Since wood fuel when used sustainably provides an energy source that does not contribute to greenhouse warming, its use in future is likely to increase. Contractors prefer to chip trees and residues green to minimise power required and machinery wear. For non-specialised combustion systems the green woodchips should then be dried to increase their calorific value and to allow buffer storage without significant dry matter loss or the development of hazardous fungal spores. As the drying of wood chips has never been rigorously defined, a study was undertaken to determine the drying characteristics of green woodchips. A drying bin was built to simulate storage drying in one dimension. Data from three drying runs using spruce and birch whole tree provided data to validate a one-dimensional heat and mass transfer drying model converted from an existing grain drying routine. The specific energy consumption varied from 2.0 MJ/kg of moisture removed using unheated air during summer drying to 5.0 MH/kg during winter when dried with air warmed by 28°C. Dry matter loss in birch during drying and a period of two months cool storage was approximately 2%. Mean evaporation rate ranged from 1.9 kg/h in winter to 2.9 kg/h in summer. This gave a drying rate of 1% and 2.2% per day, inwinter and summer respectively. Hardwoodbirch released its moisture more readily than softwood Sitkaspruce. Airflow rates used ranged from 0.26-0.63 m³/s pertonne of dry matter. The dust levels on the woodchips ranged from 3.0 mg/m³ ofair before drying up to 55 mg/m³ of air after drying. The concentrations of colony forming units on woodchips ranged from2.0 X 10⁴ cfu/m³ of air before drying up to 8.0 X 10⁵cfu/m³ of air after drying.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第17794号 / エネ博第277号 / 新制||エネ||58(附属図書館) / 30601 / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 東野 達, 教授 坂 志朗, 教授 米田 稔 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Bioenergy is one of many contributors to reducing the use of fossil fuels in order to mitigate climate change by decreasing CO2-emissions, and the potential for biofuels are large. The wood fuel pellets are a refined biofuel made of sawdust, which is dried and compressed to achieve improved fuel and transportation properties. In 2007 the amount of wood fuel pellets used for heating purposes in Sweden was 1715000 tons. The aims of this work was: to examine the moisture content and emission of monoterpenes during the drying and pelletising steps of the pellets production (Paper I); to investigate how the recirculation of drying gases affects the energy efficiency of rotary dryers and how the energy efficiency is related to the capacity of the dryer. (Paper II); to analyse the causes of the problems encountered by household end-users of pellets and investigate whether an improved pellet quality standard could reduce these problems (Paper III); to investigate how the energy consumption of the pelletising machine and chosen pellet quality parameters were affected using an increased amount of rapeseed cake in wood fuel pellets (Paper IV); and to identify gaps of knowledge about wood fuel pellet technology and needs for further research on quality, environmental and health aspects throughout the wood fuel pellet chain, from sawdust to heat. (Paper V).

This study aims to undertake a comprehensive analysis of different waste management systems for the wastes produced in Östersund municipality of Sweden with an impact assessment limited to greenhouse gas emissions and their total environmental effects in terms of global warming potential, acidification potential, and eutrophication potential. A life cycle assessment methodology is used by integrating knowledge from waste collection, transportation, waste management processes and the product utilization. The analytical framework included the definition of functional unit, system boundaries, complimentary system design, waste management, and partial use of the energy. Three different municipal solid waste management scenarios, incineration, composting, and digestion were considered for the study. All wastes from Östersund municipality were classified into biodegradable and combustible and thereafter treated for energy and compost production. Greenhouse gas emissions and total environmental impacts were quantified and evaluated their corresponding benefits compared to three different types of marginal energy production system. The results showed that the major greenhouse gas carbon dioxide and nitrous oxide emissions are greater in composting scenario, whereas methane emission is greater in digestion scenario. Composting scenario that uses additional coal fuel has greater global warming potential and acidification potential compared to other scenarios. Composting scenario using wood fuel additional energy has greater eutrophication potential. The highest reduction in global warming potential is achieved when digestion scenario replace coal energy. The greater reduction in acidification and eutrophication potential achieved when digestion scenario replaced coal energy, and wood fuel respectively. Based on the assumptions made, digestion scenario appears to be the best option to manage solid waste of Östersund municipality if the municipality goal is to reduce total environmental impact. Although there may have plentiful of uncertainties, digestion and incineration scenario results are competitive in reducing environmental effects, and based on the assumptions and factors used for the analysis, the results and conclusions from this study appear to be strong. Key words: Solid waste, incineration, composting, digestion, total environmental effect, wood fuel, biogas.

Increased markets for renewable energy feedstocks have led to increased energywood production in the Southeastern United States. Energywood requires additional processing and is often the lowest value product generated, making profitability difficult. Additionally, numerous environmental concerns surround energywood harvesting, such as potential increased erosion, applicability and adequacy of conventional water quality best management practices (BMPs), increased area in road network features due to increased machine trafficking, and reduced quantities of residual woody debris. Energywood harvesting operations have been established in the lower Mid-Atlantic region of the U.S. for several decades, and research examining these operations provides insight into various aspects of the sustainability of the practice in this region and similar locations elsewhere. Therefore, this research provides a literature review on the practice of energywood harvesting, followed by four studies on energywood harvesting operations in the lower Mid-Atlantic region of the U.S. The first study evaluated the productivity and costs of two Appalachian Mountain and three Coastal Plain energywood harvests, providing stakeholders with a comparison of harvesting operations that can be used to make better-informed decisions regarding the efficient and economical harvest of energywood. The second study compared estimated erosion, operational feature areas, BMP implementation rates, ground cover characteristics, and downed woody debris quantities following 10 energywood and 10 conventional harvests in the Mountains of Virginia. The third study detailed a survey conducted among energywood business owners in Virginia designed to characterize harvesting operations and markets, assess business owner opinions related to the current and future state of the industry, and update/expand the results of a previous survey from 2014. The fourth study combined data from the second study with data from two other independent studies, comparing site impact metrics from energywood and conventional harvests across the Mountain, Piedmont, and Coastal Plain regions of Virginia. In the first study, cut and haul costs averaged $32.07/tonne and ranged from $26.19 to $38.28/tonne. Hauling consistently comprised the largest function cost at an average of $12.24/tonne. Harvesting system analysis also highlighted the importance of ensuring a balanced equipment mix to lower costs and ensure efficiency. In the second study, conventional harvests had higher estimated erosion contributions from skid trails (P = 0.089) and averaged more estimated erosion mass overall than energywood harvests, despite being significantly smaller in size (P = 0.054). There was significantly less area in heavy slash (P = 0.076) and lower estimated mass of residual downed woody debris (P = 0.001) on energywood sites than conventional sites (10.98 and 27.95 tons/acre, respectively). Site-wide BMP implementation scores (P = 0.041), as well as those for Streamside Management Zones (SMZs) (P = 0.024), and skidding (P = 0.063) were significantly higher on energywood sites than conventional sites. BMP implementation scores were significant predictors of estimated erosion rates (P < 0.001, R² = 59%), indicating that adequate levels of existing water quality BMPs are effective for erosion control on both conventional and energywood harvests. The third study indicated that energywood harvesting operations in Virginia were generally conventional single-crew roundwood operations utilizing their own residues for energywood. Production levels varied widely with energywood comprising an average 31% of total production. Material was comminuted utilizing large (650 median horsepower) older (13.2 years average) whole-tree chippers fed by a single loader. Coastal Plain operations were larger scale than Piedmont operations, though those in the Piedmont had been in business longer. Businesses had a median of $400,000 USD invested in energywood production equipment, which was double their median investment in the previous survey. Logging businesses that had produced energywood longer were significantly (P = 0.0391) more likely to report profitability. In addition, loggers reported deriving numerous non-market benefits from energywood production (e.g., improved aesthetics and cleaner sites, leading to increased landowner satisfaction), with most business owners planning to continue production in the future. The fourth study revealed that estimated erosion was higher in the Mountains due to steep slopes and operational challenges. BMP implementation varied by region and harvest type, with energywood sites having better implementation than conventional sites, and conventional Mountain sites having lower implementation than other regions. Sufficient woody debris remained for BMPs on both harvest types in all regions, with conventional Mountain sites retaining twice that of Coastal Plain sites. BMPs effectively reduced potential erosion on both site types; therefore, increased implementation could likely lower erosion potential in problematic areas. Collectively, this research provides a wholistic representation of energywood harvesting operations in the lower Mid-Atlantic region of the U.S., allowing stakeholders in the region and other similar locations to make informed decisions regarding its sustainable harvest. / Doctor of Philosophy / Additional markets for renewable energy feedstocks have led to increased energywood (biomass) production in the Southeastern United States. Energywood is wood that is often used in the place of coal for renewable energy production. This includes wood of insufficient size, poor form, or with no other higher market value at the time of harvest. It also includes both residues from logging operations as well as stands planted to be harvested specifically for bioenergy production. Energywood requires additional processing steps and is often the lowest value product on harvesting sites, making profitability difficult to achieve. Additionally, energywood harvests may result in negative environmental impacts, such as increased erosion, increased area in road network features, and reduced quantities of residual woody debris. Finally, Best Management Practices (BMPs) have been created for conventional forest harvesting operations, but their applicability to energywood harvests has not been verified. Therefore, this research provides a literature review on the practice of energywood harvesting, followed by four studies on energywood harvesting operations in the lower Mid-Atlantic region of the U.S. The first study evaluated the productivity and costs of two Appalachian Mountain and three Coastal Plain energywood harvests, providing stakeholders with a comparison of harvesting operations that can be used to make better-informed decisions regarding the efficient and economical harvest of energywood. It also highlighted the importance of ensuring a balanced equipment mix to lower costs and ensure efficiency, and the high costs associated with hauling. The second study compared estimated erosion, operational feature areas, BMP implementation rates, ground cover characteristics, and downed woody debris quantities following 10 energywood and 10 conventional harvests in the Mountains of Virginia. Conventional harvests were more potentially erosive and had lower BMP implementation rates than energywood harvests, despite energywood harvests resulting in lower quantities of residual woody debris. The third study presents a survey conducted among energywood business owners in Virginia designed to characterize harvesting operations and markets, assess business owner opinions related to the current and future state of the industry, and update/expand the results of a previous survey from 2014. Energywood harvesting operations in Virginia were generally conventional single-crew operations utilizing chippers with energywood comprising an average 31% of total production. Loggers reported deriving numerous non-market benefits from energywood production (e.g., improved aesthetics and cleaner sites, leading to increased landowner satisfaction), with most business owners planning to continue production in the future. The fourth study combined data from the second study with data from two other independent studies, comparing site impacts from energywood and conventional harvests across the Mountain, Piedmont, and Coastal Plain regions of Virginia. Estimated erosion was higher in the Mountains due to steep slopes and operational challenges. BMP implementation varied by region and harvest type, with energywood sites having better implementation than conventional sites, and conventional Mountain sites having lower implementation than other regions. Sufficient woody debris remained for BMPs on both harvest types, regardless of region. Finally, BMPs reduced estimated erosion on both site types, suggesting increased implementation could lower erosion potential in problematic areas. Collectively, this research provides a wholistic representation of energywood harvesting operations in the lower Mid-Atlantic region of the U.S., allowing stakeholders in the region and other similar locations to make informed decisions regarding its sustainable harvest.

Women living in rural Kenya rely on wood for cooking and are exposed to elevated amounts of wood smoke. The objective of this thesis was to assess the health and quality of life benefits of installing biogas digesters on rural Kenyan dairy farms. Thirty-one farms with biogas digesters and 31 farms without digesters (referent group) were assessed for wood utilization practices, basic respiratory and self-reported health, and exposure to volatile organic compounds (VOCs). Women with biogas digesters spent less time and money acquiring wood, and less time exposed to wood smoke (p<0.01). Multivariable linear regression showed associations between daily wood consumption and having a biogas digester, family size, and number of cows. Individual VOCs were lower in cookhouses on biogas farms (p<0.001) and women with biogas digesters reported fewer respiratory symptoms. Biogas digesters are one technology that can reduce reliance on wood fuel and reduce exposures to harmful wood smoke.

<p>Den här uppsatsen grundar sig på två fältstudier i nyutlagda demonstrationsförsök på Asa försökspark som ska användas i utbildningssyfte. Studie 1 bestod av försöksytor i ett 13 år gammalt bestånd som röjts till samma röjningsförband men med tre skilda metoder; motormanuell selektiv röjning, maskinell stråkröjning och som en kombination av bägge metoderna. Syftet var att beskriva det nuvarande tillståndet, simulera fram prognoser för beståndsutvecklingen och beräkna dess ekonomiska konsekvenser fram till och med första gallring och jämföra de olika metoderna med varandra. Studie 2 bestod av försöksytor i ett 23 år gammalt eftersatt bestånd där fyra olika åtgärder testades; ingen röjning innan gallring, underröjning i samband med gallring, sen röjning och skogsbränsleuttag. Syftet var även här att jämföra de olika metoderna med varandra genom beskrivning av det nuvarande tillståndet, göra prognoser för beståndsutvecklingen och beräkna dess ekonomiska konsekvenser vid första gallring och i den här studien även fram till och med den andra gallringen. De två nya metoderna, stråkröjningsmetoderna i studie 1 och skogsbränsleuttag i studie 2, hade stor potential gentemot de konventionella metoderna.</p> / <p>This thesis is based on two field studies in a recently started demonstration experiment by the Asa Experimental Forest, where it will be used for educational purposes. Study 1 consisted of experimental plots in a 13 years old stand which have been pre-commercial thinned to the same number of tree stems but with three different methods: motor-manual selective pre-commercial thinning by brush saw, mechanical pre-commercial line thinning and as a combination of the both methods. The purpose was to describe the present status, run simulations and produce forecasts for the development of the stand and calculate the economical aspects up to and including the first thinning and then compare the different methods with each other. Study 2 consists of experimental plots in a 23 years old stand with a pre-commercial thinning backlog, where four different treatments were tested; no pre-commercial thinning at all before the first thinning, low pre-commercial thinning in connection with the first thinning, late pre-commercial thinning and extraction of wood fuel. The purpose was also here to compare the different methods with each other through describing the present status, run simulations and produce forecasts for the development of the stand and calculate the economical aspects at the first thinning and in this study also up to and including the second thinning. The two new methods, mechanical pre-commercial line thinning in study 1 and wood fuel extraction in study 2, showed a great potential in comparison with the conventional methods.</p>

Den här uppsatsen grundar sig på två fältstudier i nyutlagda demonstrationsförsök på Asa försökspark som ska användas i utbildningssyfte. Studie 1 bestod av försöksytor i ett 13 år gammalt bestånd som röjts till samma röjningsförband men med tre skilda metoder; motormanuell selektiv röjning, maskinell stråkröjning och som en kombination av bägge metoderna. Syftet var att beskriva det nuvarande tillståndet, simulera fram prognoser för beståndsutvecklingen och beräkna dess ekonomiska konsekvenser fram till och med första gallring och jämföra de olika metoderna med varandra. Studie 2 bestod av försöksytor i ett 23 år gammalt eftersatt bestånd där fyra olika åtgärder testades; ingen röjning innan gallring, underröjning i samband med gallring, sen röjning och skogsbränsleuttag. Syftet var även här att jämföra de olika metoderna med varandra genom beskrivning av det nuvarande tillståndet, göra prognoser för beståndsutvecklingen och beräkna dess ekonomiska konsekvenser vid första gallring och i den här studien även fram till och med den andra gallringen. De två nya metoderna, stråkröjningsmetoderna i studie 1 och skogsbränsleuttag i studie 2, hade stor potential gentemot de konventionella metoderna. / This thesis is based on two field studies in a recently started demonstration experiment by the Asa Experimental Forest, where it will be used for educational purposes. Study 1 consisted of experimental plots in a 13 years old stand which have been pre-commercial thinned to the same number of tree stems but with three different methods: motor-manual selective pre-commercial thinning by brush saw, mechanical pre-commercial line thinning and as a combination of the both methods. The purpose was to describe the present status, run simulations and produce forecasts for the development of the stand and calculate the economical aspects up to and including the first thinning and then compare the different methods with each other. Study 2 consists of experimental plots in a 23 years old stand with a pre-commercial thinning backlog, where four different treatments were tested; no pre-commercial thinning at all before the first thinning, low pre-commercial thinning in connection with the first thinning, late pre-commercial thinning and extraction of wood fuel. The purpose was also here to compare the different methods with each other through describing the present status, run simulations and produce forecasts for the development of the stand and calculate the economical aspects at the first thinning and in this study also up to and including the second thinning. The two new methods, mechanical pre-commercial line thinning in study 1 and wood fuel extraction in study 2, showed a great potential in comparison with the conventional methods.

Made available in DSpace on 2015-03-26T13:33:39Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3071922 bytes, checksum: 48d46b8aebf39c5cd1a3b7b837b070fa (MD5) Previous issue date: 2009-07-31 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The research objective was to develop a resource management proposal based on wood fuel usage. Relied on the classic resource management science and its principles, presuppositions and hypothesis from biological science, the research aimed to overcome theoretical vulnerabilities from developed frameworks of this science resulted of lack of prediction and explanation of empirical problems. It also aimed to introduce elements from the social science which could explain better the wood fuel usage dynamics. The analysis started with the evaluation of concepts and their relationships in the classic resource management science. After the identification of some vulnerability in the classic model, the research exposes a way that could overcome some of these by the usage of systems basic thinking and the New Institutional Economics approach. These theories showed how difficult is to comprehend collective human behavior and this evidence directed the research to new concepts and proposals which helped the process of understanding collective human behavior with wood fuel use. The application of the framework was based in Lavras Novas, district belonged to Ouro Preto city, MG, which has a complex dynamic of wood fuel usage. This application allowed a comparison of the framework with the usage pattern in the locality which allowed the analysis of the theoretical and empirical viability of the framework and made possible the suggestion of utilities of the framework to future researchers in resource management area. / O presente trabalho objetivou desenvolver uma proposta de manejo de recursos tendo como referência empírica o uso da madeira energética. Sendo orientado pela ciência clássica do manejo de recursos apoiada pelos princípios, pressupostos e hipóteses das ciências biológicas, a proposta da pesquisa consistiu em superar as vulnerabilidades teóricas dos modelos desenvolvidos por essa ciência, resultantes de anomalias empíricas não previstas e não explicadas, e introduzir elementos explicativos aos modelos por meio da identificação de alternativas teóricas nas ciências sociais. Desta maneira, a análise inicial recaiu sobre conceitos e relações entre esses conceitos, conforme apresentados pela proposição clássica de manejo de recursos. A partir dessa apresentação e da identificação das suas vulnerabilidades, houve a exposição de como a abordagem sistêmica e a teoria da nova economia institucional podem suprir, pelos conceitos, pressupostos e relações entre os conceitos, algumas daquelas vulnerabilidades. Não obstante, a partir dessas teorias, identificou-se, ainda, a complexidade da compreensão do comportamento grupal entre seres humanos, o que direcionou a investigação teórica para conceitos e proposições que permitiram apreender o comportamento coletivo em um ambiente estruturado pelo uso energético da madeira para diversos fins. A delimitação do ambiente, representado pelo distrito de Lavras Novas por apresentar uma complexa dinâmica de uso socioeconômico do recurso, permitiu a comparação do sistema teórico desenvolvido com o padrão de utilização do recurso na localidade. Isso permitiu analisar a viabilidade teórica e prática do sistema desenvolvido em relação ao padrão de utilização encontrado empiricamente e sugerir possíveis aplicabilidades do modelo para a pesquisa em manejo de recursos.