| 51. |
- Gissén, Charlott, et al.
(author)
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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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In: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 64, s. 199-210
-
Journal article (peer-reviewed)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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| 52. |
- Haus, Sylvia, et al.
(author)
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Lignocellulosic Ethanol in a Greenhouse Gas Emission Reduction Obligation System : A Case Study of Swedish Sawdust Based-Ethanol Production
- 2020
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In: Energies. - : MDPI. - 1996-1073. ; 13:5
-
Journal article (peer-reviewed)abstract
- A greenhouse gas (GHG) emission reduction obligation system has been implemented in the Swedish road transport sector to promote the use of biofuels. For transportation fuel suppliers to fulfil this obligation, the volume of biofuel required decreases with decreasing life cycle GHG emission for the biofuel, linking lower GHG emission to higher economic value. The aim of this study was to investigate how the economic competitiveness of a Swedish emerging lignocellulosic-based ethanol production system would be influenced by the reduction obligation. The life cycle GHG emission for sawdust-based ethanol was calculated by applying the method advocated in the EU Renewable Energy Directive (RED II). The saving in GHG emissions, compared with fossil liquid transportation fuels, was 93% for a potential commercial production system in southern Sweden. This, in turn, will increase the competitiveness of sawdust-based ethanol compared to the mainly crop-based ethanol currently used in the Swedish biofuel system, which has an average GHG emission saving of 68%, and will allow for an almost 40% higher price of sawdust-based ethanol, compared to the current price of ethanol at point of import. In a future developed, large-scale market of advanced ethanol, today’s GHG emission reduction obligation system in Sweden seems to afford sufficient economic advantage to make lignocellulosic ethanol economically viable. However, in a short-term perspective, emerging lignocellulosic-based ethanol production systems are burdened with economic risks and therefore need additional economic incentives to make a market introduction possible.
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| 53. |
- Ivo Achu, Nges, et al.
(author)
-
Benefits of supplementing an industrial waste anaerobic digester with energy crops for increased biogas production.
- 2012
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In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 32:1, s. 53-59
-
Journal article (peer-reviewed)abstract
- Currently, there is increasing competition for waste as feedstock for the growing number of biogas plants. This has led to fluctuation in feedstock supply and biogas plants being operated below maximum capacity. The feasibility of supplementing a protein/lipid-rich industrial waste (pig manure, slaughterhouse waste, food processing and poultry waste) mesophilic anaerobic digester with carbohydrate-rich energy crops (hemp, maize and triticale) was therefore studied in laboratory scale batch and continuous stirred tank reactors (CSTR) with a view to scale-up to a commercial biogas process. Co-digesting industrial waste and crops led to significant improvement in methane yield per ton of feedstock and carbon-to-nitrogen ratio as compared to digestion of the industrial waste alone. Biogas production from crops in combination with industrial waste also avoids the need for micronutrients normally required in crop digestion. The batch co-digestion methane yields were used to predict co-digestion methane yield in full scale operation. This was done based on the ratio of methane yields observed for laboratory batch and CSTR experiments compared to full scale CSTR digestion of industrial waste. The economy of crop-based biogas production is limited under Swedish conditions; therefore, adding crops to existing industrial waste digestion could be a viable alternative to ensure a constant/reliable supply of feedstock to the anaerobic digester.
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| 54. |
- Ivo Achu, Nges, et al.
(author)
-
High methane yields and stable operation during anaerobic digestion of nutrient-supplemented energy crop mixtures
- 2012
-
In: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 47, s. 62-70
-
Journal article (peer-reviewed)abstract
- The feasibility of digesting energy crops supplemented with macro- and micronutrients instead of manure, without the commonly applied long hydraulic retention time (HRT), was investigated in long-term, single-stage continuous stirred tank processes. The crops used were mixtures of sugar beets, maize and whole crop triticale. The organic loading rate (OLR) measured as a total solid (TS) was 1.5-5.5 kg m(-3) d(-1) and the HRT from 30 to 40 days. The results showed high methane yields, comparable to those in batch digestion, and high stability. The digestion of beets only was most stable, and showed the highest average TS-based methane yield (383 +/- 26 m(3) kg(-1)) at an OLR of 4.5 kg m(-3) d(-1) and a HRT of 40 days. No significant difference in methane yield was found for all the crop mixtures during stable operation. Nutrient addition therefore showed the same stimulatory and stabilising effects as manure with high methane yields achieved at relatively short HRTs. (c) 2012 Elsevier Ltd. All rights reserved.
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| 55. |
- Ivo Achu, Nges, et al.
(author)
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Improved utilization of fish waste by anaerobic digestion following omega-3 fatty acids extraction.
- 2012
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In: Journal of Environmental Management. - : Elsevier BV. - 0301-4797. ; 110, s. 159-165
-
Journal article (peer-reviewed)abstract
- Fish waste is a potentially valuable resource from which high-value products can be obtained. Anaerobic digestion of the original fish waste and the fish sludge remaining after enzymatic pre-treatment to extract fish oil and fish protein hydrolysate was evaluated regarding the potential for methane production. The results showed high biodegradability of both fish sludge and fish waste, giving specific methane yields of 742 and 828 m(3)CH(4)/tons VS added, respectively. However, chemical analysis showed high concentrations of light metals which, together with high fat and protein contents, could be inhibitory to methanogenic bacteria. The feasibility of co-digesting the fish sludge with a carbohydrate-rich residue from crop production was thus investigated, and a full-scale process outlined for converting odorous fish waste to useful products.
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| 56. |
- Ivo Achu, Nges, et al.
(author)
-
Stable operation during pilot-scale anaerobic digestion of nutrient-supplemented maize/sugar beet silage
- 2012
-
In: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 118, s. 445-454
-
Journal article (peer-reviewed)abstract
- Biogas production from maize/sugar beet silage was studied under mesophilic conditions in a continuous stirred tank reactor pilot-scale process. While energy crop mono-digestion is often performed with very long hydraulic retention times (HRTs), the present study demonstrated an efficient process operating with a 50-day HRT and a corrected total solids (TScorr) based organic loading rate of 3.4 kg/m3×d. The good performance was attributed to supplementation with both macro- and micronutrients and was evidenced by good methane yields (318 m3/ton TScorr) which were comparable to laboratory maximum expected yields plus low total volatile fatty acid concentrations (< 0.8 g/L). A viscoplastic and thixotropic digester fluid behaviour was observed, and the viscosity problems common in crop mono-digestion were not seen in this study. The effluent also complied with Swedish certification standards for bio-fertilizer for farmland application. Nutrient addition thus rendered a stable biogas process, while the effluent was a good quality bio-fertilizer.
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| 57. |
- Kreuger, Emma, et al.
(author)
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Anaerobic digestion of industrial hemp-Effect of harvest time on methane energy yield per hectare
- 2011
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In: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 35:2, s. 893-900
-
Journal article (peer-reviewed)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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| 58. |
- Kreuger, Emma, et al.
(author)
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Bioconversion of industrial hemp to ethanol and methane: The benefits of steam pretreatment and co-production
- 2011
-
In: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 102:3, s. 3457-3465
-
Journal article (peer-reviewed)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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| 59. |
- Kreuger, Emma, et al.
(author)
-
Biogas från Skånsk betblast - potential, teknik och ekonomi
- 2014
-
Reports (pop. science, debate, etc.)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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| 60. |
- Kreuger, Emma, et al.
(author)
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Ensiling of crops for biogas production: effects on methane yield and total solids determination
- 2011
-
In: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834. ; 4
-
Journal article (peer-reviewed)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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