| 31. |
- Alamia, Alberto, 1984, et al.
(författare)
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Design of an integrated dryer and conveyor belt for woody biofuels
- 2015
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 77, s. 92-109
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Tidskriftsartikel (refereegranskat)abstract
- Combustion or gasification of high-moisture content biomass is associated with a number of drawbacks, such as operational instabilities and lowered total efficiency. The present work proposes an integrated dryer and conveyor belt for woody biofuels with steam as the heat transfer medium. The use of low-temperature steam is favorable from a heat management point of view, but also helps to minimize the risk of fire, self-ignition and dust explosions. Furthermore, the presented dryer design represents an efficient combination of fuel transport, drying equipment and fuel feeding system.The proposed design is developed from a macroscopic energy and mass balance model that uses results from computational fluid dynamics (CFD) fuel bed modeling and experiments as its input. This CFD simulation setup can be further used to optimize the design with respect to bed height, steam injection temperatures and fuel type. The macroscopic model can be used to investigate the integration of the dryer within a larger biomass plant. Such a case study is also presented, where the dryer is tailored for integration within an indirect steam gasification system. It is found that the exergy efficiency of this dryer is 52.9%, which is considerably higher than those of other dryers using air or steam, making the proposed drying technology a very competitive choice for operation with indirect steam gasification units.
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| 32. |
- 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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| 33. |
- 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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| 34. |
- Alvarez, Rene, et al.
(författare)
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Biogas production from llama and cow manure at high altitude
- 2006
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 30:1, s. 66-75
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Tidskriftsartikel (refereegranskat)abstract
- Methane production from llama and cow manures from the Bolivian high plateau (The "Altiplano") was studied using a parallel reactor set-up consisting of 10 lab-scale biogasifiers. The effects of pressure (495 and 760 mmHg), temperature (11 and 35 degrees C), hydraulic retention time (20 and 50 days), and manure content in the slurry (10%, 20% and 50%) were evaluated with respect to productivity and methane yields based on two 2(4-1) fractional factorial designs with 8 treatments for each kind of manure. The reactors were operated semi-continuously with daily manure feeding for periods between 50 and 100 days. Temperature was the main factor effect found, and the hydraulic retention time and the manure content in feed were also found significant whereas the effect of pressure was not significant in the range studied. The methane yield obtained with cow manure at 11 degrees C was between 6.4 and 33.61 CH4 kg(-1) VS (volatile solids added) whereas at 35 degrees C the methane yield was between 49.6 and 131.31 CH4 kg(-1) VS. The methane yield from llama manure was somewhat lower than for cow manure (between 3.3 and 19.31 CH4 kg(-1) VS at 11 degrees C and between 35.6 and 84.11 CH4 kg(-1) VS at 35 degrees C, respectively). However, overall llama manure was found to be the best raw material of the two for biogas production, due to its high content of volatile solid-higher than has been previously reported for most manures-and also its high nitrogen and phosphorous content.
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| 35. |
- Alvarez, Rene, et al.
(författare)
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Low temperature anaerobic digestion of mixtures of llama, cow and sheep manure for improved methane production
- 2009
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 33:3, s. 527-533
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Tidskriftsartikel (refereegranskat)abstract
- Biogas production in anaerobic digestion in farm-scale units is typically performed under mesophilic conditions when used for producing domestic fuel and stabilizing animal waste for the use of digested manure as a fertilizer. Previous studies on the digestion of llama and cow manure have shown the feasibility of producing biogas under altiplano conditions (low pressure and low temperature) and of llama manure as a promising feedstock. The present study concerns the utilization of various mixtures of feedstocks from the Bolivian altiplano under low temperature conditions (18-25 degrees C). Laboratory scale experiments were performed on the digestion of mixtures of llama, sheep and cow manure in a semi-continuous process using ten 2-L stainless steel digesters to determine the effects of organic loading rate (OLR) and the feed composition. The semi-continuous operation of mixture of llama-cow-sheep manure proved to be a reliable system, which could be operated with good stability. The results suggest that in a system digesting a mixture of llama-cow-sheep manure at low temperature (18-25 degrees C) the maximum OLR value is between 4 and 6 kg VS m(3) d(-1). The methane yields obtained in the mixture experiments were in the range 0.07-0.14 m(3) kg(-1) VS added, with a methane concentration in the gas of between 47 and 55%. (C) 2008 Elsevier Ltd. All rights reserved.
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| 36. |
- Anasontzis, George E, 1980, et al.
(författare)
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Rice straw hydrolysis using secretomes from novel fungal isolates from Vietnam
- 2017
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 99, s. 11-20
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Tidskriftsartikel (refereegranskat)abstract
- With a production of 39 million metric tons each year, rice is one of the main agricultural products of Vietnam. Thus, rice straw is a significant by-product, whose use in a biorefinery process would contribute to the bio-based transformation of the Vietnamese and South East Asian economy. In order to find novel efficient enzyme mixtures for the hydrolysis of rice straw and other agricultural residues, we took advantage of the rapidly evolving biodiversity of Vietnam and screened 1100 new fungal isolates from soil and decaying plant tissues for their CMCase activity. We selected 36 strains and evaluated them for their cellulases, xylanases, and accessory enzymes activities. Most of these isolates belonged to the genera Aspergillus and Trichoderma. We identified a few promising isolates, such as A. brunneoviolaceus FEC 156, A. niger FEC 130 and FEC 705, and A. tubingensis FEC 98, FEC 110 and FEC 644, whose produced enzyme mixtures released a mass fraction of the sugar content of alkali-treated rice straw higher than 20%, compared to 10% for Trichoderma reesei RUT C-30. We verified that the black Aspergilli are particularly efficient in their saccharification ability. We also identified strains that although they produced low amounts of cellulases and xylanases, their enzyme mixtures had high saccharification efficiencies, indicating the importance of the synergy effect, rather than the amount of enzymes available. Our results highlight the intra-species variation, especially in the Trichoderma genus, regarding the biomass degradation characteristics and the associated range of enzymatic activities.
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| 37. |
- Andersson, Jim, et al.
(författare)
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Methanol production via pressurized entrained flow biomass gasification : Techno-economic comparison of integrated vs. stand-alone production
- 2014
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 64, s. 256-268
-
Tidskriftsartikel (refereegranskat)abstract
- The main objective with this work was to investigate techno-economically the opportunity for integrated gasification-based biomass-to-methanol production in an existing chemical pulp and paper mill. Three different system configurations using the pressurized entrained flow biomass gasification (PEBG) technology were studied, one stand-alone plant, one where the bark boiler in the mill was replaced by a PEBG unit and one with a co-integration of a black liquor gasifier operated in parallel with a PEBG unit. The cases were analysed in terms of overall energy efficiency (calculated as electricity-equivalents) and process economics. The economics was assessed under the current as well as possible future energy market conditions. An economic policy support was found to be necessary to make the methanol production competitive under all market scenarios. In a future energy market, integrating a PEBG unit to replace the bark boiler was the most beneficial case from an economic point of view. In this case the methanol production cost was reduced in the range of 11-18 Euro per MWh compared to the stand-alone case. The overall plant efficiency increased approximately 7%-units compared to the original operation of the mill and the non-integrated stand-alone case. In the case with co-integration of the two parallel gasifiers, an equal increase of the system efficiency was achieved, but the economic benefit was not as apparent. Under similar conditions as the current market and when methanol was sold to replace fossil gasoline, co-integration of the two parallel gasifiers was the best alternative based on received IRR.
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| 38. |
- Andersson, Viktor, 1983, et al.
(författare)
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Algae-based biofuel production as part of an industrial cluster
- 2014
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 71, s. 113-124
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a study on the production of biofuels from algae cultivated in municipal wastewater in Gothenburg, Sweden. A possible biorefinery concept is studied based on two cases; Case A) combined biodiesel and biogas production, and Case B) only biogas production. The cases are compared in terms of product outputs and impact on global CO2 emissions mitigation. The area efficiency of the algae-based biofuels is also compared with other biofuel production routes. The study investigates the collaboration between an algae cultivation, biofuel production processes, a wastewater treatment plant and an industrial cluster for the purpose of utilizing material flows and industrial excess heat between the actors. This collaboration provides the opportunity to reduce the CO2 emissions from the process compared to a stand-alone operation. The results show that Case A is advantageous to Case B with respect to all studied factors. It is found that the algae-based biofuel production routes investigated in this study has higher area efficiency than other biofuel production routes. The amount of algae-based biofuel possible to produce corresponds to 31 MWfuel for Case A and 26 MWfuel in Case B.
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| 39. |
- 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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| 40. |
- 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
-
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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