| 51. |
- Berghel, Jonas, et al.
(författare)
-
Superheated steam drying of sawdust in continuous feed spouted beds : a design perspective
- 2014
-
Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 71:0, s. 228-234
-
Tidskriftsartikel (refereegranskat)abstract
- Spouted bed drying technology shows promising results for the drying of unscreened sawdust in superheated steam. In this paper, the experiences from designing, running and evaluating two spouted bed continuous feed dryers are presented. Stable running conditions and drying results have been achieved. This has been particularly important for sawdust that will be compressed into pellets or briquettes. The spouted bed superheated steam dryer also shows high potential for energy efficient integration into sawmills. Our recommendation is thus, to use the outlet steam temperature as the control parameter for the outlet moisture content. A drying rate above and one below the fibre saturation level, can be identified. Visual observations through the viewing glass in the drying zone in both the dryers clearly showed that not all of the material participated in the spout at all times; there were, however, no indications of dead zones. A heat transfer analysis indicated that only about 70% of the surface area of the material was in thermal contact with the steam. This paper sums up the experiences regarding drying properties, control and system properties obtained when sawdust is dried using superheated steam as the drying medium. Further work on standardised dryers in series or in parallel is necessary to increase the capacity in the spouted bed dryer.
|
|
| 52. |
- Berglund, Maria, et al.
(författare)
-
Assessment of energy performance in the life-cycle of biogas production
- 2006
-
Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 30:3, s. 254-266
-
Tidskriftsartikel (refereegranskat)abstract
- Energy balances are analysed from a life-cycle perspective for biogas systems based on 8 different raw materials. The analysis is based on published data and relates to Swedish conditions. The results show that the energy input into biogas systems (i.e. large-scale biogas plants) overall corresponds to 20-40% (on average approximately 30%) of the energy content in the biogas produced. The net energy output turns negative when transport distances exceed approximately 200 kin (manure), or up to 700 km (slaughterhouse waste). Large variations exist in energy efficiency among the biogas systems studied. These variations depend both on the properties of the raw materials studied and on the system design and allocation methods chosen. The net energy output from biogas systems based on raw materials that have high water content and low biogas yield (e.g. manure) is relatively low. When energy-demanding handling of the raw materials is required, the energy input increases significantly. For instance, in a ley crop-based biogas system, the ley cropping alone corresponds to approximately 40% of the energy input. Overall, operation of the biogas plant is the most energy-demanding process, corresponding to 40-80% of the energy input into the systems. Thus, the results are substantially affected by the assumptions made about the allocation of a plant's entire energy demand among raw materials, e.g. regarding biogas yield or need of additional water for dilution. (c) 2005 Elsevier Ltd. All rights reserved.
|
|
| 53. |
- Bergström, Dan
(författare)
-
Productivity of harvesting dense birch stands for bioenergy
- 2016
-
Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 88, s. 142-151
-
Tidskriftsartikel (refereegranskat)abstract
- Marginal lands could be utilized for increasing energy biomass production independent of industrial roundwood procurement. Dedicated energy biomass production systems on such sites would be based on low stand establishment cost, clear-cutting at an early stage, and coppice regeneration. Harvesters designed for the processing of industrial roundwood are inefficient or too costly to use in small-diameter and dense stands, while insufficient cutting capacity and uneven space distribution of trees limit the use of modified agricultural harvesters developed for short-rotation woody-crop plantations (e.g. willow). We constructed time consumption models for clear-cutting and forwarding of whole trees from unthinned, small-diameter stands. The data originated from naturally afforested downy birch-dominated stands located in a cutaway peat production area in northern Finland. Stand age varied from 14 to 29 years and stand density was 5150-160,250 trees per hectare. In clear-cutting, a medium-sized forest harvester equipped with an accumulating felling head fitted with a circular saw disc was used, and subsequent forwarding was done using a modified medium-sized forwarder. Cutting productivity was 3-11oven-dry tons (ODt) per effective hour (E-0-h), and was highly dependent on stand characteristics (e.g. mean whole-tree volume). At a distance of 300 m, for example, the productivity of forwarding in the time study plots was 6.7-10.4 ODt E-0-h(-1). Our study indicates that energy biomass can be harvested from young downy birch thickets efficiently by clear-cutting with appropriate machinery. (C) 2016 Published by Elsevier Ltd.
|
|
| 54. |
- Berndes, Göran, 1966, et al.
(författare)
-
Strategies For 2nd Generation Biofuels In Eu - Co-firing to stimulate feedstock supply development and process integration to improve energy efficiency and economic competitiveness
- 2010
-
Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 34:2, s. 227-236
-
Tidskriftsartikel (refereegranskat)abstract
- The present biofuel policies in the European Union primarily stimulate 1st generation biofuels that are produced based on conventional food crops. They may be a distraction fromlignocellulose based 2nd generation biofuels – and also from biomass use for heat and electricity – by keeping farmers’ attention and significant investments focusing on firstgeneration biofuels and the cultivation of conventional food crops as feedstocks. This article presents two strategies that can contribute to the development of 2nd generation biofuels based on lignocellulosic feedstocks. The integration of gasification-based biofuel plants in district heating systems is one option for increasing the energy efficiency and improving the economic competitiveness of such biofuels. Another option, biomass co-firing with coal,generates high-efficiency biomass electricity and reduces CO2 emissions by replacing coal. It also offers a near-term market for lignocellulosic biomass, which can stimulate development of supply systems for biomass also suitable as feedstock for 2nd generation biofuels. Regardless of the long-term priorities of biomass use for energy, the stimulation of lignocellulosic biomass production by development of near term and cost-effective markets isjudged to be a no-regrets strategy for Europe. Strategies that induce a relevant development and exploit existing energy infrastructures in order to reduce risk and reach lower costs, are proposed an attractive complement the present and prospective biofuel policies.
|
|
| 55. |
- Bernotat, Knut, et al.
(författare)
-
Biomass fired small-scale CHP in Sweden and the Baltic States : a case study on the potential of clustered dwellings
- 2004
-
Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 27:6, s. 521-530
-
Tidskriftsartikel (refereegranskat)abstract
- Sweden as well as the three Baltic states has an abundant supply of biomass, mostly wood waste. Much of it goes into district heating (DH), which has expanded continuously since the first system started 50 years ago. DH now accounts for 43% of the heating consumption and a further expansion is possible in many directions. Firstly existing DH systems can be enlarged, secondly DH can be upgraded to combined heat and power (CHP) to a much larger extent, thirdly new DH (and CHP) systems can be implemented in many smaller places down to 1000 inhabitants or less. The last alternative, biomass and especially pellets fired small-scale cogeneration in combination with local heating networks, is the topic for this paper. It presents a method to estimate the potential for small-scale DH and CHP and results from a "test" area in southeast Sweden. The method estimates local heat demand using databases with individual and statistical property data. It identifies areas with clusters of buildings where the heat demand is enough to implement decentralized small DH networks if possible in combination with small-scale CHP. In the event for Swedish circumstances very sparsely populated test area of 36 x 48 km(2) with around 8000 inhabitants, the total heat consumption in residential buildings is estimated to 84 GWh. When we have identified the areas with clusters of buildings, we have set the minimum heat consumption in such an area to 500 MW h. The area size is varied in 250 m steps from 250 x 250 m(2) to 1000 x 1000 m(2). For the four area sizes, the method then identifies and locates 30, 38, 38,30, respectively, clustered areas with a potential for small-scale DH and CHP worth investing closer.
|
|
| 56. |
- Bernstad Saraiva, Anna, et al.
(författare)
-
Provision of pulpwood and short rotation eucalyptus in Bahia, Brazil : Environmental impacts based on lifecycle assessment methodology
- 2017
-
Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 105, s. 41-50
-
Tidskriftsartikel (refereegranskat)abstract
- Environmental impacts from cultivation of eucalyptus pulpwood and short rotation eucalyptus in northeast Brazil were investigated using lifecycle assessment methodology. The assessment considers all relevant inputs and outputs, as well as direct land use changes, assuming conversion of grassland (pasture) to areas for eucalyptus plantation. Results show that production of pulpwood eucalyptus is beneficial compared to short rotation eucalyptus in relation to all assessed impact categories, except for climate change (greenhouse gas emissions = 47 kg CO2-eq. t DM−1 pulpwood eucalyptus and 35 kg CO2-eq. t DM−1 short rotation eucalyptus). Excluding emissions from direct land use changes would increase overall GWP from investigated systems with around 5–6%, and changing the assumed land-use prior to land conversion is of decisive character for overall GWP-results from the assessed eucalyptus production systems. Modeling of nutrient balances in the short rotation production system shows a potential need to increase the input of mineral fertilizer in order to compensate for nutrient losses. This would increase environmental impacts from the short rotation system, making pulpwood eucalyptus preferable in relation to all assessed impact categories.
|
|
| 57. |
|
|
| 58. |
|
|
| 59. |
- Blennow, Kristina, et al.
(författare)
-
Forest owner motivations and attitudes towards supplying biomass for energy in Europe
- 2014
-
Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 67, s. 223-230
-
Tidskriftsartikel (refereegranskat)abstract
- The European Commission expects the use of biomass for energy in the EU to increasesignificantly between 2010 and 2020 to meet a legally binding target to cover at least 20%of EU’s total energy use from renewable sources in 2020. According to estimates made bythe member states of the EU, the direct supply of biomass from forests is expected toincrease by 45% on a volume basis between 2006 and 2020 in response to increasingdemand (Beurskens LWM, Hekkenberg M, Vethman P. Renewable energy projections aspublished in the national renewable energy action plans of the European Member states.ECN and EEA; 2011. http://https://www.ecn.nl/docs/library/report/2010/e10069.pdf[accessed 25.04.2014]; Dees M, Yousef A, Ermert J. Analysis of the quantitative tables ofthe national renewable energy action plans prepared by the 27 European Union MemberStates in 2010. BEE working paper D7.2. Biomass Energy Europe project. FELIS e Departmentof Remote Sensing and landscape information Systems, University of Freiburg,Germany; 2011). Our aims were to test the hypotheses that European private forestowners’ attitudes towards supplying woody biomass for energy (1) can be explained bytheir responses to changes in prices and markets and (2) are positive so that the forestbiomass share of the EU 2020 renewable energy target can be met. Based on survey datacollected in 2010 from 800 private forest owners in Sweden, Germany and Portugal ourresults show that the respondents’ attitudes towards supplying woody biomass for energycannot be explained as direct responses to changes in prices and markets. Our results,furthermore, imply that European private forest owners cannot be expected tosupply the requested amounts of woody biomass for energy to meet the forest biomassshare of the EU 2020 renewable energy target, at least if stemwood is to play theimportant role as studies by Verkerk PJ, Anttila P, Eggers J, Lindner M, Asikainen A. Therealisable potential supply of woody biomass fromforests in the European Union. For EcolManag 2011;261: 2007e2015, UNECE and FAO. The European forest sector outlook study II 2010e2030. United Nations, New York and Geneva; 2011 [abbreviated to EFSOS II] andElbersen B, Staritsky I, Hengeveld G, Schelhaas MJ, Naeff H, Bo¨ ttcher H. Atlas of EUbiomass potentials; 2012. Available from: http://www.biomassfutures.eu [accessed14.10.2013] suggest.
|
|
| 60. |
- Boman, Christoffer, et al.
(författare)
-
Evaluation of a constant volume sampling setup for residential biomass fired appliances : Influence of dilution conditions on particulate and PAH emissions
- 2005
-
Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 29:4, s. 258-268
-
Tidskriftsartikel (refereegranskat)abstract
- Increased concerns about particulate matter (PM) and polycyclic aromatic hydrocarbons (PAH) emissions from residential biomass combustion and their potential health effects, motivates detailed emission measurements under controlled conditions. Traditional sampling in raw flue gases can suffer from drawbacks mainly related to transient flows and the condensable nature of organic compounds. Whole flow dilution with constant volume sampling (CVS) is an alternative method but different sampling conditions may, however, influence the emission characteristics. The objective was to design a CVS system for emission measurements in residential biomass fired appliances and determine the influence of dilution sampling conditions on the characteristics and distributions of PM and PAH. Softwood pellets were combusted in a pellet stove with variations in; dilution ratio (3-7x), sampling temperature (45-75°C), dilution tunnel residence time (2-4 s) and fuel load (2.3 and 4.8 kW) according to a statistical experimental design. The sampling conditions did not influence either the emission concentrations of PM, CO and NO or the particle size distribution. Variations in residence time had no significant effect on any studied emission parameter. However, increased concentrations of organic gaseous carbon (OGC) and PAH were observed with increased dilution ratio. The distribution between particulate and semivolatile phase was influenced for 12 of the 37 analyzed PAH compounds, mainly by increased fractions of semivolatile material at higher sampling temperature. No influence of sampling temperature was observed for the concentrations of PAHtot or the dominating PAH compounds, i.e. phenanthrene, fluoranthene and pyrene. The results together with practical considerations also suggest sampling at 50±5°C and 3-4 times dilution as robust and applicable conditions in the presently designed setup. © 2005 Elsevier Ltd. All rights reserved.
|
|
