Spelling suggestions: "subject:"biomass energy"" "subject:"iomass energy""
311 |
An investigation into the synergistic action of cellulose-degrading enzymes on complex substratesThoresen, Mariska January 2015 (has links)
No description available.
|
312 |
Biofuel, land-use tradeoffs and livelihoods in Southern AfricaVon Maltitz, Graham Paul January 2014 (has links)
The rapid expansion of biofuel projects in southern Africa creates an opportune issue against which to examine land-use tradeoffs within the areas of customary land tenure. For this an ecosystems services approach is used. Jatropha curcas (L), a perennial oilseed plant which has been the key focus of most of the region’s biofuel expansion to date is used as the focus biofuel crop for which case study data were obtained from Malawi, Mozambique, Zambia and South Africa. Despite the initial enthusiasm for jatropha, most projects have proven less successful than hoped, and many have collapsed. A few are, however, still showing signs of possible success and it is two of these that form the basis of the case studies. Hugely complex tradeoffs are involved when considering biofuel as a land-use option for communal areas. They range from global impacts such as biodiversity and global climate forcing, through national concerns of rural development, national food security and national fuel security, to local household concerns around improving livelihoods. Land that is converted to biofuel needs to be removed from some previous use, and in the southern African case it is typically woodlands and the multitude of services they provide, that suffer. The nature of the tradeoffs and the people affected change over the scale under consideration. For the local farmer it is only the local issues that are of concern, but national and global forces will change the policy environment and lead to new types of development such as biofuels. Change is inevitable, and in all developments there are likely to be both winners and losers. It is clear that the impacts arising from biofuel are situation dependent, and each community and location has unique social and environmental considerations that need to be taken into account. In the case of jatropha the final realised yield and the economic returns that this can generate, will be of critical importance and remain one of the main uncertainties. There are promising signs that under certain circumstances the balance of benefits from jatropha biofuel may be positive, but if implemented incorrectly or in the wrong place, there is extensive evidence of total project failure. It is clear that evidence-based data and assessment tools are needed to assist communities, developers and government departments to make sound decisions around biofuel (or other land-use based) development. A number of such tools are suggested in the thesis. Both the use of large-scale plantations or small-scale farmer centred projects have their advantages and disadvantages. It is probable that in the correct circumstances either can work. However, large-scale plantations can have huge negative social and environmental consequences if poorly implemented. Small-scale projects, though improving livelihoods, are unlikely to take the farmers out of poverty. Tradeoffs from any land-use change are inevitable. Empirical data on biofuel impacts on the environment and society are needed for the development of sound policy. A favourable policy environment can ensure that positive benefits from biofuel are obtained, whilst minimising negative impacts. To develop this policy means that southern African countries will have to clearly understand what they wish to achieve from biofuel, as well as having a clear understanding of impacts from biofuel implementation. Sound scientific knowledge needs to underpin this process. For instance governments may wish to increase the ratio of small-scale to large-scale plantation to increase the developmental benefits, ensure biofuel is used to promote national fuel security rather than being exported, or develop a medium-scale farming sector which can help move farmers out of poverty and assist in developing a market surplus of agricultural commodities. Analysing impacts from biofuel expansion is a complex and multi-dimensional problem and as such will require multi-criteria analysis tools to develop solutions. Global, national and local tradeoffs must all be considered. In addition a wide range of stakeholders are involved and participatory processes may be needed to capture their inputs. Tools to better analyse impacts, specifically at the local level are needed. These local results need to feed into national level economic assessments. The cost of biofuel introduction should be considered against the costs of not implementing biofuel, realising that doing nothing also has a cost and long-term impact. Third-party certification provides a useful tool for shifting costs of ensuring compliance with social and environmental legislation, from the state to biofuel companies. In addition ongoing monitoring and evaluation of existing projects is needed to learn from successes and failures, to identify unintended consequences, and to increase the resilience of projects, community livelihoods and the national economy. This will have to be supplemented with additional focused and ongoing research.
|
313 |
Podnikatelský plán energetické plantáže / Business plan of energy plantationBydžovský, Matěj January 2008 (has links)
The aim of the dissertation is to create the clear directions for setting up of the business plan and to create also the real business plan of the short rotation energy plantation. The dissertation consists of two main parts. The theoretical part describes the structure of the business plan and the principles for setup, the application part contains the real business plan of the planting short rotation coppices, which could be used both as a decision tool for realization of this project in practice and as the documentation for an application for a bank loan. The business plan mentions the market opportunity, the description of the woody species, the technology of founding, growing and harvesting of the plantation, the financial plan, SWOT analysis and possible risks with suggestions for solutions.
|
314 |
Correlação entre biomassa e nutrientes de galhos e folhas em um plantio adensado de Eucalyptus grandis x Eucalyptus urophylla /Oguri, Guilherme, 1984. January 2012 (has links)
Orientador: Saulo Philipe Sebastião Guerra / Co-orientador: Kléber Pereira Lanças / Banca: José Mauro Santana da Silva / Banca: Fabio Minoru Yamaji / Resumo: Este estudo teve com objetivo avaliar a produção de biomassa e correlacionar com os nutrientes de galhos e folhas que poderão ser exportados através da colheita mecanizada, bem como o poder calorífico dos galhos em função de diferentes espaçamentos e adubações em um plantio de Eucalyptus urophylla x Eucalyptus grandis de curta rotação. O plantio da área em estudo ocorreu em dezembro de 2008, totalizando 5,8 ha. A área total foi dividida em cinco espaçamentos utilizando três diferentes doses de adubação. Nas idades de 18 meses, 24 meses e 30 meses após o plantio, foi realizado um inventário coletando informações de diâmetro a altura do peito (DAP) para escolha das árvores-amostra com o intuito de obter dados sobre a biomassa de galhos e folhas, assim como o poder calorífico dos galhos e nutrientes nas folhas e nos galhos. Amostras de galhos e folhas foram coletadas e pesadas no campo e levadas para estufa para posterior cálculo de biomassa seca por unidade de área. Os nutrientes em estudo foram os macronutrientes, nitrogênio, fósforo e potássio e; os micronutrientes, boro e zinco. Para o cálculo do poder calorífico superior (PCS) utilizou-se uma bomba calorimétrica seguindo a norma NBR 8633. Todos os resultados foram analisados pela análise de variância e, posteriormente, teste de Tukey. Concluiu-se que a biomassa de galhos e folhas aumentou de acordo com o nível de adubação e, também que aumentando a dose de fertilizantes, maior será a exportação de nutrientes nas folhas e nos galhos / Abstract: The aim of this study was to evaluate the biomass production and correlate with branches and leaves nutrients content that will be exported by mechanical harvesting, as well as the calorific value of branches as a function of spacements with three levels of fertilization in an Eucalyptus grandis x Eucalyptus urophylla short rotation forest. The forest was planted in December 2008 in a total of 5,8 ha. At 18 months, 24 months and 30 months after planting we collected information about diameter to choose the sample-trees in order to obtain branches and leaves biomass data, as well as the branches and leaves nutrients content and calorific value of branches. Leaves and branches samples were collected and weighted on the field and taken at greenhouse to calculate dry biomass. The macronutrients - N, P and K - and the micronutrients - B and Z - were studied. The gross calorific value was calculated using a calorimeter according to NBR 8633. All results were analyzed by ANOVA and Tukey test. It was concluded that branches and leaves biomass increases at the same way the fertilizer level increases and also we noted that increasing the fertilizer amount, larger will be branches and leaves export nutrients. / Mestre
|
315 |
Engineered Microbial Consortium for the Efficient Conversion of Biomass to BiofuelsAnieto, Ugochukwu Obiakornobi 08 1900 (has links)
Current energy and environmental challenges are driving the use of cellulosic materials for biofuel production. A major obstacle in this pursuit is poor ethanol tolerance among cellulolytic Clostridium species. The first objective of this work was to establish a potential upper boundary of ethanol tolerance for the cellulosome itself. The hydrolytic function of crude cellulosome extracts from C. cellulolyticum on carboxymethyl cellulose (CMC) with 0, 5, 10, 15, 20 and 25% (v/v) ethanol was determined. Results indicated that the endoglucanase activity of the cellulosome incubated in 5% and 10% ethanol was significantly different from a control without ethanol addition. Furthermore a significant difference was observed in endoglucanase activity for cellulosome incubated in 5%, 10%, 15%, 20% and 25% ethanol in a standalone experiment. Endoglucanase activity continued to be observed for up to 25% ethanol, indicating that cellulosome function in ethanol will not be an impediment to future efforts towards engineering increasing production titers to levels at least as high as the current physiological limits of the most tolerant ethanologenic microbes. The second objective of this work was to study bioethanol production by a microbial co-culture involving Clostridium cellulolyticum and a recombinant Zymomonas mobilis engineered for the utilization of oligodextrans. The recombinant Z. mobilis ZM4 pAA1 and wild type ZM4 were first tested on RM medium (ATCC 1341) containing 2% cellobiose as the carbon source. Ethanol production from the recombinant Z. mobilis was three times that observed from the wild type Z. mobilis. Concomitant with ethanol production was the reduction in OD from 2.00 to 1.580, indicating the consumption of cellobiose. No such change in OD was observed from the wild type. The recombinant ZM4 was then co-cultured with C. cellulolyticum using cellobiose and microcrystalline cellulose respectively as carbon sources. Results indicate that the recombinant ZM4 acted synergistically with C. cellulolyticum to utilize 2.0 g L-1 cellobiose, producing as much as 0.40 mM concentration of ethanol whereas only 0.20 mM ethanol was detected for the wild type ZM4 co-cultured with C. cellulolyticum under the same conditions. A co-culture of the recombinant ZM4 and C. cellulolyticum using 7.5 g L-1 microcrystalline cellulose gave lower ethanol yield than when using cellobiose. In the latter case, the recombinant began producing ethanol in 5 days whereas the wild type required 10 days to produce detectable ethanol. Future efforts will concentrate on identifying the correct concentration of cellulosic substrate at which synergy will be observed using the recombinant ZM4 and other cellulose degrading microorganisms, as well as optimizing medium formulations to better support both organisms.
|
316 |
As the smoke clears: assessing the air pollution and health benefits of a nationwide transition to clean cooking fuels in EcuadorGould, Carlos Francisco January 2021 (has links)
Air pollution is the world’s greatest environmental health risk factor and reducing exposure remains an ongoing challenge around the world. Among the world’s poor, marginalized, and rural populations, household air pollution from the inefficient burning of biomass fuels like firewood, charcoal, dung, and agricultural residues for daily household energy needs is a leading cause of morbidity and mortality, especially for children under the age of five years. However, household air pollution exposure is a modifiable risk factor and clean-burning cooking fuels like gas and electricity promise substantial health benefits for the 2.8 billion people reliant on biomass fuels. But, clean fuels remain prohibitively expensive or inaccessible for those most reliant on biomass fuels. It is in this context that I examine Ecuador – where substantial cooking gas subsidies have facilitated a nationwide transition to household clean fuel use over four decades – as a long-term case study to understand the potential for widespread clean fuel uptake to reduce air pollution exposure and improve children’s health. Chapter 1 provides background information that contextualizes the work presented in this dissertation.
In Chapter 2, I discuss the development of Ecuador’s clean fuel policies. Originally established as a part of broad social support reforms in the 1970s, direct-to-consumer subsidies that lowered the cost of liquefied petroleum gas (LPG) – a popular clean-burning cooking fuel used widely around the world – have driven a transition from 80% of households cooking primarily with firewood in the 1970s to now 90% relying primarily on LPG. However, widespread clean fuel use has come at a cost; each year, the Government of Ecuador spends approximately 1% of the national growth domestic product subsidizing LPG (300-700 million USD). To reduce this financial burden, the government has offered incentives to households to install and use induction electric stoves, which can be powered by the nation’s growing hydroelectric capacity, thereby reducing the cost of LPG subsidies and greenhouse gas emissions. To supplement national data, I administered household energy surveys in a northern province, finding that while all households regularly used LPG, 80% still used firewood for cooking. In these remote regions along the Colombian border, limited access to LPG cylinder refills remains a significant barrier to exclusive LPG use, even after decades of building a robust distribution system.
In Chapter 3, I describe results from tailored household surveys – covering energy end uses, costs and access to fuels, and fuel use preferences – administered in 808 households across coastal and Andean Ecuador. Nearly all participants reported using LPG for more than a decade and having frequent, convenient access to cheap LPG cylinder refills. Nonetheless, half of rural households and one-fifth of peri-urban households relied on firewood for cooking and to meet specific household energy needs, like space heating or heating water for bathing. Induction stoves were rare and many induction stove owners reported zero use because the required equipment had never been installed by electricity companies, their stove had broken, or they feared high electricity costs. Here, I show that nationally-representative surveys reporting only “primary cooking fuel” use may underestimate solid fuel use as a secondary option, particularly in rural areas where LPG fuel availability issues play an important role in cooking fuel decision making. These findings additionally indicate that persistent biomass use may curtail the benefits from even the most aggressive clean fuel policies and suggest that additional targeted interventions may be needed to more fully displace biomass. Furthermore, they highlight the need for more nuanced nationally- and subnationally-representative surveys to better understand the extent to which biomass fuels are used secondary to LPG throughout all regions of Ecuador.
In Chapter 4, I present results from a sensor monitoring study where we measured personal PM2.5 exposure and stove use for 48-hour monitoring periods among 157 households in peri- urban and rural Ecuador. Firewood-using participants had higher distributions of 48-hour and 10-minute PM2.5 exposure as compared with primary LPG and induction stove users. Accounting for within-subject clustering, contemporaneous firewood stove use was associated with 101 μg/m3 higher 10-min PM2.5 exposure (95% confidence interval: 94–108 μg/m3). Cooking events with clean fuels were not associated with contemporaneous increases in PM2.5 exposure. These findings confirm our expectations that in a region with low ambient air pollution, long-term cooking gas subsidies can lead to relatively low personal air pollution exposures. And yet, persistent secondary firewood use led to higher average and peak exposures, further motivating the displacement of firewood use to reduce health risks from air pollution. I also outline the methodological challenges faced in combining time-resolved sensor data on participant location, stove use monitors, and PM2.5 concentration and offered advice for future studies.
In Chapter 5, I assess whether Ecuador’s increased clean cooking fuel use has resulted in improvements in under-5 lower respiratory infection (LRI) mortality. Globally, LRIs are the leading cause of death for children under-5 and household air pollution exposure is a leading risk factor. I employ public use data on cooking fuel use and cause-coded mortalities from 1990 to 2019 to estimate the association between clean cooking fuel use and the rate of under-5 LRI mortalities at the canton (county) level in Ecuador. Using generalized additive mixed models with fixed effects for canton and study period, I observed a significant, non-linear negative association providing evidence that when more than 60% of households in a canton cook primarily with a clean fuel, increased clean fuel use is associated with reductions in under-5 LRI mortality. In total, I estimated that increased clean cooking fuel use is associated with 7,343 under-5 LRI mortalities averted since 1990.
In Chapter 6, I conclude by discussing the broader implications of my work. Energy is an important thread connecting climate change, air pollution, and human health, and pathways towards cleaner energy generation will be important drivers of climate change mitigation, reduced environmental exposures, and improved population health. Investments in clean cookstoves have had mixed results over the last 40 years, with many studies revealing only limited uptake of intervention stoves and substantial continued use of polluting traditional fuels, resulting in lower-than-expected exposure reductions and health benefits. Ecuador’s transition has been remarkable in the context of its peer low- and middle-income countries in the rest of Latin America and beyond. The findings presented in this dissertation demonstrate that cooking gas is popular; when it is made cheap and available, gas significantly displaces the use of polluting fuels. Nevertheless, even under ideal cost and access circumstances, my work also reveals that policies and interventions will need to consider specific local needs – like space heating in cold climates – to further encourage a transition toward cleaner indoor air. In the context of efforts to eliminate the use of polluting fuels in the Americas, my work offers hope that ambitious clean cooking fuel policies will improve health.
|
317 |
Výroba vodíku z biomasy II / Hydrogen Production from Biomass IIMatějka, Pavel January 2011 (has links)
This master thesis continues the master thesis Výroba vodíku z biomasy. In that work were performed first experiments of hydrogen production from beer less by dark fermentation. Further experiments will continue based on previous experiments. For the energy balance were used results from [1] and data obtained from literature searches, because the results of the experiments were not entirely satisfactory. Energy balance was calculated for a laboratory fermenter to evaluate the efficiency of energy obtainable from the hydrogen produced by fermentation in a dark laboratory conditions. It was compared the yield given in [1] and yield derived from a literature review. The conclusion presents recommendations for further research.
|
318 |
Evaluating Standard Wet Chemistry Techniques and NIR Spectroscopic Models for Determining Composition and Potential Ethanol Yields of Multi-Species Herbaceous Bioenergy CropsMonona, Ewumbua Menyoli January 2011 (has links)
Herbaceous perennials represent a considerable portion of potential biomass feedstocks available for the growing bioenergy industry. Their chemical composition and biomass yields, which are important in determining ethanol potential on an area and mass basis, vary with plant variety and type, environment, and management practices. Therefore, a study was conducted to assess the variability of lignin and carbohydrate content, biomass yields, and theoretical ethanol yields on an area basis among different herbaceous perennial species combinations grown in Minot (2008) and Williston (2008, 2009, and 2010), North Dakota (ND). After wet chemistry compositional analysis was done, the carbohydrate contents
were used to determine theoretical ethanol potential on a mass basis. Using the dry-matter yield, the theoretical ethanol yield on an area basis was also calculated for these biomass species. Total carbohydrate content for the biomass samples in Williston and Minot varied from 45 to 61% dry basis. Analysis of Variance (ANOVA) at a= 0.05 showed that carbohydrate content varied between years and environments. Also an interaction plot shows that no biomass species had consistently higher or lower carbohydrate content in the different environments. Switchgrass (Panicum vigatum L.) grown as single species or together with other perennial grasses had higher dry-matter yield and theoretical ethanol
yield potential in Williston irrigated plots while mixtures containing intermediate or tall wheatgrass species (Thinopyrum spp.) produced better yields in Minot non-irrigated plots. Variability in theoretical ethanol yield on a mass basis (3.7% coefficient of variation (CV) in Williston and 9.7% CV in Minot) was much less than the variability in dry-matter yields (27.5% CV in Williston and 14.8% CV Minot). Therefore, biomass production is much more important than composition in choosing species to grow for ethanol production.
Recently, many studies have focused on developing faster methods to determine biomass composition using near infrared (NIR) spectroscopy. Other NIR models have been developed on single biomass feedstocks but a broad-based model for mixed herbaceous perennials is yet to be developed. Therefore, NIR calibration models for lignin, glucan, and xylan were developed with 65 mixed herbaceous perennial species using a DA 7200 NIR spectrometer (950 - 1,650 nm) and GRAMS statistical software. The models for lignin and xylan had R(2) values of 0.844 and 0.872, respectively, upon validation and are classified as
good for quality assurance purposes while glucan model had an R(2) of 0.81 which is considered sufficient for screening. The R(2) and the root mean square error of prediction (RMSEP) results showed that it is possible to develop calibration models to predict chemical composition for mixed perennial biomass when compared with results for models developed for single feedstock by Wolfrum and Sluiter (2009) and Liu et al. (2010). Studying the variability in predicting constituents using NIR spectroscopy over time (hours and days), it was observed that the average CV was between 1.4 to 1.6%. The average CV
due to repacking (presentation) alone was 1.3%. The CVs for NIR predictions ranged between 1.4 to 5.7% while for wet chemistry ranged between 3.8 to 13.5%; hence, NIR predictions were more precise than wet chemistry analysis.
|
319 |
Kleintechnische BiomassevergasungZeymer, Martin, Herrmann, André, Oehmichen, Katja, Schmersahl, Ralf, Schneider, Roman, Heidecke, Patric, He, Ling, Volz, Florian 10 November 2014 (has links)
Der DBFZ Report 18 „Kleintechnische Biomassevergasung - Option für eine nachhaltige und dezentrale Energieversorgung“ fasst die wichtigsten Ergebnisse des Verbundvorhabens „Bundesmessprogramm zur Weiterentwicklung der kleintechnischen Biomassevergasung“ zusammen. Während der Projektlaufzeit von 2009 bis 2012 wurden mit Mitteln des BMU-Förderprogramms „Forschung und Entwicklung zur klimaeffizienten Optimierung der energetischen Biomassenutzung“1 reale Biomassevergasungsanlagen umfassend analysiert und bewertet. Zusammen mit den Projekterfahrungen des Deutschen Biomasseforschungszentrums gemeinnützige GmbH (DBFZ), der Hochschule Zittau-Görlitz (HSZG), des Fraunhofer Instituts für Fabrikbetrieb und -automatisierung (IFF) und des Bayerischen Zentrums für Angewandte Energieforschung e. V. (ZAE), werden auf dieser Grundlage Erkenntnisse über den Entwicklungsstand und -perspektiven in technische und methodische Grundlagen eingebettet sowie Akteuren aus Wissenschaft, Industrie, Politik und Gesellschaft zur Verfügung gestellt. Weiterhin geben die Ergebnisse der technisch-ökonomisch-ökologischen Bewertung realer Anlagen und vielversprechender Konzepte basierend auf Einzel-, Verbund- und Langzeitmessungen vor Ort einen Überblick hinsichtlich:
- der technischen Verfügbarkeit, der Leistungsfähigkeit und der Optimierungsansätze,
- der Wirtschaftlichkeit und der limitierenden sowie begünstigenden Faktoren,
- der Treibhausgasemissionen und der damit einhergehenden THG-Minderungspotenziale und
- der THG-Vermeidungskosten dieses Nutzugspfades von Biomasse.
Einführend sind die Grundlagen der kleintechnischen Biomassevergasung, also Stand der Technik, wobei mögliche Einsatzstoffe, Verfahren und Nutzungsoptionen im Fokus stehen, dargestellt. Zusammen mit der Beschreibung der notwendigen Messtechnik für eine hinreichend genaue Anlagenbilanzierung und -bewertung kann sich auch der Leser mit geringen Vorkenntnissen zunächst einen Überblick verschaffen. Die Entwicklung des Anlagenbestandes und der politischen Rahmenbedingungen verdeutlicht den derzeitigen Trend in dieser Branche.
Letztlich sollen die Ergebnisse der technisch-ökonomisch-ökologischen Bewertung einen umfassenden und transparenten Einblick in die Leistungsfähigkeit der kleintechnischen Biomassevergasung gewähren. Bestehende Probleme, Ansätze zu deren Lösung und Vorteile einer bisher verschlossenen Branche der kleintechnischen Biomassevergasung werden klar herausstellt, damit diese Ihren Beitrag für eine nachhaltige Energiebereitstellung leisten kann.
|
320 |
Biomass Energy Systems and Resources in Tropical TanzaniaWilson, Lugano January 2010 (has links)
Tanzania has a characteristic developing economy, which is dependent on agricultural productivity. About 90% of the total primary energy consumption of the country is from biomass. Since the biomass is mostly consumed at the household level in form of wood fuel, it is marginally contributing to the commercial energy supply. However, the country has abundant energy resources from hydro, biomass, natural gas, coal, uranium, solar, wind and geothermal. Due to reasons that include the limited technological capacity, most of these resources have not received satisfactory harnessing. For instance: out of the estimated 4.7GW macro hydro potential only 561MW have been developed; and none of the 650MW geothermal potential is being harnessed. Furthermore, besides the huge potential of biomass (12 million tons of oil equivalent), natural gas (45 million cubic metres), coal (1,200 million tones), high solar insolation (4.5 – 6.5 kWh/m2), 1,424km of coastal strip, and availability of good wind regime (> 4 m/s wind speed), they are marginally contributing to the production of commercial energy. Ongoing exploration work also reveals that the country has an active system of petroleum and uranium. On the other hand, after commissioning the 229km natural gas pipeline from SongoSongo Island to Dar es Salaam, there are efforts to ensure a wider application in electricity generation, households, automotive and industry. Due to existing environmental concerns, biomass resource is an attractive future energy for the world, Tanzania inclusive. This calls for putting in place sustainable energy technologies, like gasification, for their harnessing. The high temperature gasification (HTAG) of biomass is a candidate technology since it has shown to produce improved syngas quality in terms of gas heating value that has less tar. This work was therefore initiated in order to contribute to efforts on realizing a commercial application of biomass in Tanzania. Particularly, the work aimed at establishing characteristic properties of selected biomass feedstock from Tanzania. The characteristic properties are necessary input to thermochemical process designers and researchers. Furthermore, since the properties are origin-specific, this will provide baseline data for technology transfer from north to south. The characteristic properties that were established were chemical composition, and thermal degradation behaviour. Furthermore, laboratory scale high temperature gasification of the biomasses was undertaken. Chemical composition characteristics was established to palm waste, coffee husks, cashew nut shells (CNS), rice husks and bran, bagasse, sisal waste, jatropha seeds, and mango stem. Results showed that the oxygen content ranged from 27.40 to 42.70% where as that of carbon and hydrogen ranged from 35.60 to 56.90% and 4.50 to 7.50% respectively. On the other hand, the elemental composition of nitrogen, sulphur and chlorine was marginal. These properties are comparable to findings from other researchers. Based on the results of thermal degradation characteristics, it was evident that the cashew nut shells (CNS) was the most reactive amongst the analyzed materials since during the devolatilization stage the first derivative TG (DTG) peak due to hemicellulose degradation reached (-5.52%/minute) compared palm stem whose first peak was -4.81%/minute. DTG first peak for the remaining materials was indistinct. Results from the laboratory gasification experiments that were done to the coffee husks showed that gasification at higher temperature (900°C) had an overall higher gasification rate. For instance, during the inert nitrogen condition, 7% of coffee husk remained for the case of 900°C whereas the residue mass for the gasification at 800 and 700°C was 10 and 17% respectively. Steam injection to the biomass under high temperature gasification evolved the highest volumetric concentration of carbon monoxide. The CO peak evolution at 900°C steam only was 23.47 vol. % CO whereas that at 700°C was 21.25 vol. % CO. Comparatively, the CO peaks for cases without steam at 900°C and 2, 3, and 4% oxygen concentrations were 4.59, 5.93, and 5.63% respectively. The reaction mechanism of coffee husks gasification was highly correlated to zero reaction order exhibiting apparent activation energy and the frequency factor 161 kJ/mol and 3.89x104/minute respectively. / QC 20100923
|
Page generated in 0.0657 seconds