Fouling tendency in biomass-fired boilers

Although it is well known that firing biomass fuels leads to increased deposition buildup on heat transfer surfaces in boiler compared with firing coal, existing empirical knowledge about combustion of different types of biofuels is limited. The aim of this study is to give greater awareness and understanding of the circumstances which are able to decrease considerably deposition build up on heat transfer surfaces when firing different types of biofuels. The crucial part of this thesis is experimental investigation of fouling tendency while firing biomass fuels, such as straw, bark, and peat having different chemical composition. In order to give comprehensive overview of ash deposition phenomena the number of not less important issues such as mechanisms of ash deposition, effect of fouling on heat transfer, and design of boilers subjected to ash buildup were examined as well. The answers obtained in this study may be a step towards a better knowledge of firing biofuels as separately as in mixtures, and may provide solutions for successful combustion technique of biomass fuels.

Decay of linkage disequilibrium within genes across HGDP-CEPH human samples: most population isolates do not show increased LD

Background It is well known that the pattern of linkage disequilibrium varies between human populations, with remarkable geographical stratification. Indirect association studies routinely exploit linkage disequilibrium around genes, particularly in isolated populations where it is assumed to be higher. Here, we explore both the amount and the decay of linkage disequilibrium with physical distance along 211 gene regions, most of them related to complex diseases, across 39 HGDP-CEPH population samples, focusing particularly on the populations defined as isolates. Within each gene region and population we use r2 between all possible single nucleotide polymorphism (SNP) pairs as a measure of linkage disequilibrium and focus on the proportion of SNP pairs with r2 greater than 0.8. Results Although the average r2 was found to be significantly different both between and within continental regions, a much higher proportion of r2 variance could be attributed to differences between continental regions (2.8% vs. 0.5%, respectively). Similarly, while the proportion of SNP pairs with r2 > 0.8 was significantly different across continents for all distance classes, it was generally much more homogenous within continents, except in the case of Africa and the Americas. The only isolated populations with consistently higher LD in all distance classes with respect to their continent are the Kalash (Central South Asia) and the Surui (America). Moreover, isolated populations showed only slightly higher proportions of SNP pairs with r2 > 0.8 per gene region than non-isolated populations in the same continent. Thus, the number of SNPs in isolated populations that need to be genotyped may be only slightly less than in non-isolates. Conclusion The 'isolated population' label by itself does not guarantee a greater genotyping efficiency in association studies, and properties other than increased linkage disequilibrium may make these populations interesting in genetic epidemiology.

Use of Biomass Gasification for Transport

This thesis represents an overview of biomass gasification technology together with some practical aspects of this technology application for transport in Finland. The main aim of this work is an assessment whether this technology is perspective in the nearest future for the wide use on transport or not. The first part of the thesis is a kind of survey of the previous works and materials con-cerning the usage of biomass gasification for transport. The second part concentrates more on the practical moments of its use for mobile applications in Finland (taxation, emissions, etc.).

Utilisation of biomass for energy production in the North-West Russian forest industry

Traditionally, fossil fuels have always been the major sources of the modern energy production. However prices on these energy sources have been constantly increasing. The utilization of local biomass resources for energy production can substitute significant part of the required energy demand in different energy sectors. The introduction of the biomass usage can easily be started in the forest industry first as it possesses biomass in a large volume. The forest industry energy sector has the highest potential for the fast bioenergy development in the North-West Russia. Therefore, the question concerning rational and effective forest resources use is important today as well as the utilization of the forestry by-products. This work describes and analyzes the opportunities of utilising biomass, mainly, in the form of the wood by-products, for energy production processes in general, as well as for the northwest Russian forest industry conditions. The study also covers basic forest industry processes and technologies, so, the reader can get familiar with the information about the specific character of the biomass utilization. The work gives a comprehensive view on the northwest forest industry situation from the biomass utilisation point of view. By presenting existing large-scale sawmills and pulp and paper mills the work provides information for the evaluation of the future development of CHP investments in the northwest Russian forest industry.

Market of biomass fuels in Finland : IEA Bioenergy Task 40 and EUBIONET III - Country report of Finland 2009

This study considered the current situation of solid and liquid biomass fuels in Finland. The fact that industry consumes more than half of the total primary energy, widely applied combined heat and power production and a high share of solid biomass fuels in the total energy consumption are specific to the Finnish energy system. Wood is the most important source of bioenergy in Finland, representing 20% of the total energy consumption in 2007. Almost 80% of the woodbased energy is recovered from industrial by-products and residues. As a member of the European Union, Finland has committed itself to the Union’s climate and energy targets, such as reducing its overall emissions of green house gases to at least 20% below 1990 levels by 2020, and increasing the share of renewable energy in the gross final consumption. The renewable energy target approved for Finland is 38%. The present National Climate and Energy Strategy was introduced in November 2008. The strategy covers climate and energy policy measures up to 2020, and in brief thereafter, up to 2050. In recent years, the actual emissions have exceeded the Kyoto commitment and the trend of emissions is on the increase. In 2007, the share of renewable energy in the gross final energy consumption was approximately 25% (360 PJ). Without new energy policy measures, the final consumption of renewable energy would increase to 380 PJ, which would be approximately only 31% of the final energy consumption. In addition, green house gas emissions would exceed the 1990 levels by 20%. Meeting the targets will need the adoption of more active energy policy measures in coming years. The international trade of biomass fuels has a substantial importance for the utilisation of bioenergy in Finland. In 2007, the total international trading of solid and liquid biomass fuels was approximately 77 PJ, of which import was 62 PJ. Most of the import is indirect and takes place within the forest industry’s raw wood imports. In 2007, as much as 21% of wood energy was based on foreign-origin wood. Wood pellets and tall oil form the majority of export streams of biomass fuels. The indirect import of wood fuels peaked in 2006 to 61 PJ. The foreseeable decline in raw wood import to Finland will decrease the indirect import of wood fuels. In 2004– 2007, the direct trade of solid and liquid biomass fuels has been on a moderate growth path. In 2007, the import of palm oil and export of bio-diesel emerged, as a large, 170 000 t/yr biodiesel plant came into operation in Porvoo.

Effect of extracts from citric biomass, rusted coffee leaves and coffee berry husks on Phoma costarricencis of coffee plants

Phoma leaf spot, caused by Phoma costarricensis poses a serious threat to coffee (Coffea arabica) production, especially in the highlands of the state of Minas Gerais, Brazil. Extracts of citric biomass, coffee berry husks and coffee leaves severely affected by rust caused by Hemileia vastatrix, were evaluated against P. costarricensis. In an in vitro assay, aqueous extracts of rusted leaves and berry husks plus the commercial extracts based on citric biomass named Ecolife® and Agromil® were tested at various dilutions on the mycelial growth inhibition of P. costarricensis. In vivo, coffee seedlings maintained in glasshouse, were sprayed with these extracts seven days before inoculation of P. costarricensis. Only extracts from citric biomass had inhibitory effects on the fungus. In vivo, Ecolife® (5 ml/l), Agromil® (5 g/l) and the aqueous extract of rusted coffee leaves (dilution 1:6) reduced Phoma leaf spot. Both, Ecolife® and the extract of rusted coffee leaves were significantly more effective in reducing the area under the lesion progress curve when applied at lower doses, indicating a possible effect on the induction of resistance.

Dry biomass distribution in a cerrado sensu stricto site in Brazil central

The Cerrado has been the main source of firewood and charcoal in Brazil, but despite being one of the hot spots for conservation of the world's biodiversity, neither plantations of native species nor sustainable management has been adopted in the region. The aim of this work was to investigate the biomass distribution and the potential for energy production of the cerrado species. The study was conducted in a cerrado sensu stricto site at the Água Limpa Farm (15º 56'14'' S and 47º 46'08'' W) in the Cerrado Biosphere Reserve. An area of 63.54ha was divided in 20 x 50m plots and, a random sample consisting of ten of these plots, representing 1.56% of the study-site, was assessed. All woody individuals from 5 cm diameter at 30 cm above ground level were identified and measured. Each individual was felled, the twigs thinner than 3cm were discarded while the larger branches and the trunks, both with bark, were weighted separately. After that, 2.5cm transverse sections of the trunk with bark were taken at 0, 25, 50, 75 and 100% of the length. A similar sample was also taken at the base of each branch. A total of 47 species in 35 genera and 24 families were found, with an average density of 673 individuals per ha. The diameter distribution showed a reversed-J shape with 67% of the individuals up to 13cm, while the maximum diameter was 32.30cm. Seven species represented 72% of the total biomass. In general, the species with higher production per tree were among those with higher production per ha. This content was distributed by diameter classes, reaching a maximum of 2.5ton/ha between 9 to 13cm and then, decreasing to 0.96 ton/ha between 29 to 33cm diameter. Carbon sequestering was 6.2ton/ha (until the actual stage of cerrado) based on an average 50% carbon content in the dry matter. The heat combustion of the wood varied from 18,903kj/kg to 20,888kj/kg with an average of 19,942kj/kg. The smaller diameter classes fix more carbon due to the large number of small plants per ha. But, for a species that reached larger dimensions and contained individuals in all diameter classes, Vochysia thyrsoidea, one can verify an increase in carbon fixation from 1.41 kg/ha in the first class (5 to 9cm) to 138,3kg/ha in the last (25 to 33cm). That indicates that it is possible to select species that reach larger size with a higher capacity of carbon accumulation per plant. The species that reached larger dimensions, with a production per tree above average and had high calorific power values were Dalbergia miscolobium, Pterodon pubescens and Sclerolobium paniculatum. These species have potential for use in fuelwood plantations and sustainable management.

Forest Biomass Resources and Technological Prospects for the Production of Second-generation Biofuels in Finland by 2020

Introduction of second-generation biofuels is an essential factor for meeting the EU’s 2020 targets for renewable energy in the transport sector and enabling the more ambitious targets for 2030. Finland’s forest industry is strongly involved in the development and commercialising of second-generation biofuel production technologies. The goal of this paper is to provide a quantified insight into Finnish prospects for reaching the 2020 national renewable energy targets and concurrently becoming a large-scale producer of forest biomass based second-generation biofuels feeding the increasing demand in European markets. The focus of the paper is on assessing the potential for utilising forest biomass for liquid biofuels up to 2020. In addition, technological issues related to the production of second-generation biofuels were reviewed. Finland has good opportunities to realise a scenario to meet 2020 renewable energy targets and for large-scale production of wood based biofuels. In 2020, biofuel production from domestic forest biomass in Finland may reach nearly a million ton (40 PJ). With the existing biofuel production capacity (20 PJ/yr) and national biofuel consumption target (25 PJ) taken into account, the potential net export of biofuels from Finland in 2020 would be 35 PJ, corresponding to 2–3% of European demand. Commercialisation of second-generation biofuel production technologies, high utilisation of the sustainable harvesting potential of Finnish forest biomass, and allocation of a significant proportion of the pulpwood harvesting potential for energy purposes are prerequisites for this scenario. Large-scale import of raw biomass would enable remarkably greater biofuel production than is described in this paper.

Developing markets of energy biomass – local and global perspectives

The thesis explores global and national-level issues related to the development of markets for biomass for energy. The thesis consists of five separate papers and provides insights on selected issues. The aim of Paper I was to identify methodological and statistical challenges in assessing international solid and liquid biofuels trade and provide an overview of the Finnish situation with respect to the status of international solid and liquid biofuels trade. We found that, for the Finnish case, it is possible to qualify direct and indirect trade volumes of biofuels. The study showed that indirect trade of biofuels has a highly significant role in Finland and may be a significant sector also in global biofuels trade. The purpose of Paper II was to provide a quantified insight into Finnish prospects for meeting the national 2020 renewable energy targets and concurrently becoming a largescale producer of forest-biomass-based second-generation biofuels for feeding increasing demand in European markets. We found that Finland has good opportunities to realise a scenario to meet 2020 renewable energy targets and for large-scale production of wood-based biofuels. The potential net export of transport biofuels from Finland in 2020 would correspond to 2–3% of European demand. Paper III summarises the global status of international solid and liquid biofuels trade as illuminated by several separate sources. International trade of biofuels was estimated at nearly 1 EJ for 2006. Indirect trade of biofuels through trading of industrial roundwood and material by-products comprises the largest proportion of the trading, with a share of about two thirds. The purpose of Paper IV was to outline a comprehensive picture of the coverage of various certification schemes and sustainability principles relating to the entire value-added chain of biomass and bioenergy. Regardless of the intensive work that has been done in the field of sustainability schemes and principles concerning use of biomass for energy, weaknesses still exist. The objective of Paper V was to clarify the alternative scenarios for the international biomass market until 2020 and identify the underlying steps needed toward a wellfunctioning and sustainable market for biomass for energy purposes. An overall conclusion drawn from this analysis concerns the enormous opportunities related to the utilisation of biomass for energy in the coming decades.

Biomass of tree species as a response to planting density and interspecific competition

Planting trees is an important way to promote the recovery of degraded areas in the Caatinga region. Experiments (E1, E2, and E3) were conducted in a randomized blocks design, with three, three, and five replicates, respectively. The objectives were to evaluate biomass of the shoots of: a) gliricidia (G) and sabiá (S), as a response to planting density; b) G, S, and neem (N) in competition; c) G, and S in agroforestry. E1 was conducted in split-plots, and planting densities (400, 600, 800, 1000, and 1200 plants ha-1) as subplots. E2 consisted of a factorial comprising the following plots: GGG, NGN, SGS, NNN, GNG, SNS, SSS, GSG, NSN (each letter represents a row of plants). E3 was conducted with G and S in agroforestry experiment. The trees were harvested after 54, 42, and 27 months old, in E1, E2 and E3, respectively. In E1, G presented higher green biomass of the stems and leaf at smaller densities than S, but lower green biomass of branches at most densities. The species did not differ for mean stem dry biomass and leaf dry biomass, but G showed higher branch dry biomass at most densities. Higher planting densities increased green and dry biomass of stems, branches, and leaves in S, but decreased those characteristics in G, with the exception of leaf dry mass, which was not influenced by density. In E2, the behavior of each species was identical in plots containing the same or different species. Griricidia showed the highest green biomass of stems and branches, and the highest values for geren biomass of the leaf were observed for gliricidia and neem. The highest stem, branch, and leaf dry biomass values were obtained for G, S, and N, respectively. In E3, G was superior for stem and leaf green biomass, and for stem and branch dry biomass. There were no differences between species for the other biomass values.

ABOVEGROUND AND BELOWGROUND BIOMASS AND CARBON ESTIMATES FOR CLONAL EUCALYPTUS TREES IN SOUTHEAST BRAZIL

Eucalyptus plantations represent a short term and cost efficient alternative for sequestrating carbon dioxide from the atmosphere. Despite the known potential of forest plantations of fast growing species to store carbon in the biomass, there are relatively few studies including precise estimates of the amount of carbon in these plantations. In this study it was determined the carbon content in the stems, branches, leaves and roots of a clonal Eucalyptus grandis plantation in the Southeast of Brazil. We developed allometric equations to estimate the total amount of carbon and total biomass, and produced an estimate of the carbon stock in the stand level. Altogether, 23 sample trees were selected for aboveground biomass assessment. The roots of 9 of the 23 sampled trees were partially excavated to assess the belowground biomass at a singletree level. Two models with DBH, H and DBH2H were tested. The average relative share of carbon content in the stem, branch, leaf and root compartments was 44.6%, 43.0%, 46.1% and 37.8%, respectively, which is smaller than the generic value commonly used (50%). The best-fit allometric equations to estimate the total amount of carbon and total biomass had DBH2H as independent variable. The root-to-shoot ratio was relatively stable (C.V. = 27.5%) probably because the sub-sample was composed of clones. Total stand carbon stock in the Eucalyptus plantation was estimated to be 73.38 MgC ha-1, which is within the carbon stock range for Eucalyptus plantations.

ALLOMETRIC MODELS FOR ESTIMATING ABOVEGROUND BIOMASS AND BIOMASS ALLOCATION OF CAPIXINGUI TREES (Croton floribundus Spreng.) IN AN AGRISILVICULTURAL SYSTEM

ABSTRACT The objective of this study was to select allometric models to estimate total and pooled aboveground biomass of 4.5-year-old capixingui trees established in an agrisilvicultural system. Aboveground biomass distribution of capixingui was also evaluated. Single- (diameter at breast height [DBH] or crown diameter or stem diameter as the independent variable) and double-entry (DBH or crown diameter or stem diameter and total height as independent variables) models were studied. The estimated total biomass was 17.3 t.ha-1, corresponding to 86.6 kg per tree. All models showed a good fit to the data (R2ad > 0.85) for bole, branches, and total biomass. DBH-based models presented the best residual distribution. Model lnW = b0 + b1* lnDBH can be recommended for aboveground biomass estimation. Lower coefficients were obtained for leaves (R2ad > 82%). Biomass distribution followed the order: bole>branches>leaves. Bole biomass percentage decreased with increasing DBH of the trees, whereas branch biomass increased.

BIOMASS SUPPLY CHAIN ANALYSIS WITH DENSIFIED WASTE

ABSTRACT The possibility to vary the energy matrix, thus reducing the dependency on fossil fuels, has amplified the acceptance of biomass as an alternative fuel. Despite being a cheap and renewable option and the fact that Brazil is a major producer of waste from agriculture and forestry activities, the use of these materials has barriers due to its low density and low energetic efficiency, which can raise the costs of its utilization. Biomass densification has drawn attention due to its advantage in comparison to in natura biomass due to its better physical and combustion characteristics. The objective of this paper is to evaluate the impact of biomass densification in distribution and transport costs. To reach this objective, a mathematical model was used to represent decisions at a supply chain that coordinates the purchase and sale of forestry and wood waste. The model can evaluate the options to deliver biomass through the supply chain combining demand meeting and low cost. Results point to the possibility of an economy of 60% in transport cost and a reduction of 63% in the required quantity of trucks when densified waste is used. However, costs related to the densifying process lead to an increase of total supply costs of at least 37,8% in comparison to in natura waste. Summing up, the viability of biomass briquettes industry requires a cheaper densification process.