| 1. |
- Barta, Zsolt, et al.
(författare)
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Effects of steam pretreatment and co-production with ethanol on the energy efficiency and process economics of combined biogas, heat and electricity production from industrial hemp
- 2013
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Background: The study presented here has used the commercial flow sheeting program Aspen Plus (TM) to evaluate techno-economic aspects of large-scale hemp-based processes for producing transportation fuels. The co-production of biogas, district heat and power from chopped and steam-pretreated hemp, and the co-production of ethanol, biogas, heat and power from steam-pretreated hemp were analysed. The analyses include assessments of heat demand, energy efficiency and process economics in terms of annual cash flows and minimum biogas and ethanol selling prices (MBSP and MESP). Results: Producing biogas, heat and power from chopped hemp has the highest overall energy efficiency, 84% of the theoretical maximum (based on lower heating values), providing that the maximum capacity of district heat is delivered. The combined production of ethanol, biogas, heat and power has the highest energy efficiency (49%) if district heat is not produced. Neither the inclusion of steam pretreatment nor co-production with ethanol has a large impact on the MBSP. Ethanol is more expensive to produce than biogas is, but this is compensated for by its higher market price. None of the scenarios examined are economically viable, since the MBSP (EUR 103-128 per MWh) is higher than the market price of biogas (EUR 67 per MWh). The largest contribution to the cost is the cost of feedstock. Decreasing the retention time in the biogas process for low solids streams by partly replacing continuous stirred tank reactors by high-rate bioreactors decreases the MBSP. Also, recycling part of the liquid from the effluent from anaerobic digestion decreases the MBSP. The production and prices of methane and ethanol influence the process economics more than the production and prices of electricity and district heat. Conclusions: To reduce the production cost of ethanol and biogas from biomass, the use of feedstocks that are cheaper than hemp, give higher output of ethanol and biogas, or combined production with higher value products are primarily suggested. Further, practical investigations on increased substrate concentration in biogas and ethanol production, recycling of the liquid in anaerobic digestion and separation of low solids flows into solid and a liquid fraction for improved reactor applications deserves further attention.
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| 2. |
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| 3. |
- Björnsson, Lovisa
(creator_code:cre_t)
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Pretreating non-wood lignocellulosic material (e.g. bagasse) to produce ethanol, comprises adding organic acid or organic acid-producing bacteria to lignocellulosic material, and storing and heating the organic acid-impregnated material
- 2012
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- NOVELTY - Pretreating non-wood lignocellulosic material containing less than 5 wt.% starch or sugar for producing ethanol from lignocellulose, comprises: (a) adding organic acid or organic acid-producing bacteria to the lignocellulosic material; (b) storing the lignocellulosic material in presence of organic acid for at least 2 weeks in an atmosphere of less than 5% oxygen to obtain organic acid-impregnated material; and (c) heating the organic acid-impregnated material at a temperature of at least 190 degrees C for at least 5 minutes to obtain pretreated lignocellulosic material. USE - The method is useful for pretreating non-wood lignocellulosic material to produce ethanol, where the non-wood lignocellulosic material is bagasse (preferably sugar cane bagasse or sweet Sorghum bagasse), sugar cane trash, wheat straw, rice straw, Sorghum species, Arundo, Miscanthus or agricultural residues (all claimed). ADVANTAGE - The method: avoids the need of inorganic acid or base (sulfur dioxide), and utilizes containers which are less corrosion resistant, hence economical; has higher net energy gain; utilizes organic acid which is biodegradable, and produces degradation products (e.g. 5-hydroxymethylfurfural and furfural which acts as inhibitory substances in the subsequent fermentation process), thus environmentally friendly. DETAILED DESCRIPTION - Pretreating non-wood lignocellulosic material containing less than 5 wt.% starch or sugar for producing ethanol from lignocellulose, comprises: (a) adding organic acid or organic acid-producing bacteria to the lignocellulosic material; (b) storing the lignocellulosic material in the presence of organic acid for at least 2 weeks in an atmosphere of less than 5% oxygen to obtain organic acid-impregnated material; and (c) heating the organic acid-impregnated material at a temperature of at least 190 degrees C for a period of at least 5 minutes to obtain pretreated lignocellulosic material, where no inorganic acid or base including sulfur dioxide is added in the method.
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| 4. |
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| 5. |
- Gissén, Charlott, et al.
(författare)
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Comparing energy crops for biogas production Yields, energy input and costs in cultivation using digestate and mineral fertilisation
- 2014
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 64, s. 199-210
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Tidskriftsartikel (refereegranskat)abstract
- Analyses of six crops grown in southern Sweden for biogas production (hemp, sugar beet, maize, triticale, grass/clover ley, winter wheat) showed varying performance regarding methane yield per hectare and energy input and costs in the production and supply of crops as biogas feedstock. The highest biomass and biogas yield was observed for sugar beet. Crops with lower risk of negative environmental impact in cultivation, such as ley and hemp, produced less than half the methane energy yield per hectare. Triticale, also having less risk of negative environmental impact, gave an energy yield similar to that of winter wheat grain and maize. Replacing most of the mineral fertiliser with biogas digestate did not, with the exception for hemp, influence crop yields per hectare, but energy input in cultivation decreased by on average 34% for the six crops tested. For hemp and sugar beet the biogas feedstock costs for the freshly harvested crop per GJ methane were close to that of the economic reference crop, winter wheat grain. For maize, beet tops and first and second year ley, the feedstock costs were lower, and for triticale much lower. When ensiled crops were used for biogas the feedstock costs increased and only those of triticale silage remained slightly lower than the cost of dried wheat grain. However, all feedstock costs were so high that profitable biogas production based solely on ensiled crops would be difficult to achieve at present Swedish biogas sales prices. (c) 2014 Elsevier Ltd. All rights reserved.
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| 6. |
- Kreuger, Emma, et al.
(författare)
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Anaerobic digestion of industrial hemp-Effect of harvest time on methane energy yield per hectare
- 2011
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 35:2, s. 893-900
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Tidskriftsartikel (refereegranskat)abstract
- There is a worldwide emphasis to increase the share of renewable transportation fuels. When using agricultural land for production of renewable transportation fuels, the energy output per hectare for different crops and transportation fuels is a crucial factor. In this study, the gross methane energy yield per hectare from anaerobic digestion of industrial hemp (Cannabis sativa L.), was determined at four different harvest times between July and October in Southern Sweden, a cold climate region. The biomass yield was determined for three years and the methane yield was determined for two years through the biochemical methane potential test. The highest biomass yield, 16 tonnes dry matter per hectare on an average, and the highest methane energy yield per hectare was achieved when the hemp was harvested in September or October, with an average gross methane energy yield of 136 +/- 24 GJ per hectare. There was no significant difference in the specific methane yield between the harvest times; the average being 234 +/- 35 m(3) per tonne volatile solids. Biogas from hemp turned out to be a high yielding alternative to the currently dominating renewable transportation fuels produced from crops grown in Sweden: ethanol from wheat and biodiesel from rapeseed. (C) 2010 Elsevier Ltd. All rights reserved.
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| 7. |
- Kreuger, Emma, et al.
(författare)
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Bioconversion of industrial hemp to ethanol and methane: The benefits of steam pretreatment and co-production
- 2011
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Ingår i: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 102:3, s. 3457-3465
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Tidskriftsartikel (refereegranskat)abstract
- Several scenarios for ethanol production, methane production (by anaerobic digestion) and co-production of these, using autumn harvested hemp as substrate, were investigated and compared in terms of gross energy output. Steam pretreatment improved the methane production rate compared with mechanical grinding. The methane yield of steam pretreated stems was similar both with and without pre-hydrolysis with cellulolytic enzymes. Co-production of ethanol and methane from steam pretreated stems gave a high yield of transportation fuel, 11.1-11.7 MJ/kg processed stem dry matter (DM); more than twice that of ethanol production alone from hexoses, 4.4-5.1 MJ/kg processed stem DM. Co-production from the whole hemp plant would give 2600-3000 L ethanol and 2800-2900 m(3) methane, in total 171-180 GJ per 10,000 m(2) of agricultural land, based on a biomass yield of 16 Mg DM. Of this, the yeast and enzymes from ethanol production were estimated to contribute 700 m(3) (27 GJ) of methane. (C) 2010 Elsevier Ltd. All rights reserved.
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| 8. |
- Kreuger, Emma, et al.
(författare)
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Biogas från Skånsk betblast - potential, teknik och ekonomi
- 2014
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Rapport (populärvet., debatt m.m.)abstract
- Sammanfattning I Skåne odlas 34 500 ha sockerbetor för sockerutvinning och i Sverige 36 000 ha (Jordbruksstatistik årsbok 2014). Vid insamling och rötning av blasten från betorna i Skåne skulle drygt 200 GWh biogas kunna produceras per år och driva minst 19 000 bilar eller 1000 bussar. Men idag lämnas den i fält. Tidigare studier har visat att betblast från sockerproduktion är på gränsen till lönsamt att skörda och använda för biogasproduktion (Lantz, 2013b). I det här projektet har flera forskare, en biogasproducent och en representant för betodlarna gemensamt tagit fram och undersökt ett par förslag för hur skörd, lagring och rötning av betblast kan genomföras och hur olika tillvägagångssätt påverkar kostnader och klimatpåverkan. Dessa innefattar en jämförelse av två olika skördekedjor och undersökning av effekterna av att fraktionera betblast före lagring och rötning på; biogasproduktion, ekonomi och klimatpåverkan. För dessa beräkningar antogs att endast betblast rötades i en biogasanläggning med en årlig produktion om 172 TJ (48 GWh) metan. Effekterna av att introducera icke fraktionerad och fraktionerad betblast i en samrötningsanläggning analyserades också. Dessutom arrangerades en skördedemonstration i oktober 2013 i samarbete med Skånska Biobränslebolaget (länk till video). Analysen av skördeteknik har begränsats till skörd av blast från betor odlade för sockerproduktion, vilket är det som görs i Sverige idag. Om sockerbetor odlas endast för biogasproduktion kan andra skördetekniker för betor och blast vara aktuella. Studien har visat att när biogas från betblast ersatte fossil energi som drivmedel så sänktes utsläppen av klimatgaser kraftigt, med 80 %. Därmed uppfylldes EUs hållbarhetskriterier för biodrivmedel, både enligt dagens direktiv (35 % reduktion) och föreslagna framtida (60 % reduktion). Viktigt i detta sammanhang är att blasten är en restprodukt och den konkurrerar inte om åkermark för livsmedelsproduktion. I Skåne skulle ca 200 GWh biogas kunna produceras från betblast vid dagens sockerbetsproduktion. Men, även för den andel av blasten som skördas under september (motsvarande ca 40 GWh), då det är mer gynnsamt än vid senare skörd, är det svårt att hitta ekonomisk hållbarhet. Studien tyder på att kostnader och klimatpåverkan är de samma om betblast fraktioneras eller ej. I fallstudien framkom att fraktionering av betblasten gav praktisk möjlighet att ta emot mer material i den studerade samrötningsanläggningen. Vätskefraktionen kunde då ersätta vatten i förbehandlingen och mera torrsubstans (TS) kunde tas emot med den fasta fraktionen innan uppehållstiden begränsade mängden i rötningsprocessen. Att ersätta vatten i förbehandlingsanläggningen ger mindre kapitalkostnader per producerad MWh jämfört med om man skulle röta denna fraktion i en dedikerad anläggning. Men, inte heller i fallstudien medförde fraktionering lägre kostnader per producerad mängd metan. Blastskörden visade sig vara högre i september, 3,6 ton torrsubstans per hektar (t TS/ha), än i oktober, 3,2 t TS/ha, vilket gör det fördelaktigare att samla in blast i september än oktober. Av de skörde- och transportkedjor som teoretiskt utvärderades i projektet var det ekonomiskt mest fördelaktigt med en skördekedja där en mindre mängd blast samlades in (55 % av tillgänglig mängd) för att minimera maskinernas väntetider. Alternativet har dock nackdelen att en större andel kvarlämnad blast gör att en större andel av fältets ytafår ojämn förfruktseffekt i efterföljande gröda jämfört med ett scenario då större andel av blasten samlas in. Priset för skörd (i september) och lagring beräknades till 1,7–2,1 kr/kg TS både med och utan fraktionering. Detta är högre än det pris som tidigare beräknats (Gissén et al. 2014), vilket bedöms som underskattat. Tester av fraktionering av betblast gjordes i liten skala med en äppeljuicepress. Metanpotentialtester gjordes på de olika fraktionerna. Pressning av strimlad blast (13 % TS) gav en vätskefraktion (7 % TS) motsvarande en fjärdedel av våtvikten och 3 fjärdedelar återstod som fast fraktion (15 % TS). Den fasta fraktionen gav dubbelt så högt metanutbyte per kg våtvikt som vätskefraktionen, men ingen signifikant skillnad i metanutbyte per kg organiskt material. Ingen inverkan av sortval på betblastskörden eller metanutbyte per kg organiskt material kunde hittas vid test av fem sockerbetssorter som förädlats fram för sockerproduktion. När fraktionerad blast används kan möjlighet finnas att dubbelanvända lager för den våta fraktionen och rötrest. Det gäller även för andra flytande substrat som behöver lagras. Studien visar att dubbelanvändning kan påverka investeringskostnaderna för rötrestlagret signifikant och en närmare undersökning av om det är praktiskt möjligt vore intressant. När flera positiva faktorer samspelar kan det finnas möjlighet att med dagens förhållanden producera biogas som biodrivmedel från betblast på ett ekonomiskt hållbart sätt. Exempel på identifierade positiva faktorer är: högt blastutbyte, användning av underutnyttjade jordbruksredskap, rötning i befintliga anläggningar för att fylla ut substratluckor, korta transportsträckor och direktanvändning av färsk betblast utan lagring. Det är troligtvis endast för en liten del av den totala mängden blast som tillräckligt många positiva faktorer samspelar för att den idag ska kunna vara ekonomiskt intressant att använda för biogasproduktion.
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| 9. |
- Kreuger, Emma, et al.
(författare)
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Ensiling of crops for biogas production: effects on methane yield and total solids determination
- 2011
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ensiling is a common method of preserving energy crops for anaerobic digestion, and many scientific studies report that ensiling increases the methane yield. In this study, the ensiling process and the methane yields before and after ensiling were studied for four crop materials. Results: The changes in wet weight and total solids (TS) during ensiling were small and the loss of energy negligible. The methane yields related to wet weight and to volatile solids (VS) were not significantly different before and after ensiling when the VS were corrected for loss of volatile compounds during TS and VS determination. However, when the TS were measured according to standard methods and not corrected for losses of volatile compounds, the TS loss during ensiling was overestimated for maize and sugar beet. The same methodological error leads to overestimation of methane yields; when TS and VS were not corrected the methane yield appeared to be 51% higher for ensiled than fresh sugar beet. Conclusions: Ensiling did not increase the methane yield of the studied crops. Published methane yields, as well as other information on silage related to uncorrected amounts of TS and VS, should be regarded with caution.
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| 10. |
- Lantz, Mikael, et al.
(författare)
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An economic comparison of dedicated crops vs agricultural residues as feedstock for biogas of vehicle fuel quality
- 2017
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Ingår i: AIMS Energy. - : American Institute of Mathematical Sciences (AIMS). - 2333-8326 .- 2333-8334. ; 5:5, s. 838-863
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Tidskriftsartikel (refereegranskat)abstract
- The vast majority of the biofuels presently used in the EU are so called first generation biofuels produced from crops. Concerns of food security, displacement of food crop production and indirect land use change (iLUC) has led to the introduction of measures to reduce the use of first generations biofuels and promote so called advanced biofuels based on feedstock that does not compete with food/feed crops, such as waste and agricultural residues. In Sweden, 60% of the biofuel consumption is already based on waste/residual feedstock, and a unique feature of the Swedish biofuel supply is the relatively large use of biogas for transport, representing 9% of the current use of biofuels. The use of waste/residues dominates the biogas production, but agricultural residues, representing a large domestic feedstock potential, are barely used at present. This could indicate that biofuels from such feedstock is non-competitive compared both to fossil fuels and to biofuels produced from crops and waste under existing policy framework. This study show that without subsidies, the production cost of biogas as biofuel from all non-food feedstocks investigated (grass, crop residues and manure) is higher than from food crops. A shift from food crops to residues, as desired according to EU directives, would thus require additional policy instruments favoring advanced biofuel feedstock. Investment or production subsidies must however be substantial in order for biogas from residues to be competitive with biogas from crops.
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