| 1. |
- Alvors, Per, et al.
(författare)
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Research and development challenges for Swedish biofuel actors – three illustrative examples : Improvement potential discussed in the context of Well-to-Tank analyses
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Currently biofuels have strong political support, both in the EU and Sweden. The EU has, for example, set a target for the use of renewable fuels in the transportation sector stating that all EU member states should use 10% renewable fuels for transport by 2020. Fulfilling this ambition will lead to an enormous market for biofuels during the coming decade. To avoid increasing production of biofuels based on agriculture crops that require considerable use of arable area, focus is now to move towards more advanced second generation (2G) biofuels that can be produced from biomass feedstocks associated with a more efficient land use.Climate benefits and greenhouse gas (GHG) balances are aspects often discussed in conjunction with sustainability and biofuels. The total GHG emissions associated with production and usage of biofuels depend on the entire fuel production chain, mainly the agriculture or forestry feedstock systems and the manufacturing process. To compare different biofuel production pathways it is essential to conduct an environmental assessment using the well-to-tank (WTT) analysis methodology.In Sweden the conditions for biomass production are favourable and we have promising second generation biofuels technologies that are currently in the demonstration phase. In this study we have chosen to focus on cellulose based ethanol, methane from gasification of solid wood as well as DME from gasification of black liquor, with the purpose of identifying research and development potentials that may result in improvements in the WTT emission values. The main objective of this study is thus to identify research and development challenges for Swedish biofuel actors based on literature studies as well as discussions with the the researchers themselves. We have also discussed improvement potentials for the agriculture and forestry part of the WTT chain. The aim of this study is to, in the context of WTT analyses, (i) increase knowledge about the complexity of biofuel production, (ii) identify and discuss improvement potentials, regarding energy efficiency and GHG emissions, for three biofuel production cases, as well as (iii) identify and discuss improvement potentials regarding biomass supply, including agriculture/forestry. The scope of the study is limited to discussing the technologies, system aspects and climate impacts associated with the production stage. Aspects such as the influence on biodiversity and other environmental and social parameters fall beyond the scope of this study.We find that improvement potentials for emissions reductions within the agriculture/forestry part of the WTT chain include changing the use of diesel to low-CO2-emitting fuels, changing to more fuel-efficient tractors, more efficient cultivation and manufacture of fertilizers (commercial nitrogen fertilizer can be produced in plants which have nitrous oxide gas cleaning) as well as improved fertilization strategies (more precise nitrogen application during the cropping season). Furthermore, the cultivation of annual feedstock crops could be avoided on land rich in carbon, such as peat soils and new agriculture systems could be introduced that lower the demand for ploughing and harrowing. Other options for improving the WTT emission values includes introducing new types of crops, such as wheat with higher content of starch or willow with a higher content of cellulose.From the case study on lignocellulosic ethanol we find that 2G ethanol, with co-production of biogas, electricity, heat and/or wood pellet, has a promising role to play in the development of sustainable biofuel production systems. Depending on available raw materials, heat sinks, demand for biogas as vehicle fuel and existing 1G ethanol plants suitable for integration, 2G ethanol production systems may be designed differently to optimize the economic conditions and maximize profitability. However, the complexity connected to the development of the most optimal production systems require improved knowledge and involvement of several actors from different competence areas, such as chemical and biochemical engineering, process design and integration and energy and environmental systems analysis, which may be a potential barrier.Three important results from the lignocellulosic ethanol study are: (i) the production systems could be far more complex and intelligently designed than previous studies show, (ii) the potential improvements consist of a large number of combinations of process integration options wich partly depends on specific local conditions, (iii) the environmental performance of individual systems may vary significantly due to systems design and local conditons.From the case study on gasification of solid biomass for the production of biomethane we find that one of the main advantages of this technology is its high efficiency in respect to converting biomass into fuels for transport. For future research we see a need for improvements within the gas up-grading section, including gas cleaning and gas conditioning, to obtain a more efficient process. A major challenge is to remove the tar before the methanation reaction.Three important results from the biomethane study are: (i) it is important not to crack the methane already produced in the syngas, which indicates a need for improved catalysts for selective tar cracking, (ii) there is a need for new gas separation techniques to facilitate the use of air oxidation agent instead of oxygen in the gasifier, and (iii) there is a need for testing the integrated process under realistic conditions, both at atmospheric and pressurized conditions.From the case study on black liquor gasification for the production of DME we find that the process has many advantages compared to other biofuel production options, such as the fact that black liquor is already partially processed and exists in a pumpable, liquid form, and that the process is pressurised and tightly integrated with the pulp mill, which enhances fuel production efficiency. However, to achieve commercial status, some challenges still remain, such as demonstrating that materials and plant equipment meet the high availability required when scaling up to industrial size in the pulp mill, and also proving that the plant can operate according to calculated heat and material balances. Three important results from the DME study are: (i) that modern chemical pulp mills, having a potential surplus of energy, could become important suppliers of renewable fuels for transport, (ii) there is a need to demonstrate that renewable DME/methanol will be proven to function in large scale, and (iii) there is still potential for technology improvements and enhanced energy integration.Although quantitative improvement potentials are given in the three biofuel production cases, it is not obvious how these potentials would affect WTT values, since the biofuel production processes are complex and changing one parameter impacts other parameters. The improvement potentials are therefore discussed qualitatively. From the entire study we have come to agree on the following common conclusions: (i) research and development in Sweden within the three studied 2G biofuel production technologies is extensive, (ii) in general, the processes, within the three cases, work well at pilot and demonstration scale and are now in a phase to be proven in large scale, (iii) there is still room for improvement although some processes have been known for decades, (iv) the biofuel production processes are complex and site specific and process improvements need to be seen and judged from a broad systems perspective (both within the production plant as well as in the entire well-to-tank perspective), and (v) the three studied biofuel production systems are complementary technologies. Futher, the process of conducting this study is worth mentioning as a result itself, i.e. that many different actors within the field have proven their ability and willingness to contribute to a common report, and that the cooperation climate was very positive and bodes well for possible future collaboration within the framework of the f3 center.Finally, judging from the political ambitions it is clear that the demand for renewable fuels will significantly increase during the coming decade. This will most likely result in opportunities for a range of biofuel options. The studied biofuel options all represent 2G biofuels and they can all be part of the solution to meet the increased renewable fuel demand.
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| 2. |
- Ahlberg, Erik, et al.
(författare)
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"Vi klimatforskare stödjer Greta och skolungdomarna"
- 2019
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Ingår i: Dagens nyheter (DN debatt). - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- DN DEBATT 15/3. Sedan industrialiseringens början har vi använt omkring fyra femtedelar av den mängd fossilt kol som får förbrännas för att vi ska klara Parisavtalet. Vi har bara en femtedel kvar och det är bråttom att kraftigt reducera utsläppen. Det har Greta Thunberg och de strejkande ungdomarna förstått. Därför stödjer vi deras krav, skriver 270 klimatforskare.
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| 3. |
- Björnsson, Lovisa, et al.
(författare)
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Introduction of grass-clover crops as biogas feedstock in cereal-dominated crop rotations. Part II: Effects on greenhouse gas emissions
- 2014
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Ingår i: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector. - 9780988214576 ; , s. 134-141
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Konferensbidrag (refereegranskat)abstract
- In an analysis of climate effects, increased soil organic carbon will have a dual effect due to both increased soil fertility and carbon sequestration. Even so, soil carbon changes are neglected in many crop production LCAs. In the present study, the introduction of grass-clover crops in cereal-dominated crop production was evaluated. The grass-clover crops were used for biogas production, and the digested residue was recycled to the farm as biofertilizer. A shift from the cereal-dominated crop rotation to integrated production of food crops and one or two years of grass-clover crops used as biogas feedstock would result in avoided emissions of 2-3 t CO2-eq. ha-1 a-1. Integrated food and energy crop production would in this case improve soil organic carbon content at the same time as resulting in considerably decreased greenhouse gas emissions from the cultivation system.
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| 4. |
- 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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| 5. |
- Prade, Thomas, et al.
(författare)
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Including a one-year grass ley increases soil organic carbon and decreases greenhouse gas emissions from cereal-dominated rotations – A Swedish farm case study
- 2017
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Ingår i: Biosystems Engineering. - : Elsevier BV. - 1537-5110 .- 1537-5129. ; 164, s. 200-212
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Tidskriftsartikel (refereegranskat)abstract
- Increased soil organic carbon (SOC) content has been shown to increase soil fertility and carbon sequestration, but SOC changes are frequently neglected in life cycle assessment (LCA) studies of crop production. This study used a novel LCA application using simulated SOC changes to examine the greenhouse gas (GHG) impact of a combined food and energy crop production from a crop rotation perspective. On a case pig farm, introduction of one year of grass ley into a cereal-dominated crop rotation was simulated. The grass and pig manure were used for biogas production and the digestion residues were used as fertiliser on the farm. This crop rotation shift increased the SOC stocks by an estimated 27 and 49% after 50 years and at steady state, respectively. The estimated corresponding net wheat yield increase due to higher SOC was 8–16% and 16–32%, respectively, indicating that initial loss of low-yield oat production can be partly counterbalanced. Net SOC increase (corresponding to 2 t CO2-eq ha−1 a−1) was the single most important variable affecting the GHG balance. When biogas replaced fossil fuels, GHG emissions of the combined energy-food crop rotation were approx. 3 t CO2-eq ha−1 a−1 lower than for the current food crop rotation. Sensitivity analyses led to variation of only 2–9% in the GHG balance. This study indicates that integrated food and energy crop production can improve SOC content and decrease GHG emissions from cropping systems. It also demonstrates the importance of including SOC changes in crop production-related LCA studies.
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| 6. |
- Prade, Thomas, et al.
(författare)
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Introduction of grass-clover crops as biogas feedstock in cereal dominated crop rotations. Part I: Effects on soil organic carbon and food production
- 2014
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Ingår i: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector. - 9780988214576 ; , s. 1032-1040
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Konferensbidrag (refereegranskat)abstract
- Changes of soil organic carbon (SOC) ontent can have a substantial effect on greenhouse gas emissions, but are rarely included in cropproduction LCAs. SOC content strongly influences soil fertility and therefore crop yields, but is declining in many European soils. The present study investigated if integration of 1-2 years of grass-clover crops in a cereal-dominated crop rotation can increase the SOC pool and how this would impact food production. Results show that when grass-clover crops are integrated, the potential SOC content at steady state will be 41 to 52% higher than in the conventional cereal-dominated crop rotation. The net increase of wheat yields based on SOC improvements indicate that for a crop rotation with one year of grass-clover crops, the initial loss of food production can be counterbalanced due to the impact on fertility of the SOC increase.
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| 7. |
- Prade, Thomas, et al.
(författare)
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Sustainable Cereal Straw Management: Use as Feedstock for Emerging Biobased Industries or Cropland Soil Incorporation?
- 2021
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Ingår i: Waste and Biomass Valorization. - : Springer Science and Business Media LLC. - 1877-2641 .- 1877-265X. ; 12, s. 5649-5663
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Tidskriftsartikel (refereegranskat)abstract
- Sustainability goals regarding biobased chemicals and fuels can lead to increased demand for cereal straw, which could lead to undesirable effects on soil organic matter (SOM) content. The aim of this study was to evaluate the effects of removing straw on SOM, using a life cycle approach based on agricultural statistics and soil carbon modelling. This regional evaluation in southern Sweden showed that the general restrictions on straw removal recommended in many European studies, with demands on the incorporation of at least half of the aboveground straw, is not an efficient means of SOM preservation. Unrestricted straw removal in combination with the cultivation of intermediate crops leads to a much higher SOM build-up. Such measures will increase the availability of removable straw 2.5 times, at little extra cost. The findings of this study demonstrate the necessity of regional evaluation, taking new findings on the impact of straw incorporation on SOM into consideration. This is important for both regional emerging biobased industries, where unnecessary restrictions on straw removal might hamper the development of new production pathways, and for future sustainability in agriculture, where well-intended but inefficient SOM preservation strategies might hinder the implementation of more efficient measures.[GRAPHICS].
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| 8. |
- Svensson, Mattias, et al.
(författare)
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Biogas production from crop residues on a farm-scale level: is it economically feasible under conditions in Sweden?
- 2005
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Ingår i: Bioprocess and Biosystems Engineering. - : Springer Science and Business Media LLC. - 1615-7605 .- 1615-7591. ; 28:3, s. 139-148
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion would enable the energy potential of agricultural crop residues such as sugar beet tops and straw to be harnessed. Sweden is so spread out that full utilisation of this potential by centralised slurry-based technology is difficult. It appears that simple but effective high-solids reactor systems have a better chance of being economically viable on a farm-scale level (50500 kW). In the present study, the financial prospects of high-solids digestion, using either single-stage fed-batch or two-stage batch reactor systems, are compared on a farm-scale level (50 kW) with those of conventional slurry digestion, on the basis of experimental results and observations on a laboratory- and pilot-scale. The gas produced can be used for heat, combined heat and power or as vehicle fuel. The results indicate high-solids single-stage fed-batch operations to stand the best chances of being competitive, particularly in connection with organic farming. The methane yield, degree of gas utilisation, and operational costs were found to have the strongest impact on the financial success of the process.
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