| 1. |
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| 2. |
- Kimming, Marie, et al.
(författare)
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Biomass from agriculture in small-scale combined heat and power plants - A comparative life cycle assessment
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 35, s. 1572-1581
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Tidskriftsartikel (refereegranskat)abstract
- The results show that the biomass-based scenarios reduce greenhouse gas emissions considerably compared to the scenario based on fossil fuel, but have higher acidifying emissions. Scenario 1 has by far the best performance with respect to global warming potential and the advantage of utilizing a byproduct and thus not occupying extra land. Scenario 2 and 3 require less primary energy and less fossil energy input than 1, but set-aside land for willow production must be available. The low electric efficiency of scenario 3 makes it an unsuitable option. (C) 2011 Elsevier Ltd. All rights reserved.
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| 3. |
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| 4. |
- Dimitriou, Ioannis, et al.
(författare)
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Slow expansion and low yields of willow short rotation coppice in Sweden; implications for future strategies
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 35:11, s. 4613-4618
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Tidskriftsartikel (refereegranskat)abstract
- About 16 000 ha of commercial willow Short Rotation Coppice (SRC) fields for production of biomass for energy were planted in the early 1990s in Sweden. The cultivated with SRC area has remained almost stable and was slightly decreased during the last years despite the incentives and predictions for drastic increases. Similar incentives and predictions in other countries have been lately launched. The bioenergy produced in the planted SRC areas in Sweden has been lower than anticipated, partly due to the lower than expected biomass yields and the termination of some willow SRC plantations. Explanations for the low yields are depicted based on analyzing the results of a survey where 175 willow SRC growers participated. Lower biomass yields are attributed to: (i) the low input in management activities; (ii) the choice of land for the willow SRC plantation; (iii) and the level of personal involvement of the farmer. Understanding the reasons to earlier years' performance of willow SRC is important for development of better performing systems in the future, in Sweden as well as in other countries. © 2011 Elsevier Ltd.
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| 5. |
- Poudel, Bishnu Chandra, et al.
(författare)
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Effects of climate change on biomass production and substitution in north-central Sweden
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier. - 0961-9534 .- 1873-2909. ; 35:10, s. 4340-4355
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Tidskriftsartikel (refereegranskat)abstract
- In this study we estimate the effects of climate change on forest production in north-central Sweden, as well as the potential climate changemitigation feedback effects of the resulting increased carbon stock and forest product use. Our results show that an average regional temperature rise of 4 °C over the next 100 years may increase annual forest production by 33% and potential annual harvest by 32%, compared to a reference case without climate change. This increased biomass production, if used to substitute fossil fuels and energy-intensive materials, can result in a significant net carbon emission reduction. We find that carbon stock in forest biomass, forest soils, and wood products also increase, but this effect is less significant than biomass substitution. A total net reduction in carbon emissions of up to 104 Tg of carbon can occur over 100 years, depending on harvest level and reference fossil fuel. © 2011 Elsevier Ltd.
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| 6. |
- Scarfone, Antonio, et al.
(författare)
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Storage dynamics and fuel quality of poplar chips
- 2014
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 62, s. 17-25
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Tidskriftsartikel (refereegranskat)abstract
- Poplar cultivation for wood/timber production has a growth production cycle of about 10-15 years. Usually the stem is separated from the crown and used to produce material of different kind such as veneer, pallets, panels, etc. For wood industries,. crowns generally represent waste material to be disposed of, causing economic and time losses. It is generally believed that the costs of managing crown biomass are higher than the potential incomes obtainable. Nonetheless, it is worthwhile investigating the possibility of using these byproducts as energy source and evaluating their value as a fuel. However, storing such residues presents several problems connected with spontaneous microbial degradation.The aim of this work was to evaluate the storage effects on chipped biomass deriving from the crown and stem wood of poplar and how they affect fuel quality and dry matter losses.A storage trial was carried out with three piles of stem wood chips and three of crown chips coming from a 15 year old poplar plantation. The piles were stored outdoors for six months under the same climatic conditions.The effect of storage on fuel quality was evaluated with respect to moisture content, gross and net calorific values, chemical composition, ash content, and bulk density.The variation of temperatures inside each pile due to heat development was continuously monitored and showed different trends between piles depending on source material. Results showed that chips from crown material had better storage properties and exhibited lower decay than chips from stem wood. (C) 2014 Elsevier Ltd. All rights reserved.
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| 7. |
- Sipos, Balint, et al.
(författare)
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Steam pretreatment of dry and ensiled industrial hemp for ethanol production
- 2010
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 34:12, s. 1721-1731
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Tidskriftsartikel (refereegranskat)abstract
- Biomass can be converted into liquid and gaseous biofuels with good efficiency. In this study, the conversion of industrial hemp (Cannabis sativa L.), a biomass source that can be cultivated with a high biomass yield per hectare, was used. Steam pretreatment of dry and ensiled hemp was investigated prior to ethanol production. The pretreatment efficiency was evaluated in terms of sugar recovery and polysaccharide conversion in the enzymatic hydrolysis step. For both materials, impregnation with 2% SO2 followed by steam pretreatment at 210 degrees C for 5 min were found to be the optimal conditions leading to the highest overall yield of glucose. Simultaneous saccharification and fermentation experiments carried out with optimised pretreatment conditions resulted in ethanol yields of 163 g kg(-1) ensiled hemp (dry matter) (71% of the theoretical maximum) and 171 g kg(-1) dry hemp (74%), which corresponds to 206-216 l Mg-1 ethanol based on initial dry material. (C) 2010 Elsevier Ltd. All rights reserved.
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| 8. |
- 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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| 9. |
- Nordberg, Åke, et al.
(författare)
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Selective desorption of carbon dioxide from sewage sludge for in-situ methane enrichment : Enrichment experiments in pilot scale
- 2012
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 37, s. 196-204
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Tidskriftsartikel (refereegranskat)abstract
- The application of in-situ methane enrichment for upgrading the biogas from anaerobic digestion to vehicle fuel or natural gas quality, has been studied in pilot scale and by computer simulation of the desorption step. Pilot plant experiments have been performed using a 19 m(3) and 15 m(3) continuously stirred tank reactor operating with municipal sewage sludge at mesophilic conditions connected respectively to a 90 dm(3) and 140 dm(3) external bubble column for selective desorption of CO2. The results show that the CH4 yield is unchanged during the experiments, and accordingly there is no evidence that the oxygen in the air used in the desorption of CO2 has a negative impact on the CH4 producing activity. The sludge recirculation system must be designed to avoid leakage of air into the digester, in order to maintain a low N-2 concentration in the biogas. At best, a biogas with a volume fraction of 87% CH4 and (p N-2 = 2% was obtained. The CH4 loss however amounted to 8%, which is unsatisfactory. The experimental results are compared with previous data in the literature and explanations are deducted for the difference in the performance. Computer simulations reveal that the sludge flow rate recirculated through the desorption column should be as low as possible to minimize the loss of CH4. An increased air flow rate through the desorption column and an increased desorption column volume will promote the desorption of CO2 and improve the ratio of CO2 to CH4 desorption.
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| 10. |
- Hansson, P.A., et al.
(författare)
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Air emissions from the fuel supply system of a Swedish CHP plant and the effects of stricter emission regulations
- 2003
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Ingår i: Biomass and Bioenergy. - 1873-2909 .- 0961-9534. ; 24:1, s. 59-68
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work was to quantify the energy use and production of air emissions by supply systems for different biofuels used in a typical Swedish combined heat and power plant. In addition, the effects of the future reductions in the total amounts of exhaust gas emissions, as a result of stricter emission regulations for transport and off-road equipment, were studied. A model was developed and used for the calculations. Input data were collected from a plant situated some 100 km from Stockholm in Sweden. Biofuels used by the plant include chips from limbs and tops, by-products from sawmills and chips from willow energy plantations. The results show that residues from sawmills are very favourable in terms of the studied environmental parameters. Air emissions from limbs and tops is 5-8 times greater than that from sawmills. The use of a terminal for temporary storage means that additional transport and loading operations are necessary which result in a 30% increase in air emissions. The most important effects of the stricter emission regulations are that emissions of nitrous oxides (NOx) caused by the supply system will decrease by up to 70% within 10 years and that the unburned hydrocarbon (HC) emissions will decrease by 30-35%. © 2002 Elsevier Science Ltd. All rights reserved.
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