| 1. |
- Aguilar Cabezas, Francisco X
(författare)
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Assessment of residential wood energy consumption using German household-level data
- 2019
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 126, s. 117-129
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Tidskriftsartikel (refereegranskat)abstract
- The residential sector accounts for about half of annual wood energy consumption in Germany. We applied a left-censored Tobit model to a cross-sectional dataset to quantify factors affecting household-level German residential wood energy consumption in years 2005, 2010 and 2014. Explanatory variables distinguished between (1) heating technology, dwelling characteristics and alternative energies; (2) woody biomass accessibility and weather; as well as (3) households' socio demographic characteristics. Results show that wood energy consuming households with central heaters used an additional 0.83-1.82 m(3) year(-1) of wood. Households' wood energy consumption showed a positive correlation with residence area and elastic responses to year of building construction. Greater elasticities in wood energy consumption were found when alternative energy prices exceeded US$ 1,050-1,330 per ton of oil-equivalent net calorific value. Local accessibility of woody biomass measured through forest ownership and forest density was associated with greater wood for energy consumption by an average 0.27-0.52 m(3) year(-1) and 0.13-0.25 m(3) year(-1), respectively. In addition, wood energy consumption increased proportionally with increasing rurality. Elasticity of household wood energy consumption with respect to heating degree days was estimated at 0.83-1.15. Among demographic variables, households at lower and higher income levels exhibited greater amounts of wood energy consumption. Results provide evidence that greater adoption of central wood energy heaters, price competitiveness of wood energy over alternative energies, and improving access to wood energy sources can lead to greater residential wood energy consumption in Germany.
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| 2. |
- Aguilar Cabezas, Francisco X
(författare)
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Comparison of small area estimation methods applied to biopower feedstock supply in the Northern US region
- 2019
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 121, s. 64-77
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Tidskriftsartikel (refereegranskat)abstract
- Increasing interest in utilization of forest biomass for bioenergy has prompted extensive contemporary research regarding costs, supply and technology for efficiently producing electricity and other forms of renewable energy. One challenge facing both researchers and users is obtaining precise estimates of available forest biomass within plausible supply areas for individual power plants. Due to the wide distribution of power plants poised to co-fire with forest biomass, assessing its availability requires methods that can yield precise and low-bias estimates of aboveground forest biomass and other key attributes at varying spatial scales. Small area estimation (SAE) methods have high potential to accomplish this due to the availability of national forest inventory data, combined with satellite imagery and other forms of remotely-sensed auxiliary information. The study assessed several indirect, direct and composite estimators of four forest attributes: aboveground tree biomass, biomass of small-diameter trees, biomass of tops and limbs, and volume at the county-level and within the estimated supply areas around power plants across 20 states in the contiguous Northern U.S. Composite estimators using both k-nearest neighbors imputation and multiple linear regression provided superior estimates of indicators of forest biomass availability based on both precision and bias at the county-level at sampling intensities as low as 10-20%, compared to the other SAE methods examined. The composite estimator using k-nearest neighbors imputation was subsequently shown to produce precise estimates of forest biomass availability for selected power plant supply areas.
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| 3. |
- Ahlberg-Eliasson, Karin, et al.
(författare)
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Production efficiency of Swedish farm-scale biogas plants
- 2017
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 97, s. 27-37
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Tidskriftsartikel (refereegranskat)abstract
- Biogas from agricultural waste streams represents an important way to produce fossil-free energy, allow nutrient recycling and reduce greenhouse gas emissions. However, biogas production from agricultural substrates is currently far from reaching its full potential. In Sweden, the number of biogas plants and their output have increased in recent years, but they are still experiencing harsh economic conditions. A recent evaluation (2010–2015) of 31 farm-scale biogas production facilities in Sweden sought to identify parameters of importance for further positive development. In this paper, data on plant operation, gas yield and digestate quality for 27 of these plants are summarised and statistically analysed to investigate factors that could allow an increase in overall biogas production and in nutrient content in the digestate. The analysis showed that addition of co-substrates to manure results in higher gas production, expressed as both specific methane potential and volumetric gas production, than when manure is the sole substrate. Use of co-substrate was also found to be influential for the nutrient content of the digestate. These observed improvements caused by co-digestion should be considered when subsidy systems for manure-based biogas processes are being created, as they could also improve the economics of biogas production. However, to achieve higher efficiency in existing biogas plants and to improve the situation for future investments, a more detailed, long-term evaluation programme should also be considered.
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| 4. |
- Albertsson, Johannes, et al.
(författare)
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Effects of competition between short-rotation willow and weeds on performance of different clones and associated weed flora during the first harvest cycle
- 2014
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 70, s. 364-372
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the ability of willow clones to compete with weeds, willow shoot biomass and plant mortality were measured over the first harvest cycle for 10 commercial and two breeding clones at three different sites in southern Sweden. Two levels of weed pressure (weeded and not weeded) were employed and the effects of cutback or not after the first growing season were compared for willow clones under weed pressure. There were significant differences between clones in their ability to compete with weeds, measured as willow shoot growth reduction in plots with weeds, at two of the three sites. However, shoot biomass reduction due to weeds was large in all the clones, with Stina and SW Inger among the least affected. Mean shoot growth reduction after the first harvest cycle for the commercial clones was 68.3%, 91.2% and 94.3% at the three sites and the corresponding plant mortality was 9.8%, 57.3% and 56.2% under weed pressure. Significant clonal differences in yield, under weed-free conditions, were found at all three sites. Significant clonesite interactions were found for both growth reduction and biomass production. Cutting back shoots after the establishment season, under weed pressure, resulted in higher mean plant mortality and lower mean willow shoot biomass after one harvest cycle at two of the three sites. The weed flora was initially dominated by annuals, but became dominated by perennial weeds during the first harvest cycle. (C) 2014 Elsevier Ltd. All rights reserved.
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| 5. |
- Albertsson, Johannes, et al.
(författare)
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Effects of mechanical weed control or cover crop on the growth and economic viability of two short-rotation willow cultivars
- 2016
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 91, s. 296-305
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Tidskriftsartikel (refereegranskat)abstract
- Willow grown as short rotation coppice (SRC) is sensitive to weed competition, so herbicide treatment combined with mechanical weed control is recommended when establishing a plantation. This study compares that practice with two mechanical, row crop cultivator (RC) and row crop cultivator with torsion weeder (RCT), and two cultural treatments, cover crop (CC) and cut cover crop (CCC), to control weeds. Willow responses to these treatments were compared during the first three years after planting using two cultivars, Gudrun and Tordis with broad and narrow leaves, respectively. At harvest, the RCT treatment had produced 27% more biomass than the RC treatment (13.9 vs 11.0 Mg ha(-1) dry matter) and approximately three times more than the cultural treatments. However, the standard control treatment, herbicides and row crop cultivator (HRC), produced more than all other treatments (17.3 Mg ha(-1) dry matter). The two cultural treatments had higher plant mortality (CC 26.2% and CCC 32.8%) than the other treatments (HRC 2.7%, RC 7.0% and RCT 7.0%) after the first harvest cycle. No interaction between cultivar and treatment was found for willow shoot biomass, weed biomass or plant mortality. Overall, however, Gudrun had lower plant mortality and less weed biomass after the first harvest cycle than Tordis. All treatment and cultivar combinations gave positive financial annual returns when the whole life-span of the plantation was considered. This study suggests that without using herbicides, it is possible to establish a willow SRC plantation that produce enough to be economically viable. (C) 2016 Elsevier Ltd. All rights reserved.
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| 6. |
- Anerud, Erik
(författare)
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Evaluation of an improved design for large-scale storage of wood chip and bark
- 2021
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 154
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Tidskriftsartikel (refereegranskat)abstract
- A developed bioeconomy needs better storage methods for wood chips and forest industry by-products, since increasing demands for more assortments, more storage will be necessary Today, solutions for coping with storage-related problems, such as dry matter losses and risk of self-ignition, are based on separating assortments into smaller piles and avoiding large-scale long-term storage of chips. A safe and efficient storage solution is needed to enable wood chip production all year round and not be limited to just-in-time production during the cold heating season when there is a large demand. This might result in a more robust system with larger buffer capacities, a less stressful working environment for chipping and transport contractors, and a better yearly machine utilisation. This study evaluated storage outcomes for wood chips and bark when using an improved storage design that created assortment separation using concrete walls and a semipermeable sheet for cover. The new design enabled efficient area utilisation and increased fire safety. The storage outcome was also improved in terms of moisture content, dry matter losses and temperature development compared to conventional open-air piles.
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| 7. |
- Anerud, Erik, et al.
(författare)
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Fuel quality and dry matter losses of stored wood chips - Influence of cover material
- 2021
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 150
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Tidskriftsartikel (refereegranskat)abstract
- Irregular seasonal demand from heat- and combined heat and power plants means that outdoor storage of forest fuels is an inevitable step in the forest fuel supply chain. Storage of fresh comminuted biomass render substantial dry matter and energy losses. Covering can protect wood chips from rewetting, leading to a higher net calorific value and lower dry matter losses, and thus increase the amount of available energy. This study examined the combined effect of covering material on fuel quality and the amount available energy from wood chips stored in a full-scale pile. The combined changes in fuel quality and dry matter loss reduced the amount of accessible energy by 9.8% in the uncovered part, by 5.6% when covered with water proof or light semi-permeable cover materials and by 1.0% when covered with a thicker semi permeable material. Fuel quality of wood chips can be improved by covering the piles during storage but the gain is affected by the type of cover material. Seasonal storage in properly covered chip piles facilitate an increased annual utilisation of chippers and chip trucks which reduces overall biomass supply chain cost.
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| 8. |
- Backlund, Ingegerd, et al.
(författare)
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Biorefinery product potentials using tree biomass as feedstock - A survey on opportunities and threats to the new wood products industry
- 2014
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 70, s. 207-216
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Tidskriftsartikel (refereegranskat)abstract
- A questionnaire survey on the potential of biorefinery products was carried out along with an analysis of energy prices and wood assortments. Electricity production was considered to have the potential for the highest investment return over ten years, followed by solid wood products, bioenergy assortments and textiles. Only pulp and paper were perceived as returning lower potential investment values over the next ten years than over the next five. Of the survey respondents, 95% believed that the value of woody biomass will increase over the next ten years, mainly through its replacement of oil-based products, although there will be problems due to lack of suitable raw material. A wide range of chemical products were described but a greater confidence in more traditional solid fuel products still prevails. Stemwood is the most favored part of the tree with only a few respondents saying that they wanted specific chemicals extracted. The electricity price and wood fuel price were found to be strongly correlated and 91% of respondents said their products would be affected by the electricity price. Electricity prices within OECD countries are expected to increase by 15% from 2011 to 2035, with wood fuel prices increasing by roughly 10% during the same period. Therefore, the electricity price could become a decisive factor in the future use of biomass in biorefineries. Our results suggest that large-scale commercial biorefinery production will soon be possible but new wood assortment classifications are needed that include both fiber properties and chemical properties such as extractive content.
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| 9. |
- Bergström, Dan
(författare)
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Productivity of harvesting dense birch stands for bioenergy
- 2016
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 88, s. 142-151
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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.
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| 10. |
- Blennow, Kristina, et al.
(författare)
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Forest owner motivations and attitudes towards supplying biomass for energy in Europe
- 2014
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 67, s. 223-230
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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.
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