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| 12. |
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| 13. |
- Björnsson, Lovisa, et al.
(author)
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Bioolja från befintliga kraftvärmeverk-en systemstudie : Sammanfattning av ett forskningssamarbete mellan Lunds Tekniska Högskola, Karlstad universitet och Kraftringen Energi
- 2021. - Rapport 123
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Reports (pop. science, debate, etc.)abstract
- Samhällets pågående omställning mot minskade utsläpp av växthusgaser kräver bland annat stora mängder fasta biobränslen och flytande biodrivmedel. Den svenska biobränslepotentialen domineras av bi- och restprodukter från skogen, som sågspån från sågverken och grenar och toppar (sk grot) från avverkning av skog. Att omvandla trä till flytande bränslen med hög omvandlingseffektivitet är utmanande, och kräver kommersialisering av ny och innovativ teknik. Behovet av flytande biodrivmedel i transportsektorn har därför hittills framför allt tillgodosetts genom import. Ett utökat och resurseffektivt utnyttjande av den inhemska potentialen av biomassa från skogen skulle kunna vara en viktig komponent i att nå både målet om ett fossilfritt samhälle och mål om miljömässig hållbarhet och spårbarhet för råvaran. Kraftvärmesektorn är i stora delar redan fossilfri och hanterar redan idag inhemska fasta bio-bränslen från skogen. I befintliga kraftvärmeverk finns potential för ökad nyttjandegrad av anläggningen, en befintlig infrastruktur för bränslehantering och möjlighet till värmeavsättning i fjärrvärmenät. Detta skapar förutsättningar för att i tillägg till el och värme komplettera med processer för produktion av flytande energibärare från inhemska, spårbara och hållbara biobränslen från skogen.I denna skrift sammanfattas ett forskningsprojekt där möjligheten att vidareutveckla en befintlig kraftvärmeanläggning genom integrerad produktion av pyrolysolja undersökts. Vi har ställt oss frågor som: Kan vi åstadkomma inhemsk produktion av flytande bränsle från skogsbaserade fasta biobränslen genom att kraftvärmeproduktion kombineras med pyrolysoljeproduktion? Kan detta förbättra konkurrenskraften för kraftvärmeverket vid ett framtida vikande behov av fjärrvärme inom bostadssektorn? Vad innebär möjligheten att bli producent av pyrolysolja både för egen förbrukning och för andra marknader som transportsektorn, för kraftvärmeverket och för klimatet?
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| 14. |
- Björnsson, Lovisa, et al.
(author)
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Effects of support material on the pattern of volatile fatty acid accumulation at overload in anaerobic digestion of semi-solid waste
- 1997
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In: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 1432-0614 .- 0175-7598. ; 47, s. 640-644
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Journal article (peer-reviewed)abstract
- Anaerobic degradation of a semi-solid waste with a total solids content of 4% particulate matter, much of it insoluble, was investigated in four laboratory-scale reactors. Two of the reactors were equipped with different textile materials for immobilisation of microorganisms, while the other two were used as continuously-stirred-tank reactor references, A constant organic loading rate and hydraulic retention time were used in the start-up period; the hydraulic retention time was then decreased and the effects of this change were monitored. Volatile fatty acid (VFA) concentration and pH were chosen as indicators of the microbial status in the reactors. The reactors with support material showed a greater resistance to overload than did the continuously-stirred-tank reactors. This is in agreement with many studies undertaken on the anaerobic treatment of wastewater. However, no problems with clogging occurred, showing that a support material is also applicable in systems treating waste containing large amounts of insoluble, particulate matter. The pH was comparable to VFA for indicating an approaching process failure. However, the pattern of VFA accumulation was qualitatively different between the reactors with and without support material, Obviously the metabolic pattern of mixed cultures changes when the microorganisms are immobilised.
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| 15. |
- Björnsson, Lovisa, et al.
(author)
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Emerging technologies for the production of biojet fuels from wood—can greenhouse gas emission reductions meet policy requirements?
- 2024
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In: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; 14:6, s. 7603-7622
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Journal article (peer-reviewed)abstract
- The transition from fossil jet fuel to biojet fuel is an important step towards reducing greenhouse gas (GHG) emissions from aviation. To enable such a fuel shift, the Swedish Government introduced a GHG emission reduction mandate of 27% by 2030 for aviation fuel sold in Sweden, forcing fuel suppliers to blend in biojet fuel in fossil jet fuel. A similar policy instrument is being discussed within the EU. Biojet fuels with life cycle GHG emissions 90% lower than those for fossil jet fuel are projected to be available by 2025, which by far exceeds the requirement of 65% lower emissions in the EU Renewable Energy Directive. The purpose of this study was to carry out life cycle assessments for a number of wood-fuel-based production chains near commercialization and to determine whether they meet the Swedish projection and the EU requirement. The study illustrates what can be achieved in a region with high availability of wood fuels and access to heat and power with low GHG emissions. The production chains studied include the production of hydrocarbon intermediates via (i) fast pyrolysis, (ii) hydrothermal liquefaction, (iii) thermal gasification followed by Fischer–Tropsch-synthesis, and (iv) cellulosic ethanol fermentation followed by upgrading of these four intermediates to biojet fuel and other liquid biofuels. The results show that all the production chains studied can deliver biojet fuels with 89–91% lower GHG emissions than fossil jet fuels. Non-fossil hydrogen is required to achieve low emissions in the upgrading of intermediates from fast pyrolysis and hydrothermal liquefaction.
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| 19. |
- Björnsson, Lovisa, et al.
(author)
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Evaluation of new methods for the monitoring of alkalinity dissolved hydrogen and the microbial community in anaerobic digestion
- 2001
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In: Water Research. - 1879-2448. ; 35:12, s. 2833-2840
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Journal article (peer-reviewed)abstract
- New methods for spectrophotometric alkalinity measurement, dissolved hydrogen monitoring and for obtaining a fingerprint of the microbial community were evaluated as tools for process monitoring in anaerobic digestion. The anaerobic digestion process was operated at organic loading rates of 1.5, 3.0 and 4.5g volatile solids l-1d-1 and subjected to pulse loads of carbohydrate, lipid, protein and a mixed sludge substrate. The spectrophotometric alkalinity monitoring method showed good agreement with traditional titrimetric alkalinity monitoring and has the advantage of being easy to modify to on-line monitoring applications. The on-line monitoring of dissolved hydrogen gave valuable information about approaching process overload and can be a good complement to the conventional monitoring of volatile fatty acids. Changing process conditions were also reflected in the microbial fingerprint that could be achieved by partitioning in two-phase systems. The investigated methods showed potential for application in increasing our understanding of the anaerobic digestion process as well as for being applicable for monitoring in the complex environment of full-scale anaerobic digestion processes.
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| 20. |
- Björnsson, Lovisa, et al.
(author)
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Evaluation of parameters for monitoring an anaerobic co-digestion process
- 2000
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In: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 1432-0614 .- 0175-7598. ; 54:6, s. 844-849
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Journal article (peer-reviewed)abstract
- The system investigated in this study is an anaerobic digester at a municipal wastewater treatment plant operating on sludge from the wastewater treatment, co-digested with carbohydrate-rich food-processing waste. The digester is run below maximum capacity to prevent overload. Process monitoring at present is not extensive, even for the measurement of on-line gas production rate and off-line pH. Much could be gained if a better program for monitoring and control was developed, so that the full capacity of the system could be utilised without the risk of overload. The only limit presently set for correct process operation is that the pH should be above 6.8. In the present investigation, the pH was compared with alkalinity, gas production rate, gas composition and the concentration of volatile fatty acids (VFA). Changes in organic load were monitored in the full-scale anaerobic digester and in laboratory-scale models of the plant. Gas-phase parameters showed a slow response to changes in load. The VFA concentrations were superior for indicating overload of the microbial system, but alkalinity and pH also proved to be good monitoring parameters. The possibility of using pH as a process indicator is, however, strongly dependent on the buffering capacity. In this study, a minor change in the amount of carbohydrates in the substrate had drastic effects on the buffering effect of the system.
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