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- 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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| 2. |
- 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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| 3. |
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| 4. |
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| 5. |
- 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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| 6. |
- 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
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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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