The United Kingdom has committed itself to ambitious and legally-binding Greenhouse Gas emission reduction, and renewable energy contribution targets. Energy production from biomass is expected to play a significant role in achieving these targets. The PhD Research Project as presented in this Thesis provides an analysis of the UK’s indigenous biomass resources, and the potential they offer in servicing domestic bioenergy requirements. The biomass resource supply chain dynamics within the UK, govern the availability of these indigenous resources. By modelling these supply chain dynamics, an assessment has been undertaken; the principle aim of which was to evaluate the potential contribution that indigenous biomass resources can make towards the UK’s future energy mix. This Research finds that the United Kingdom has considerable indigenous biomass resources that could potentially be made available, if the UK were able to develop its supply chains to appropriately mobilise these resources. However, the specific demands and the direction of development of the UK’s future bioenergy sector, as driven by the UK Government’s current strategies and policies; demonstrate degrees of incompatibility with the forecast potential of biomass resource availability. The consequence of this disparity is likely to result in rising biomass resource imports to balance the UK’s future energy demands. Further analysis highlights the potential impacts, inherent uncertainties, and risks to the United Kingdom’s bioenergy sector; associated with trade within future global biomass resource markets. The concluding themes are based on analyses and discussions that indicate that the UK should implement strategies to develop its indigenous resources, and develop its supply chains to optimise these resources; rather than become heavily reliant on imports from the global markets.

The wood energy market remains nascent in the UK, despite climate change policies and energy security concerns. Transaction costs have been identified as one barrier to woodfuel development. However, few studies provide explicit insights into such barriers to spontaneous exchange in this sector and how they influence its formation. The study approaches the development of woodfuel in the South West Region of England through Transaction Costs Economics (TCE) and aims to identify the appropriate governance structure of the supply chain as a response to existing transactions costs. When transaction costs increase, seamless market exchange gradually gives way to credible contracting and even to full vertical integration or unified ownership. The TCE approach provides insights to analyse friction and barriers to exchange and allows for a dialogue between economics, law and day-to-day business decision-making. Fuel procurement from woodfuel suppliers to woodfuel users is central to this project in looking at the barriers to exchange. Original data was collected through 42 in-depth interviews, mainly with suppliers themselves but also from Forestry Commission, regional agencies, NGOs and lobbies involved. The results suggest the influence of transaction costs. Also, there is some evidence that wood-energy regional actors are embracing organisational diversity from known rural business structures to less familiar ones in the UK, such as cooperatives and new partnerships as answers to, among other factors, transaction costs. The evidence suggests that not only support to demand and supply is necessary, as generally identified, but it is also needed at its interface by supporting the governance of the supply chain. Some practical implications for both public and private sectors are identified to better articulate the response to this need.

This thesis provides a detailed exploration of the way that four large research-council-funded bioenergy projects have engaged with the politics of bioenergy sustainability. Given the contested nature of sustainable development and the nature of the science in question, this thesis takes a discourse analysis approach to critically examine the functioning of these projects in the context of the wider politics surrounding the issue of bioenergy sustainability. Drawing on in depth interviews and a wide-ranging analysis of the literature, this thesis presents a number of findings. While used in strategically ambiguous ways, under the dominant ecologically modernising discourse governing bioenergy, sustainability is primarily constructed as synonymous with least-cost decarbonisation. Policy support for bioenergy is built around a technologically optimistic storyline, underpinned by a number of assumptions, including a linear view of scientific policy making. This dominant discourse around bioenergy has been challenged in two main ways. The first of these has rejected the over emphasis on carbon balances and economics as the primary metrics against which bioenergy sustainability should be measured. Decarbonising our energy supply has become increasingly dislocated from its underlying (disputed) ethical and moral rationales. As such it has seemingly become an end in its own right. The second challenge is more subtle and involves a rejection of the framing of bioenergy sustainability as a scientific and technical problem. Although reproducing a more administrative type discourse, the science initiatives explored in this thesis appear to reinforce much of the dominant discourse. As well as reflecting certain practices associated with the governments focus on scientific policy making, a lack of reflexivity to the strategic aims of energy policy within science also reflects a strong positivism and shared reliance on the perceived linearity of scientific policy making. It is argued that if science is to be liberated to fully respond to the challenges of sustainability, scientists need to be more reflexive as to the (political) role of science in modern environmental controversies, questioning both what their impacts might be and whose interests they are serving.

There is an abundance of reports and articles on the extent of future bioenergy usage. Decision-makers might turn to bioenergy projections in hopes of making informed decisions for policies or investments. This report aims to highlight irregularities and differences regarding calculations and results in 15 global bioenergy projection studies for the year 2050, and to find underlying connections by applying a metaanalysis with a methodological focus. Statistical distributions were made for the projected global bioenergy potentials. A growth rate study based on the projected global bioenergy potentials was made and used as a simple “reality check”. Regarding Sweden and the EU, it was investigated whether decisions has been made based on estimated bioenergy potentials. The final aim was to make recommendations for bioenergy decision-makers and policy-makers. There are many statistical distributions fitting the projections for 2050. The distribution functions showed that with a 95 % confidence level, the bioenergy projections in 2050 is 151.3 EJ. The interquartile range of all studies included in this report for primary bioenergy in the year 2050 was shown to be 120-400 EJ, with minimum value of 30 EJ and maximum of 1600 EJ. A mere third of the projection values were in the vicinity of a linear or exponential trendline based on historical values. The historical annual average growth rate for bioenergy from 1971 to 2011 was found to be 1.9 percent. A higher growth rate is required to achieve the larger quantities that are projected in most studies, the most extreme rate was 7.6 percent, which is far above the average. The EU has adopted a biomass action plan partly based on bioenergy projections by the European Energy Agency in 2006. National and international energy projection reports influence Swedish politics, albeit not directly in propositions. The difference between individual reports and articles projected bioenergy level in 2050 is significant. It is recommended to read more than one. Most forecasting models and estimates will likely perform poorly numerically, so it is recommended to look for underlying factors, connected longterm trends, or behavioral consequences.

Master of Science / Department of Agricultural Economics / Aleksan Shanoyan / The purpose of this research is to evaluate and gain a better understanding of the economic feasibility of Kansas farmers growing energy sorghum for biofuel production. The net returns for 11 crop systems that included a no-till or reduced-till option and the rotations involved wheat, grain sorghum, dual-purpose sorghum, and photoperiod sensitive sorghum were simulated in SIMETAR© developed by Richardson, Shumann, and Feldman (2004) using historical data on yields and prices. The price and yield data originates from an agronomic study conducted in Hesston, KS. The biomass yields for the 3 varieties of sorghum are based on experimental work performed in Manhattan, KS. The sorghum biomass prices were obtained from the United States Department of Agriculture Agricultural Marketing Service. Costs for the crop systems are based on the 2014 Kansas State University Herbicide handbook (Thompson et al. 2014), Dhuyvetter, O’Brien, and Tonsor (2014), and Dhuyvetter (2014). The net returns were simulated under five contract scenarios including: a Spot Market contract, a Minimum Price contract, a BCAP Price contract, and 2 levels of the Gross Revenue Guarantee contracts – 60% and 100%. Risk analysis was performed on the simulated net returns through use of the Excel add-in SIMETAR©. Stochastic efficiency analysis was used to evaluate the systems based on the distribution of net returns and risk preferences. The findings are summarized around three important factors influencing farmers’ economic feasibility of growing sorghum for biofuel use: crop systems, risk preferences, and contract specification. Results indicate that the no-till wheat and dual-purpose sorghum crop system without biomass production has the lowest costs and the no-till wheat and photoperiod sensitive sorghum system has the highest production cost. The crop systems that have a no-till option allow for the highest grain and biomass yields. Also, crop systems rotated with wheat are more preferred among producers due to higher net returns. The NTWDPS With system under the BCAP Price contract has the highest net returns and is highest in preference. The findings indicate that the risk aversion does affect the decision to produce sorghum for biofuel, but the effect is not very significant. In terms of contract specification, the results indicate that for Kansas producers, the BCAP Price contract will offer the highest net returns. These findings contribute additional insight on factors affecting Kansas farmers’ economic feasibility of producing sorghum for biofuel and can have important implications for biofuel industry actors and policy makers.

Around forty percent of the world´s population, mostly inhabitants of countries with developing economies, rely on the traditional usage of biomass for energy purposes. The major negative consequences are environmental and health effects. Additionally, the most remarkable social consequence is rural poverty which is directly linked to lack of access to electricity. This places the questions related to biomass utilization for energy production at the core of global welfare. The present work was performed as a part of a larger research project funded by Formas and which involves Swedish and Kenyan partners. The aim of this study was to gather basic knowledge about the characteristics of relevant biomass from sub-Saharan Africa, more specifically from Kenya. Eight different types of biomass, including agroforestry trees, agricultural residues, and water hyacinth, were evaluated according to fuel characteristics and thermochemical properties. Ultimate and proximate analyses of the collected biomass were carried out, in addition to heating values analyses. Moreover, the biomass was pelletized and a thermogravimetric analysis was performed in a single pellet reactor.  Finally, the composition of the residual ashes was determined. The results show that there was a large variation in the fuel characteristics and thermochemical behaviour of the studied agricultural residues and water hyacinth biomass types, whereas agroforestry trees had rather similar properties and thermochemical behaviour when combusted at the same temperature. In addition, results from the ash composition analyses showed large differences among the studied biomass types, which can be used to better predict and solve problems related to the combustion of these biomass types.

Processos fisiológicos que modulam a aclimatação fotossintética e o crescimento de plantas ao aumento da concentração de CO2 atmosférico são desconhecidos para a maioria das espécies da região amazônica. Neste sentido, este estudo buscou compreender o comportamento fotossintético e a alocação de carbono em Senna reticulata. Esta espécie ocorre em regiões amazônicas que passam por períodos de seca e alagamento e como estratégia de estabelecimento possui crescimento rápido e alta capacidade fotossintética. O objetivo deste estudo foi comparar os parâmetros de trocas gasosas e de crescimento de plantas cultivadas em câmaras de topo aberto sob diferentes concentrações de CO2 (380ppm-ambiente e 760ppm-elevado). Foram realizadas 6 coletas a cada 15 dias, nas quais foram mensurados pontos relativos as curvas AxPAR e AxCi, calculando-se os parâmetros fotossintéticos de cada curva. Os parâmetros de crescimento foram medidos em coletas destrutivas (biomassa) e não destrutivas (área foliar, altura e nº de folhas). As plantas do tratamento elevado apresentaram maior assimilação fotossintética aos 30 e 45 dias de experimento. Após este período foi observada uma mudança no padrão de alocação (de folha para raízes) e as plantas do elevado apresentaram aclimatação na fotossíntese. A aclimatação foi caracterizada primeiramente por uma redução na velocidade de carboxilação da Rubisco, que foi concomitante com a redução na concentração de N e C foliar. A partir disso ocorreu aumento na senescência das folhas, redução na área foliar e redução na concentração de clorofilas. Somente aos 90 dias é que houve um aumento de 30% na biomassa total das plantas submetidas ao tratamento elevado, resultante do aumento de massa principalmente das raízes e folhas. A transpiração e a respiração das plantas do elevado tenderam a ser menores ao longo de todo o tempo, sendo esta diferença significativa apenas aos 75 dias. Apesar das folhas possuírem menor área foliar e número de folhas, foi observado pela análise de massa especifica das folhas que as plantas do tratamento elevado possuem maior massa em relação às do ambiente, possivelmente pelo maior acúmulo de amido. A eficiência no uso da água foi maior nas plantas do elevado aos 30, 75 e 90 dias. A partir desses dados é possível concluir que S. reticulata submetida ao dobro da concentração atual de CO2, desenvolve processos de aclimatação fotossintética sob longa exposição ao elevado CO2, porém consegue produzir mais biomassa. / Physiological processes that modulate growth and photosynthetic acclimation of plants to increased atmospheric CO2 concentration are unknown for most species in the Amazon region. This study aimed to understand the photosynthesis and carbon allocation in Senna reticulata. This species occurs in the Amazonian regions that experience periods of drought and flooding and it has a fast growth and a high photosynthetic capacity as a strategy for its establishment. S. reticulata plants were grown in open top chambers under different concentrations of CO2 (380ppm Ambient - 760ppm Elevated) and their gas exchange and growth were compared. The harvests were performed at 15, 30, 45, 60, 75 and 90 days of experiment. At each date, AxPAR and AxCi curves were carried out to calculate the photosynthetic parameters. Growth parameters included biomass, leaf area, height and number of leaves. The plants of elevated CO2 presented higher photosynthetic assimilation at 30 and 45 days of experiment. After this period was observed a change in the carbon allocation (e.g. root to leaf) and the plants at elevated CO2 demonstrated a photosynthetic acclimation. This acclimation was characterized primarily by a reduction in velocity of carboxylation of Rubisco, which was concomitant with the reduction in N and C concentration in leaves. Also, the plants at elevated CO2 showed an increase in leaf senescence and a reduction in leaf area and chlorophyll concentration. After 90 days there was an increase (i.e. 30%) in total biomass of plants growing under elevated CO2, due to increase of roots and leaves biomass. The transpiration and respiration rates of plants at elevated CO2 tended to be lower throughout the experiment and the significant difference was found at 75 days. Although the leaves have less leaf area and leaf number, it was observed that specific leaf area from elevated CO2 treatment showed higher biomass when compared to ambient CO2. That difference possibly occurred due to greater starch accumulation. The water use efficiency was greater in plants from the elevated CO2 at 30, 75 and 90 days. From these data we conclude that S. reticulata grown at the elevated CO2 produces more biomass despite occurs the photosynthetic acclimation under long exposure to high CO2.

Tendo em vista o potencial de uso de biomassa obtida do capim-elefante como combustível de fonte renovável em regiões semiáridas, este trabalho teve por objetivo avaliar os efeitos de seis doses de nitrogênio (44, 200, 400, 600, 800 e 1000 kg.ha-1) e de sete lâminas de água (precipitação e irrigação com 0, 40, 54, 100, 135, 148 e 200% da evapotranspiração potencial da cultura - ETc) em sete idades de corte (46, 82, 112, 139, 169, 202 e 231 dias) sobre a produtividade de biomassa seca (BMS, kg.ha-1), altura (m) e índice de área foliar (IAF, m2.m-2) de capim-elefante, cultivar Cameroon. O experimento foi conduzido em Neossolo Quartzarênico localizado em Beberibe (CE), entre maio de 2012 e março de 2013. As doses de nitrogênio constituíram as parcelas e as lâminas de irrigação as subparcelas, segundo o delineamento em blocos casualizados, com quatro repetições. Os tratamentos de irrigação foram dispostos perpendicularmente e os tratamentos de doses de nitrogênio foram dispostos paralelamente à linha lateral de irrigação. Os blocos experimentais foram constituídos por 36 parcelas de 5 x 15 m e o tratamento sem irrigação (L0), com 6 doses de nitrogênio e 4 repetições, foi implantado em local separado para evitar influência da área irrigada. Como fonte de nitrogênio, utilizou-se o sulfato de amônio aplicado a lanço, parcelado em três aplicações. O manejo e a definição do momento de irrigação foi realizado por meio da determinação da capacidade de armazenamento de água no solo e do cálculo da ETc pelo método de Penman-Monteith-FAO. Em relação à BMS, o capim-elefante respondeu ao aumento da adubação nitrogenada e das lâminas de água nas 7 idades de corte avaliadas. O maior acúmulo de BMS ocorreu no tratamento combinado entre 135% ETc e 400 kg.ha-1 de N, aos 231 dias, com 239,85 kg.ha-1.dia-1. A produção de capim-elefante respondeu às lâminas de irrigação em todas as idades de corte analisadas e a maior resposta, em acúmulo diário de BMS de capim-elefante, obtida no tratamento 100% ETc aos 82 dias com 43,46 kg.ha-1.mm-1. As produtividades obtidas nos tratamentos 135, 148 e 200% ETc, a partir dos 82 até 231 dias de idades de corte, foram as maiores e não diferiram significativamente. A produção de BMS de capim-elefante não respondeu ao aumento da adubação nitrogenada isoladamente em seis idades de corte (a partir de 82 até 231) e houve resposta ao aumento da adubação nitrogenada isoladamente aos 46 dias de idade entre as doses 44 e 1000 kg.ha-1 de N, com 3780 e 5005 kg.ha-1 de BMS, respectivamente. A maior resposta, em acúmulo de BMS de capim-elefante, ocorreu no tratamento de 800 kg.ha-1 de N aos 231 dias com 15,383 kg.ha-1.kg-1 de N. O IAF e a altura do capim-elefante responderam às lâminas de água e não responderam à adubação nitrogenada. O IAF e a altura podem ser utilizados como parâmetro na estimativa de produção de BMS de capim elefante até 112 e 202 dias após o corte, respectivamente. Não houve correlação entre o IAF e altura do capim-elefante. / Due to the potential use of elephant-grass biomass as a source of renewable fuel in semi-arid regions, this study aimed to evaluate the effects of six nitrogen rates (44, 200, 400, 600, 800 and 1000 kg.ha-1) and seven irrigation levels (0, 40, 54, 100, 135, 148 and 200% of crop evapotranspiration - ETc) in seven cropping ages (46, 82, 112, 139, 169, 202 and 231 days) on elephant-grass, Cameroon cultivar, dry biomass yield (BMS, kg.ha-1), height (m) and leaf area index (LAI, m2.m-2). The trial was conducted in a Quartzipsamment soil located in Beberibe, Ceará State, Brazil, semiarid region, from May 2012 to March 2013. The nitrogen rates were the main plots and the irrigation levels comprised the subplots, according to a randomized block design with four replications. Irrigation treatments perpendicularly arranged (line source system sprynkler) and nitrogen rates were arranged in parallel to the lateral irrigation line. The experimental block consisted of 36 plots with 5 x 15 m and the treatment without irrigation (L0), with 6 nitrogen rates and 4 replications, was carried out in separate location to avoid infuence of the irrigated area. The nitrogen source was ammonium sulphate, was topdressed onto soil surface, in three split applications during the trial. The irrigation timing and management definition was performed by soil water storage capacity determination and through the Penman-Monteith-FAO crop evapotranspiration calculation. Regarding to BMS production, elephant-grass responded to nitrogen fertilization and irrigation in 7 evaluated periods, and the highest BMS (kg.ha-1.day-1) accumulation response was obtained in the combined treatment 135% ETc and 400 kg.ha-1 N at after 231 days with 239.85 kg.ha-1.day-1. Regarding to irrigation depths treatments, the elephant-grass production increased in all analyzed periods, and the largest BMS (kg.ha-1.day-1) accumulation response was found in treatment 100% ETc after 82 days with 43.46 kg.ha-1.mm-1 applied. The yield in treatments 125, 148 and 200% ETc in cutting ages from 82 to 231 days were the highest and did not differ significantly. The elephant-grass did not respond to nitrogen rates after 6 periods evaluated (82 to 231 days) however the N fertilization responded at the age of 46 days with 3.780 e 5005 kg.ha-1 de BMS between treatments of 44 e 1000 kg.ha-1 de N, respectively and the most intense BMS accumulation response was observed in treatment 800 kg.ha-1 of N at 231 days with 15,4 kg.ha-1.kg-1 N applied. The LAI and height of elephant-grass responded to water depths and did not respond to nitrogen fertilization. Both can be adopted as an elephant grass BMS yield estimation parameter from the age of 112 to 202 days after cutting, respectively. However, BMS versus LAI and LAI versus height interaction showed no correlation between the data collection periods, thus those variables should not be adopted for yield estimation purpose for this crop.

Submitted by Eunice Novais (enovais@uepg.br) on 2018-07-24T18:08:19Z No. of bitstreams: 2 license_rdf: 1037 bytes, checksum: 996f8b5afe3136b76594f43bfda24c5e (MD5) RAFAELA FABER DE CAMPOS.pdf: 3462807 bytes, checksum: 7d5b40498bba51c7d7e5694876f08985 (MD5) / Made available in DSpace on 2018-07-24T18:08:19Z (GMT). No. of bitstreams: 2 license_rdf: 1037 bytes, checksum: 996f8b5afe3136b76594f43bfda24c5e (MD5) RAFAELA FABER DE CAMPOS.pdf: 3462807 bytes, checksum: 7d5b40498bba51c7d7e5694876f08985 (MD5) Previous issue date: 2017-02-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A biomassa sempre foi uma fonte de energia utilizada pelo homem, antes mesmo da utilização de petróleo e gás natural. Porém nos últimos anos com a necessidade de mitigação das mudanças climáticas e, com o aumento da demanda mundial por energias alternativas, além da energia solar, eólica e hidrelétrica, uma delas é a utilização de biomassa vegetal. Este tipo de energia representa 10% do fornecimento mundial. A maior parte desta biomassa ainda é proveniente de florestas nativas, chamada de “biomassa tradicional”, causando impacto, de certa forma, ao meio ambiente. Entretanto, a utilização do bambu como biomassa para geração de energia torna-se uma alternativa sustentável e interessante, pois dentre suas várias características, destaca-se sua facilidade de propagação. Desta forma, o objetivo, do presente trabalho foi avaliar o potencial energético de quatro espécies de bambu, in natura e em forma de carvão. As espécies selecionadas foram Phyllostachys aurea A. C. Rivière (bambu dourado), Chusquea gracilis McClure & Smith (criciúma), Chusquea mimosa McClure & Smith (caratuva) e Merostachys multiramea Hackel (taquara lixa), do município de São Mateus do Sul, PR. As espécies de bambu foram avaliadas quanto ao teor de umidade, massa específica, composição química imediata, rendimento gravimétrico em carvão e ao poder calorífico superior. A espécie Phyllostachys aurea in natura apresentou poder calorífico superior de 18,91 MJ kg-1 e teor de cinzas de 0,49%. O carvão, 25,05 MJ kg-1 e 1,24%, respectivamente. Os valores de teor de cinzas para as biomassas in natura das espécies Merostachys multiramea, Chusquea gracilis e Chusquea mimosa, foram de 3,95%, 2,76% e 4,90% e, carbonizadas ficaram com valor de 5,43%, 6,43% e 7,93%, respectivamente. O poder calorifico superior da espécie C. mimosa foi de 25,55 MJ kg-1, mas devido a grande geração de cinzas após queima e massa específica de 0,20 g cm-3 in natura e de 0,10 g cm-3 do carvão, talvez sejam características mais interessantes para utilização como carvão ativado. A massa específica do Phyllostachys aurea foi de 0,63 g cm-3 in natura e 0,41 g cm-3, carbonizada. O alto teor de cinzas das espécies pode estar relacionado aos teores de constituintes minerais presentes no vegetal. Apesar disso, todas as espécies apresentaram características favoráveis para a utilização com fins energéticos, mas a espécie Phyllostachys aurea foi a que se apresentou mais semelhante às características apresentadas pela madeira de eucalipto, comumente utilizada para este fim. / Biomass has always been an energy source utilized by humans, even before, the use of oil and natural gas. However, in the last couple of years, the need to mitigate climate change and the global demand increase for alternative fuel, besides Solar, Eolic and Hydro energies, one of them is the use of vegetal biomass. Such energy represents 10% of the world supply. Most of this biomass still comes from native forests and it’s called “traditional biomass”, causing great impact, in some way, to the environment. On the other hand, the use of bamboo as biomass for the generation of energy becomes a sustainable and interesting alternative, because among its characteristics, it’s spread ease is highlighted. In this sense, the goal of the present research, is to analyze the energy potential of four bamboo species, in natura and in charcoal form. The selected species were Phyllostachys aurea A.C. Rivière (golden bamboo), Chusquea gracilis McClure & Smith (criciúma), Chusquea mimosa McClure & Smith (caratuva) and Merostachys multiramea Hackel (sandpaper taquara), from the city of São Mateus do Sul, PR. The bamboo species were evaluated according to their moisture rate, specific mass, immediate chemical composition, coal gravimetric yield and superior calorific value. The Phyllostachys aurea species in natura presented superior calorific value of 18.91 MJ kg -1 and ash rate of 0.49%. The coal presented 25.05 MJ kg -1 and 1.24%, respectively. The ash rate value for Merostachys multiramea, Chusquea gracilis e Chusquea mimosa were 3.95%, 2.76% e 4.90%, whereas carbonized they were 5.43%, 6.43% e 7.93%, respectivey. The C. mimosa species’ superior calorific value was 25.55 MJ kg-1 but due to great ash generation after the burn and specific mass of 0.20 g cm-3 in natura and 0.10 g cm-3 in coal, may be better characteristics for activated charcoal use. Phyllostachys aurea’s specific mass was 0.63 g cm-3 in natura and 0.41 g cm-3 carbonized. The species’ high ash rate may be related to the mineral constituent rate present in the plant. In spite of that, all species presented favorable characteristics to use for energetic purposes, but the Phyllostachys aurea species was the one which presented itself more similar to those characteristics presented by eucapiltus wood, commonly used for this purpose.

<p>Plant biomass is an abundant source of renewable energy, but the efficiency of its conversion into liquid fuels is low. One reason for this inefficiency is the recalcitrance of biomass to extraction and saccharification of cell wall polysaccharides. This recalcitrance is due to the complex and rigid structure of the plant cell wall. A better understanding of the genes effecting cell wall composition in bioenergy crops could improve feedstock quality and increase conversion efficiency. To identify genetic loci associated with biomass quality traits, we utilized genome-wide association studies (GWAS) in an 840-line <i>Sorghum</i> diversity panel. We identified several QTL from these GWAS including some for lignin composition and saccharification. Linkage disequilibrium (LD) analysis suggested that multiple polymorphisms are driving the association of SNPs within these QTL. Sequencing and further analysis led to the identification of a SNP within the coding region of a gene encoding phenylalanine ammonia-lyase (PAL) that creates a premature stop codon and co-segregates with an increase in the ratio of syringyl (S) to guaiacyl (G) lignin. A comparison of net PAL activity between lines with and without the mutation revealed that this mutation results in decreased PAL activity. </p>