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| 2. |
- Barrios Latorre, Sergio Alejandro, et al.
(författare)
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Exploring the benefits of intermediate crops : Is it possible to offset soil organic carbon losses caused by crop residue removal?
- 2024
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Ingår i: Agricultural Systems. - 0308-521X .- 1873-2267. ; 215
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Agriculture plays a central role as a feedstock provider for the bioeconomy. However, utilization competing with food production and associated land use change have previously been a matter of debate. Nonetheless, strengthening the productivity of agroecosystems through sustainable intensification can prevent the depletion of natural resources, enhance food security, and facilitate adaptation to and mitigation of climate change. OBJECTIVE: This study explores the effects of combining crop residue removal for use as biomass feedstock with the establishment of intermediate crops to compensate for organic carbon depletion in arable land in Sweden. METHODS: The analysis relied on Swedish national agricultural statistics at the highest available spatial resolution (yield survey district). Crop residue calculations factored in crop:residue ratios, and harvestable and recoverable potentials. A model was devised to estimate land availability for cultivating intermediate crops based on generalized crop rotation sequences, and a spatial interpolation was employed to determine oilseed radish yields as a model intermediate crop. Estimates of long-term soil carbon inputs hinged on biomass carbon content and humification coefficients dependent on soil clay content. RESULTS AND CONCLUSION: The total annual residual biomass availability in the country stands at approximately 2139 kt per year. The potential harvestable biomass production from intermediate crops was estimated at 383 kt per year. However, spatial differences were evident in total biomass production and effects on soil organic carbon inputs. For the majority of districts, the inclusion of intermediate crops could offset the negative effect of a complete removal of crop residues on soil organic carbon inputs. In other cases, establishing intermediate crops could not compensate for these negative effects, but some differences were observed when comparing the harvesting and the incorporation of the intermediate crops' biomass. Spatial disparities originated from variations in soil texture, intermediate crop yield, and rotation sequences. SIGNIFICANCE: This research is an attempt to address the challenge of maintaining and increasing the soil carbon stocks under the context of a growing biomass demand in a developing biobased economy. It highlights the divergent effects of combining crop residue removal with the inclusion of intermediate crops under distinct agroecological conditions in the Northern European context. By giving estimates on biomass availability and effects on soil organic carbon inputs, we provide information that can support decision making for bioeconomy planning and sustainable resource utilization. This also has long-term implications for preservation of soil fertility, agricultural productivity and climate change mitigation.
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| 3. |
- Björnsson, Lovisa, et al.
(författare)
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Grass biomass as biofuel feedstock –sustainable or not?
- 2017
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Ingår i: European Biomass Conference and Exhibition Proceedings, 25thEUBCE, June 2017. - 2282-5819. - 9788889407172 ; 2017, s. 39-40
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Konferensbidrag (refereegranskat)abstract
- Low carbon input due to increasing specialization, intensification and reduced use of bio-fertilizer, leads to soil organic carbon (SOC) decreases in arable land. This is an emerging problem in Europe in general, where 45% of the EU soils have low and declining SOC content. SOC losses from agricultural soils influence soil fertility, putting food security at risk, and contributes to greenhouse gas (GHG) emissions. An agricultural practice rendering loss of SOC is thus not sustainable in the long term, and measures must be taken to reverse this trend. However, existing policies for agriculture and biofuels address these issues in isolation, SOC impact is not considered when sustainability criteria for biofuels are defined in the EU renewable energy directive (RED). The aim of this study was to illustrate the relevance of SOC impact on integrated production of food and grass as energy crop for biofuel production. This diversification of current cereal dominated crop rotations proved an efficient tool to reverse SOC losses, simultaneously producing a grass-based biofuel with low climate impact. Since SOC-related aspects are excluded in EU RED, the GHG reduction calculated according to the directive does, however, not meet the 60% GHG reduction demand. This narrow perspective causes potentially interesting double benefits to be missed.
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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- Lantz, Mikael, et al.
(författare)
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Biogas and ethanol from wheat grain or straw : Is there a trade-off between climate impact, avoidance of iLUC and production cost?
- 2018
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Current EU policy calls for decreased emissions of greenhouse gases (GHG) by i.e., replacing fossil fuel in the transportation sector with sustainable biofuels. To avoid indirect land use change (iLUC), the EU at the same time strives to limit the use of crops and to increase the use of residues. In this study we compare climate impact and production cost for biogas and ethanol based on wheat grain and straw, respectively, in a Swedish context. The economic competitiveness for ethanol from straw vs. grain is evaluated based on the mandatory emission reduction for fossil vehicle fuels implemented since July 2018 in Sweden. The result of this study clearly shows that biogas and ethanol from straw have the lowest GHG emissions regardless of the calculation method used, although biofuels from grain also fulfill EU GHG reduction criteria even when suggested iLUC factors are included. It was also shown that the cost of producing straw-based biofuels was higher, thus there is a trade-off between climate impact and costs. The GHG reduction mandate adopted in Sweden partly compensates for this, but is not enough to make ethanol from straw competitive from an economic perspective.
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| 9. |
- Prade, Thomas, et al.
(författare)
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Can domestic production of iLUC-free feedstock from arable land supply Sweden’s future demand for biofuels?
- 2017
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Ingår i: Journal of Land Use Science. - 1747-423X .- 1747-4248. ; 12:6, s. 407-441
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Tidskriftsartikel (refereegranskat)abstract
- The increasing biofuel production from agricultural crops has been suggested to cause indirect land use change (iLUC). This increases interest in biofuel feedstocks that qualify as iLUC-free: (1) residues without a market, (2) crops from previously unused arable land, (3) additional crops and (4) biomass from intensified production. In the present study, biofuel potential from such feedstocks was quantified for Sweden and compared against the predicted biofuel demand from agricultural resources in 2030. The results indicate that straw (category 1) could cover up to 37% of future biofuel demand. Grass leys from intensified production (category 4), set-aside and abandoned land (category 2) and excess grass silage (category 1) could cover up to 79%. Intermediate and ecological focus area crops (category 3) could contribute up to 21%. To realize the biofuel targets, a high implementation rate of additional iLUC-free feedstock is needed. Future studies need to investigate impacts of low-iLUC policies.
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| 10. |
- Prade, Thomas, et al.
(författare)
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EU sustainability criteria for biofuels potentially restrict ley crop production on marginal land for use as biogas substrate
- 2013
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Ingår i: Grassland Science in Europe. ; 18, s. 528-530
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Konferensbidrag (refereegranskat)abstract
- Ley crops can be grown to provide a substrate for biogas vehicle-fuel production on a range of soils including marginal land. According to EU regulations, such biofuel currently has to achieve an emission reduction of 35%, but tightened goals of 50 and 60% will come into effect as early as 2017. In two field trials (one on marginal soil, one on productive soil) ley crop mixtures were tested and the biomass DM yield was determined. In a life-cycle assessment approach, the emissions of the production chain for biogas-vehicle-fuel were estimated for a range of biomass DM yields. The results show that the emission intensity per energy unit of fuel produced is an asymptotic function of the DM yield. Currently, marginal lands not competing with food production can provide biofuels fulfilling the emission reduction requirements. However, a tightening of the goals to 50 or 60% is likely to cause a shift in biomass production towards better soils, potentially causing competition with food and feed production. Alternatively, the CO2 emissions from biomass production of marginal soils need to be further reduced, e.g. by increased nitrogen fixation or reduced machinery use.
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