| 1. |
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| 2. |
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| 3. |
- 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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| 4. |
- Ahlgren, S., et al.
(författare)
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Ammonium nitrate fertiliser production based on biomass : Environmental effects from a life cycle perspective
- 2008
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 99:17, s. 8034-8041
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Tidskriftsartikel (refereegranskat)abstract
- Ammonium nitrate and calcium ammonium nitrate are the most commonly used straight nitrogen fertilisers in Europe, accounting for 43% of the total nitrogen used for fertilisers. They are both produced in a similar way; carbonate can be added as a last step to produce calcium ammonium nitrate. The environmental impact, fossil energy input and land use from using gasified biomass (cereal straw and short rotation willow (Salix) coppice) as feedstock in ammonium nitrate production were studied in a cradle-to-gate evaluation using life cycle assessment methodology. The global warming potential in the biomass systems was only 22-30% of the impact from conventional production using natural gas. The eutrophication potential was higher for the biomass systems due to nutrient leaching during cultivation, while the acidification was about the same in all systems. The primary fossil energy use was calculated to be 1.45 and 1.37 MJ/kg nitrogen for Salix and straw, respectively, compared to 35.14 MJ for natural gas. The biomass production was assumed to be self-supporting with nutrients by returning part of the ammonium nitrate produced together with the ash from the gasification. For the production of nitrogen from Salix, it was calculated that 3914 kg of nitrogen can be produced every year from 1 ha, after that 1.6% of the produced nitrogen has been returned to the Salix production. From wheat straw, 1615 kg of nitrogen can be produced annually from 1 ha, after that 0.6% of the nitrogen has been returned. © 2008 Elsevier Ltd. All rights reserved.
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| 5. |
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| 6. |
- Ahlgren, Serina, et al.
(författare)
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Consequential Life Cycle Assessment of Nitrogen Fertilisers Based on Biomass – a Swedish perspective
- 2012
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Ingår i: Insciences Journal. - : Insciences Organization. - 1664-171X. ; 2, s. 80-101
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Tidskriftsartikel (refereegranskat)abstract
- The production of mineral nitrogen represents a large fossil energy input in Swedish agriculture. However, mineral nitrogen can be produced in the Haber-Bosch synthesis, with input from renewable energy. This could lower the dependency on fossil energy and the emissions of greenhouse gases in agricultural production. The aim of this study was to investigate the land use, energy use and greenhouse gas emissions from the production of ammonium nitrate based on biomass, using consequential life cycle assessment methodology. Three scenarios are studied. In one scenario the Haber-Bosch synthesis is integrated in an existing forest residue fired combined heat and power plant. In another two scenarios thermochemical gasification of biomass in combination with Haber-Bosch synthesis is studied, using either straw or short rotation coppice (Salix) as raw material. The results showed that the greenhouse gas emissions and use of fossil energy can be significantly lowered. The size of emission reductions compared to using fossil fuels as raw material is dependent on choice of data, but also choice of functional unit and if e.g. indirect land use change is included. The study also showed that using green nitrogen in rapeseed production substantially can lower the carbon footprint. Further, we argue that production of nitrogen based on renewables should be a high-priority activity, as nitrogen is one of the pillars for a secure food and bioenergy supply for a growing world population.
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| 7. |
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| 8. |
- Ahlgren, Serina, et al.
(författare)
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Det svenska jordbrukets framtida drivmedelsförsörjning
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med detta arbete är att visa på möjligheter för det svenska jordbruket att bli försörjt med drivmedel även i en framtid, när oljan har blivit för dyr eller sällsynt för att kunna användas i tillräcklig omfattning. Detta projekt studerar möjligheterna att ersätta fossil diesel med första och andra generationens förnybara drivmedel, och omfattar drivmedel från råvaror med ursprung i både jord- och skogsbruk. De drivmedel som studeras är etanol, rapsmetylester (RME), biogas, Fischer-Tropsch diesel (FTD), dimetyleter (DME) och metanol. Arealbehov, energibalans och kostnader har beräknats. Studien visar att det finns tillräckligt med arealer i Sverige för att lantbruket ska kunna bli självförsörjande med drivmedel. För de drivmedel som baseras på grödor framförallt första generationens drivmedel) kommer dock mängden mat som är möjlig att producera att minska. Andra generationens drivmedel kan med fördel produceras från biprodukter som halm och matproduktionen behöver då inte minskas
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| 9. |
- Ahlgren, S., et al.
(författare)
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Future fuel supply systems for organic production based on Fischer-Tropsch diesel and dimethyl ether from on-farm-grown biomass
- 2008
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Ingår i: Biosystems Engineering. - : Elsevier BV. - 1537-5110 .- 1537-5129. ; 99:1, s. 145-155
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Tidskriftsartikel (refereegranskat)abstract
- The effects of making a 1000 ha organic farm self-sufficient in renewable fuel were studied. Biomass grown on-farm can be transported to large fuel production facilities and the fuel transported back to the farm. Two fuels, Fischer-Tropsch diesel (FTD) and dimethyl ether (DME), produced from either straw or short-rotation willow coppice (Salix), were studied. The environmental impact, land use and energy balance were calculated using life-cycle methodology. It was calculated that the straw-based systems had only 32-39% of the impact on global warming (kg [CO2-eq]) compared to the Salix-based systems. For acidification and eutrophication, the differences between the systems were less significant. The energy balances were 8.9 and 9.6 for FTD and 10.1 and 10.0 for DME, from straw and Salix, respectively. To become self-sufficient in FTD, 108 ha has to be set aside for Salix production or 261 ha of straw collected from the existing crop rotation. For DME the corresponding figures are 38 and 70 ha. The many by-products in the FTD scenarios explain the large difference between fuels. Comparing FTD and DME, the differences in environmental impact were small. Considering this, FTD is a more likely alternative since DME requires a pressurised infrastructure system and engine modifications. © 2007 IAgrE.
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| 10. |
- Ahlgren, Serina, et al.
(författare)
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Green nitrogen
- 2011
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Rapport (refereegranskat)
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| 11. |
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| 12. |
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| 13. |
- Ahlgren, Serina, et al.
(författare)
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Nitrogen fertiliser production based on biogas - Energy input, environmental impact and land use
- 2010
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 101, s. 7181-7184
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present paper was to investigate the land use, environmental impact and fossil energy use when using biogas instead of natural gas in the production of nitrogen fertilisers The biogas was assumed to be produced from anaerobic digestion of ley grass and maize. The calculations showed that 1 ha of agricultural land in south-west Sweden can produce 1.7 metric ton of nitrogen in the form of ammonium nitrate per year from ley grass, or 3 6 ton from maize The impact on global warming, from cradle to gate, was calculated to be lower when producing nitrogen fertiliser from biomass compared with natural gas Eutrophication and acidification potential was higher in the biomass scenarios The greatest advantage of the biomass systems however lies in the potential to reduce agriculture's dependency on fossil fuels In the biomass scenarios, only 2-4 MJ of primary fossil energy was required, while 35 MJ/kg N was required when utilising natural gas (C) 2010 Elsevier Ltd All rights reserved
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| 14. |
- Ahlgren, Serina, et al.
(författare)
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Tractive power in organic farming based on fuel cell technology : Energy balance and environmental load
- 2009
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Ingår i: Agricultural Systems. - : Elsevier BV. - 0308-521X .- 1873-2267. ; 102:1-3, s. 67-76
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Tidskriftsartikel (refereegranskat)abstract
- This study analysed a future hypothetical organic farm self-sufficient in renewable tractor fuel. Biomass from the farm was assumed to be transported to a central fuel production plant and the fuel returned to the farm, where it was utilised in fuel cell powered tractors. The land use, energy balance and environmental impact of five different scenarios were studied. In the first two scenarios, straw was used as raw material for production of hydrogen or methanol via thermochemical gasification. In the third and fourth scenarios, short rotation forest (Salix) was used as raw material for the same fuels. In the fifth scenario, ley was used as raw material for hydrogen fuel via biogas production. The straw scenarios had the lowest impact in all studied environmental impact categories since the Salix scenarios had higher soil emissions and the ley scenario had comparatively large emissions from the fuel production. The energy balance was also favourable for straw, 16.3 and 19.5 for hydrogen and methanol respectively, compared to Salix 14.2 and 15.6. For ley to hydrogen the energy balance was only 6.1 due to low efficiency in the fuel production. In the Salix scenarios, 1.6% and 2.0% of the land was set aside for raw material production in the hydrogen and methanol scenarios respectively. In the straw scenarios no land needed to be reserved, but straw was collected on 4.3% and 5.3% of the area for hydrogen and methanol respectively. To produce hydrogen from ley, 4% of the land was harvested. The study showed that the difference in environmental performance lay in choice of raw material rather than choice of fuel. Hydrogen is a gas with low volumetric energy density, which requires an adapted infrastructure and tractors equipped with gas tanks. This leads to the conclusion that methanol probably will be the preferred choice if a fuel cell powered farm would be put into practice in the future. © 2009 Elsevier Ltd. All rights reserved.
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| 15. |
- Ahmadi Moghaddam, Elham, et al.
(författare)
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Assessment of Novel Routes of Biomethane Utilization in a Life Cycle Perspective
- 2016
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Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media SA. - 2296-4185. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Biomethane, as a replacement for natural gas, reduces the use of fossil-based sources and supports the intended change from fossil to bio-based industry. The study assessed different biomethane utilization routes for production of methanol, dimethyl ether (DME), and ammonia, as fuel or platform chemicals and combined heat and power (CHP). Energy efficiency and environmental impacts of the different pathways was studied in a life cycle perspective covering the technical system from biomass production to the end product. Among the routes studied, CHP had the highest energy balance and least environmental impact. DME and methanol performed competently in energy balance and environmental impacts in comparison with the ammonia route. DME had the highest total energy output, as fuel, heat, and steam, among the different routes studied. Substituting the bio-based routes for fossil-based alternatives would give a considerable reduction in environmental impacts such as global warming potential and acidification potential for all routes studied, especially CHP, DME, and methanol. Eutrophication potential was mainly a result of biomass and biomethane production, with marginal differences between the different routes.
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| 16. |
- Ahmadi Moghaddam, Elham, et al.
(författare)
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Energy balance and global warming potential of biogas-based fuels from a life cycle perspective
- 2015
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Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 132, s. 74-82
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Tidskriftsartikel (refereegranskat)abstract
- Biogas is a multifunctional energy carrier currently used for co-generation or compressed biomethane as vehicle fuel. Gas-to-liquid (GTL) technology enables conversion of biogas into other energy carriers with higher energy density, facilitating fuel distribution. The energy efficiency and global warming potential (GWP) for conversion of biogas to compressed biogas (CBG), liquefied biogas (LBG), Fischer–Tropsch diesel (FTD), methanol and dimethyl ether (DME) were studied in a life cycle perspective covering the technical system from raw biogas to use in city buses. CBG, methanol and DME showed the best specific fuel productivity. However, when fuel distribution distances were longer, DME, LBG and methanol showed the best energy balance. Methanol, FTD and DME emitted half the GWP of LBG and CBG. Choice of electricity mix had a large impact on GWP performance. Overall, taking into account the different impact categories, combustion properties and fuel yield from raw biogas, DME showed the best performance of the fuel conversion scenarios assessed.
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| 17. |
- Ahmadi Moghaddam, Elham, et al.
(författare)
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Exploring the potential for biomethane production by willow pyrolysis using life cycle assessment methodology
- 2019
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Ingår i: Energy, Sustainability and Society. - : Springer Science and Business Media LLC. - 2192-0567. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundBiomethane, as a potential substitute for natural gas, reduces the use of fossil-based sources, promoting bioenergy applications. Biomethane for energy use can be produced using a variety of biomass types and technologies. Biomethane from farmland crops is currently produced by anaerobic digestion (AD) of energy crops, which is a biological treatment of organic material resulting in biomethane and digestate. Recently, thermochemical conversion technologies of biomass to biomethane have gained attention. Pyrolysis is a thermochemical process whereby woody biomass is converted to fuel gas and biochar. This study assessed the land use efficiency of producing biomethane through a maize-based AD system compared with switching to a willow-based biomethane system using pyrolysis as an emerging technology. The energy performance and climate impact of the two pathways were assessed from a land use perspective, using life cycle assessment methodology. The entire technical system, from biomass production to delivery of biomethane as the end product, was included within the analysis. The study also investigated how the climate impact was affected when biochar was applied to soil to act as a soil amendment and carbon sequestration agent or when biochar was used as an energy source.ResultsPyrolysis of willow had a higher external energy ratio and climate mitigation effect than maize-based AD as a result of lower primary energy inputs and lower methane loss in the pyrolysis process and upgrading units. Furthermore, the biochar from willow pyrolysis, when used as a soil amendment or energy source, contributed significantly to the climate impact mitigation potential in both cases. Substituting fossil gas with biomethane gave a considerable reduction in climate impact in all scenarios, especially in the case of willow pyrolysis. The willow pyrolysis system acted as a carbon sink, resulting in a negative climate impact, counteracting global warming.ConclusionFrom a land use perspective, the transition from maize-based AD to a willow-based pyrolysis system for biomethane production could be beneficial regarding the energy performance and climate impact. Application of biochar to the soil in the willow scenario contributed significantly to counteracting emissions of greenhouse gases.
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| 18. |
- Ahmadi Moghaddam, Elham, et al.
(författare)
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Gas Hydrates as a Means for Biogas and Biomethane Distribution
- 2021
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Ingår i: Frontiers in Energy Research. - : Frontiers Media SA. - 2296-598X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Biomethane is receiving great attention as a renewable energy gas with lower environmental impacts and diversified sources of production. However, availability of gas infrastructure is an important factor in biomethane development and use. Biomethane can be distributed by the natural gas or local biogas grid. Biomethane can also be road-transported as compressed biomethane (CBG) or liquefied bio-methane (LBG). Biomethane could be distributed via gas hydration technology, where methane molecules are physically trapped within the crystalline structures of frozen host water molecules as gas hydrate compounds. Using life cycle assessment methodology, this study compared the energy performance and climate impact of two gas hydrate scenarios, biogas hydrate and biomethane hydrate, with that of a base case distributing biomethane as CBG. The technical system, from biogas upgrading, hydration, compression and road transport to filling station of biomethane as CBG, was included in the analysis. Results of this study show that distribution of biomethane as gas hydrates had a lower energy performance and higher climate impact than compressed biomethane distribution. The low energy performance was due to high electricity demand in hydrate formation and dissociation processes. The gas hydrate scenarios also had higher climate impacts as a result of high methane losses from hydrate formation and dissociationdissociation and emissions related to energy source use. Biogas upgrading to biomethane also significantly contributed to methane losses and climate impact of the scenarios studied.
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| 19. |
- Andersson, Johan, 1986-, et al.
(författare)
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Askfilter för rening av svavelväte i deponigas
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Deponigas bildas under syrefria förhållanden i deponier genom mikrobiell nedbrytning av organiskt material. Gasens sammansättning kan variera mycket, men från svenska deponier brukar den generellt bestå av 40-60 % metan, 30-40 % koldioxid och 5-20 % kvävgas. Svavelväte (H2S) är en mycket giftig och korrosiv gas som finns i deponigas i varierande omfattning, från 10 till 30 000 ppm (motsvarar 0,001-3,0 %). Det är önskvärt att deponigas används för el och/eller värmeproduktion, men för att detta ska vara möjligt behöver H2S-halten renas till låga nivåer (< 200 ppm). Höga halter H2S ökar slitaget på motor/panna och därmed frekvensen på servicetillfällen. Det leder till dyra underhållskostnader och i slutändan till förkortad livslängd för anläggningen. För att minska korrosionen är det vanligt att rökgastemperaturen justeras upp, men det leder samtidigt till lägre verkningsgrad och därmed till sämre energiutnyttjande av gasen. I en del fall bedöms gasens innehåll av H2S vara för högt för att kunna användas för energiproduktion. Under 2015 facklades 53 GWh deponigas i Sverige, vilket i många fall beror på problem med höga halter H2S. Rening av deponigas från H2S leder således till flera nyttigheter; gasens energiinnehåll används effektivare, underhålls- och servicekostnaderna för förbränningsanläggningarna minskar och utsläpp av försurande svaveldioxid från förbränning av deponigas reduceras. Det finns kommersiell reningsteknik för H2S men den är dyr, både vad gäller kapitalkostnad och driftkostnad. Därmed finns ett behov av att ta fram nya billigare reningstekniker som förbättrar driftekonomin vid deponierna och som möjliggör att även deponigas med höga H2S-halter kan utnyttjas för nyttig energiomvandling. RISE (f.d. JTI - Inst. för jordbruks och miljöteknik) utvecklar tillsammans med SLU nya, potentiellt kostnadseffektiva metoder för att uppgradera biogas till drivmedelskvalité. En av metoderna baseras på att gasen får passera en bädd av fuktig aska (ett s.k. askfilter) varvid koldioxid och H2S fixeras. Hypotesen i det här projektet var att askor med ursprung från förbränning av avfall, RT-flis eller liknande kan användas för att rena bort höga halter H2S från deponigas. Denna typ av askor ska i regel ändå avsättas på deponier och om reningseffekten är god skulle det ge synergieffekter i form av att askan först används för att rena deponigas från svavel innan den avsätts som konstruktionsmaterial på deponier. I det här projektet utfördes två försök i pilotskala vid en svensk deponi med mycket höga halter H2S, ca 15 000 ppm. Olika gasflöden studerades (0,7-7,6 m3/h) medan askvolymen var lika i de båda försöken, 0,37 m3. Halten H2S i den renade gasen var genomgående mycket låg under behandling, < 10 ppm vid låga gasflöden och < 200 ppm vid höga gasflöden. Två asktyper undersöktes och båda visade sig ha mycket god förmåga att fixera H2S, 44-61 g H2S/kg torr aska. Vid jämförelse med litteraturvärden är det bara en studie som visar upptag i samma storleksordning, övriga studier ligger ca en tiopotens lägre i upptag. Utifrån försöksresultaten bestämdes den tekniska och ekonomiska potentialen för askfilter som reningsmetod. Beräkningarna gjordes för olika typanläggningar för att på så sätt täcka in vanligt förekommande deponier. För normalstora deponier med gasflöden på 100-1 000 m3/h och H2S-halter mellan 100 och 1 000 ppm uppgår askbehovet till 10-130 ton torr aska per år. För specialfallet där halten H2S är extremt hög ökar askbehovet och för en anläggning med 15 000 ppm H2S och ett gasflöde på 200 m3/h krävs det ca 800 ton torr aska per år. Överlag är det emellertid beskedliga mängder aska som krävs och skulle t.ex. samtliga svenska deponier använda aska för gasrening skulle askbehovet endast vara 0,2-0,3 % av den årliga svenska askproduktionen. De ekonomiska beräkningarna visar att askfilter är en konkurrenskraftig metod för att rena bort H2S. För specialfallet med extremt höga halter H2S visade det sig att kostnaden för askfilter är drygt 20 % lägre jämfört med den för ändamålet billigaste konventionella reningstekniken på marknaden. Även vid rening av deponigas med mer normala halter H2S står sig askfilter väl. Vid låga flöden kring 100 m3/h är askfilter klart billigare jämfört med litteraturvärden för konventionell reningsteknik. Skalfördelarna tycks dock vara större för de konventionella reningsteknikerna och därför blir skillnaden mellan reningskostnaden för askfilter jämfört med annan teknik mindre vid högre gasflöden. De låga reningskostnaderna för askfilter kan öppna upp möjligheter för deponier som idag inte renar gas från H2S. Under projektet kontaktades 15 svenska deponier och ingen av dessa hade någon form av H2S-rening. Med rening kan deponigas däremot användas effektivare, t.ex. genom minskad fackling, ökad verkningsgrad för el- och värmeproduktion samt minskat slitage på pannor och förbränningsutrustning. Dessutom minskar emissioner av svavel till atmosfären, vilket även minskar potentiella luktproblem kring deponin. För fortsatt utveckling är utformning och design av en prototyp av en askfiltermodul i fullskala en central del. Vidare måste den behandlade askan undersökas vad gäller urlakningsegenskaper, lagringsbarhet och användbarhet som konstruktionsmaterial på deponier tillsammans med en bedömning av de samlade miljökonsekvenserna. Försök i fullskala bör även göras vid fler deponier med olika gasflöden och H2S-halter i deponigasen för att verifiera prestanda från de genomförda pilotförsöken.Deponigas bildas under syrefria förhållanden i deponier genom mikrobiell nedbrytning av organiskt material. Gasens sammansättning kan variera mycket, men från svenska deponier brukar den generellt bestå av 40-60 % metan, 30-40 % koldioxid och 5-20 % kvävgas. Svavelväte (H2S) är en mycket giftig och korrosiv gas som finns i deponigas i varierande omfattning, från 10 till 30 000 ppm (motsvarar 0,001-3,0 %). Det är önskvärt att deponigas används för el och/eller värmeproduktion, men för att detta ska vara möjligt behöver H2S-halten renas till låga nivåer (< 200 ppm). Höga halter H2S ökar slitaget på motor/panna och därmed frekvensen på servicetillfällen. Det leder till dyra underhållskostnader och i slutändan till förkortad livslängd för anläggningen. För att minska korrosionen är det vanligt att rökgastemperaturen justeras upp, men det leder samtidigt till lägre verkningsgrad och därmed till sämre energiutnyttjande av gasen. I en del fall bedöms gasens innehåll av H2S vara för högt för att kunna användas för energiproduktion. Under 2015 facklades 53 GWh deponigas i Sverige, vilket i många fall beror på problem med höga halter H2S. Rening av deponigas från H2S leder således till flera nyttigheter; gasens energiinnehåll används effektivare, underhålls- och servicekostnaderna för förbränningsanläggningarna minskar och utsläpp av försurande svaveldioxid från förbränning av deponigas reduceras. Det finns kommersiell reningsteknik för H2S men den är dyr, både vad gäller kapitalkostnad och driftkostnad. Därmed finns ett behov av att ta fram nya billigare reningstekniker som förbättrar driftekonomin vid deponierna och som möjliggör att även deponigas med höga H2S-halter kan utnyttjas för nyttig energiomvandling. RISE (f.d. JTI - Inst. för jordbruks och miljöteknik) utvecklar tillsammans med SLU nya, potentiellt kostnadseffektiva metoder för att uppgradera biogas till drivmedelskvalité. En av metoderna baseras på att gasen får passera en bädd av fuktig aska (ett s.k. askfilter) varvid koldioxid och H2S fixeras. Hypotesen i det här projektet var att askor med ursprung från förbränning av avfall, RT-flis eller liknande kan användas för att rena bort höga halter H2S från deponigas. Denna typ av askor ska i regel ändå avsättas på deponier och om reningseffekten är god skulle det ge synergieffekter i form av att askan först används för att rena deponigas från svavel innan den avsätts som konstruktionsmaterial på deponier. I det här projektet utfördes två försök i pilotskala vid en svensk deponi med mycket höga halter H2S, ca 15 000 ppm. Olika gasflöden studerades (0,7-7,6 m3/h) medan askvolymen var lika i de båda försöken, 0,37 m3. Halten H2S i den renade gasen var genomgående mycket låg under behandling, < 10 ppm vid låga gasflöden och < 200 ppm vid höga gasflöden. Två asktyper undersöktes och båda visade sig ha mycket god förmåga att fixera H2S, 44-61 g H2S/kg torr aska. Vid jämförelse med litteraturvärden är det bara en studie som visar upptag i samma storleksordning, övriga studier ligger ca en tiopotens lägre i upptag. Utifrån försöksresultaten bestämdes den tekniska och ekonomiska potentialen för askfilter som reningsmetod. Beräkningarna gjordes för olika typanläggningar för att på så sätt täcka in vanligt förekommande deponier. För normalstora deponier med gasflöden på 100-1 000 m3/h och H2S-halter mellan 100 och 1 000 ppm uppgår askbehovet till 10-130 ton torr aska per år. För specialfallet där halten H2S är extremt hög ökar askbehovet och för en anläggning med 15 000 ppm H2S och ett gasflöde på 200 m3/h krävs det ca 800 ton torr aska per år. Överlag är det emellertid beskedliga mängder aska som krävs och skulle t.ex. samtliga svenska deponier använda aska för gasrening skulle askbehovet endast vara 0,2-0,3 % av den årliga svenska askproduktionen. De ekonomiska beräkningarna visar att askfilter är en konkurrenskraftig metod för att rena bort H2S. För specialfallet med extremt höga halter H2S visade det sig att kostnaden för askfilter är drygt 20 % lägre jämfört med den för ändamålet bill
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Brandgård, J., et al.
(författare)
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Monitoring growth of the methanogenic archaea Methanobacterium formicicum using an electronic nose
- 2001
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Ingår i: Biotechnology letters. - 0141-5492 .- 1573-6776. ; 23:4, s. 241-248
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Tidskriftsartikel (refereegranskat)abstract
- Growth of the methanogenic archaea, Methanobacterium formicicum, in pure culture was monitored by analysing samples from the gas phase with an array of chemical gas sensors (an 'electronic nose'). Analyses of the methane and protein formation rates were used as independent parameters of growth, and the data obtained from the electronic nose were evaluated using principal component analysis (PCA). We found that different growth phases can be distinguished with the electronic nose followed by PCA evaluation. The fast response of the sensors in combination with the high correlations with other parameters measuring growth show that the electronic nose can be a useful tool to rapidly determine methanogenic growth.
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| 25. |
- Cheng, G., et al.
(författare)
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Microbial community development during syngas methanation in a trickle bed reactor with various nutrient sources
- 2022
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media Deutschland GmbH. - 0175-7598 .- 1432-0614. ; 106, s. 5317-5333
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Tidskriftsartikel (refereegranskat)abstract
- Microbial community development within an anaerobic trickle bed reactor (TBR) during methanation of syngas (56% H2, 30% CO, 14% CO2) was investigated using three different nutrient media: defined nutrient medium (241 days), diluted digestate from a thermophilic co-digestion plant operating with food waste (200 days) and reject water from dewatered digested sewage sludge at a wastewater treatment plant (220 days). Different TBR operating periods showed slightly different performance that was not clearly linked to the nutrient medium, as all proved suitable for the methanation process. During operation, maximum syngas load was 5.33 L per L packed bed volume (pbv) & day and methane (CH4) production was 1.26 L CH4/Lpbv/d. Microbial community analysis with Illumina Miseq targeting 16S rDNA revealed high relative abundance (20–40%) of several potential syngas and acetate consumers within the genera Sporomusa, Spirochaetaceae, Rikenellaceae and Acetobacterium during the process. These were the dominant taxa except in a period with high flow rate of digestate from the food waste plant. The dominant methanogen in all periods was a member of the genus Methanobacterium, while Methanosarcina was also observed in the carrier community. As in reactor effluent, the dominant bacterial genus in the carrier was Sporomusa. These results show that syngas methanation in TBR can proceed well with different nutrient sources, including undefined medium of different origins. Moreover, the dominant syngas community remained the same over time even when non-sterilised digestates were used as nutrient medium. Key points: •Independent of nutrient source, syngas methanation above 1 L/Lpbv/D was achieved. •Methanobacterium and Sporomusa were dominant genera throughout the process. •Acetate conversion proceeded via both methanogenesis and syntrophic acetate oxidation. Graphical abstract: [Figure not available: see fulltext.] © 2022, The Author(s).
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| 26. |
- Edström, Mats, et al.
(författare)
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Anaerobic treatment of animal byproducts from slaughterhouses at laboratory and pilot scale
- 2003
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Ingår i: Applied Biochemistry and Biotechnology. - 0273-2289 .- 1559-0291. ; 109:1-3, s. 127-138
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Tidskriftsartikel (refereegranskat)abstract
- Different mixtures of animal byproducts, other slaughterhouse waste (i.e., rumen, stomach and intestinal content), food waste, and liquid manure were codigested at mesophilic conditions (37°C) at laboratory and pilot scale. Animal byproducts, including blood, represent 70-80% of the total biogas potential from waste generated during slaughter of animals. The total biogas potential from waste generated during slaughter is about 1300 MJ/cattle and about 140 MJ/pig. Fed-batch digestion of pasteurized (70°C, 1 h) animal byproducts resulted in a fourfold increase in biogas yield (1.14 L/g of volatile solids [VS]) compared with nonpasteurized animal byproducts (0.31 L/g of VS). Mixtures with animal byproducts representing 19-38% of the total dry matter were digested in continuous-flow stirred tank reactors at laboratory and pilot scale. Stable processes at organic loading rates (OLRs) exceeding 2.5 g of VS/(L·d) and hydraulic retention times (HRTs) less than 40 d could be obtained with total ammonia nitrogen concentrations (NH4-N + NH3-N) in the range of 4.0-5.0 g/L. After operating one process for more than 1.5 yr at total ammonia nitrogen concentrations >4 g/L, an increase in OLR to 5 g of VS / (L·d) and a decrease in HRT to 22 d was possible without accumulation of volatile fatty acids.
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| 27. |
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| 28. |
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| 29. |
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| 30. |
- Engstam, Linus, et al.
(författare)
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Grid-supported electrolytic hydrogen production: Cost and climate impact using dynamic emission factors
- 2023
-
Ingår i: Energy Conversion and Management. - 0196-8904. ; 293
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen production based on a combination of intermittent renewables and grid electricity is a promising approach for reducing emissions in hard-to-decarbonise sectors at lower costs. However, for such a configuration to provide climate benefits it is crucial to ensure that the grid electricity consumed in the process is derived from low-carbon sources. This paper examined the use of hourly grid emission factors (EFs) to more accurately determine the short-term climate impact of dynamically operated electrolysers. A model of the interconnected northern European electricity system was developed and used to calculate average grid-mix and marginal EFs for the four bidding zones in Sweden. Operating a 10 MW electrolyser using a combination of onshore wind and grid electricity was found to decrease the levelised cost of hydrogen (LCOH) to 2.40-3.63 euro/kgH2 compared with 4.68 euro/kgH2 for wind-only operation. A trade-off between LCOH and short-term climate impact was revealed as specific marginal emissions could exceed 20 kgCO2eq/kgH2 at minimum LCOH. Both an emission-minimising operating strategy and an increased wind-to-electrolyser ratio was found to manage this trade-off by enabling simultaneous cost and emission reductions, lowering the marginal carbon abatement cost (CAC) from 276.8 euro/tCO2eq for wind-only operation to a minimum of 222.7 and 119.3 euro/tCO2eq respectively. Both EF and LCOH variations were also identified between the bidding zones but with no notable impact on the marginal CAC. When using average grid-mix emission factors, the climate impact was low and the CAC could be reduced to 71.3-200.0 euro/tCO2eq. In relation to proposed EU policy it was demonstrated that abiding by hourly renewable temporal matching principles could ensure low marginal emissions at current levels of fossil fuels in the electricity mix.
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| 31. |
- Ericsson, Niclas, et al.
(författare)
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Biogas plant management decision support – A temperature and time-dependent dynamic methane emission model for digestate storages
- 2020
-
Ingår i: Bioresource technology reports. - : Elsevier BV. - 2589-014X. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- The aim was to develop a temperature and time-dependent model that can calculate the methane production in an anaerobic digester and its subsequent digestate storage tank under realistic and variable conditions. With a daily resolution, the model was applied to a Swedish dairy farm under two different climatic conditions. The most influential parameters were hydraulic retention time and the substrate specific first order reaction rates in the digester, which have a big influence on the residual biogas potential, and hence the potential methane production in the digestate storage. The management of the storage can have a large impact on the emissions from the storage due to its temperature dependence. The model can be used to support plant design and operation of anaerobic digesters and storages, but further research is needed to determine first-order reaction rates and the relationship between the ambient and digestate temperatures at different times of the year.
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| 32. |
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| 33. |
- Ericsson, Niclas, et al.
(författare)
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Climate impact and energy efficiency from electricity generation through anaerobic digestion or direct combustion of short rotation coppice willow
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 132, s. 86-98
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Tidskriftsartikel (refereegranskat)abstract
- Short rotation coppice willow is an energy crop used in Sweden to produce electricity and heat in combined heat and power plants. Recent laboratory-scale experiments have shown that SRC willow can also be used for biogas production in anaerobic digestion processes.Here, life cycle assessment is used to compare the climate impact and energy efficiency of electricity and heat generated by these measures. All energy inputs and greenhouse gas emissions, including soil organic carbon fluxes were included in the life cycle assessment. The climate impact was determined using time-dependent life cycle assessment methodology.Both systems showed a positive net energy balance, but the direct combustion system delivered ninefold more energy than the biogas system. Both systems had a cooling effect on the global mean surface temperature change. The cooling impact per hectare from the biogas system was ninefold higher due to the carbon returned to soil with the digestate.Compensating the lower energy production of the biogas system with external energy sources had a large impact on the result, effectively determining whether the biogas scenario had a net warming or cooling contribution to the global mean temperature change per kWh of electricity. In all cases, the contribution to global warming was lowered by the inclusion of willow in the energy system. The use of time-dependent climate impact methodology shows that extended use of short rotation coppice willow can contribute to counteract global warming. (C) 2014 Elsevier Ltd. All rights reserved.
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| 34. |
- Ericsson, Niclas, et al.
(författare)
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The effect of Soil Organic Carbon and the Time Frame on the GWP in a Short Rotation Coppice LCA
- 2012
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Ingår i: European Biomass Conference and Exhibition Proceedings. - 2282-5819. ; , s. 2235-2237
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The energy delivered from short rotation coppice willow is expected to increase in Sweden. Expanding the area of willow will lead to land use changes which may affect soil organic carbon stocks. Many previous life cycle assessments on climate impact of willow exclude soil organic stock changes. These studies also use different system time frames, depending on how long the plantation is expected to prevail. In the present work the global warming potential was assessed for a short rotation coppice willow system established on a 20-year old fallow, including and excluding soil organic carbon, using different time frames and functional units. The global warming potential using a time frame of 24 years was -16.3 kg CO2-eq • GJ-1 including soil organic carbon compared to 6.7 kg CO2-eq • GJ-1 when excluded, showing the importance to consider soil organic carbon changes in life cycle assessments of short rotation coppice when a land use change take place. The time frame and the functional unit chosen were also shown to have an influence on the climate impact.
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| 35. |
- Ericsson, Niclas, et al.
(författare)
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Time-dependent climate impact and energy efficiency of combined heat and power production from short-rotation coppice willow using pyrolysis or direct combustion
- 2017
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Ingår i: Global Change Biology Bioenergy. - : Blackwell Publishing Ltd. - 1757-1693 .- 1757-1707. ; 9:5, s. 876-890
-
Tidskriftsartikel (refereegranskat)abstract
- A life cycle assessment of a Swedish short-rotation coppice willow bioenergy system generating electricity and heat was performed to investigate how the energy efficiency and time-dependent climate impact were affected when the feedstock was converted into bio-oil and char before generating electricity and heat, compared with being combusted directly. The study also investigated how the climate impact was affected when part of the char was applied to soil as biochar to act as a carbon sequestration agent and potential soil improver. The energy efficiencies were calculated separately for electricity and heat as the energy ratios between the amount of energy service delivered by the system compared to the amount of external energy inputs used in each scenario after having allocated the primary energy related to the inputs between the two energy services. The energy in the feedstock was not included in the external energy inputs. Direct combustion had the highest energy efficiency. It had energy ratios of 10 and 36 for electricity and heat, respectively. The least energy-efficient scenario was the pyrolysis scenario where biochar was applied to soils. It had energy ratios of 4 and 12 for electricity and heat, respectively. The results showed that pyrolysis with carbon sequestration might be an option to counteract the current trend in global warming. The pyrolysis system with soil application of the biochar removed the largest amount of CO2 from the atmosphere. However, compared with the direct combustion scenario, the climate change mitigation potential depended on the energy system to which the bioenergy system delivered its energy services. A system expansion showed that direct combustion had the highest climate change mitigation potential when coal or natural gas were used as external energy sources to compensate for the lower energy efficiency of the pyrolysis scenario.
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| 36. |
- Ericsson, Niclas, et al.
(författare)
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Time-dependent climate impact of a bioenergy system - methodology development and application to Swedish conditions
- 2013
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Ingår i: GCB Bioenergy. - : Wiley. - 1757-1693 .- 1757-1707. ; 5, s. 580-590
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Tidskriftsartikel (refereegranskat)abstract
- The area of dedicated energy crops is expected to increase in Sweden. This will result in direct land use changes, which may affect the carbon stocks in soil and biomass, as well as yield levels and the use of inputs. Carbon dioxide (CO2) fluxes of biomass are often not considered when calculating the climate impact in life cycle assessments (LCA) assuming that the CO2 released at combustion has recently been captured by the biomass in question. With the extended time lag between capture and release of CO2 inherent in many perennial bioenergy systems, the relation between carbon neutrality and climate neutrality may be questioned. In this paper, previously published methodologies and models are combined in a methodological framework that can assist LCA practitioners in interpreting the time-dependent climate impact of a bioenergy system. The treatment of carbon differs from conventional LCA practice in that no distinction is made between fossil and biogenic carbon. A time-dependent indicator is used to enable a representation of the climate impact that is not dependent on the choice of a specific characterization time horizon or time of evaluation and that does not use characterization factors, such as global warming potential and global temperature potential. The indicator used to aid in the interpretation phase of this paper is global mean surface temperature change (T-s(n)). A theoretical system producing willow for district heating was used to study land use change effects depending on previous land use and variations in the standing biomass carbon stocks. When replacing annual crops with willow this system presented a cooling contribution to T-s(n). However, the first years after establishing the willow plantation it presented a warming contribution to T-s(n). This behavior was due mainly to soil organic carbon (SOC) variation. A rapid initial increase in standing biomass counteracted the initial SOC loss.
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| 37. |
- Fredriksson, H., et al.
(författare)
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Use of on-farm produced biofuels on organic farms : Evaluation of energy balances and environmental loads for three possible fuels
- 2006
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Ingår i: Agricultural Systems. - : Elsevier BV. - 0308-521X .- 1873-2267. ; 89:1, s. 184-203
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to evaluate systems making organic farms self-sufficient in farm-produced bio-based fuels. The energy balance and environmental load for systems based on rape methyl ester (RME), ethanol and biogas were evaluated using a life cycle perspective. Complete LCAs were not performed. Important constraints when implementing the systems in practice were also identified. The RME scenario showed favourable energy balance and produced valuable by-products but was less positive in some other aspects. The use of land was high and thereby also the emissions associated with cultivation. Emissions, with the exception of CO2, during utilisation of the fuel were high compared to those of the other fuels in the study. The technology for production and use of RME is well known and easy to implement at farm scale. The production of ethanol was energy consuming and the by-products were relatively low value. However, the area needed for cultivation of raw material was low compared to the RME scenario. The production and utilisation of ignition improver and denaturants were associated with considerable emissions. Suitable ethanol production technology is available but is more optimal for large scale systems. The biogas scenario had a low relative need for arable land, which also resulted in smaller soil emissions to air and water. Another advantage was the potential to recycle plant nutrients. On the other hand, the potential emissions of methane from storage of digestate, upgrading of biogas and methane losses during utilisation of fuel produced a negative impact, mainly on global warming. Small scale technology for biogas cleaning and storage is not fully developed and extensive tractor modifications are necessary. The global warming effects of all three systems studied were reduced by 58-72% in comparison to a similar farming system based on diesel fuel. However, the fuel costs were higher for all scenarios studied compared to current diesel prices. In particular, the large costs for seasonal storage of gas meant that the biogas scenario described is currently not financially viable. © 2005 Elsevier Ltd. All rights reserved.
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| 38. |
- Grim, Johanna, et al.
(författare)
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Comparison of pasteurization and integrated thermophilic sanitation at a full-scale biogas plant : Heat demand and biogas production
- 2015
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 79, s. 419-427
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Tidskriftsartikel (refereegranskat)abstract
- Sanitation is required for biogas plants handling slaughterhouse and food waste according to EU legislation. The standard method is pasteurization at 70 °C for 60 min, but integrated thermophilic sanitation (ITS), requiring 52 °C for 10 h in the digester, has been approved by the Swedish Board of Agriculture. This work compares pasteurization and ITS regarding heat demand and biogas production, using a full-scale plant in Uppsala, Sweden, as a case study. The plant currently uses pasteurization and thermophilic (52 °C) digestion. The impact of pasteurization on biogas production and process performance was examined at laboratory-scale. The heat demand for pasteurization was surveyed at the full-scale plant, while for ITS a process design was developed and the heat demand was theoretically calculated. The results showed that pasteurization had no significant effect on process performance or biogas production. The heat demand of pasteurization was measured to be 1.92 ± 0.29 MJ (kg VS)−1 (64.7 kWh t−1), while ITS was calculated to require 1.04 MJ (kg VS)−1 (35.1 kWh t−1). This represented 9% and 5% of biogas energy production, respectively. Changing sanitation method to ITS would hence reduce the heat demand at the plant by 46%, corresponding to annual savings of 4380 GJ (1.22 GWh).
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| 39. |
- Grim, Johanna, et al.
(författare)
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Demand-Orientated Power Production from Biogas: Modeling and Simulations under Swedish Conditions
- 2015
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Ingår i: Energy and Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 29, s. 4066-4075
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Tidskriftsartikel (refereegranskat)abstract
- The total share of intermittent renewable electricity is increasing, intensifying the need for power balancing in future electricity systems. Demand-orientated combined heat and power (CHP) production from biogas has potential for this purpose. An agricultural biogas plant, using cattle manure and sugar beet for biogas and CHP production, was analyzed here. The model Dynamic Biogas plant Model (DyBiM) was developed and connected to the Anaerobic Digestion Model No. 1 (ADM1). Flexible scenarios were simulated and compared against a reference scenario with continuous production, to evaluate the technical requirements and economic implications of demand-orientated production. The study was set in Swedish conditions regarding electricity and heat price, and the flexibility approaches assessed were increased CHP and gas storage capacity and feeding management. The results showed that larger gas storage capacity was needed for demand-orientated CHP production but that feeding management reduced the storage requirement because of fast biogas production response to feeding. Income from electricity increased by 10%, applying simple electricity production strategies to a doubled CHP capacity. However, as a result of the currently low Swedish diurnal electricity price variation and lack of subsidies for demand-orientated electricity production, the increase in income was too low to cover the investment costs. Nevertheless, DyBiM proved to be a useful modeling tool for assessing the economic outcome of different flexibility scenarios for demand-orientated CHP production.
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| 40. |
- Hansson, Mikael, et al.
(författare)
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Early warning of disturbances in a laboratory-scale MSW biogas process.
- 2002
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Ingår i: Water Science and Technology. - 0273-1223 .- 1996-9732. ; 45:10, s. 255-260
-
Tidskriftsartikel (refereegranskat)abstract
- The use of near-infrared spectroscopy (NIR) to monitorthe dynamics of a biogas process was evaluated using multivariate data analysis. The digester was a completely stirred 8 I tank reactor fed with the organic fraction of source-sorted MSW. Intermittently the digester was overloaded with feed. Before and after overload on-line monitoring of NIR spectra and off-line analysis in the liquid and the gas phase of traditional chemical variables and microbial biomass, determined as total concentration of phospholipid fatty acids (PLFA and PLEL), were done. The dynamics that occurred due to overloading could be followed using principal component analysis of the obtained NIR-spectra. In addition, the response to changes in the digester fluid was reproducible and could be detected within five minutes, which can be considered as real-time monitoring. Selected wavelengths in the region 800-2,000 nm were used to make a PLS1 -regression with propionate. The regression resulted in a good correlation for propionate (R= 0.94 and RMSEP of 0.21 g/l in the range of 0.3-3 g/l). The results indicate the possibility to develop an early warning biogas control system based on near-infrared spectroscopy monitoring of propionate.
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| 41. |
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| 42. |
- Hansson, P.-A., et al.
(författare)
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Self-sufficiency of motor fuels on organic farms : Evaluation of systems based on fuels produced in industrial-scale plants
- 2007
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Ingår i: Agricultural Systems. - : Elsevier BV. - 0308-521X .- 1873-2267. ; 94:3, s. 704-714
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the present work was to evaluate systems for making organic farms self-sufficient in bio-based fuels. The energy efficiency and environmental load for systems based on rape methyl ester (RME), ethanol and biogas produced by processing raw material from the farm in industrial-scale plants were evaluated using a life cycle perspective. Eventual constraints when implementing the systems in practice were also identified and the farmer's costs for the systems estimated. The RME scenario showed some good characteristics; the energy efficiency and potential effects on global warming were favourable, the technology well known and no engine modifications were necessary. However, the high price of the organically produced rapeseed made the fuel expensive. The ethanol scenario provided fuel at a comparatively low cost, but the energy efficiency was low and existing engines would have to be modified. The biogas scenario was not as economically advantageous, due to high costs for storage and transport of the biogas and the extensive tractor modifications needed. The calculations further showed that systems based on so-called exchange of fuels, i.e. when the farm produces raw material for one type of biofuel, but instead uses another type of biofuel more suitable for its own tractors, were an economically favourable way of supplying the organic farms with 'self-produced' bio-based fuels. The exchange scenario based on delivery of organic wheat to a large-scale plant and use of RME at the farm was somewhat more expensive than scenarios based on production of biogas raw material at the farm. However, the wheat/RME system has the advantage of being possible to put into practice immediately, since industrial-scale wheat ethanol plants are in operation and RME fuel is available on the market. © 2007 Elsevier Ltd. All rights reserved.
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| 43. |
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| 44. |
- Janke, Leandro, et al.
(författare)
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Modelling synthetic methane production for decarbonising public transport buses: A techno-economic assessment of an integrated power-to-gas concept for urban biogas plants
- 2022
-
Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 259
-
Tidskriftsartikel (refereegranskat)abstract
- The integration of power-to-gas (PtG) technology into existing urban anaerobic digestion (AD) plants could be an interesting concept to recycle biogenic CO2 and increase CH4 production as renewable fuel to further decarbonize public transport buses (PTB). However, such implementation is challenging for several reasons, including power restrictions during peak load, physical and temporal availability of CO2 from AD plants, and the need for expensive intermediate gas storages to avoid mismatch between the constrained synthetic CH4 production and the variable fuel demand. To investigate whether synthetic CH4 could be a feasible alternative for buses currently powered by fossil fuels, a dynamic model was built for discrete-event simulations of PtG technology integrated into an urban AD plant designed to supply biomethane as fuel for bus fleets. Different scenarios were assessed, including variations in power availability to run a proton exchange membrane electrolyser as well as variations in the production scale of synthetic CH4 based on ex-situ biological methanation. The results show that a constrained power utilization (maximum of 12 h per day) increased the production cost of synthetic CH4 by 20%. In contrast, an increase in PtG production capacity from 0.75 MWth to 2.25 MWth decreased costs by 16%. From the PTB operators’ perspective, the total cost of ownership (TCO) increased in all analysed scenarios when replacing diesel buses by gas buses powered by synthetic CH4. However, when using synthetic CH4 as drop-in fuel to replace natural gas in existing gas bus fleets, the TCO could be reduced up to 4.4% depending on the PtG plant configuration and the assumed fossil fuel price. Furthermore, our results show that a carbon tax on fossil fuels has only a limited effect on promoting synthetic CH4 as alternative fuel for PTB, and additional incentives should be put in place to prioritize a fuel switch, especially for existing gas bus fleets.
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| 45. |
- Janke, Leandro, et al.
(författare)
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Optimizing power-to-H-2 participation in the Nord Pool electricity market: Effects of different bidding strategies on plant operation
- 2020
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Ingår i: Renewable Energy. - : Elsevier BV. - 0960-1481. ; 156, s. 820-836
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Tidskriftsartikel (refereegranskat)abstract
- The operation of power-to-X systems requires measures to control the cost and sustainability of electricity purchased from spot markets. This study investigated different bidding strategies for the day-ahead market with a special focus on Sweden. A price independent order (PIO) strategy was developed assisted by forecasting electricity prices with an artificial neural network. For comparison, a price dependent order (PDO) with fixed bid price was used. The bidding strategies were used to simulate H2 production with both alkaline and proton exchange membrane electrolysers in different years and technological scenarios. Results showed that using PIO to control H2 production helped to avoid the purchase of expensive and carbon intense electricity during peak loads, but it also reduced the total number of operating hours compared to PDO. For this reason, under optimal conditions for both bidding strategies, PDO resulted in an average of 10.9% lower levelised cost of H2, and more attractive cash flows and net present values than PIO. Nevertheless, PIO showed to be a useful strategy to control costs in years with unexpected hourly price behaviour such as 2018. Furthermore, PIO could be successfully demonstrated in a practical case study to fulfil the on-demand requirement of an industrial captive customer.
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| 46. |
- Janke, Leandro, et al.
(författare)
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Techno-Economic Assessment of Demand-Driven Small-Scale Green Hydrogen Production for Low Carbon Agriculture in Sweden
- 2020
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Ingår i: Frontiers in Energy Research. - : Frontiers Media SA. - 2296-598X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Wind power coupled to hydrogen (H2) production is an interesting strategy to reduce power curtailment and to provide clean fuel for decarbonizing agricultural activities. However, such implementation is challenging for several reasons, including uncertainties in wind power availability, seasonalities in agricultural fuel demand, capital-intensive gas storage systems, and high specific investment costs of smallscale electrolysers. To investigate whether on-site H2 production could be a feasible alternative to conventional diesel farming, a model was built for dynamic simulations of H2 production from wind power driven by the fuel demand of a cereal farm located on the island of Gotland, Sweden. Different cases and technological scenarios were considered to assess the effects of future developments, H2 end-use, as well as production scale on the levelised- and farmers’ equivalent annual costs. In a single-farm application, H2 production costs varied between 21.20–14.82 €/kg. By sharing a power-to-H2 facility among four different farms of 300-ha each, the specific investment costs could be significantly decreased, resulting in 28% lower H2 production costs than when facilities are not shared. By including delivery vans as additional H2 consumers in each farm, costs of H2 production decreased by 35% due to the higher production scale and more distributed demand. However, in all cases and technological scenarios assessed, projected diesel price in retailers was cheaper than H2. Nevertheless, revenues from leasing the land to wind power developers could make H2 a more attractive option even in single-farm applications as early as 2020. Without such revenues, H2 is more competitive than diesel where power-to-H2 plants are shared by at least two farms, if technological developments predicted for 2030 come true. Also, out of 20 different cases assessed, nine of them showed a carbon abatement cost lower than the current carbon tax in Sweden of 110 €/tCO2, which demonstrate the potential of power-to-H2 as an effective strategy to decarbonize agricultural systems.
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| 47. |
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| 49. |
- Jönsson, Håkan, et al.
(författare)
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System för återföring av fosfor i källsorterade fraktion av urin, fekalier, matavfall och i liknande rötat samhälls- och lantbruksavfall
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten behandlar system för återföring av fosfor från källsorterade fraktioner av urin, fekalier och matavfall, samt teknik för att omfördela fosfor från djurgårdar med fosforöverskott till gårdar med underskott. Arbetet har finansierats av Naturvårdsverket inom regeringsuppdraget M2012/317/Ke Uppdrag om hållbar återföring av fosfor. Rapporten belyser effekter på Giftfri miljö och God bebyggd miljö och i viss mån klimatpåverkan och energianvändning. Större delen av fosforn i gödsel och rötrest kan med befintlig teknik (centrifug eller skruvpress) separeras ut i en fast fraktion vars vikt endast är ca 10 % av det urspungliga materialets. Detta underlättar transport av fosfor från gårdar med överskott till gårdar med brist. Genom effektivt stöd till införandet av denna teknik bör fördelningen av fosfor i jordbruket snabbt kunna förbättras. Klosettvatten‐(KL‐)sortering, d.v.s. att toalettavlopp samlas separat, hygieniseras och återförs som gödsel, kan väsentligt förbättra återföringen av växtnäring från avlopp och ger samtidigt flera andra miljöfördelar. Kadmium‐fosforkvoten i källsorterat KL‐vatten är 11‐13 mg kadmium per kg fosfor, vilket är lägre än i naturgödsel. Införande av KL‐system ger en kraftig reduktion av spridningen av humanpatogener och antibiotikaresistenta bakterier till miljön. Systemet minskar också utsläpp av hormoner och läkemedelsrester liksom av övergödande ämnen till vatten, speciellt vid bräddning. Införandet av KL‐sortering skulle totalt sett minska utsläpp av växthusgaser och användningen av energi och dessutom ge god potential för sambehandling med matavfall. Systemet passar i storstad och i glesbygd. Det finns redan ca 122 000 anläggningar med slutna tankar i Sverige och det källsorterade KL‐vattnet från dessa kan snabbt återföras till kretsloppet. Källsorterad urin har låga tungmetallhalter, kadmium‐fosforkvoten är endast 0,3‐2 mg kadmium per kg fosfor. Urinsortering ger synergier i form av stor reduktion av hormoner och läkemedelsrester och minskade utsläpp av övergödande ämnen till vatten, speciellt vid bräddning. Utsläppen av växthusgaser och energianvändningen minskar, men synergierna är mindre än för KL‐sortering, då spridningen av humanpatogener knappt påverkas och sambehandling med matavfall inte är trolig. Källsorterat matavfall från hushåll har en högre kadmium‐fosforkvot (ca 37 mg kadmium per kg fosfor) än källsorterad urin eller KL‐vatten, men matavfall från andra källor, t.ex. livsmedelshandel, är troligen renare. Mängden fosfor som återförs med rötat matavfall är redan idag lika stor som den skulle bli om KL‐vattnet från alla befintliga tankar återfördes till lantbruk och utbyggnadstakten är hög. Det finns stora möjligheter till synergi med KL‐system genom samhantering och –behandling. Gödsel från källsorterade produkter bedöms ha god acceptans. För att öka återföringen av källsorterad avloppsnäring behövs organisatoriska förbättringar, information, utbildning om kretsloppssystem och ett miljömål som inkluderar kväve.
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| 50. |
- Kalita, Saurav, et al.
(författare)
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Energy performance of compressed biomethane gas production from co-digestion of Salix and dairy manure: factoring differences between Salix varieties
- 2023
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Ingår i: Biotechnology for Biofuels and Bioproducts. - 2731-3654. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Biogas from anaerobic digestion is a versatile energy carrier that can be upgraded to compressed biomethane gas (CBG) as a renewable and sustainable alternative to natural gas. Organic residues and energy crops are predicted to be major sources of bioenergy production in the future. Pre-treatment can reduce the recalcitrance of lignocellulosic energy crops such as Salix to anaerobic digestion, making it a potential biogas feedstock. This lignocellulosic material can be co-digested with animal manure, which has the complementary effect of increasing volumetric biogas yield. Salix varieties exhibit variations in yield, composition and biomethane potential values, which can have a significant effect on the overall biogas production system. This study assessed the impact of Salix varietal differences on the overall mass and energy balance of a co-digestion system using steam pre-treated Salix biomass and dairy manure (DaM) to produce CBG as the final product. Six commercial Salix varieties cultivated under unfertilised and fertilised conditions were compared. Energy and mass flows along this total process chain, comprising Salix cultivation, steam pre-treatment, biogas production and biogas upgrading to CBG, were evaluated. Two scenarios were considered: a base scenario without heat recovery and a scenario with heat recovery. The results showed that Salix variety had a significant effect on energy output-input ratio (R), with R values in the base scenario of 1.57-1.88 and in the heat recovery scenario of 2.36-2.94. In both scenarios, unfertilised var. Tordis was the best energy performer, while the fertilised var. Jorr was the worst. Based on this energy performance, Salix could be a feasible feedstock for co-digestion with DaM, although its R value was at the lower end of the range reported previously for energy crops.
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