| 1. |
- 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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| 2. |
- Ivo Achu, Nges, et al.
(författare)
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High methane yields and stable operation during anaerobic digestion of nutrient-supplemented energy crop mixtures
- 2012
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 47, s. 62-70
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Tidskriftsartikel (refereegranskat)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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| 3. |
- 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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| 4. |
- Parawira, Wilson, et al.
(författare)
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Energy production from agricultural residues: high methane yields in pilot scale two-stage anaerobic digestion
- 2008
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 32:1, s. 44-50
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Tidskriftsartikel (refereegranskat)abstract
- There is a large, unutilised energy potential in agricultural waste fractions. In this pilotscale study, the efficiency of a simple two-stage anaerobic digestion process was investigated for stabilisation and biomethanation of solid potato waste and sugar beet leaves, both separately and in co-digestion. A good phase separation between hydrolysis/ acidification and methanogenesis was achieved, as indicated by the high carbon dioxide production, high volatile fatty acid concentration and low pH in the acidogenic reactors. Digestion of the individual substrates gave gross energy yields of 2.1–3.4 kWh/kg VS in the form of methane. Co-digestion, however, gave up to 60% higher methane yield, indicating that co-digestion resulted in improved methane production due to the positive synergism established in the digestion liquor. The integrity of the methane filters (MFs) was maintained throughout the period of operation, producing biogas with 60–78% methane content. A stable effluent pH showed that the methanogenic reactors had good ability to withstand the variations in load and volatile fatty acid concentrations that occurred in the two-stage process. The results of this pilot-scale study show that the two-stage anaerobic digestion system is suitable for effective conversion of semi-solid agricultural residues as potato waste and sugar beet leaves.
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| 5. |
- Sipos, Balint, et al.
(författare)
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Steam pretreatment of dry and ensiled industrial hemp for ethanol production
- 2010
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 34:12, s. 1721-1731
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Tidskriftsartikel (refereegranskat)abstract
- Biomass can be converted into liquid and gaseous biofuels with good efficiency. In this study, the conversion of industrial hemp (Cannabis sativa L.), a biomass source that can be cultivated with a high biomass yield per hectare, was used. Steam pretreatment of dry and ensiled hemp was investigated prior to ethanol production. The pretreatment efficiency was evaluated in terms of sugar recovery and polysaccharide conversion in the enzymatic hydrolysis step. For both materials, impregnation with 2% SO2 followed by steam pretreatment at 210 degrees C for 5 min were found to be the optimal conditions leading to the highest overall yield of glucose. Simultaneous saccharification and fermentation experiments carried out with optimised pretreatment conditions resulted in ethanol yields of 163 g kg(-1) ensiled hemp (dry matter) (71% of the theoretical maximum) and 171 g kg(-1) dry hemp (74%), which corresponds to 206-216 l Mg-1 ethanol based on initial dry material. (C) 2010 Elsevier Ltd. All rights reserved.
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| 6. |
- Pettersson, Malin, et al.
(författare)
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Recycling of ash from co-incineration of waste wood and forest fuels: An overlooked challenge in a circular bioenergy system
- 2020
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 0961-9534. ; 142C
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Tidskriftsartikel (refereegranskat)abstract
- Wood ash recycling to forests after logging residues harvest is important to ensure long-term sustainable forest management, however, it is not recycled in Sweden at the level required to compensate for current logging residue out-take. A problem in this context is wood ash contamination through co-incineration of waste wood with forest fuels, a practice driven by the political goal of a circular bioenergy system. We performed a case study of co-incineration at a typical Swedish district heating (DH) plant, which showed that the forest fuel ash alone could be recycled to forests due to high nutrient levels. Co-incineration with waste wood resulted however in such high levels of contaminants that the ash was landfilled as hazardous waste. Our assessment of the Swedish DH sector showed that wood ash contamination through co-incineration is common, and that only a minor proportion of the ash from forest fuels is recycled to the forest. It also revealed a lack of reliable data regarding ash production and management, making implementation and evaluation of effective countermeasures difficult. Practical measures to enable wood ash recycling, such as removal of waste wood from the fuel mix, incineration of separate fuels, and ash after-treatment, are hampered by technical and economic barriers. Furthermore, no comprehensive policy tools currently exist on either a national or EU level that facilitate wood ash recycling. Thus, we conclude that comprehensive and efficient policy tools are urgently needed to overcome current barriers, and stimulate large-scale recycling of wood ash for long-term sustainable forest fuel utilisation.
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