Microalgae refer to a kind of autotrophic microorganism with rich nutrition and high photosynthetic utilization degree, which are widely living in the sea and land. Microalgae can be converted into bio energy such as biogas, biodiesel and bio oil. This thesis presents a review on the different cultivation methods and energy conversion techniques of microalgae. Through comparison with other biomass feedstocks, the advantages and disadvantages of microalgae are detailed. Since the large scale of microalgae bioenergy production has not been achieved yet, the commercial production requirements and the sustainability of microalgae are analysed. As a result, high lipid content, less cultivated land use and short life time circle are thought to be the typical advantages of microalgae that it can be considered as a potential substitute of fossil fuel.

Supercritical water gasification (SCWG) is an innovative hydrothermal technique, employing supercritical water (SCW, T≥374oC, P≥22.1 MPa) as the reaction media, to convert wet biomass or aqueous organic waste directly into hydrogen (H2)-rich synthetic gas (syngas). In the first stage of this research, a secondary pulp/paper-mill sludge (SPP, provide by AbitibiBowater Thunder Bay Operations) was gasified at temperatures of 400-550oC for 20 to 120 min in a high-pressure batch reactor for H2 production. The highest H2 yield achieved was 14.5 mol H2/kg SPP (on a dry basis) at 550oC for 60 min. In addition, SPP exhibited higher H2-generation potential than sewage sludges, likely attributed to its higher pH and higher volatile matter and alkali salt contents. In the second stage, a novel two-step process for sludge treatment was established. The first step involved the co-liquefaction of SPP with waste newspaper in a batch reactor at varying mixing ratios, aimed at converting the organic carbons in the feedstocks into valuable bio-crude and water-soluble products. The highest heavy oil (HO) yield (26.9 wt%) was obtained at 300oC for 20 min with a SPP-to-newspaper ratio of 1:2. This co-liquefaction process transformed 39.1% of the carbon into HOs, where 16.3% of the carbon still remained in the aqueous waste. Next, an innovative Ru0.1Ni10/γ-Al2O3 catalyst (10 wt% Ni, Ru-to-Ni molar ratio=0.1), with long-term stability and high selectivity for H2 production, was developed for the SCWG of 50 g/L glucose, where no deactivation was observed after 33 h on stream at 700oC, 24 MPa and a WHSV (weight hourly space velocity) of 6 h-1. The H2 yield was maintained at ~50 mol/kg feedstock. The addition of small amounts of Ru to Ni10/γ-Al2O3 was found to be effective in enhancing Ni dispersion and increasing the reducibility of NiO. Finally, the Ru0.1Ni10/γ-Al2O3 catalyst together with an activated carbon (AC) supported catalyst (Ru0.1Ni10/AC) were utilized for treating the aqueous by-product from sludge-newspaper co-liquefaction using a continuous down-flow tubular reactor. More than 90% of the carbon in the waste was destroyed at 700oC with the highest H2 yield of 71.2 mol/kg carbon noted using Ru0.1Ni10/AC. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-04-27 17:20:49.193

Made available in DSpace on 2017-07-10T17:40:49Z (GMT). No. of bitstreams: 1 Augustinho_Borsoi.pdf: 946334 bytes, checksum: 3830973e363901f9e916e0746cf6fec0 (MD5) Previous issue date: 2015-07-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Plants spaced by an equal distance compete minimally for nutrients, light and other factors, thus, proper spatial distribution of the plants is essential to maximize the performance of the crop. In this sense, the aim of this study was to evaluate the agronomic and technological performance of sweet sorghum at different row spacings and plant densities. The experiment was conducted in the experimental area of the State University of West Paraná (UNIOESTE) in Marechal Candido Rondon-PR, in the summer crop of 2013/2014 and second crop of 2014/2015. The experimental design consisted of randomized blocks in a 4x4 factorial scheme, with four spacings (0.25, 0.5, 0.8 and 1.0 m between rows) and four plant densities (50, 75, 100 and 125 thousand plants ha-1). We evaluated the following parameters: plant height, stem diameter, number of tillers, number and length of internodes, total dry mass, productivity and Brix content. In the second crop we also assessed the percentage of saccharose and the total sugar recoverable. The results showed the influence of row spacing on the production of stems and plant dry mass. Smaller spacings provided better results in both seasons (2013/14 and 2014/15). In the second crop, the production of stems ranged from 12.2 to 50.8 t ha-1 in 2013 and from 9 to 51 t ha-1 in 2014. As for the normal growing season 2013/14, the average production of stems was 92.67 t ha-1, whereas in the season 2014/15 production was 83.32 t ha-1. There was no significant difference (p ≤ 0.05) in what concerns to Brix in the summer crops (average 20.5 °Bx) and in the second crop the average Brix content was 12.2 °Bx. Smaller spacings resulted in better agronomic characteristics and technological / Plantas espaçadas de forma equidistante competem minimamente por nutrientes, luz e outros fatores e a adequada distribuição espacial das plantas é essencial para maximizar o desempenho da cultura. Nesse sentido, o objetivo deste trabalho foi avaliar as características agronômicas e tecnológicas do sorgo sacarino em diferentes espaçamentos entre linhas e densidades de plantas. O experimento foi conduzido na área experimental da Universidade Estadual do Oeste do Paraná (UNIOESTE), em Marechal Cândido Rondon-PR, nas de verão de 2013/2014 e 2014/2015 e na segunda safra no ano de 2013 e 2014. Foi utilizado delineamento de blocos ao acaso em esquema fatorial (4x4), com quatro espaçamentos (0,25; 0,5; 0,8 e 1,0 m entre linhas) e quatro densidades de plantas (50; 75; 100 e 125 mil plantas ha-1). Foram avaliadas a altura de plantas, diâmetro de colmo, número de perfilhos, número de internódios, comprimento de internódios, massa seca total, produtividade e teor de Brix. Na segunda safra também foram avaliadas o POL (sacarose aparente) e ATR (açúcares totais recuperáveis). Os resultados demonstraram influência do espaçamento entre linhas sobre a produtividade de colmos e massa seca de planta, onde espaçamentos menores proporcionaram melhores resultados na safra 2013/14 e 2014/15. Para a segunda safra, a produtividade de colmos variou entre 12,2 a 50,8 t ha-1 na safra 2013 e de 9 a 51 t ha-1 na safra 2014. Já para a safra normal 2013/14, a produtividade média de colmos foi de 92,67 t ha-1 e 83,32 t ha-1 na safra 2014/15. Não foi verificada diferença significativa (p ≤ 0,05) para a variável Brix nas safras de verão (média 20,5 graus Brix), já na segunda safra o Brix médio foi 12,2. Menores espaçamentos resultam em melhores características agronômicas e características tecnológicas

Thesis (MBA)--Stellenbosch University, 2011. / The global energy industry is actively moving toward renewable energy sources in order to meet the ever-increasing demand for energy in a sustainable manner. The South African government, however, has only recently begun creating an environment which is truly conducive to investment into the renewable energy industry. Metso, a Finnish multi-national corporation, has a strong global position in the field of biomass-based power generation for heat, power or combined heat and power applications. The corporation has developed a modular biomass-based power generation solution for power generation in the 3MW to 10MW range, which is highly automated and can essentially operate without the need for extensive human intervention and is known as the Metso Bio-energy Solution. Considering the current state of the South African energy environment, Metso management requested the researcher to investigate the opportunities that exist in the South African market for Metso’s Bio-energy Solution, and to propose a market entry strategy which Metso should follow in order to enter the South African market. In the findings, the researcher observed that South Africa has a clear potential for the development of a bio-energy industry for power generation, although the limited availability of biomass in certain regions and the various harvesting methods in industries such as the forestry and sugar industries do restrict the access to this resource. The municipal solid waste industry appears to be an area of interest as well, although very little information exists regarding the volumes of waste available and sorting practices, which may be required in order to access these resources. Interviews were held with experts in the field of energy, renewable energy and energy policy in order to obtain opinions on the market potential for Metso’s Bio-energy Solution. The general perception of all interviewees was that the technology has its place within the South African energy mix. The interviewees, however, did confirm that there currently appears to be a major focus on wind and solar energy in the country, although biomass technology may well be a better solution due to its baseload capabilities. It was found that the local policy environment, the lack of government initiative on renewable energy licensing and unclear tariff structures have all inhibited the proliferation of the renewable energy industry. In many cases, frustration with power outages and policy delays has caused companies to invest in biomass co-firing facilities for their own consumption. The factors for success for biomass-based technologies in the South African market would appear to be directly linked to job creation potential, access to reliable and sustainable biomass resources and access to investment capital, from both private equity and the state. It is the recommendation of the researcher that Metso enters into a joint venture with a large international environmental finance company, which would base their business model on the technology provided by Metso, whilst securing the political and financial support for projects of this nature in the country.

Hydrothermal carbonisation (HTC) could form the basis for rendering human faecal wastes safe whilst at the same time generating a carbon-rich material (hydrochar) and providing prospects for the recovery of energy. The work presented here has an objective of the search for optimal conditions for the HTC conversion of human faecal waste. Primary sewage sludge (PSS) and synthetic faeces (SF), of various moisture contents, were used as feedstocks to investigate the kinetics of decomposition of solids during HTC over a range of reaction times and temperatures. Decomposition was found to follow first-order kinetics, and the corresponding activation energies were obtained. Temperature was of primary importance to influence solid decomposition. Higher temperatures resulted in higher solids conversion to hydrochar. The energy contents of the hydrochars from PSS carbonised at 140 200oC for 4 h ranged from 21.5 to 23.1 MJ kg 1. Moisture content was found to affect the HTC process and feedstocks, with higher initial moisture contents resulted in lower hydrochar yields. The effect of reaction conditions on the characteristics of the hydrochar, liquid and gas products from HTC of faecal material, and the conditions leading to optimal hydrochar characteristics were investigated using a Response Surface Methodology (RSM). Models were developed here which could aid in the identification of reaction conditions to tailor such products for specific end uses. The results showed that the amount of carbon retained in hydrochars decreased as temperature and time increased, with carbon retentions of 64 77% at 140 and 160oC, and 50 62% at 180 and 200oC. Increasing temperature and reaction time increased the energy content of the hydrochar from 17 19 MJ kg 1 but reduced its energy yield from 88 to 68%. HTC at 200oC for 240 min resulted in hydrochars suitable for fuel, while carbonation at 160oC for 60 min produced hydrochars appropriate for carbon storage when applied to the soil. Theoretical estimates of methane yields resulting from subsequent anaerobic digestion (AD) of the liquid by-products are presented, with the highest yields obtained following carbonisation at 180oC for 30 min. In general, HTC at 180oC for 60 min and 200oC for 30 min resulted in hydrochars having optimal characteristics, and also for obtaining optimal methane yields. Maillard reaction products were identified in the liquid fractions following carbonisations at the higher temperatures. It was also found that the TOC, COD and BOD of the liquid products following HTC increased as the reaction temperature and time were increased and that these would require further treatment before being discharged. The results indicated that the gaseous phase following HTC contained carbon dioxide, nitrogen dioxide, nitric oxide, ammonia, and hydrogen sulphide indicating that additional treatment would be required before discharge to the atmosphere. In order to identify the optimum conditions leading to greater filterability of slurry resulted from HTC, the effects of reaction temperature and time on the filterability of PSS and SF slurries were investigated and optimised using RSM. It was shown that filterability improved as the reaction temperature and time at which the solids were carbonised was increased, with the best filtration results being achieved at the highest temperature (200°C) and longest treatment time (240 min) employed here. The specific cake resistance to filtration of the carbonised slurries was found to vary between 5.43 x 1012 and 2.05 x 1010 m kg 1 for cold filtration of PSS, 1.11 x 1012 and 3.49 x 1010 m kg 1 for cold filtration of SF, and 3.01 x 1012 and 3.86 x 1010 m kg 1 for hot filtration of SF, and decreased with increasing reaction temperature and time for carbonisation. There was no significant difference in specific resistance between cold and hot filtration of SF. The RSM models employed here were found to yield predictions that were close to the experimental results obtained, and should prove useful in designing and optimising HTC filtration systems for generating solids for a wide variety of end uses. Mass and energy balances of a semi-continuous HTC of faecal waste at 200oC and a reaction time of 30 min were conducted and based on recovering steam from the process as well energy from the solid fuel (hydrochar) and methane from digestion of the liquid by-product. The effect of the feedstock solids content and the quantity of feed on the mass and energy balances were investigated. Preheating the feed to 100oC using heat recovered from the process was found to significantly reduce the energy input to the reactor by about 59%, and decreased the heat loss from the reactor by between 50 60%. For feedstocks containing 15 25% solids (for all feed rates), energy recycled from the flashing off of steam and combustion of the hydrochar would be sufficient for preheating the feed, operating the reactor and drying the wet hydrochar without the need for any external sources of energy. Alternatively, for a feedstock containing 25% solids for all feed rates, energy recycled for the flashing off of steam and combustion of the methane provides sufficient energy to operate the entire process with an excess energy of about 19 21%, which could be used for other purposes.

Made available in DSpace on 2017-05-12T14:47:16Z (GMT). No. of bitstreams: 1 Shaiane__Lucas.pdf: 2393290 bytes, checksum: 9e5c684ef130e9552f01b3191e3e8e1d (MD5) Previous issue date: 2015-02-20 / This study evaluated the hydrogen and methane production from cassava starch wastewater in reactors in series. The acidogenic and methanogenic reactors were operated in a continuous flow and trials were divided into three stages. In Stage 1, three essays for hydrogen production evaluated the effect of initial pH (6.0 and 4.5), substrate concentration (1.4, 1.1 and 2.2 g total carbohydrates.L-1) and strategies to control biomass (by disposal or change in the structure of such support material with low density polyethylene) in anaerobic reactors of fixed bed and upflow at 36 °C. The best operating condition among the evaluated ones was pH 6.0 and concentration of 1.4 g total carbohydrates.L-1, which resulted in Hydrogen Volumetric Productions (HVP) of 229 mL.L-1.d-1 and yield of 29.4 mL.g-1total carbohydrate. The best strategy to control biomass was the sort of bed with polyethylene cylinders, which provided the least changes in flow regime and excessive growth of biomass. In Stage 2, the effect of inoculum source was evaluated in two packed-bed reactors operating according to the following conditions: pH 6.0; 2 g.L-1concentration of substrate, 20 g.L-1.d-1organic loading rate (OLR) and hydraulic retention time (HRT) of 2-hour. In the inoculated reactor with autofermented effluent, the answers were: 550 mL.L-1.d-1and hydrogen yield of 38mL.g-1total carbohydrates. These values were higher than those observed for the reactor inoculated with anaerobic heat-treated sludge, which indicated that the use of simple inoculums is a viable strategy for hydrogen production under the tested conditions. In addition to these essays, the influence of ORL and HRT were also evaluated. The increase of ORL (10 to 20 g-total carbohydrates.L-1.d-1) and decrease of HRT (4 to 2 hour) resulted in a higherhydrogen production (467 mL.L-1.d-1), hydrogen percentage in the studied biogas (40%) and molar flow rate (2.16 mmol.h-1). Therefore, the average yield of 30 mL H2.g-1 total carbohydrate was the same for both conditions tested. In general, butyric acid was associated with higherhydrogen production, followed by acetic and propionic acids, besides ethanol, in the five analyzed essays. In Stage 3, methane production from the acidified effluent was evaluated in a horizontal anaerobic reactor of fixed bed and continuous flow, operated at mesophilic temperature. The operating conditions were divided into four stages, whose variations were: initial pH (5.0 and 7.0), OLR (1.54; 3.54 and 6 g-COD.L-1.d-1) and HRT (5; 1.5 and 1.1 d). The results of effluent pH greater than 7.0, volatile acidity/total alkalinity of 0.2 and 98% removal of organic matter showed that the reactor performance was not impaired by the separation of acidogenic and methanogenic stages. The highest production of methane was observed in Phase IV, with pH 5.0, 6 g.L-1.d-1 OLR and 1.1 d HRT, resulting in average values of 0.82 L.L-1.d-1 for volumetric methane production, 0.85 L.g-1CODremoved yield and 80% methane in biogas composition. The energy efficiency in the combined system was 17% higher than the one observed in the single system for the treatment of cassava starch wastewater. / Este trabalho avaliou a produção de hidrogênio e metano a partir de efluente de fecularia de mandioca em sistema combinado. Os reatores acidogênico e metanogênico foram operados em fluxo contínuo, e os ensaios divididos em três etapas. Na Etapa 1, três ensaios para produção de hidrogênio avaliaram o efeito do pH inicial (6,0 e 4,5), concentração de substrato (1,4, 1,1 e 2,2 g carboidratos totais.L-1) e estratégias de controle da biomassa (por descarte ou mudança na estruturação do material suporte de polietileno de baixa densidade) em reatores anaeróbios de leito fixo e fluxo ascendente, à temperatura de 36 C. A melhor condição operacional dentre as avaliadas foi pH 6,0 e concentração de 1,4 g carboidratos totais.L-1, que resultou em Produções Volumétricas de Hidrogênio (PVH) de 229 mL.L-1.d-1 e rendimento de 29,4 mL.g-1 carboidrato total. A melhor estratégia de controle de biomassa foi a ordenação do leito com cilindros de polietileno, a qual proporcionou menores alterações no regime de escoamento e crescimento excessivo da biomassa. Na Etapa 2, o efeito da fonte de inóculo foi avaliado em dois reatores de leito empacotado nas condições operacionais pH 6,0; concentração de substrato de 2 g.L-1, Carga Orgânica Volumétrica aplicada (COV) de 20 g.L-1.d-1 e Tempo de Detenção Hidráulica (TDH) de 2 horas. No reator inoculado com efluente autofermentado verificou-se PVH de 550 mL.L-1.d-1 e rendimento de hidrogênio de 38 mL.g-1 carboidratos totais. Esses valores foram maiores que os observados para o reator inoculado com lodo anaeróbio tratado termicamente, os quais indicaram que a utilização de inóculos simples representa uma estratégia viável para produção de hidrogênio nas condições testadas. Além desses ensaios, a influência da COV e do TDH também foi avaliada. O aumento COV (de 10 para 20 g.L-1.d-1) e a redução do TDH (de 4 para 2 h) resultaram em maior produção de hidrogênio (467 mL.L-1.d-1), percentual de hidrogênio no biogás (40%) e vazão molar (2,16 mmol.h-1). Entretanto, o rendimento médio de 30 mL H2.g-1 carboidrato total foi igual para as duas condições testadas. De modo geral, o ácido butírico foi associado à maior produção de gás hidrogênio, seguido dos ácidos acético e propiônico, além de etanol, nos cinco ensaios realizados. Na Etapa 3, a produção de metano a partir do efluente acidificado foi avaliada em reator anaeróbio horizontal de leito fixo e fluxo contínuo, operado em condição mesofílica de temperatura. As condições operacionais foram divididas em quatro fases, com variação do pH inicial (5,0 e 7,0), da COV (1,54; 3,54 e 6 g DQO.L-1.d-1) e do TDH (5; 1,5 e 1,1 d). Os resultados de pH efluente superior a 7,0, relação acidez volátil/alcalinidade total de 0,2 e remoção de 98% da matéria orgânica evidenciam que o desempenho do reator não foi prejudicado pela separação das fases acidogênica e metanogênica. A maior produção de metano foi observada na Fase IV, com pH 5,0, COV de 6 g.L-1.d-1e TDH de 1,1 d, que resultou em valores médios de produção volumétrica de metano de 0,82 L.L-1.d-1, rendimento de 0,85 L.g-1DQOremovida e 80% de metano na composição do biogás. O rendimento energético no sistema combinado foi 17% superior ao observado em sistema único no tratamento de efluente de fecularia.

The thesis describes a completely new biofuel system to generate particle-free heat from combustion of ash-containing biofuel particles at high temperatures. The suggested system gives opportunities to introduce biofuels in new areas. Main components in the suggested system is a heat radiating combustion chamber intended for pulverized wood, combined with regenerators to extract heat from flue gases and simultaneously preheating the combustion air. The thesis contains a description of the suggested system, theoretical considerations, calculations regarding the combustion, and includes results from tests performed. The results from calculations and tests performed concludes that the system is workable and possible to apply. / Uppsatsen beskriver ett helt nytt system för att åstadkomma partikelfri värme och höga temperaturer från biobränslen. Det föreslagna systemet ger goda möjligheter att använda biobränslen inom helt nya områden. Systemet består huvudsakligen av en brännkammare för träpulver, utförd som en hålrumsstrålare, samt regenerativa värmeväxlare mellan avgående rökgas och inkommande förbränningsluft. Uppsatsen innehåller en beskrivning av det föreslagna systemet, teoretiska överväganden, beräkningar rörande förbränningen, samt redovisar resultat från gjorda försök. Resultat från beräkningar och genomförda försök visar att det föreslagna systemet fungerar och är praktiskt möjligt att tillämpa.

Uppsatsen behandlar olika aspekter av skogsbränslemarknaden mot bakgrund av biobränslets ökande betydelse i den svenska energiförsörjningen. Biobränslets andel av den totala svenska energitillförseln har ökat stadigt de senaste två decennierna. Ökningen hänger mycket samman med att värmesektorn, och då i främsta hand värmeverken, har ökat användningen av biobränslen och en stor andel av denna utgörs av skogsbränslen, dvs avverkningsrester och biprodukter från skogsindustrin. Skatter på fossila bränslen har varit en viktig drivkraft. Uppsatsen gör en beskrivning av vilka aktörerna på skogsbränslemarknaden är och hur kedjan från skogen till slutanvändare ser ut. Analysen är baserad på egna intervjuer av såväl säljare och användare av skogbränslen men också på sekundärdata av olika slag. Statistiken är bristfällig. Trenden för priser på skogsbränslen är uppåtgående och såväl säljare som användare väntar sig att priserna ska fortsätta upp i reala termer. Skogsbränslemarknaden ser ut att vara en fungerande (effektiv) marknad trots att den är förhållandevis ny och stadd i kraftig förändring. Många aktörer gör att konkurrensen är påtaglig i alla led. Det finns konkurrens både på säljarsidan och användarsidan. Dessutom sker viss import och export. Import av pellets är särskilt viktig. Men det sker också import av flis och samt rundved (för flisning). Det finns ett element av regionalisering förknippad med höga transportkostnader för lastbilstransporter. / I discuss various aspects of the market for wood fuels against the background of the increasing importance of bio fuels in the Swedish energy system. The use of bio fuels as a share of total energy supply in Sweden has increased considerably during the last couple of decades. Taxes on fossil fuels explain the increase in use of bio energy. It is district heating (fjärrvärme) which is the main user of wood fuels (outside the paper and sawmill industries themselves). The supply chain from the cutting of logs to the end user is described. I base the description/analysis on interviews with suppliers and users of wood fuels as well as secondary sources. Statistics on wood fuels are generally deficient. Prices on wood fuels have increased in real terms and market actors (producers as well as users) expect prices to continue to increase in the medium term. The market for wood fuels appears to be an efficient one despite the lack of standards and the despite the fact that it is a “new” market. There are a fairly large number of producers as well as users and there are no barriers to entry. The market is also “contestable” in the sense that wood fuels are imported. There is though an element of regionalisation of the wood fuel market due to high transportation costs.

<p>The thesis describes a completely new biofuel system to generate particle-free heat from combustion of ash-containing biofuel particles at high temperatures.</p><p>The suggested system gives opportunities to introduce biofuels in new areas.</p><p>Main components in the suggested system is a heat radiating combustion chamber intended for pulverized wood, combined with regenerators to extract heat from flue gases and simultaneously preheating the combustion air.</p><p>The thesis contains a description of the suggested system, theoretical considerations, calculations regarding the combustion, and includes results from tests performed.</p><p>The results from calculations and tests performed concludes that the system is workable and possible to apply.</p> / <p>Uppsatsen beskriver ett helt nytt system för att åstadkomma partikelfri värme och höga temperaturer från biobränslen.</p><p>Det föreslagna systemet ger goda möjligheter att använda biobränslen inom helt nya områden.</p><p>Systemet består huvudsakligen av en brännkammare för träpulver, utförd som en hålrumsstrålare, samt regenerativa värmeväxlare mellan avgående rökgas och inkommande förbränningsluft.</p><p>Uppsatsen innehåller en beskrivning av det föreslagna systemet, teoretiska överväganden, beräkningar rörande förbränningen, samt redovisar resultat från gjorda försök.</p><p>Resultat från beräkningar och genomförda försök visar att det föreslagna systemet fungerar och är praktiskt möjligt att tillämpa.</p>

<p>Uppsatsen behandlar olika aspekter av skogsbränslemarknaden mot bakgrund av biobränslets ökande betydelse i den svenska energiförsörjningen. Biobränslets andel av den totala svenska energitillförseln har ökat stadigt de senaste två decennierna. Ökningen hänger mycket samman med att värmesektorn, och då i främsta hand värmeverken, har ökat användningen av biobränslen och en stor andel av denna utgörs av skogsbränslen, dvs avverkningsrester och biprodukter från skogsindustrin. Skatter på fossila bränslen har varit en viktig drivkraft.</p><p>Uppsatsen gör en beskrivning av vilka aktörerna på skogsbränslemarknaden är och hur kedjan från skogen till slutanvändare ser ut. Analysen är baserad på egna intervjuer av såväl säljare och användare av skogbränslen men också på sekundärdata av olika slag. Statistiken är bristfällig. Trenden för priser på skogsbränslen är uppåtgående och såväl säljare som användare väntar sig att priserna ska fortsätta upp i reala termer.</p><p>Skogsbränslemarknaden ser ut att vara en fungerande (effektiv) marknad trots att den är förhållandevis ny och stadd i kraftig förändring. Många aktörer gör att konkurrensen är påtaglig i alla led. Det finns konkurrens både på säljarsidan och användarsidan. Dessutom sker viss import och export. Import av pellets är särskilt viktig. Men det sker också import av flis och samt rundved (för flisning). Det finns ett element av regionalisering förknippad med höga transportkostnader för lastbilstransporter.</p> / <p>I discuss various aspects of the market for wood fuels against the background of the increasing importance of bio fuels in the Swedish energy system. The use of bio fuels as a share of total energy supply in Sweden has increased considerably during the last couple of decades. Taxes on fossil fuels explain the increase in use of bio energy. It is district heating (fjärrvärme) which is the main user of wood fuels (outside the paper and sawmill industries themselves).</p><p>The supply chain from the cutting of logs to the end user is described. I base the description/analysis on interviews with suppliers and users of wood fuels as well as secondary sources. Statistics on wood fuels are generally deficient. Prices on wood fuels have increased in real terms and market actors (producers as well as users) expect prices to continue to increase in the medium term.</p><p>The market for wood fuels appears to be an efficient one despite the lack of standards and the despite the fact that it is a “new” market. There are a fairly large number of producers as well as users and there are no barriers to entry. The market is also “contestable” in the sense that wood fuels are imported. There is though an element of regionalisation of the wood fuel market due to high transportation costs.</p>