| 1. |
- Adler, Anneli, et al.
(author)
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Variation of growth and phenology traits in poplars planted in clonal trials in Northern Europe-implications for breeding
- 2021
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 14, s. 426-444
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Journal article (peer-reviewed)abstract
- The increased demand for wood to replace oil-based products with renewable products has lifted focus to the Baltic Sea region where the environment is favorable for woody biomass growth. The aim of this study was to estimate broad-sense heritabilities and genotype-by-environment (GxE) interactions in growth and phenology traits in six climatically different regions in Sweden and the Baltics. We tested the hypothesis that both bud burst and bud set have a significant effect on the early growth of selected poplar clones in Northern Europe. Provenance hybrids of Populus trichocarpa adapted to the Northern European climate were compared to reference clones with adaptation to the Central European climate. The volume index of stemwood was under low to medium genetic control with heritabilities from 0.22 to 0.75. Heritabilities for phenology traits varied between 0.31 and 0.91. Locally chosen elite clones were identified. GxE interactions were analyzed using pairwise comparisons of the trials. Three different breeding zones for poplars between the latitudes of 55 degrees N and 60 degrees N in the Baltic Sea Region were outlined. The studied provenance hybrids with origin from North America offer a great possibility to broaden the area with commercial poplar plantations in Northern Europe and further improve the collection of commercial clones to match local climates. We conclude that phenology is an important selection criterion after growth.
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| 2. |
- Aronsson, Pär, et al.
(author)
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Impact of nitrogen fertilization to short-rotation willow coppice plantations grown in Sweden on yield and economy
- 2014
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 7, s. 993-1001
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Journal article (peer-reviewed)abstract
- A fertilization trial was carried out in established short-rotation willow coppice (SRWC) plantations of two bred varieties of willow (Salix spp.; "Tora" and "Jorr") at five sites in central Sweden between 2008 and 2010. Mineral nitrogen was applied at four different rates: No fertilization (Control), 160 kg nitrogen ha(-1) as a single dose after harvest (Economy), 60-100-60 kg nitrogen ha(-1) in year 1-2-3 (Normal), and 160 kg nitrogen ha(-1) year(-1) in years 1-3 (Intensive), using a randomized block design with four replicates. The yield response (biomass increase per kg fertilizer nitrogen) was 65, 67 and 46 kg kg(-1) in the Economy, Normal and Intensive treatments, respectively. The results from the fertilization trial were used for economic calculations of different fertilization strategies given varying costs for fertilization and marginal value of the increased yield (price received for wood chips minus the costs for harvest and transportation of wood chips to a district heating plant). Comparative calculations were made based on data from a previous fertilization trial during the first cutting cycle of old, non-bred varieties. The calculations showed positive net present values of fertilizing bred willow varieties given a realistic fertilization response and a price for wood chips close to the market price for forestry-based wood chips in Sweden.
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| 3. |
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| 4. |
- Dimitriou, Ioannis, et al.
(author)
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Impact of Populus plantations on water and soil quality
- 2017
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 10, s. 750-759
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Journal article (peer-reviewed)abstract
- Trees of genus Populus (in our context primarily poplars) are predominantly grown in Sweden in small plantations on arable land in southern and central parts of the country to produce biomass for energy and other purposes. This study evaluated the effects (i) of poplar plantations on groundwater quality, by determining differences in leaching of nitrogen and phosphorus to groundwater, and (ii) of poplar and hybrid aspen plantations on soil quality in terms of carbon in the top- and subsoil. The study was conducted comparing Populus plantations in Sweden with adjacent fields with cereals and grasslands. The experiment concerning the groundwater leaching was conducted in eight poplar plantations along three growing seasons (2012-2015). For the soil carbon experiments, 19 poplar and two hybrid aspen plantations and the respective reference fields were sampled. NO3-N leaching from poplar plantations was significantly lower than that from reference fields with cereals, but not when compared with grasslands. Spring NO3-N leaching was significantly lower in poplars than in the reference fields, whereas leaching of NO3-N in autumn did not differ. Concentrations of PO4-P in the groundwater of poplar plantations were lower compared to the respective ones of the reference fields. There were no clear trends observed when comparing carbon concentrations in the topsoil of the poplar and hybrid aspen plantations compared to the respective adjacent reference fields. For the subsoil, the average carbon concentrations in the poplar and hybrid aspen plantations were equal to the respective ones of cereals, but were higher when compared to grassland.
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| 5. |
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| 6. |
- Edelfeldt, Stina, et al.
(author)
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Effects of Cutting Length, Orientation and Planting Depth on Early Willow Shoot Establishment
- 2015
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 8, s. 796-806
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Journal article (peer-reviewed)abstract
- To assess the effects of different planting systems on early performance (survival, shoot emergence time, number of shoots, maximum shoot height and biomass shoot production) of willow, cuttings of varying lengths were planted horizontally at different depths and compared with vertically planted cuttings. Cutting lengths of (i) 25-200 cm and (ii) 7-21 cm were studied in a field experiment and in a box experiment, respectively. Shorter cuttings planted deeper had a lower survival rate and emerged a few days later compared to longer cuttings planted shallower. The performance was considerably higher at the apical part of the cuttings, regardless of cutting length. Longer cuttings planted shallow had a higher performance. Vertically planted cuttings produced more biomass and shoots per length unit than horizontally planted cuttings. We conclude that planting systems based on the use of longer horizontally planted cuttings would probably lead to an uneven establishment and gaps in the stand caused by apical dominance. Also, to achieve the same performance, the need of planting material would be considerably higher compared to systems with vertically planted cuttings. To obtain a fast and more even early establishment of willows, we recommend the use of vertically planted cuttings with a length of at least 20 cm. If cuttings are planted horizontally, they should not be planted deeper than 5 cm.
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| 7. |
- Edelfeldt, Stina, et al.
(author)
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Establishment and Early Growth of Willow at Different Levels of Weed Competition and Nitrogen Fertilization
- 2016
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 9, s. 763–772-
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Journal article (peer-reviewed)abstract
- To evaluate the effects of weed competition and nitrogen fertilization on the early growth performance of willow, cuttings of the clone Tora (Salix schwerinii x S. viminalis) were planted in buckets together with model weeds (spring barley or white mustard) sown 15, 26, and 30 days after willow planting. The buckets were fertilized with 30 or 90 kg N ha(-1). Willow with weeds sown after 15 days produced less biomass and smaller leaf area and had a lower maximum shoot height compared to willow planted without weeds and willow with weeds sown after 26 or 30 days. Fertilization with 90 kg N ha(-1) gave higher willow biomass production in willow with weeds sown after 26 or 30 days. Type of model weed had no effect on willow performance. Weed biomass and maximum shoot height were higher in weeds planted without willows compared to the willow-weed mixtures. A high nitrogen level gave more weed biomass when planted without willows and in the willow-weed mixture with weeds sown after 15 days. We conclude that for the given high density of willow, competition from weeds emerging soon after willow planting had strong effect on early production. Furthermore, if there is a risk of weed infestation, fertilization should be delayed.
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| 8. |
- Englund, Oskar, 1982, et al.
(author)
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Meeting Sustainability Requirements for SRC Bioenergy: Usefulness of Existing Tools, Responsibilities of Involved Stakeholders, and Recommendations for Further Developments
- 2012
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In: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 5:3, s. 606-620
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Journal article (peer-reviewed)abstract
- Short rotation coppice (SRC) is considered an important biomass supply option for meeting the European renewable energy targets. This paper presents an overview of existing and prospective sustainability requirements, Member State reporting obligations and parts of the methodology for calculating GHG emissions savings within the EU Renewable Energy Directive (RED), and shows how these RED-associated sustainability criteria may affect different stakeholders along SRC bioenergy supply chains. Existing and prospective tools are assessed on their usefulness in ensuring that SRC bioenergy is produced with sufficient consideration given to the RED-associated criteria. A sustainability framework is outlined that aims at (1) facilitating the development of SRC production systems that are attractive from the perspectives of all stakeholders, and (2) ensuring that the SRC production is RED eligible. Producer manuals, EIAs, and voluntary certification schemes can all be useful for ensuring RED eligibility. However, they are currently not sufficiently comprehensive, neither individually nor combined, and suggestions for how they can be more complementary are given. Geographical information systems offer opportunities for administrative authorities to provide stakeholders with maps or databases over areas/fields suitable for RED-eligible SRC cultivation. However, proper consideration of all relevant aspects requires that all stakeholders in the SRC supply chain become engaged in the development of SRC production systems and that a landscape perspective is used.
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| 9. |
- Hammar, Torun, et al.
(author)
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Climate Impact of Willow Grown for Bioenergy in Sweden
- 2014
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In: Bioenergy Research. - : Springer-Verlag New York. - 1939-1234 .- 1939-1242. ; 7:4, s. 1529-1540
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Journal article (peer-reviewed)abstract
- Short-rotation coppice willow (SRCW) is a fast-growing and potentially high-yielding energy crop. Transition to bioenergy has been identified in Sweden as one strategy to mitigate climate change and decrease the current dependency on fossil fuel. In this study, life cycle assessment was used to evaluate and compare the climate impacts of SRCW systems, for the purpose of evaluating key factors influencing the climate change mitigation potential of SRCW grown on agricultural land in Sweden. Seven different scenarios were defined and analysed to identify the factors with the most influence on the climate. A carbon balance model was used to model carbon fluxes between soil, biomass and atmosphere under Swedish growing conditions. The results indicated that SRCW can act as a temporary carbon sink and therefore has a mitigating effect on climate change. The most important factor in obtaining a high climate change-mitigating effect was shown to be high yield. Low yield gave the worst mitigating effect of the seven scenarios, but it was still better than the effect of the reference systems, district heating produced from coal or natural gas.
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| 10. |
- Hammar, Torun, et al.
(author)
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Time-Dynamic Effects on the Global Temperature When Harvesting Logging Residues for Bioenergy
- 2015
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 8, s. 1912-1924
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Journal article (peer-reviewed)abstract
- The climate mitigation potential of using logging residues (tree tops and branches) for bioenergy has been debated. In this study, a time-dependent life cycle assessment (LCA) was performed using a single-stand perspective. Three forest stands located in different Swedish climate zones were studied in order to assess the global temperature change when using logging residues for producing district heating. These systems were compared with two fossil reference systems in which the logging residues were assumed to remain in the forest to decompose over time, while coal or natural gas was used for energy. The results showed that replacing coal with logging residues gave a direct climate benefit from a single-stand perspective, while replacing natural gas gave a delayed climate benefit of around 8-12 years depending on climate zone. A sensitivity analysis showed that the time was strongly dependent on the assumptions for extraction and combustion of natural gas. The LCA showed that from a single-stand perspective, harvesting logging residues for bioenergy in the south of Sweden would give the highest temperature change mitigation potential per energy unit. However, the differences between the three climate zones studied per energy unit were relatively small. On a hectare basis, the southern forest stand would generate more biomass compared to the central and northern locations, which thereby could replace more fossil fuel and give larger climate benefits.
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| 11. |
- Hjelm, Birger, et al.
(author)
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Diameter–Height Models for Fast-growing Poplar Plantations on Agricultural Land in Sweden
- 2015
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 8, s. 1759-1768
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Journal article (peer-reviewed)abstract
- There is increasing interest in using poplar plantations as sources of bioenergy in many countries, but optimizing their management, robust models for estimating and monitoring their structure, growth and biomass are required. The presented study explores the diameter-height relationships of poplars in 40 plantations on agricultural land located in central and southern Sweden, in order to provide tools for an easy estimation of standing biomass of poplar stands. Diameter and height measurements of 167 trees were included: 117 for calibration and 50 for validation. The constructed diameter-height equations were developed using a mixed-effect modelling approach to address the variations among sites of the plantations and obtain a flexible tool capable of providing locally calibrated estimates. Different models with various structures and stand variables, such as mean diameter and age, were tested. The best model presented R (2) values of 0.87 and 0.96, for the fixed and mixed model parts, respectively. Thus, it appears to be capable of providing useful estimates of heights of poplar stands from measurements of stem diameters in sample plots, thereby facilitating the planning and management of Swedish poplar plantations as future energy feedstock.
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| 12. |
- Karacic, Almir, et al.
(author)
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An Analysis of Poplar Growth and Quality Traits to Facilitate Identification of Climate-Adapted Plant Material for Sweden
- 2021
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 14, s. 409-425
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Journal article (peer-reviewed)abstract
- Poplar plantations harbor large potential as a renewable source of biomass for bioenergy and other industrial applications. The overall aim of this study is to analyze growth, phenology, stem form, and branching characteristics of 32 poplar clones grown in a trial in southern Sweden for their suitability to be grown as industrial feedstock. In a linear mixed model, performed for diameter at breast height and stem volume, the precision was improved by the use of two competition indices. The significance of phenology and quality characteristics for growth performance and ranking of poplar clones was evaluated through genotypic correlations, and multivariate hierarchical cluster analysis used to group the material. All traits showed moderate to high broad sense heritability. In general, higher stem volume was positively correlated with later leaf senescence, and uncorrelated with spring phenology. Selection efficiency for stem diameter and height was greatly improved between age 3 and 6 years allowing a better precision in selecting a subset of clones to be further tested in production plots and pilot plantations. Two commercial Populus maximowiczii Henry x trichocarpa Torr. & Gray cultivars performed best, while some intraspecific hybrids of P. trichocarpa are considered useful to genetically diversify commercial plantations in Southern Sweden (Belgian clones) or establish plantations in north-central parts of Sweden (Swedish clones). The cluster analysis emphasized growth traits and the grouping of the clones corresponded to their origin (or parentage). The results will facilitate decisions on the use of studied material in breeding, further testing and commercial deployment of poplar plantations in Sweden.
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| 13. |
- Kudahettige, Rasika L., et al.
(author)
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Characterization of bioethanol production from hexoses and xylose by the white rot fungus trametes versicolor
- 2012
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In: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 5:2, s. 277-285
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Journal article (peer-reviewed)abstract
- Bioethanol production by white rot fungus (Trametes versicolor), identified from fungal mixture in naturally decomposing wood samples, from hexoses and xylose was characterized. Results showed that T. versicolor can grow in culture, under hypoxic conditions, with various mixtures of hexoses and xylose and only xylose. Xylose was efficiently fermented to ethanol in media containing mixtures of hexoses and xylose, such as MBMC and G11XY11 media (Table 1), yielding ethanol concentrations of 20.0 and 9.02 g/l, respectively, after 354 h of hypoxic culture. Very strong correlations were found between ethanolic fermentation (alcohol dehydrogenase activity and ethanol production), sugar consumption and xylose catabolism (xylose reductase, xylitol dehydrogenase and xylulokinase activities) after 354 h in culture in MBMC medium. In a medium (G11XY11) containing a 1:1 glucose/xylose ratio, fermentation efficiency of total sugars into ethanol was 80% after 354 h.
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| 14. |
- Langeveld, H., et al.
(author)
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Assessing Environmental Impacts of Short Rotation Coppice (SRC) Expansion: Model Definition and Preliminary Results
- 2012
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In: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 5:3, s. 621-635
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Journal article (peer-reviewed)abstract
- Short rotation coppice (SRC) systems can play a role as feedstock for bioenergy supply contributing to EU energy and climate policy targets. A scenario depicting intensive arable crop cultivation in a homogeneous landscape (lacking habitat structures) was compared to a scenario including SRC cultivation on 20 % of arable land. A range of indicators was selected to assess the consequences of SRC on soil, water and biodiversity, using data from the Rating-SRC project (Sweden and Germany). The results of the assessment were presented using spider diagrams. Establishment and use of SRC for bioenergy has both positive and negative effects. The former include increased carbon sequestration and reduced GHG emissions as well as reduced soil erosion, groundwater nitrate and surface runoff. SRC can be used in phytoremediation and improves plant and breeding bird biodiversity (exceptions: grassland and arable land species) but should not be applied in dry areas or on soils high in toxic trace elements (exception: cadmium). The scenario-based analysis was found useful for studying the consequences of SRC cultivation at larger scales. Limitations of the approach are related to data requirements and compatibility and its restricted ability to cover spatial diversity and dynamic processes. The findings should not be generalised beyond the representativeness of the data used.
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| 15. |
- Li, Muyang, et al.
(author)
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Prediction of Cell Wall Properties and Response to Deconstruction Using Alkaline Pretreatment in Diverse Maize Genotypes Using Py-MBMS and NIR
- 2017
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In: Bioenergy Research. - : Springer. - 1939-1234 .- 1939-1242. ; 10:2, s. 329-343
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Journal article (peer-reviewed)abstract
- In this work, we explore the ability of several characterization approaches for phenotyping to extract information about plant cell wall properties in diverse maize genotypes with the goal of identifying approaches that could be used to predict the plant’s response to deconstruction in a biomass-to-biofuel process. Specifically, a maize diversity panel was subjected to two high-throughput biomass characterization approaches, pyrolysis molecular beam mass spectrometry (py-MBMS) and near-infrared (NIR) spectroscopy, and chemometric models to predict a number of plant cell wall properties as well as enzymatic hydrolysis yields of glucose following either no pretreatment or with mild alkaline pretreatment. These were compared to multiple linear regression (MLR) models developed from quantified properties. We were able to demonstrate that direct correlations to specific mass spectrometry ions from pyrolysis as well as characteristic regions of the second derivative of the NIR spectrum regions were comparable in their predictive capability to partial least squares (PLS) models for p-coumarate content, while the direct correlation to the spectral data was superior to the PLS for Klason lignin content and guaiacyl monomer release by thioacidolysis as assessed by cross-validation. The PLS models for prediction of hydrolysis yields using either py-MBMS or NIR spectra were superior to MLR models based on quantified properties for unpretreated biomass. However, the PLS models using the two high-throughput characterization approaches could not predict hydrolysis following alkaline pretreatment while MLR models based on quantified properties could. This is likely a consequence of quantified properties including some assessments of pretreated biomass, while the py-MBMS and NIR only utilized untreated biomass.
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| 16. |
- Lutter, Reimo
(author)
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Effect of Early Thinning Treatments on Above-Ground Growth, Biomass Production, Leaf Area Index and Leaf Growth Efficiency in a Hybrid Aspen Coppice Stand
- 2020
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 13, s. 197-209
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Journal article (peer-reviewed)abstract
- The bioeconomy strategies in the EU are expected to lead to increased consumption of woody biomass. The empirical knowledge of asexually regenerated hybrid aspen (Populus tremula L. x P. tremuloides Michx.) coppice stand production and responses to silvicultural treatments is still poor. In hemiboreal Estonia, four different management treatments (corridor thinning with ~67% removal, cross-corridor thinning with ~89% removal, single-tree thinning with ~97% removal and control with no management activity) were applied in a 2-year-old hybrid aspen coppice stand, and effects on tree above-ground biomass and leaf characteristics were investigated during three post-thinning years. Hybrid aspen mean annual increment of above-ground biomass peaked at 6.3 (range: 3.6-8.5) Mg ha(-1) in year 4, suggesting 4-5 years as an optimal age for bioenergy harvest. The above-ground growth characteristics of dominant trees did not differ from control area. The current annual increment of the height, biomass and leaf growth efficiency (LGE) of dominant trees under single-tree thinning remained even lower compared with the other treatments. Dominant trees were more efficient in resource use, as their LGE values were 21-50% higher compared with the stand average value. Poor growth, high mortality and low LGE in single-tree thinning indicate that the low density of remaining trees created an imbalance between leaf area and parent root system. The hybrid aspen coppice stand showed a high biomass production during early development. We recommend modest early thinning in vegetative hybrid aspen stands to ensure a sufficient balance between leaf area and parent root system.
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| 17. |
- Mohammadi, Ali, 1983-, et al.
(author)
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Energy Production Features of Miscanthus Pellets Blended with Pine Sawdust
- 2024
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In: Bioenergy Research. - : Springer Nature. - 1939-1234 .- 1939-1242. ; 17:1, s. 491-504
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Journal article (peer-reviewed)abstract
- The primary objective of this study was to evaluate the qualities of Miscanthus pellets blended with pine sawdust at various ratios (Miscanthus/pine sawdust—0:100, 25:75, 50:50, 75:25, and 100:0) and relate them to energy generation potential under typical production conditions of the widely used bioenergy production technologies according to literature. Samples of each material were milled to the required sizes and blended in the proportions mentioned above. Water was added (6%) to each mixture to achieve a uniform moisture content of 10% on wet basis. The mixtures were then subjected to pressure agglomeration in the form of mechanical compression using a single pellet press so that homogeneously sized fuel pellets were obtained. Thereafter, the pure and blended pellet samples were examined using a range of analytical techniques to reveal any alterations in characteristics important to the utilization of the pellets as a green energy source. The results showed that, although temperature variations generally caused an estimated 6% moisture loss on a wet basis during pelleting with positive influence on the features of the pellets, the quality of the pellets in terms of ash composition (2–4%), hardness (41–46 kg/pellet), and heating value (20–21 MJ/kg) was in general more desirable for the blended pellets than for pure Miscanthus pellet. Structural analysis also revealed low levels of hydrophobic groups in the blends relative to pure Miscanthus, which were consistent with the fractions of pine sawdust and were also the reason for the pellets’ increased hardness.
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| 18. |
- Mohan Pawar, Prashant, et al.
(author)
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QTL Mapping of Wood FT-IR Chemotypes Shows Promise for Improving Biofuel Potential in Short Rotation Coppice Willow (Salix spp.)
- 2018
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 11, s. 351-363
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Journal article (peer-reviewed)abstract
- An increasing interest to convert lignocellulosic biomass into biofuels has highlighted the potential of using willows for this purpose, due to its fast growth in short rotation coppice systems. Here, we use a mapping population of 463 individuals of a cross between Salix viminalis and S. viminalis x S. schwerinii to investigate the genetic background of different wood chemical traits, information of importance for breeding towards different uses of wood. Furthermore, using a subset of the mapping population, the correlation between biogas production and chemical traits was investigated. The phenotyping of wood was carried by Furrier-transformed-Infrared spectrometry (FT-IR) and water content analysis. Quantitative trait loci (QTLs) analysis was used to identify regions in the genome of importance for the phenotypic variation of these chemical traits. We found 27 QTLs for various traits. On linkage group (LG) VI-1, QTLs for signals assigned to G-lignin, lignin, and the S/G ratio were collocated and on LG XIV we found a cluster of QTLs representing signals assigned to lignin, cellulose, hemicellulose, and water. The QTLs explained from 3.4 to 6.9% of the phenotypic variation indicating a quantitative genetic background where many genes influence the traits. For the biogas production, a positive and negative correlation was seen with the signals assigned to acetyl and lignin, respectively. This study represents a first step in the understanding of the genetic background of wood chemical traits for willows, information needed for complementary studies, mapping of important genes, and for breeding of varieties for biofuel production purposes.
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| 19. |
- Mola-Yudego, Blas, et al.
(author)
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How Much Yield Should We Expect from Fast-Growing Plantations for Energy? Divergences Between Experiments and Commercial Willow Plantations
- 2015
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 8, s. 1769-1777
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Journal article (peer-reviewed)abstract
- How representative are yields from experimental plots compared to large-scale commercial implementation? This study analyses the yields of fast-growing willow plantations for energy reported in experimental trials in Sweden during the period 1980-2012 compared with those from commercial willow plantations for the period 1986-2006. The study reviews 16 academic publications, which include 466 records from experimental plots, and records from 2073 commercial plantations across the country. The average yield recorded from experiments was 7.7 odt ha(-1) year(-1), compared to commercial plantations' yields 2.6 and 4.2 odt ha(-1) year(-1) for the first and second rotations, respectively. The measured area of the experimental plots seems to have an effect in the overestimation of the average yields, which can be attributed to extrapolation errors. In addition, to explain the broad differences between yield estimates, we identify the following as potential factors: near-optimal management practices and choice of land age differences and rotation lengths, edge effects, measurement methods, harvesting losses, increased mortality, and increased probability of hazard. The results can help to rationalize the expectations derived from experiments and to a more realistic planning of future plantation schemes.
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| 20. |
- Natarajan, Karthikeyan, et al.
(author)
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Optimal Locations for Methanol and CHP Production in Eastern Finland
- 2012
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In: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 5:2, s. 412-423
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Journal article (peer-reviewed)abstract
- Finland considers energy production from woody biomass as an efficient energy planning strategy to increase the domestic renewable energy production in order to substitute fossil fuel consumption and reduce greenhouse gas emissions. Consequently, a number of developmental activities are implemented in the country, and one of them is the installation of second generation liquid biofuel demonstration plants. In this study, two gasification-based biomass conversion technologies, methanol and combined heat and power (CHP) production, are assessed for commercialization. Spatial information on forest resources, sawmill residues, existing biomass-based industries, energy demand regions, possible plant locations, and a transport network of Eastern Finland is fed into a geographically explicit Mixed Integer Programming model to minimize the costs of the entire supply chain which includes the biomass supply, biomass and biofuel transportation, biomass conversion, energy distribution, and emissions. The model generates a solution by determining the optimal number, locations, and technology mix of bioenergy production plants. Scenarios were created with a focus on biomass and energy demand, plant characteristics, and cost variations. The model results state that the biomass supply and high energy demand are found to have a profound influence on the potential bioenergy production plant locations. The results show that methanol can be produced in Eastern Finland under current market conditions at an average cost of 0.22 €/l with heat sales (0.34 €/l without heat sales). The introduction of energy policy tools, like cost for carbon, showed a significant influence on the choice of technology and CO 2 emission reductions. The results revealed that the methanol technology was preferred over the CHP technology at higher carbon dioxide cost (>145 €/t CO2). The results indicate that two methanol plants (360 MW biomass) are needed to be built to meet the transport fuel demand of Eastern Finland
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| 21. |
- Nielsen, Fredrik, et al.
(author)
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Sequential Targeting of Xylose and Glucose Conversion in Fed-Batch Simultaneous Saccharification and Co-fermentation of Steam-Pretreated Wheat Straw for Improved Xylose Conversion to Ethanol
- 2017
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In: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 10:3, s. 800-810
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Journal article (peer-reviewed)abstract
- Efficient conversion of both glucose and xylose in lignocellulosic biomass is necessary to make second-generation bioethanol from agricultural residues competitive with first-generation bioethanol and gasoline. Simultaneous saccharification and co-fermentation (SSCF) is a promising strategy for obtaining high ethanol yields. However, with this method, the xylose-fermenting capacity and viability of yeast tend to decline over time and restrict the xylose utilization. In this study, we examined the ethanol production from steam-pretreated wheat straw using an established SSCF strategy with substrate and enzyme feeding that was previously applied to steam-pretreated corn cobs. Based on our findings, we propose an alternative SSCF strategy to sustain the xylose-fermenting capacity and improve the ethanol yield. The xylose-rich hydrolyzate liquor was separated from the glucose-rich solids, and phases were co-fermented sequentially. By prefermentation of the hydrolyzate liquor followed fed-batch SSCF, xylose, and glucose conversion could be targeted in succession. Because the xylose-fermenting capacity declines over time, while glucose is still converted, it was advantageous to target xylose conversion upfront. With our strategy, an overall ethanol yield of 84% of the theoretical maximum based on both xylose and glucose was reached for a slurry with higher inhibitor concentrations, versus 92% for a slurry with lower inhibitor concentrations. Xylose utilization exceeded 90% after SSCF for both slurries. Sequential targeting of xylose and glucose conversion sustained xylose fermentation and improved xylose utilization and ethanol yield compared with fed-batch SSCF of whole slurry.
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| 22. |
- Normark, Monica, et al.
(author)
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Biochemical Conversion of Torrefied Norway Spruce After Pretreatment with Acid or Ionic Liquid
- 2016
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In: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 9:1, s. 355-368
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Journal article (peer-reviewed)abstract
- The chemical effects of torrefaction and the possibility to combine torrefaction with biochemical conversion were explored in experiments with five preparations of wood of Norway spruce that had been torrefied using different degrees of severity. Compositional analysis and analyses using solid-state CP/MAS C-13 NMR, Fourier-transform infrared (FTIR) spectroscopy, and Py-GC/MS showed small gradual changes, such as decreased hemicellulosic content and increased Klason lignin value, for torrefaction conditions in the range from 260 A degrees C and 8 min up to 310 A degrees C and 8 min. The most severe torrefaction conditions (310 A degrees C, 25 min) resulted in substantial loss of glucan and further increase of the Klason lignin value, which was attributed to conversion of carbohydrate to pseudo-lignin. Even mild torrefaction conditions led to decreased susceptibility to enzymatic hydrolysis of cellulose, a state which was not changed by pretreatment with sulfuric acid. Pretreatment with the ionic liquid (IL) 1-butyl-3-methylimidazolium acetate overcame the additional recalcitrance caused by torrefaction, and the glucose yields after 72 h of enzymatic hydrolysis of wood torrefied at 260 A degrees C for 8 min and at 285 A degrees C for 16.5 min were as high as that of IL-pretreated non-torrefied spruce wood. Compared to IL-pretreated non-torrefied reference wood, the glucose production rates after 2 h of enzymatic hydrolysis of IL-pretreated wood torrefied at 260 A degrees C for 8 min and at 285 A degrees C for 16.5 min were 63 and 40 % higher, respectively. The findings offer increased understanding of the effects of torrefaction and indicate that mild torrefaction is compatible with biochemical conversion after pretreatment with alternative solvents that disrupt pseudo-lignin-containing lignocellulose.
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| 23. |
- Ohlsson, Jonas, et al.
(author)
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Biomass Recalcitrance in Willow Under Two Biological Conversion Paradigms: Enzymatic Hydrolysis and Anaerobic Digestion
- 2020
-
In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 13, s. 260-270
-
Journal article (peer-reviewed)abstract
- Biomass recalcitrance, the inherent resistance of plants towards deconstruction, negatively affects the viability of biorefineries. This trait is not only dictated by the properties of the biomass but also by the conversion system used and its interactions with specific features of the biomass. Here, biomass recalcitrance to anaerobic digestion (AD) was assessed using a biomethanation potential (BMP) assay. Plant material (n = 94) was selected from a large population of natural Salix viminalis accessions, previously evaluated for biomass recalcitrance using hydrothermal pretreatment-enzymatic hydrolysis. Correlations between yields from the two biological conversion systems were evaluated, as well as the influence of biomass compositional features, analyzed by pyrolysis-molecular beam mass spectrometry (py-MBMS), and other biomass physical properties on conversion performance. BMP values averaged 198.0 Nml CH4/g biomass after 94 days, ranging from 28.6 to 245.9. S lignin and carbohydrate-derived spectral features were positively correlated with performance under both systems, whereas G lignin, p-coumaric acid, and ferulic acid-derived ions were negatively correlated with yields and rates. Most spectral features were more strongly correlated with enzymatic hydrolysis yields compared to methane production. For early-stage methane production and rate, recalcitrance factors were similar compared to enzymatic hydrolysis, with weaker correlations observed at later timepoints. The results suggest that although variation in methane potential was considerably lower than enzymatic hydrolysis yields, a reduced recalcitrance under this system will still be of importance to improve early conversion rates. Spectral features of low methane-producing samples indicate the presence of inhibitory substances, warranting further study.
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| 24. |
- Pezoa-Conte, Ricardo, et al.
(author)
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Aqueous Extraction of the Sulfated Polysaccharide Ulvan from the Green Alga Ulva rigida : Kinetics and Modeling
- 2017
-
In: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 10:3, s. 915-928
-
Journal article (peer-reviewed)abstract
- The incentives for utilizing a versatile range of renewable feedstocks in novel ways are continuously increasing. Sulfated polysaccharides from green algae, such as ulvan, are interesting due to the rare sugar constituents which can be utilized for new materials and chemicals in industry. However, before valorization fractionation needs to be performed in a controlled way. In the current work, the kinetics of the aqueous extraction of ulvan was studied in the temperature range 60–130 °C. The highest yield of 97.6 wt.% was attained after 2 h of extraction at 130 °C, and the extraction efficiency was observed to be heavily temperature dependent. Interestingly, two regimes of extraction kinetics were observed, presumably due to the different ulvan fractions contained within the cell wall of green algae. The experimental data was modeled with first-order kinetics, and an apparent activation energy of 53.8 kJ mol−1 was obtained for the process. The algal residue was processed using simultaneous saccharification and fermentation, and 0.48 g ethanol g−1 of sugars was obtained.
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| 25. |
- Porsö, Charlotta, et al.
(author)
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Time-Dependent Climate Effects of Eucalyptus Pellets Produced in Mozambique Used Locally or for Export
- 2016
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In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 9, s. 942-954
-
Journal article (peer-reviewed)abstract
- By using surplus land for biomass production, Mozambique could produce wood pellets for domestic use or export to the European market to meet increasing demand. This study investigated the time-dependent climate effects and energy balance of production and use of pellets from short rotation coppice eucalyptus cultivated on surplus land in Mozambique. Two end-users of the pellets produced were studied: power production in Mozambique and heat and power production in Sweden. A time-dependent life cycle assessment method was used, expressing climate impact as annual temperature change, which highlights the time aspect inherent in bioenergy systems by including annual greenhouse gas fluxes of both fossil and biogenic origins. The results showed an initial cooling effect of the pellet systems studied due to carbon sequestration in soil and biomass, counteracting the temperature warming effect from greenhouse gas emissions associated with the production system. The temperature cooling effect of carbon sequestration increased most in the beginning of the studied time period, while the temperature warming effect from the production system continued to increase, resulting in a net temperature warming effect over time. Local use of the pellets in Mozambique was shown to have a temperature cooling effect during a longer period (39 years) than their export and use in Sweden (27 years). Compared with fossil fuels such as coal or natural gas, eucalyptus pellets proved to be better from a climate perspective for both end-users studied.
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| 26. |
- Porsö, Charlotta, et al.
(author)
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Time-Dependent Climate Impact and Energy Efficiency of Internationally Traded Non-torrefied and Torrefied Wood Pellets from Logging Residues
- 2018
-
In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 11, s. 139-151
-
Journal article (peer-reviewed)abstract
- Demand for wood pellets as a renewable alternative to fossil fuels has increased in the past decade. However, production and use of wood pellets involves several operations (biomass extraction, chipping, transport, drying, milling, pelleting, combustion) with negative impacts on e.g. the climate. In this study, the energy efficiency and climate impact of production and use of non-torrefied and torrefied wood pellets were analysed and compared. The wood pellets, produced from logging residues extracted from a boreal coniferous forest stand (Norway spruce (Picea abies (L.) H. Karst)) in northern Sweden, were assumed to be exported and finally used in a power plant. Time-dependent life cycle assessment, expressing the climate impact as global temperature change over time, was used to include annual greenhouse gas fluxes of both fossil and biogenic origin. The results showed that carbon stock changes due to extraction of logging residues contributed most of the warming effect on global temperature. Due to greater demand for raw material, a higher warming impact per gigajoule fuel was obtained for torrefied wood pellets than for non-torrefied wood pellets. However, torrefied wood pellets demonstrated a lower climate impact (per GJ electricity) when advantages such as higher electrical energy efficiency and higher co-firing rate were included. A general conclusion from this study is that replacing coal with non-torrefied or torrefied wood pellets made from logging residues can mitigate climate change. The energy output of these systems was about sevenfold the primary energy input.
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| 27. |
- Prade, Thomas, et al.
(author)
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Impact of Harvest Date and Cutting Length of Grass Ley and Whole-Crop Cereals on Methane Yield and Economic Viability as Feedstock for Biogas Vehicle Fuel Production
- 2019
-
In: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 12:1, s. 137-149
-
Journal article (peer-reviewed)abstract
- Grass ley and whole-crop cereals used for biogas production are often finely chopped for subsequent ensiling and anaerobic digestion. Chopping can impact not only ensiling stability, digestibility and risk of process hick-ups in the digester but also harvesting capacity and fuel consumption. Based on field experiment data, the aim of this study was to investigate how three different nominal cutting lengths in the range of 3.5 mm to 12.5 mm impact methane yield and economic viability of grass ley and whole-crop cereals used as biogas substrate. A shorter cutting length affected the specific methane potential differently for the different crops, + 14 to − 25%. In biogas vehicle fuel production, balancing the additional energy and economic costs for shorter cutting length required an increased methane potential of less than 1% and 3%, respectively. As long as a decrease in cutting length increased the methane potential, the energy balance and economic result improved, despite higher energy inputs. However, mechanisms behind the impact on methane potential deserve further attention. In conclusion, we have shown that it is economically viable to produce methane gas, as a vehicle fuel, from several agricultural crops grown in the south of Sweden, i.e. grass ley and whole-crop rye and wheat, when they are harvested/chopped with a forager, ensiled as biogas feedstocks and processed to methane gas in a large-scale biogas plant.
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| 28. |
- Siwale, Workson, et al.
(author)
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Fuel Wood Pellets Produced from Sawdust of Scots Pine Mature and Juvenile Wood : Self-Heating and Off-Gassing Tests at Industrial Scale
- 2024
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In: Bioenergy Research. - : Springer. - 1939-1234 .- 1939-1242.
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Journal article (peer-reviewed)abstract
- This study investigated self-heating and off-gassing of Scots pine (Pinus sylvestris) wood pellets made from sawdust generated from separated mature and juvenile wood. The pellets were produced at an industrial scale and stored in large piles of about 7.2 tonnes. The production process involved drying the sawdust using three different methods and to varying moisture contents. The results indicated significant influences of both raw material type (F(6) = 61.97, p < 0.05) and drying method (F(2) = 65.38, p < 0.05) on the self-heating of the pellets. The results from the multiple regression analysis further showed that both the raw material type and pellet moisture content significantly influenced the temperature increase, with strong correlations observed for pellets produced using low-temperature drying (F(3, 14) = 83.52, multiple R2 = 0.95, p < 0.05), and medium temperature drying (F(3, 13) = 62.05, multiple R2 = 0.93, p < 0.05). The pellets produced from fresh mature wood sawdust were found to be more prone to self-heating and off-gassing while steam drying the sawdust at high temperature and pressure led to a significant reduction in heat and gas generation across all materials. The heightened self-heating and off-gassing in mature wood pellet can be attributed to a higher proportion of sapwood in the raw material. The probable explanations to the observed differences are in line with biological mechanisms for self-heating and off-gassing, as well as the chemical oxidation of fatty and resin acids.
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| 29. |
- Siwale, Workson, et al.
(author)
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Influence of Sapwood/Heartwood and Drying Temperature on Off-Gassing of Scots Pine Wood Pellets
- 2024
-
In: Bioenergy Research. - : Springer. - 1939-1234 .- 1939-1242. ; 17:1, s. 479-490
-
Journal article (peer-reviewed)abstract
- Wood pellets produced from fresh sawdust can form and release uncontrolled gases during bulk storage, a tendency referred to as off-gassing. This study investigated the off-gassing tendencies of Scots pine wood pellets made from separated sapwood and heartwood sawdust. The effects of drying temperature, raw material storage, as well as varying proportions of sapwood and heartwood were also investigated. There was a strong linear correlation between off-gassing and sapwood content, with correlation coefficient (R) values greater than 0.9 at p < 0.001 for all the off-gases. An increase in sapwood content of the feedstock led to a significant increase in off-gassing of CO2, CO, and CH4, and O2 consumption. The drying temperature of the raw material had a significant effect on off-gassing of both sapwood (F (8, 26) = 51.32, p < 0.05) and heartwood (F (8, 26) = 334.1, p < 0.05) pellets. Increasing the drying temperature for heartwood resulted in increased off-gassing, while for sapwood, the off-gassing reduced. Storage of sapwood raw material before pelletization reduced the off-gassing of wood pellets, whereas for heartwood, it had no significant impact. Based on the results, it is suggested that a biological process, in combination with the chemical oxidation of fatty acids, lay behind the off-gassing of wood pellets.
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| 30. |
- Stoklosa, Ryan J., et al.
(author)
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Fractionation and Improved Enzymatic Deconstruction of Hardwoods with Alkaline Delignification
- 2015
-
In: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 8:3, s. 1224-1234
-
Journal article (peer-reviewed)abstract
- In this work, an alkaline delignification was investigated for several industrially relevant hardwoods to understand the kinetics of xylan solubilization and degradation and the role of residual lignin content in setting cell wall recalcitrance to enzymatic hydrolysis. Between 34 and 50 % of the xylan was solubilized during the heat-up stage of the pretreatment and undergoes degradation, depolymerization, as well as substantial disappearance of the glucuronic acid substitutions on the xylan during the bulk delignification phase. An important finding is that substantial xylan is still present in the liquor without degradation. Cellulose hydrolysis yields in the range of 80 to 90 % were achievable within 24–48 h for the diverse hardwoods subjected to delignification by alkali at modest enzyme loadings. It was found that substantial delignification was not necessary to achieve these high hydrolysis yields and that hybrid poplar subjected to pretreatment removing only 46 % of the lignin was capable of reaching yields comparable to hybrid poplar pretreated to 67 or 86 % lignin removal. Decreasing the lignin content was found to increase the initial rate of cellulose hydrolysis to glucose while lignin contents under approximately 70 mg/g original biomass were found to slightly decrease the maximum extent of hydrolysis, presumably due to drying-induced cellulose aggregation and pore collapse. Pretreatments were performed on woodchips, which necessitated a “disintegration” step following pretreatment. This allowed the effect of comminution method to be investigated for the three hardwoods subjected to the highest level of delignification. It was found that additional knife-milling following distintegration did not impact either the rate or extent of glucan and xylan hydrolysis.
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| 31. |
- Verwijst, Theo, et al.
(author)
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Assumptions Made in Protocols for Shoot Biomass Estimation of Short-Rotation Willow Clones Underlie Differences in Results Between Destructive and Non-destructive Methods
- 2015
-
In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 8, s. 1424-1432
-
Journal article (peer-reviewed)abstract
- Yield estimates from single stands in short-rotation willow (Salix spp.) have been reported to differ substantially, depending on the estimation methods used. The magnitude of differences in estimates resulting from different methods may vary among clones on the same site. This indicates that some assumptions, implicitly made by using a certain method, cannot be generalised for all clones. To assess why estimates of different methods may differ and why the magnitude of the differences may be clone-specific for a given site, a number of assumptions underlying destructive and non-destructive protocols for the estimation of aboveground willow biomass were tested. Apart from general problems in satisfying the demands of representative sampling and meeting the assumptions that underlie the proper use of statistical models, it was found that basic assumptions with regard to the physical structure and phenology of willow may lead to the observed differences. For a given clone, the moisture content of willow shoots may vary over time and may be dependent on shoot size. For a given shoot, the moisture content of basal, apical and central stem parts may differ, with the magnitude of differences being dependent on the clone. Stem taper and curvature may be clone-specific and can also underlie differences in biomass estimates obtained by different methods. To improve estimates of aboveground biomass in short-rotation willow, it is important to state explicitly the assumptions underlying the methods used and, wherever possible, to test the assumptions and evaluate the effects of their violation on the resulting estimates.
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| 32. |
- Vico, Giulia, et al.
(author)
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Consistent Poplar Clone Ranking Based on Leaf Phenology and Temperature Along a Latitudinal and Climatic Gradient in Northern Europe
- 2021
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In: Bioenergy Research. - : Springer Nature. - 1939-1234 .- 1939-1242. ; 14:2, s. 445-459
-
Journal article (peer-reviewed)abstract
- In Northern Europe, poplars (Populus) can provide biomass for energy and material use, but most available clones were developed for lower latitudes and are unlikely to be well adapted to higher latitudes, even under warmer climates. We thus need to understand how clones respond to climatic conditions and photoperiod, and how these responses can be predicted. We answer these questions exploiting leaf phenological data of Populus clones, grown in six sites across the Baltic region, in Northern Europe, for 2 years with contrasting climatic conditions. Regarding the effects of climatic conditions and photoperiod, within each site, higher temperatures advanced the timing and enhanced the speed of spring and autumn phenology, but reduced the effective growing season length. Across sites, latitude affected the timing of spring and autumn phenology, the speed of spring phenology, and the effective growing season length; clone affected only the timing of phenology. Regarding the predictability of clone response to growing conditions, the growing degree day (GDD) model could not predict spring phenology, because the growing degree day threshold for a specific phenological stage was not only clone-, but also latitude- and year-specific. Yet, this GDD threshold allowed a robust ranking of clones across sites and years, thus providing a tool to determine the relative differences across clones, independently of latitude and temperature. A similar, but not as strong, pattern was observed in the timing of spring and autumn phenological stages. Hence, while prediction of spring phenology remains elusive, the ranking of clones based on observations of their phenology in a single location can provide useful indications on the clones’ relative performance under different latitudes and climates.
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| 33. |
- Victorin, Mirjam, et al.
(author)
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Characterization of Mechanically Pretreated Wheat Straw for Biogas Production
- 2020
-
In: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 13:3, s. 833-844
-
Journal article (peer-reviewed)abstract
- Biogas production from wheat straw is one strategy of converting biomass to bioenergy, but pretreatment of the lignocellulosic material is necessary in order to render the substrate biodegradable. In this study, four different mechanical pretreatments of wheat straw were investigated: roll milling, extrusion, pelletization, and hammer milling. The effects of the pretreatments on anaerobic digestion (AD) at 37 °C and on enzymatic hydrolysis (EH) with Cellic CTec2 at 50 °C were analyzed in terms of biochemical methane potential (BMP), maximum daily methane production (DMPmax), and EH yield as amount of released glucan/initial glucan content. Roll milling generated the highest BMP of 287 NmL CH4 gVS−1, an increase of 21% compared with untreated wheat straw. Extrusion provided the highest methane production rate (52 NmL CH4 gVS−1 day−1), the lowest floating capacity, and a high bulk density. It was further concluded that a linear relationship exists between the DMPmax and the EH yield (R2 = 0.768) which for roll-milled size fractioned wheat straw was even stronger (R2 = 0.900) but weaker for mechanically pretreated non-size fractioned straw (R2 = 0.625). Specific surface analysis and EH of 0.25–1-mm particles revealed that mechanical pretreatment most likely affect other physiochemical properties in wheat straw, such as the crystallinity or melting of the outer wax layer, which in turn affects AD and EH processes differently.
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| 34. |
- Weih, Martin, et al.
(author)
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Assessment of Genotype Ranking in Long-term Biomass Production of Salix Based on Juvenile Plant Traits: Breeding Implications
- 2009
-
In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 2, s. 29-36
-
Journal article (peer-reviewed)abstract
- Willow (Salix spp.) is among the most promising energy crops to be grown on agricultural land and breeding research to increase biomass yield of this perennial crop is performed in Europe and North America. Biomass willows are grown in short rotation and harvests are performed every 3 to 5 years (i. e., at 3- to 5-year cutting cycles) for a period of up to 25 years. However, breeding programs to improve long-term biomass yield are often relying on the results of short-term screening studies performed on juvenile plants. A pre-requisite for successful breeding of perennial energy crops is thus the identification of relevant juvenile plant traits indicative of long-term plant performance under field conditions. In this study a number of juvenile plant traits, measured at various Salix genotypes grown in a short-term experiment were evaluated in terms of their capacity to predict the long-term performance in biomass production after the first and second cutting cycle. The objective was to develop a simple model linking juvenile plant traits such as shoot biomass, total leaf area and leaf nitrogen (N) concentration to the long-term biomass productivity of field-grown plants. A two-component regression model combining juvenile shoot biomass and leaf N concentration provided the highest prediction accuracy (coefficients of determination around 0.8). The model based on two easy-to-measure juvenile plant traits clearly has implications for willow breeding programs. The implications for breeding are discussed in the light of the possibilities and limitations associated with the chosen approach.
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| 35. |
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| 36. |
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| 37. |
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| 38. |
- Welc, Monika, et al.
(author)
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Effects of Cutting Phenology (Non-dormant Versus Dormant) on Early Growth Performance of Three Willow Clones Grown Under Different Weed Treatments and Planting Dates
- 2017
-
In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 10, s. 1094-1104
-
Journal article (peer-reviewed)abstract
- To assess the effects of cutting phenology on early growth performance of three willow clones grown under different weed treatments and planting dates, freshly harvested (non-dormant) and cold-stored (dormant) cuttings from willow clone Tora, Jorr, and Olof were planted in bucket experiment outdoors in central Sweden on five planting dates (May-June 2013) with or without a model weed (spring barley). Non-dormant cuttings sprouted faster than dormant cuttings when planted early in the season. For cuttings planted later in the season, bud sprouting was affected only by willow clone. Aboveground biomass production was affected by cutting phenology, planting date, clone, and weed treatment. When planted on May 3 and May 10, biomass produced from non-dormant and dormant cuttings did not differ, while willows grown from dormant cuttings produced 59% more aboveground biomass than willows grown from non-dormant cuttings when planted on May 24-June 16. Tora produced on average 12% more biomass than Jorr and Olof, and weed competition reduced aboveground biomass production on average with 36%. The ability of willow to suppress weeds (WSA) was 26 (non-dormant cuttings) and 12% (dormant cuttings) higher for willows planted on May 3 compared with WSA of willows grown from cuttings planted later in the season. The ability to tolerate competition from weeds (WT) was 51 and 52% lower for willows grown from non-dormant and dormant cuttings planted late in the season compared with WT of willows planted earlier in the season. We conclude that planting with long-term cold storage of willow cuttings can be replaced with planting freshly harvested cuttings when planting is performed in early season, and that weed competition strongly reduces biomass production. Weed control during the establishment phase is crucial in order to maximize willow biomass production.
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| 39. |
- Welc, Monika, et al.
(author)
-
Effects of Propagule Phenology (Non-Dormant Versus Dormant) and Planting System (Vertical Versus Horizontal) on Growth Performance of Willow Clones Grown Under Different Weeding Regimes
- 2018
-
In: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 11, s. 703-714
-
Journal article (peer-reviewed)abstract
- To assess the effects of propagule phenology and planting system on growth performance of three willow clones grown under different weeding regimes, a field experiment was performed in central Sweden 2014-2016. Freshly harvested (non-dormant) and cold-stored (dormant) cuttings (planted vertically) and billets (planted horizontally) from willow clones Tordis, Tora, and Jorr were planted in weeded and in unweeded plots. Sprouting was significantly higher for willows grown from non-dormant (74%) than dormant (58%) propagules and for cuttings (84%) compared with billets (42%). Survival was higher for willows from non-dormant propagules in weeded (71%) compared with unweeded (63%) plots, willows from dormant propagules in weeded (72%) compared with unweeded (60%) plots, and for willows from cuttings (93%) compared with billets (39%). During 2014-2016, aboveground biomass production was significantly higher for willows from cuttings (11.71 t DW ha(-1)) than from billets (6.13 t DW ha(-1)), grown in weeded (15.29 t DW ha(-1)) than in unweeded (2.55 t DW ha(-1)) plots, and differed significantly among willow clones (11.48, 9.27, and 6.01 t DW ha(-1) for Tordis, Tora, and Jorr, respectively). In this study, (i) planting with cold-stored and freshly harvested willow propagules was equally successful and therefore cold storage could be potentially avoided and replaced with planting of freshly harvested propagules in early spring; however, (ii) in terms of measured growth performance parameters, willows grown from cuttings performed better than grown from billets; and (iii) weed competition significantly reduced survival and aboveground biomass production, confirming that weed control during establishment of willow is crucial.
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| 40. |
- Xu, X., et al.
(author)
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Landscape Metrics and Land-Use Patterns of Energy Crops in the Agricultural Landscape
- 2023
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In: Bioenergy Research. - : Springer Nature. - 1939-1234 .- 1939-1242. ; 16:4, s. 2178-2191
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Journal article (peer-reviewed)abstract
- Energy crops are a new player in the traditional agricultural landscape. The present paper analyses the land uses surrounding and the spatial characteristics of the main energy crops in Sweden (willow, poplar, hybrid aspen and reed canary grass) compared to traditional agricultural crops during the period 2006–2018. Spatial metrics (number of shape characterising points, shape index and rectangularity ratio) are calculated for each field, as well as the nearby land uses at varying distances, at radius: 500 m, 1000 m, 2000 m and 5000 m. A total of 1560 energy crop fields are studied in the 2006 dataset and 3416 fields in the 2018 dataset, which are compared to 58,246 fields with cereal crops in 2006 and 131,354 fields in the 2018 dataset. Results show that, despite being established on previous agricultural land, energy crops present a different spatial profile compared to traditional agricultural crops. Field shapes present less complexity than before, and the overall spatial features become more regular with time in both cases of energy crops and cereals, suggesting an increasing trend in cost-efficient agricultural practices and planning. Important differences concerning land use diversity at different scales are found between plantations versus grasses. In general, willow plantations are located in agriculture-dominated areas (> 70% at 500 m, > 50% at 2000 m), whereas reed canary grass is in forest-dominated landscapes (> 30% at 500 m, > 60% at 2000 m); both contribute to diversifying existing land uses although with varying effects. The results of this study are a basis to assess the impacts of energy crops at landscape level and can translate into applications in energy policy and planning.
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| 41. |
- Wittek, Peter, et al.
(author)
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Compactly Supported Basis Functions as Support Vector Kernels for Classification
- 2011
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In: IEEE Transactions on Pattern Analysis and Machine Intelligence. - : IEEE computer. - 0162-8828 .- 1939-3539. ; 33:10, s. 2039-2050
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Journal article (peer-reviewed)abstract
- Wavelet kernels have been introduced for both support vector regression and classification. Most of these wavelet kernels do not use the inner product of the embedding space, but use wavelets in a similar fashion to radial basis function kernels. Wavelet analysis is typically carried out on data with a temporal or spatial relation between consecutive data points. We argue that it is possible to order the features of a general data set so that consecutive features are statistically related to each other, thus enabling us to interpret the vector representation of an object as a series of equally or randomly spaced observations of a hypothetical continuous signal. By approximating the signal with compactly supported basis functions and employing the inner product of the embedding L(2) space, we gain a new family of wavelet kernels. Empirical results show a clear advantage in favor of these kernels.
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