was calculated based on the analysis of Antares [14]. Antares proposed a capital cost estimate of 382 USD/kWe. The capital cost was then found using the heating rate of the existing coalfired plant. The Oamp。熱能與動力工程畢業(yè)論文外文翻譯 外文文獻： Biomass cofiring options on the emission reduction and electricity generation costs in coalfired power plants Abstract Cofiring offers a nearterm solution for reducing CO2 emissions from conventional fossil fuel power plants. Viable alternatives to longterm CO2 reduction technologies such as CO2 sequestration, oxyfiring and carbon loop bustion are being discussed, but all of them remain in the early to mid stages of development. Cofiring, on the other hand, is a wellproven technology and is in regular use though does not eliminate CO2 emissions entirely. An incremental gain in CO2 reduction can be achieved by immediate implementation of biomass cofiring in nearly all coalfired power plants with minimum modifications and moderate investment, making cofiring a nearterm solution for the greenhouse gas emission problem. If a majority of coalfired boilers operating around the world adopt cofiring systems, the total reduction in CO2 emissions would be substantial. It is the most efficient means of power generation from biomass, and it thus offers CO2 avoidance cost lower than that for CO2 sequestration from existing power plants. The present analysis examines several cofiring options including a novel option external indirect firing using bustion or gasification in an existing coal or oil fired plant. Capital and operating costs of such external units are calculated to determine the return on investment. Two of these indirect cofiring options are analyzed along with the option of direct cofiring of biomass in pulverizing mills to pare their operational merits and cost advantages with the gasification option. 1. Introduction The evidence of the effects of anthropogenic emission on global climate is overwhelming [1]. The threat of increasing global temperatures has subjected the use of fossil fuels to increasing scrutiny in terms of greenhouse gas GHG and pollutant emissions. The issue of global warming needs to be addressed on an urgent basis to avoid catastrophic consequences for humanity as a whole. Socolow and Pacala [2] introduced the wedge concept of reducing CO2 emissions through several initiatives involving existing technologies, instead of a single future technology or action that may take longer to develop and stronger willpower to implement. A wedge represents a carboncutting strategy that has the potential to grow from zero today to avoiding 1 billion tons of carbon emissions per year by 2055. It has been estimated [3] that at least 15 strategies are currently available that, with scaling up, could represent a wedge of emissions reduction. Although a number of emission reduction options are available to the industry, many of them still face financial penalties for immediate implementation. Some measures are very site/location specific while others are still in an early stage of development. Carbon dioxide sequestration or zero emission power plants represent the future of a CO2 emissionsfree power sector, but they will take years to e to the mainstream market. The cost of CO2 capture and sequestration is in the range of 40e60 US$/ton of CO2, depending on the type of plant and where the CO2 is stored [4,5]. This is a significant economic burden on the industry, and could potentially escalate the cost of electricity produced by as much as 60%. Canada has vast amounts of biomass in its millions of hectares of managed forests, most of which remain untapped for energy purposes. Currently, large quantities of the residues from the wood products industry are sent to landfill or are incinerated [6]. In the agricultural sector, grain crops produce an estimated 32 million tons of straw residue per year. Allowing for a straw residue of 85% remaining in the fields to maintain soil fertility, 5 million tons would still be available for energy use. Due to an increase in land productivity, significant areas of land in Canada, which were earlier farmed, are no longer farmed. These lands could be planted withfastgrowing energy crops, like switchgrass offering potentially large quantities of biomass for energy production [6]. Living biomass plants absorb CO2 from the atmosphere. So, its bustion/gasification for energy production is considered carbon neutral. Thus if a certain amount of biomass is fired in an existing fossil coal, coke or oil fuel fired plant generating some energy, the plant could reduce firing the corresponding amount of fossil fuel in it. Thus, a power plant with integrated biomass cofiring has a lower CO2 contribution over conventional coalfired plants. Biomass cofiring is one technology that can be implemented immediately in nearly all coalfired power plants in a relatively short period of time and without the need for huge investments. It has thus evolved to be a nearterm alternative to reducing the environmental impact of electricity generation from coal. Biomass cofiring offers the least cost among the several technologies/ options available for greenhouse gas reduction [7]. Princ