| 1. |
- Abedinifar, S., et al.
(author)
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Ethanol production by Mucor indicus and Rhizopus oryzae from rice straw by separate hydrolysis and fermentation
- 2009
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In: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 33:5, s. 828-833
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Journal article (peer-reviewed)abstract
- Rice straw was successfully converted to ethanol by separate enzymatic hydrolysis and fermentation by Mucor indicus, Rhizopus oryzae, and Saccharomyces cerevisiae. The hydrolysis temperature and pH of commercial cellulase and β-glucosidase enzymes were first investigated and their best performance obtained at 45 °C and pH 5.0. The pretreatment of the straw with dilute-acid hydrolysis resulted in 0.72 g g-1 sugar yield during 48 h enzymatic hydrolysis, which was higher than steam-pretreated (0.60 g g-1) and untreated straw (0.46 g g-1). Furthermore, increasing the concentration of the dilute-acid pretreated straw from 20 to 50 and 100 g L-1 resulted in 13% and 16% lower sugar yield, respectively. Anaerobic cultivation of the hydrolyzates with M. indicus resulted in 0.36-0.43 g g-1 ethanol, 0.11-0.17 g g-1 biomass, and 0.04-0.06 g g-1 glycerol, which is comparable with the corresponding yields by S. cerevisiae (0.37-0.45 g g-1 ethanol, 0.04-0.10 g g-1 biomass and 0.05-0.07 glycerol). These two fungi produced no other major metabolite from the straw and completed the cultivation in less than 25 h. However, R. oryzae produced lactic acid as the major by-product with yield of 0.05-0.09 g g-1. This fungus had ethanol, biomass and glycerol yields of 0.33-0.41, 0.06-0.12, and 0.03-0.04 g g-1, respectively.
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| 2. |
- Alvarez, Rene, et al.
(author)
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Biogas production from llama and cow manure at high altitude
- 2006
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In: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 30:1, s. 66-75
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Journal article (peer-reviewed)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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| 3. |
- Alvarez, Rene, et al.
(author)
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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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In: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 33:3, s. 527-533
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Journal article (peer-reviewed)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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| 4. |
- Berggren, Mårten, et al.
(author)
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Biomass co-firing potentials for electricity generation in Poland—Matching supply and co-firing opportunities
- 2008
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In: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 32:9, s. 865-879
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Journal article (peer-reviewed)abstract
- As part of the European Union (EU) accession treaty, Poland is obliged to increase the share of renewable electricity production to 7.5% by 2010 (from a present share of about 2% in 2002). Most of this increase is expected to be covered by biomass-based electricity generation. This paper investigates the potential for co-firing of biomass and coal in the Polish power-generation system. More specifically, this study focuses on matching potentials in biomass supply with opportunities for co-firing biomass in existing coal-fired power plants. Available estimates of biomass supply and information on the power plant infrastructure are used as input for modelling the co-firing potential for each of the 16 regions in Poland ("Voivodship"). The modelling also gives the additional cost of the electricity and the CO2-avoidance cost for the co-firing. The result shows a potential of electricity produced from biomass in co-firing of 1.6-4.6% (2.3-6.6 TWhe) of the total electricity production in 2010. Adding this potential to the existing production of about 2% electricity from renewable energy sources (RES-E) gives an overall contribution of RES-E in the range 3.6-6.6%. The additional cost for the implementation of co-firing is less than €20 per MWhe (the average electricity price in Poland in 2003 was €96 per MWhe) corresponding to a CO2-avoidance cost of less than €20 per tonne CO2. In summary it can be concluded that although co-firing can serve as a low-cost option for near-term increase of RES-E, there is still an additional 0.9-3.9% of other RES-E production required to be developed to reach the 2010 target of 7.5% RES-E. The results call for quick action with respect to implementation of co-firing, if Poland should have any chance to reach the RES-E target by 2010.
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| 5. |
- Berglund, Maria, et al.
(author)
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Assessment of energy performance in the life-cycle of biogas production
- 2006
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In: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 30:3, s. 254-266
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Journal article (peer-reviewed)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.
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| 6. |
- Boman, Christoffer, et al.
(author)
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Evaluation of a constant volume sampling setup for residential biomass fired appliances : Influence of dilution conditions on particulate and PAH emissions
- 2005
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In: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 29:4, s. 258-268
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Journal article (peer-reviewed)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.
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| 7. |
- Börjesson, Pål, et al.
(author)
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Environmental systems analysis of biogas systems - Part 1: Fuel-cycle emissions
- 2006
-
In: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 30:5, s. 469-485
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Journal article (peer-reviewed)abstract
- Fuel-cycle emissions of carbon dioxide (CO2) carbon oxide (CO), nitrogen oxides (NOx), sulphur dioxide (SO2), hydrocarbons (HC), methane (CH4), and particles are analysed from a life-cycle perspective for different biogas systems based oil six different raw materials. The gas is produced in large- or farm-scale biogas plants, and is used in boilers for heat production, in turbines for co-generation of heat and electricity, or as a transportation fuel in light- and heavy-duty vehicles. The analyses refer mainly to Swedish conditions. The levels of fuel-cycle emissions vary greatly among the biogas systems studied, and are significantly affected by the properties of the raw material digested, the energy efficiency of the biogas production, and the status of the end-use technology. For example, fuel-cycle emission may vary by a factor of 3-4, and for certain gases by up to a factor of 11, between two biogas systems that provide an equivalent energy service. Extensive handling of raw materials, e.g. ley cropping or collection of waste-products such as municipal organic waste, is often a significant source of emissions. Emission from the production phase of the biogas exceeds the end-use emissions for several biogas systems and for specific emissions. Uncontrolled losses of methane, e.g. leakages from stored digestates or from biogas upgrading, increase the fuel-cycle emissions of methane considerably. Thus, it is necessary to clearly specify the biogas production system and enduse technology being studied in order to be able to produce reliable and accurate data oil fuel-cycle emission. (c) 2005 Elsevier Ltd. All rights reserved.
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| 8. |
- Börjesson, Pål, et al.
(author)
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Environmental systems analysis of biogas systems - Part II: The environmental impact of replacing various reference systems
- 2007
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In: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 31:5, s. 326-344
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Journal article (peer-reviewed)abstract
- This paper analyses the overall environmental impact when biogas systems are introduced and replace various reference systems for energy generation, waste management and agricultural production. The analyses are based on Swedish conditions using a life-cycle perspective. The biogas systems included are based on different combinations of raw materials and final use of the biogas produced (heat, power and transportation fuel). A general conclusion is that biogas systems normally lead to environmental improvements, which in some cases are considerable. This is often due to indirect environmental benefits of changed land use and handling of organic waste products (e.g. reduced nitrogen leaching, emissions of ammonia and methane), which often exceed the direct environmental benefits achieved when fossil fuels are replaced by biogas (e.g. reduced emissions of carbon dioxide and air pollutants). Such indirect benefits are seldom considered when biogas is evaluated from an environmental point of view. The environmental impact from different biogas systems can, however, vary significantly due to factors such as the raw materials utilised, energy service provided and reference system replaced. (c) 2007 Elsevier Ltd. All rights reserved.
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| 9. |
- Börjesson, Pål, et al.
(author)
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The prospects for willow plantations for wastewater treatment in Sweden
- 2006
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In: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 30:5, s. 428-438
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Journal article (peer-reviewed)abstract
- The concept of willow vegetation filters for the treatment of nutrient-rich wastewater has the potential to address two of our most serious environmental problems today -water pollution and climate change- in a cost-efficient way. Despite several benefits, including high treatment efficiency, increased biomass yields, improved energy and resource efficiency, and cost savings, willow vegetation filters have so far only been implemented to a limited degree in Sweden. This is due to various kinds of barriers, which may be the result of current institutional, structural and technical/geographical conditions. This paper discusses the prospects of a more widespread utilisation of willow plantations for wastewater treatment in Sweden, including existing incentives and barriers, based on current knowledge and experience. (c) 2005 Elsevier Ltd. All rights reserved.
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| 10. |
- De, S., et al.
(author)
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Impact of cofiring biomass with coal in power plants - A techno-economic assessment
- 2009
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In: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 33:2, s. 283-293
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Journal article (peer-reviewed)abstract
- Biomass cofiring in existing coal-fired boilers has emerged as a prospective option for voluntary reduction in CO2 emissions to mitigate the global warming problem. However, the associated cost increase plays a crucial role for this retrofitting. A techno-economic model for the estimation of economics of cofiring is presented in this paper using the pilot plant test results for biomass cofiring and general heat and mass balance. A sensitivity analysis is carried out with this developed model to investigate the effects of different operating and logical parameters on the economics of biomass coal cofiring process. Significant results of this sensitivity analysis are also presented in this paper. The presented results may be useful for a plant owner to decide regarding the economic feasibility of retrofitting for biomass cofiring. On the other hand, it will also help to estimate the required incentives for this purpose. (C) 2008 Elsevier Ltd. All rights reserved.
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