The background of this work is to suggest ways to take care of branches and tops of trees that today are left out in the north of Sweden after logging because it has to low value to be worth transporting. A solution to this is to place small chemical factories in the sparsely populated areas in the inland of Norrland that can take care of the forest residues and break it into valuable chemicals directly in the forest an then transport it to a market. The aim of this work was to find out if it´s a good idea to invest in these small chemical factories in the north of Sweden. This study has been carried out using literature study and interviews of key people. The largest part of the result comes from the interviews. The results of this study show that the small chemical factory is a good idea. Forest residues contains many valuable substances that should be greater used today. The results section of the report describes various factor that are crucial for the small chemical factory and these are: the products that can be produced, what technology that is suitable, if there is an market, who should be taking care of the factory and how the inland endurance will be affected. The conclusions that can be drawn from the study is that the small chemical factory should produce high-grade-sary chemicals directed at the chemical market. It may also be noted that there is existing technology that can be used in the factories, what has been done in the laboratories today can be implemented in the factory. The market will obviously depend on which product that will be produces, but finding a suitable market should not be impossible. The inland endurance will be positively impacted, among other things, the social endurance is enhances when these small chemical factories creates job opportunities in the inland and it can lead to decreasing the emigration.

Made available in DSpace on 2014-06-11T19:35:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-11Bitstream added on 2014-06-13T20:07:13Z : No. of bitstreams: 1 canettieri_ev_dr_guara.pdf: 1796157 bytes, checksum: 7fcb0f5216d983d4edb448126758bf47 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O presenta trabalho visou estabelecer as condições de hidrólise ácida do resíduo florestal de eucalipto a cinética dessa reação. Para atingier os objetivos deste trabalho, foi utilizada metodologia estatística (Planejamento Fatorial e Metodologia de Superfície de Resposta - RSM). A espécie arbórea utilizada neste estudo foi o Eucalyptus grandis de 7 anos de idade. Numa primeira etapa do trabalho, foram realizados ensaios de hidrólise catalisada com ácido em reator de aço inox de 1,4 L de acordo com um Planejamento Fatorial de 2 8-4, para avaliar o efeito de oito variáveis: o tamanho de partícula do resíduo (TR), temperatura (T), tempo de reação (t), umidade do resíduo na solução ácida (E), concentração do ácido (CA), tipo de ácido (A) e relação resíduo/solução ácida (R/A) sobre a extração de xilose da fração hemicelulósica do resíduo de eucalipto. Este estudo revelou que as variáveis significativas foram a temperatura, a concentração do ácido sulfúrico e a relação resíduo/solução ácida para a remoção daxilose da fração hemicelulósica do resíduo de eucalipto na região de estudo... . / The aim of this work was to establish optimal conditions for hydrolysis of eucalyptus forest residues and investigate the kinetics of this reaction. Research was conducted making use of response surface methodology (RSM) and a seven-year old Eucalyptus grandis tree. In the first phase of this work, hydrolysis tests were carried out in a 1,4L stainless steel reactor according to a 2 8-4 fractional factorial design, in order to evaluate the effects of eight variables (residue particle size, temperature, reaction time, residue moisture, soaking of the residue in acid solution, acid concetration, type of acid and ratio of residue/acid solution) on xylose extraction from the hemicellulosic fracation of eucalyptus residue. The results showed that, taking into account the type of reactor utilized, the variables temperature, sulfuric acid concentration and ratio of eucalyptus residue/acid solution in the ranges... (Complete abstract, click electronic address below).

Resumo: O presenta trabalho visou estabelecer as condições de hidrólise ácida do resíduo florestal de eucalipto a cinética dessa reação. Para atingier os objetivos deste trabalho, foi utilizada metodologia estatística (Planejamento Fatorial e Metodologia de Superfície de Resposta - RSM). A espécie arbórea utilizada neste estudo foi o Eucalyptus grandis de 7 anos de idade. Numa primeira etapa do trabalho, foram realizados ensaios de hidrólise catalisada com ácido em reator de aço inox de 1,4 L de acordo com um Planejamento Fatorial de 2 8-4, para avaliar o efeito de oito variáveis: o tamanho de partícula do resíduo (TR), temperatura (T), tempo de reação (t), umidade do resíduo na solução ácida (E), concentração do ácido (CA), tipo de ácido (A) e relação resíduo/solução ácida (R/A) sobre a extração de xilose da fração hemicelulósica do resíduo de eucalipto. Este estudo revelou que as variáveis significativas foram a temperatura, a concentração do ácido sulfúrico e a relação resíduo/solução ácida para a remoção daxilose da fração hemicelulósica do resíduo de eucalipto na região de estudo... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: The aim of this work was to establish optimal conditions for hydrolysis of eucalyptus forest residues and investigate the kinetics of this reaction. Research was conducted making use of response surface methodology (RSM) and a seven-year old Eucalyptus grandis tree. In the first phase of this work, hydrolysis tests were carried out in a 1,4L stainless steel reactor according to a 2 8-4 fractional factorial design, in order to evaluate the effects of eight variables (residue particle size, temperature, reaction time, residue moisture, soaking of the residue in acid solution, acid concetration, type of acid and ratio of residue/acid solution) on xylose extraction from the hemicellulosic fracation of eucalyptus residue. The results showed that, taking into account the type of reactor utilized, the variables temperature, sulfuric acid concentration and ratio of eucalyptus residue/acid solution in the ranges... (Complete abstract, click electronic address below). / Orientador: João Andrade de Carvalho Júnior / Coorientador: João Batista de Almeida e Silva / Banca: Silvio Jorge Coelho Simões / Banca: Luiz Fernando Costa Nascimento / Banca: George Jackson de Moraes Rocha / Banca: Raul Eduardo Piad Barreras / Doutor

Made available in DSpace on 2017-07-10T17:36:57Z (GMT). No. of bitstreams: 1 2013_Diss_Leonardo_StreyProt.pdf: 1886831 bytes, checksum: f0eb61d130d6fa0e5a0fa7362ee15fa8 (MD5) Previous issue date: 2013-08-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work proposes the use of the bark of Pinus elliottii, a residue of wood processing, as biosorbent in the removal of metal ions Cd2+, Pb2+ and Cr3+solutions fortified, as an alternative to conventional treatment methods, such as precipitation, ion exchange, electrochemical treatment, flocculation and filtration. The biosorbent was characterized by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR) and point of zero charge (pHPCZ). Adsorption tests were performed aiming to determine the optimal conditions of pH, mass of adsorbent and contact time for the adsorption process. The adsorption kinetics was evaluated by pseudofirst and pseudosecond order models, Elovich and intraparticle diffusion. Adsorption isotherms for each metal were constructed, which were linearized according to mathematical models of Langmuir, Freundlich and Dubinin-Radusckevich. To compare this biosorbent with a commercial adsorbent, comparative studies with activated charcoal were performed . Furthermore, we evaluated the ability of desorption of materials and the influence of temperature on adsorption of metals studied by pine bark. The characterization of the biosorbent by SEM showed a rough and heterogeneous surface, important adsorption characteristics. From the FT-IR was identified compounds such as lignin, cellulose and hemicellulose, which favor the adsorption process. The pHPZC obtained was 3.5. The mass tests showed that 8 g L-1 biosorbent are sufficient for efficient removal of metal ions in solution. From the tests of pH, optimum conditions were obtained: 7.0 for Cd and 5.0 to Pb and Cr. The equilibrium time for adsorptive process were 40, 20 and 80 min for Cd, Pb and Cr, respectively. With the application of kinetic models is possible to suggest that the main limiting step for adsorption of these metal ions may be the chemisorption. The mathematical models that best fitted for the adsorption pine bark were Dubinin-Radushkevich for Cd, Freundlich for Pb, and Langmuir and Freundlich for Cr. The increase in temperature increased removal efficiency and, furthermore, with the thermodynamic parameters, it was found that the adsorption process is controlled by chemisorption. Desorption values were low, indicating a strong interaction of the metal with the surface of the adsorbent. In comparative studies with activated coal its possible to concluded that, despite the bark of Pinus elliottii present an adsorption efficiency less than this, the same satisfactory results of adsorption and removal of metal ions present in solutions fortified. Thus, it is concluded that the use of the bark of Pinus elliottii as biosorbents showed a promising alternative for the decontamination of contaminated water bodies by metal ions Cd, Pb and Cr / O presente trabalho propõe a utilização da casca de Pinus elliottii, um resíduo do beneficiamento da madeira, como biossorvente na remoção dos íons metálicos Cd2+, Pb2+ e Cr3+ de meio aquoso, como alternativa aos métodos convencionais de tratamento, como a precipitação, troca iônica, tratamento eletroquímico, floculação e filtração. O biossorvente foi caracterizado por meio de microscopia eletrônica de varredura (MEV), espectroscopia na região do infravermelho (FT-IR) e ponto de carga zero (pHPCZ). Após a caracterização foram realizados testes de adsorção objetivando determinar as condições ideais de pH, massa de adsorvente e tempo de contato para o processo de adsorção. A cinética de adsorção foi avaliada pelos modelos de pseudoprimeira ordem, pseudossegunda ordem, Elovich e difusão intrapartícula. Foram construídas as isotermas de adsorção para cada metal, as quais foram linearizadas conforme os modelos matemáticos de Langmuir, Freundlich e Dubinin-Radusckevich. Visando comparar este biossorvente com um adsorvente comercial, foram realizados estudos comparativos com o carvão ativado. Além disso, foram avaliados a capacidade de dessorção dos materiais e a influência da temperatura no processo de adsorção dos metais em estudo pela casca de pinus. A caracterização do biossorvente por meio da técnica de MEV mostrou uma superfície irregular e heterogênea, importantes características de adsorção. A partir da FT-IR foi possível identificar grupos funcionais comuns a estrutura da lignina, celulose e hemicelulose, os quais favorecem o processo de adsorção. O pHPCZ obtido foi de 3,5. Os testes de massa demonstraram que 8 g L-1 do biossorvente são suficientes para uma remoção eficiente dos íons metálicos em solução. A partir dos testes de pH, as condições ideais obtidas foram: 7,0 para Cd e, 5,0 para Pb e Cr. Os tempos de equilíbrio para o processo adsortivo foram 40, 20 e 80 min, para Cd, Pb e Cr, respectivamente. Com a aplicação dos modelos cinéticos sugere-se que a etapa limitante para a adsorção destes íons metálicos pode ser a quimiossorção. Os modelos matemáticos que melhor se ajustaram para a adsorção em casca de pinus foram Dubinin-Radushkevich para o Cd, Freundlich para Pb e, Langmuir e Freundlich para o Cr. O incremento na temperatura aumentou eficiência de remoção e, além disso, com os parâmetros termodinâmicos, concluiu-se que o processo de adsorção é controlado pela quimissorção. Os valores de dessorção foram baixos, indicando uma forte interação dos metais com a superfície do adsorvente. Com os estudos comparativos com o carvão ativado foi possível concluir que apesar da casca de Pinus elliottii apresentar uma eficiência de adsorção menor que este, a mesma apresentou resultados satisfatórios de adsorção e remoção dos íons metálicos presentes nas soluções fortificadas. Assim, conclui-se que a utilização da casca de Pinus elliottii como biossorvente mostrou-se uma alternativa promissora para descontaminação de corpos hídricos contaminados pelos íons metálicos Cd, Pb e Cr

Activated carbon is a highly adsorbing material and has various scopes of uses depending on needs. It is used in many industries and applications e.g. to clean industrial wastewater, in medicine, discolor sugar and so on. What makes AC such a good adsorbent is its porous structure which gives it a high surface area.  This report consists of three parts; general information about Activated Carbon (AC) and its characteristics, to give the reader a sufficient background about AC for continuous understanding throughout the report, an experimental investigation in chemical activation of carbon with phosphoric acid as the chemical reagent and sawdust from both Cuban and Swedish Pine tree as precursors, and a second experimental investigation in chemical activation of carbon with Zinc Sulfate as the chemical reagent and sawdust from Cuban Pine tree as the precursor. For the first experimental part as well as for the second the objective is how to best combine the three parameters; acid concentration, impregnation ratio and activation temperature in order to get the best adsorption performance when preparing activated carbon with different precursor specimens and chemical reagents. The experiments with phosphoric acid activation show that treatment with 40% acid concentration at 400 °C produce an activated carbon with good properties for ammonia adsorption and good iodine number. If a 30% phosphoric acid is used for activation, an activation temperature of 500 °C is recommended. With an impregnation ratio of 1, good adsorption was obtained in the activated carbon produced from Swedish pine while using Cuban pine a higher adsorption was obtained with an impregnation ratio of 2. The experiments with Zinc Sulfate activation show that influence of the sulfate concentration (between 10 % and 40 %) and temperature (between 400 °C and 500°C) on the properties for ammonia adsorption in the produced activated carbon was considerable for low impregnation ratio (0.5 and 1). In general, activation conditions of 20% zinc sulfate concentration, 400 °C and impregnation ratio: 1 are enough to produce an activated carbon with good properties for ammonia adsorption. The adsorption of carbon tetrachloride was lower. Activated carbons produced with 10 % zinc sulfate concentration, 0.5 impregnation ratio and 400 °C activation temperature (the mildest studied conditions) show already good iodine number and BET surface area.  The main conclusion from the thesis work is that the optimal conditions vary widely with wanted results. Therefore a suggestion for future work is to narrow the research to fewer variables and more repetition of the samples.

Dependence on fossil fuels in the electric sector is one of the major contributors towards Greenhouse gas (GHG) emissions. The increase in renewable contribution has been observed in recent years but there is still potential to utilize wood waste in rural communities for electricity generation promoting energy independence and sustainable development. For this study, a life cycle assessment approach was utilized to estimate the emissions of electricity produced from wood residue in a rural community. Therefore, the process from planting to supply for bioenergy facility to generate electricity are included. The results showed a decrease of 92-96 % in global warming potential resulting from the use of wood residues as compared to that of Grid electricity, natural gas, and coal-fired power plants. Then, a two-layer supply chain network comprising of feedstock supply sites and candidate power plant locations are considered to determine ideal locations for facilitating the bioenergy facility to minimize overall system cost and GHG emissions. The multi objective mathematical model aims to handle various decisions such as power plant location and technology selection, allocation of suppliers to power plants, biomass harvesting, storage, and transportation decisions in the considered supply chain network. The model developed was applied to case study region of Grenada County, Mississippi. The solution with no GHG restriction facilitates higher power plant capacity, 25 MW with lower system cost and satisfies 32.11 % of the total electricity demand of the case study area. Whereas the solution with highest GHG restrictions reduces the power plant capacity to 10 MW, that satisfies 10.22 % of the total electricity demand with increase in total overall system due to the increase in purchase of electricity from external sources as penalty cost. Furthermore, the investigation was extended to multiple counties of Mississippi to determine the feasibility of bioenergy facilities to be located using wood waste as fuel source. The techno-enviro-economic assessment showed the competitiveness of LCOE with the existing electricity supplier as well as other renewable sources such as solar, and wind. The findings of this research can facilitate in decision making process for promoting renewable energy in existing energy supply sources.

N-methylmorpholine-N-oxide has shown a positive effect for the pretreatmentof lignocelluloses. Pretreatment by NMMO was developed to enhance thedigestibility of lignocellulosic biomass.Barely straw and forest residue were pretreated by N-methylmorpholine-Noxide(NMMO) prior to anaerobic digestion. The effectiveness of NMMOtreatmenton straw and forest residue was examined as well as the recycling andreuse of NMMO for the next pretreatment process. During the first experimentalseries pretreatments were performed at 90 °C for 3h and 30h, followed bydigestion of the pretreated material for 41 days. Low methane yield was found inthese experiments due to high organic loading rate. In the second series therecycling and reuse of NMMO was investigated on straw. The pretreatmentswere carried out at 90 °C for 30 hr and the recycling and reuse were performedin three times. After treatments with fresh, as well as 1, 2, 3 times recycledNMMO methane yield of 0.45, 0.42, 0.38 and 0.4 Nm3/kg VS were obtained. / Program: Masterutbildning i energi- och materialåtervinning - industriell bioteknik

The purpose of this study is to create an understanding of what potential social impacts (both positive and negative) the concept of P&F will have and could have if an implementation of the process would be done. Interviews are mainly used for providing input to the method S-LCA (Social Life Cycle Assessment) and by that fulfil the purpose. Two questions will be addressed: What are the potential social impacts of the P&F concept on the stakeholders: worker, value chain actors, local community, and society, if integrated into an already existing pulp mill? What are the differences in terms of social impacts between the first and second generation of biofuels? Two methods are used to fulfil the purpose and to answer the related questions. First method is S-LCA as mentioned above. Second method is thematic analysis, where data from interviews is transformed into codes, then quantified and lastly divided into themes. The two mentioned methods work in parallel with each other. The result from thematic analysis shows that subcategories with high social impacts are, technology development, health and safety and contribution to economic development, mainly due to new equipment, job creations and technology. The results from the reference scales show an overall positive score, which means a positive social effect on a potential implementation of the P&F. It was noted that the sustainable future of the concept is strongly connected with positive social impacts like technological development and costs for investments in new equipment on an industrial scale. Several factors are important to consider when assessing an implementation of a process like P&F, and further focus should be put on assessing the negative subcategory health and safety related to a potential new fuel. For this to be possible, there is a necessity to further develop the S-LCA methodology. As the S-LCA to a larger part measures the potential negative impacts, one challenge will be to develop the methodology for the assessment of potential positive social impacts. The S-LCA is an ongoing developing process, where contributions from applying, demonstrating, and sharing findings play a significant role for future research. / Syftet med denna studie är att skapa en förståelse för vilka potentiella sociala effekter (både positiva och negativa) begreppet P&F kommer att ha och skulle kunna ha om en implementering av processen skulle göras. Intervjuer används främst för att ge input till metoden S-LCA (Social Life Cycle Assessment) och därmed uppfylla syftet. Två frågor kommer att behandlas: Vilka är de potentiella sociala effekterna av P&F-konceptet på intressenterna: arbetstagare, aktörer i värdekedjan, lokalsamhället och samhället, om de integreras i en redan befintlig massafabrik? Vilka är skillnaderna när det gäller sociala effekter mellan första och andra generationens biodrivmedel? Två metoder används för att uppfylla syftet och för att besvara de relaterade frågorna. Första metoden är S-LCA som nämnts ovan. Den andra metoden är tematisk analys, där data från intervjuer omvandlas till koder, sedan kvantifieras och slutligen delas in i teman. De två nämnda metoderna fungerar parallellt med varandra. Resultatet från den tematiska analysen visar att underkategorier med stor social påverkan är, teknikutveckling, hälsa och säkerhet och bidrag till ekonomisk utveckling, främst på grund av ny utrustning, jobbskapande och teknik. Resultaten från referensskalorna visar en övergripande positiv poäng, vilket innebär en positiv social effekt på en potentiell implementering av P&F. Det noterades att konceptets hållbara framtid är starkt kopplad till positiva sociala effekter som teknisk utveckling och kostnader för investeringar i ny utrustning i industriell skala. Flera faktorer är viktiga att ta hänsyn till när man bedömer ett genomförande av en process som P&F, och ytterligare fokus bör läggas på att bedöma den negativa underkategorin hälsa och säkerhet i samband med ett potentiellt nytt bränsle. För att detta ska vara möjligt är det nödvändigt att vidareutveckla S-LCA-metoden. Eftersom S-LCA till en större del mäter de potentiella negativa effekterna blir en utmaning att utveckla metoden för bedömning av potentiella positiva sociala effekter. S-LCA är en pågående utvecklingsprocess, där bidrag från att tillämpa, demonstrera och dela resultat spelar en viktig roll för framtida forskning.

Im Zuge der zunehmenden energetischen Holznutzung fällt vermehrt Holzasche als Abfallprodukt an. Obwohl die Asche potenziell für die Nährstoffrückführung in Wälder genutzt werden könnte, findet dies in Deutschland aktuell kaum statt, da negative ökologische Auswirkungen befürchtet werden, die Handhabbarkeit von Holzasche schwierig ist und hinsichtlich des Nährstoffhaushalts der Wälder keine Notwendigkeit gesehen wird. Durch eine Verarbeitung der Asche zu Rinde-Asche-Pellets (RIA-Pellets) sollte die ökologische Verträglichkeit erhöht und die Handhabbarkeit verbessert werden. Im Rahmen der vorliegenden Arbeit wurde untersucht, wie RIA-Pellets auf bodenchemische Parameter sowie den Ernährungszustand der Bäume wirken. Dazu wurden zwei Versuchsflächen in der Oberlausitz (Ostsachsen) etabliert: ein 38-jähriger Kiefernbestand auf einem Braunerde-Podsol aus eiszeitlichem Elbschotter im Tiefland sowie drei Fichtenbestände im Alter von 36 bis 49 Jahren auf einer Braunerde aus Lösslehm über Granodioritzersatz im Hügelland. Im Jahr 2011 wurde eine Behandlung mit 4 t ha-1 RIA-Pellets durchgeführt und auf dem Hügellandsstandort zusätzlich eine Vergleichsvariante mit 3,5 t ha-1 Dolomitkalk angelegt. Daraufhin wurden bodenchemische Parameter (pH-Wert, AKe, Nährstoff-Gesamtgehalte, C/N-Verhältnis) sowie Nadelspiegelwerte der Bäume untersucht. Außerdem wurde der zu erwartende Nährstoffverlust mittelalter Nadelholzbestände im Rahmen der Durchforstungen in den kommenden 20 Jahren abschätzend quantifiziert und den sonstigen Stoffflüssen der untersuchten Standorte gegenübergestellt. Auf dem sorptionsschwachen Tieflandsstandort mit Kiefer führten RIA-Pellets in einer Dosis von 4 t ha-1 innerhalb von zwei Jahren zu einer moderaten Erhöhung des pH-Werts um 0,6 Einheiten, einer Zunahme der Kationenaustauschkapazität von 267 auf 338 mmolc kg-1 sowie einer Erhöhung der Basensättigung von 45 auf 90 %. Zudem war eine signifikante Erhöhung der Gesamtgehalte von Ca, Mg und Mn zu verzeichnen. Auf dem sorptionsstarken Boden des Hügellandsstandort mit mittelalten Fichtenbeständen hatte die gleiche Dosis von RIA-Pellets ebenfalls zwei Jahre nach der Ausbringung zu wesentlich geringeren Effekten geführt. Zwar war auch hier ein pH-Anstieg um 0,3 Einheiten zu verzeichnen. Die RIA-Pellets beeinflussten jedoch die AKe und die Basensättigung nicht und die Nährstoff-Gesamtgehalte nur bei Ca und Mn. Alle Effekte waren auf beiden Versuchsflächen auf die Humusauflage begrenzt. Im Vergleich zu einer Kalkung trat die Wirkung der RIA-Pellets langsamer ein und fiel geringer aus. Die Behandlung mit RIA-Pellets führte nach zwei Jahren zu keiner Veränderung der Nadelspiegelwerte auf beiden Versuchsflächen. Die Untersuchung der oberirdischen Bestandesbiomasse zeigte, dass bereits mittelalte Nadelbaumbestände im Rahmen von Durchforstungen bei intensiven Aushaltungsszenarien erhebliche Nährstoffentzüge zu verkraften haben. So stieg die Biomasseentnahme bei Vollbaumnutzung gegenüber konventioneller Nutzung nur um den Faktor 1,3, während die Nährstoffentzüge um den Faktor 1,8 (Ca) bis 4,0 (P, Kiefer) stiegen. Die Nährstoffzusammensetzung der RIA-Pellets unterschied sich aufgrund der Herkunft der Asche (Verbrennung von Rinde und Holz in einem Sägewerk) von der eines Vollbaums. Daher läge der Kompensationsbedarf für die Nährstoffentzüge in den nächsten 20 Jahren bei Vollbaumnutzung im Kie-fernbestand bei 0,7 (Ca) bis 2,0 t ha-1 (P) und im mittelalten Fichtenbestand bei 1,3 (Ca) bis 12,8 t ha-1 (P). Der Vergleich der drei untersuchten unterschiedlich alten Fichtenbestände hat gezeigt, dass der Waldrestholzanteil und somit auch die zusätzliche Biomasse- und Nährstoffentnahme umso höher ist, je jünger bzw. geringer dimensioniert der Bestand ist. Die Betrachtung von Kiefern- und Fichtenbestände zeigte baumartenspezifische Unterschiede bei der Verteilung der oberirdischen Bestandesbiomasse auf die einzelnen Biomassekompartimente sowie der Nährstoffgehalte in den jeweiligen Kompartimenten. Die überschlägigen Nährstoffbilanzen für beide Versuchsflächen haben gezeigt, dass die Nährstoffentzüge mit der geernteten Biomasse bei Vollbaumnutzung in einer ähnlichen Größenordnung lagen, wie die Verluste mit dem Sickerwasser und die Festlegung im Biomassezuwachs. Auch ohne die Berücksichtigung von Nährstoffentzügen mit der Biomassenutzung wiesen die Standorte aufgrund des Nachwirkens historischer Säureeinträge bereits negative Stoffbilanzen für Ca und Mg auf. Die vorliegende Arbeit verdeutlicht, dass die Holzascherückführung in Wälder keinen drastischen Eingriff in die Stoffflüsse natürlicher Ökosysteme darstellt. Vielmehr handelt es sich um den Versuch, die Folgen der aktuellen menschlichen Aktivitäten im Bereich intensiver Biomassenutzung zumindest hinsichtlich der Nährstoffnachhaltigkeit abzumildern. Die intensive Biomassenutzung reiht sich dabei als eine weitere Form menschlichen Eingreifens in die Stoffflüsse des Ökosystems Wald in eine seit Jahrhunderten stattfindende Nutzungs- und damit Störungsgeschichte durch Streunutzung, Waldumbau zu Nadelholzforsten und atmosphärische Säure- und Stoffeinträge ein.

Human society releases greenhouse gas emissions to the atmosphere while providing housing, heat, mobility and industrial production. Man-made greenhouse gas emissions are the main causes of climate change, coming mainly from burning fossil fuels and land-use changes. Sustainably managed forests play an important role in climate change mitigation with the prospect of sustainably providing essential materials and services as part of a low-carbon economy, both through the substitution of fossil-intensive fuels and material and through their potential to capture and store carbon in the long-term perspective. The overall aim of this thesis was to develop a methodology under a life cycle perspective to assess the climate impact of the sustainable use of forest biomass in bioenergy and material systems. To perform this kind of analysis a methodological framework is needed to accurately compare the different biological and technological systems with the aim to minimize the net carbon dioxide emissions to the atmosphere and hence the climate impact. In such a comparison, the complete energy supply chains from natural resources to energy end-use services has to be considered and are defined as the system boundaries. The results show that increasing biomass production through more intensive forest management or the usage of more productive tree species combined with substitution of non-wood products and fuels can significantly reduce global warming. The biggest single factor causing radiative forcing reduction was using timber to produce wood material to replace energy-intensive construction materials such as concrete and steel. Another very significant factor was replacing fossil fuels with forest residues from forest thinning, harvest, wood processing, and post-use wood products. The fossil fuel that was replaced by forest biomass affected the reductions in greenhouse gas emissions, with carbon-intensive coal being most beneficial to replace. Over the long term, an active and sustainable management of forests, including their use as a source for wood products and bioenergy allows the greatest potential for reducing greenhouse gas emissions.