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Hammar, T., Stendahl, J., Sundberg, C., Holmström, H. & Hansson, P.-A. (2019). Climate impact and energy efficiency of woody bioenergy systems from a landscape perspective. Biomass and Bioenergy, 120, 189-199
Open this publication in new window or tab >>Climate impact and energy efficiency of woody bioenergy systems from a landscape perspective
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2019 (English)In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 120, p. 189-199Article in journal (Refereed) Published
Abstract [en]

The climate impact of bioenergy is debated, especially due to potential land use change effects and biogenic carbon fluxes. This study assessed the climate impact and energy efficiency of conventional long-rotation forest residues (branches, tops and stumps) and short-rotation forestry (willow) from a landscape perspective. A time-dependent life cycle assessment method, which considers the timing of biogenic carbon fluxes and the impact on global temperature over time, was combined with GIS mapping to assess the impact for a specific Swedish region (Uppsala County), i.e. a 'real' landscape. The results showed that harvesting forest residues decreased the forest carbon stocks over the landscape, while growing willow on previous fallow land increased the total carbon stocks. On average, energy ratios of 49 MJ MJ(-1) for branches and tops, and 30 MJ MJ(-1) for stumps and willow was found. Harvesting forest residues from the studied landscape resulted in climate impacts of around 0.8.10(-15) K MJ(-1) heat for branches and tops, and 1.3.10(-15) K MJ(-1) heat for stumps. Willow energy gave the lowest climate impact of about -0.6,10(-15) K MJ(-1) heat. The landscape analysis showed that spatial variations in the region had an effect on energy efficiency and climate impact, but that this effect was relatively small. A more important factor was the time frame chosen for the analysis, especially for long-rotation forest systems. Methodological choices such as spatial scale (stand or landscape perspective), allocation method and functional unit also influenced the results.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Global warming, Temperature change, Soil organic carbon, Salix, GIS, Forest residues, Stumps, Land use, Biogenic carbon, LCA
National Category
Other Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-242253 (URN)10.1016/j.biombioe.2018.11.026 (DOI)000454887700019 ()2-s2.0-85057143425 (Scopus ID)
Note

QC 20190131

Available from: 2019-01-31 Created: 2019-01-31 Last updated: 2019-01-31Bibliographically approved
Henryson, K., Sundberg, C., Kätterer, T. & Hansson, P.-A. -. (2018). Accounting for long-term soil fertility effects when assessing the climate impact of crop cultivation. Agricultural Systems, 164, 185-192
Open this publication in new window or tab >>Accounting for long-term soil fertility effects when assessing the climate impact of crop cultivation
2018 (English)In: Agricultural Systems, ISSN 0308-521X, E-ISSN 1873-2267, Vol. 164, p. 185-192Article in journal (Refereed) Published
Abstract [en]

Soil organic carbon (SOC) dynamics influence the climate impact of crop cultivation, both through affecting net carbon exchange between the soil and the atmosphere and through affecting soil fertility. Higher soil fertility can enhance yield, and consequently make more plant residues available for carbon sequestration in the soil. This feedback mechanism between SOC and yield is commonly not included when assessing the environmental impact of crop production using system analysis tools like life cycle assessment (LCA). Therefore, this study developed a modelling framework where the SOC-yield feedback mechanism is included in climate impact assessment of crop cultivation, and which could be applied in LCAs. The framework was constructed by combining a model for SOC dynamics, yield response to SOC changes in a Swedish long-term field experiment and climate impact assessment. The framework employs a dynamic approach, with a time-distributed emissions inventory and a time-dependent climate impact assessment model, complemented by the most common climate metric, global warming potential (GWP). A case study applying the framework to barley cultivation was performed to explore the quantitative effect of including the feedback mechanism on the calculated climate impact. The case study involved simulating a fertiliser-induced 10% yield increase during one year and assessing the climate impact over 100 years. The effect of solely including SOC dynamics without the yield response to SOC decreased climate impact per kg barley by about three-fold more than only accounting for the 10% temporary yield increase. When the feedback mechanism was included, the estimated climate impact decreased five-fold more than when SOC changes were not included. These results show that SOC changes affect the climate impact of cultivation, not only through affecting net CO2 exchanges between soil and atmosphere, as previously acknowledged by other studies, but also through changing the system performance. The quantitative results obtained in this study show that this could be an important aspect to include in order to avoid introducing systematic error when assessing the long-term climate impact of crop management changes that affect yield or SOC dynamics.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Carbon sequestration, Crop yield, Greenhouse gases, Life cycle assessment, Soil organic carbon, Soil quality
National Category
Environmental Sciences related to Agriculture and Land-use
Identifiers
urn:nbn:se:kth:diva-228728 (URN)10.1016/j.agsy.2018.03.001 (DOI)000437075800017 ()2-s2.0-85046621642 (Scopus ID)
Funder
Swedish Research Council Formas, 229-2013-82
Note

QC 20180529

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-07-23Bibliographically approved
Roos, E., Mie, A., Wivstad, M., Salomon, E., Johansson, B., Gunnarsson, S., . . . Watson, C. A. (2018). Risks and opportunities of increasing yields in organic farming. A review. Agronomy for Sustainable Development, 38(2), Article ID 14.
Open this publication in new window or tab >>Risks and opportunities of increasing yields in organic farming. A review
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2018 (English)In: Agronomy for Sustainable Development, ISSN 1774-0746, E-ISSN 1773-0155, Vol. 38, no 2, article id 14Article, review/survey (Refereed) Published
Abstract [en]

Current organic agriculture performs well in several sustainability domains, like animal welfare, farm profitability and low pesticide use, but yields are commonly lower than in conventional farming. There is now a re-vitalized interest in increasing yields in organic agriculture to provide more organic food for a growing, more affluent population and reduce negative impacts per unit produced. However, past yield increases have been accompanied by several negative side-effects. Here, we review risks and opportunities related to a broad range of sustainability domains associated with increasing yields in organic agriculture in the Northern European context. We identify increased N input, weed, disease and pest control, improved livestock feeding, breeding for higher yields and reduced losses as the main measures for yield increases. We review the implications of their implementation for biodiversity, greenhouse gas emissions, nutrient losses, soil fertility, animal health and welfare, human nutrition and health and farm profitability. Our findings from this first-of-its-kind integrated analysis reveal which strategies for increasing yields are unlikely to produce negative side-effects and therefore should be a high priority, and which strategies need to be implemented with great attention to trade-offs. For example, increased N inputs in cropping carry many risks and few opportunities, whereas there are many risk-free opportunities for improved pest control through the management of ecosystem services. For most yield increasing strategies, both risks and opportunities arise, and the actual effect depends on management including active mitigation of side-effects. Our review shows that, to be a driving force for increased food system sustainability, organic agriculture may need to reconsider certain fundamental principles. Novel plant nutrient sources, including increased nutrient recycling in society, and in some cases mineral nitrogen fertilisers from renewable sources, and truly alternative animal production systems may need to be developed and accepted.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Organic agriculture, Yield, Biodiversity, Soil fertility, Animal welfare, Nutrition, Environment
National Category
Environmental Sciences related to Agriculture and Land-use
Identifiers
urn:nbn:se:kth:diva-227235 (URN)10.1007/s13593-018-0489-3 (DOI)000430228400008 ()2-s2.0-85042867508 (Scopus ID)
Note

QC 20180518

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2018-05-18Bibliographically approved
Henryson, K., Hansson, P.-A. & Sundberg, C. (2018). Spatially differentiated midpoint indicator for marine eutrophication of waterborne emissions in Sweden. The International Journal of Life Cycle Assessment, 23(1), 70-81
Open this publication in new window or tab >>Spatially differentiated midpoint indicator for marine eutrophication of waterborne emissions in Sweden
2018 (English)In: The International Journal of Life Cycle Assessment, ISSN 0948-3349, E-ISSN 1614-7502, Vol. 23, no 1, p. 70-81Article in journal (Refereed) Published
Abstract [en]

In life cycle assessment (LCA), eutrophication is commonly assessed using site-generic characterisation factors, despite being a site-dependent environmental impact. The purpose of this study was to improve the environmental relevance of marine eutrophication impact assessment in LCA, particularly regarding the impact assessment of waterborne nutrient emissions from Swedish agriculture. Characterisation factors were derived using site-dependent data on nutrient transport for all agricultural soils in Sweden, divided into 968 catchment areas, and considering the Baltic Sea, the receiving marine compartment, as both nitrogen- and phosphorus-limited. These new characterisation factors were then applied to waterborne nutrient emissions from typical grass ley and spring barley cultivation in all catchments. The site-dependent marine eutrophication characterisation factors obtained for nutrient leaching from soils varied between 0.056 and 0.986 kg N-eq/kg N and between 0 and 7.23 kg N-eq/kg P among sites in Sweden. On applying the new characterisation factors to spring barley and grass ley cultivation at different sites in Sweden, the total marine eutrophication impact from waterborne nutrient emissions for these crops varied by up to two orders of magnitude between sites. This variation shows that site plays an important role in determining the actual impact of an emission, which means that site-dependent impact assessment could provide valuable information to life cycle assessments and increase the relevance of LCA as a tool for assessment of product-related eutrophication impacts. Characterisation factors for marine eutrophication impact assessment at high spatial resolution, considering both the site-dependent fate of eutrophying compounds and specific nutrient limitations in the recipient waterbody, were developed for waterborne nutrient emissions from agriculture in Sweden. Application of the characterisation factors revealed variations in calculated impacts between sites in Sweden, highlighting the importance of spatial differentiation of characterisation modelling within the scale of the impact.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2018
Keywords
Baltic Sea, Characterisation factors, Fate, LCIA, Life cycle assessment, Life cycle impact assessment, Nutrient limitation, Site-dependent
National Category
Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-240259 (URN)10.1007/s11367-017-1298-7 (DOI)000419167100006 ()2-s2.0-85014916549 (Scopus ID)
Note

QC 20181213

Available from: 2018-12-13 Created: 2018-12-13 Last updated: 2018-12-13Bibliographically approved
Hammar, T., Sundberg, C., Stendahl, J., Larsolle, A. & Hansson, P.-A. -. (2017). Life cycle assessment of climate impact of bioenergy from a landscape. In: European Biomass Conference and Exhibition Proceedings 2017: . Paper presented at European Biomass Conference and Exhibition 2017 (pp. 1493-1497). ETA-Florence Renewable Energies, 2017(25thEUBCE)
Open this publication in new window or tab >>Life cycle assessment of climate impact of bioenergy from a landscape
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2017 (English)In: European Biomass Conference and Exhibition Proceedings 2017, ETA-Florence Renewable Energies , 2017, Vol. 2017, no 25thEUBCE, p. 1493-1497Conference paper, Published paper (Refereed)
Abstract [en]

Bioenergy is a renewable energy source that can replace fossil energy sources in order to decrease greenhouse gas emissions. Assessing the climate impact of bioenergy systems involves methodological choices that may influence the result. Choice of climate metric is one example that has been discussed in several papers recently, and choice of spatial scale is another factor that can impact the results. In this paper, different types of spatial scales (stand, theoretical landscape and real landscape) were used for assessing the time-dependent climate impact of bioenergy from short-rotation coppice willow and stumps harvested from conventional forests in Sweden. The result showed that the spatial scale has importance for the climate impact, especially for long-rotation forestry. However, the climate impact of both types of bioenergy systems was lower than for fossil coal over time, independently of spatial scale used. A landscape perspective was considered to be most relevant from a climate policy perspective.

Place, publisher, year, edition, pages
ETA-Florence Renewable Energies, 2017
Series
European Biomass Conference and Exhibition Proceedings, ISSN 2282-5819 ; 2017
Keywords
Forest residues, Geographical information system (GIS), Land use, Willow
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-224856 (URN)2-s2.0-85043771808 (Scopus ID)
Conference
European Biomass Conference and Exhibition 2017
Funder
Swedish Energy Agency, (project 36089-1 and 41976-1)
Note

QC 20180327

Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2018-03-27Bibliographically approved
Njenga, M., Mahmoud, Y., Mendum, R., Iiyama, M., Jamnadass, R., de Nowina, K. R. & Sundberg, C. (2017). Quality of charcoal produced using micro gasification and how the new cook stove works in rural Kenya. Environmental Research Letters, 12(9), Article ID 095001.
Open this publication in new window or tab >>Quality of charcoal produced using micro gasification and how the new cook stove works in rural Kenya
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2017 (English)In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 12, no 9, article id 095001Article in journal (Refereed) Published
Abstract [en]

Wood based energy is the main source of cooking and heating fuel in Sub-Saharan Africa. Its use rises as the population increases. Inefficient cook stoves result in fuel wastage and health issues associated with smoke in the kitchen. As users are poor women, they tend not to be consulted on cook stove development, hence the need for participatory development of efficient woodfuel cooking systems. This paper presents the findings of a study carried out in Embu, Kenya to assess energy use efficiency and concentrations of carbon monoxide and fine particulate matter from charcoal produced using gasifier cook stoves, compared to conventional wood charcoal. Charcoal made from Grevillea robusta prunings, Zea mays cob (maize cob) and Cocos nucifera (coconut shells) had calorific values of 26.5 kJ g(-1), 28.7 kJ g-1 and 31.7 kJ g(-1) respectively, which are comparable to conventional wood charcoal with calorific values of 33.1 kJ g(-1). Cooking with firewood in a gasifier cook stove and use of the resultant charcoal as by-product to cook another meal in a conventional charcoal stove saved 41% of the amount of fuel compared to cooking with firewood in the traditional three stone open fire. Cooking with firewood based on G. robusta prunings in the traditional open fire resulted in a concentration of fine particulate matter of 2600 mu g m(-3), which is more than 100 times greater than from cooking with charcoal made from G. robusta prunings in a gasifier. Thirty five percent of households used the gasifier for cooking dinner and lunch, and cooks preferred using it for food that took a short time to prepare. Although the gasifier cook stove is energy and emission efficient there is a need for it to be developed further to better suit local cooking preferences. The energy transition in Africa will have to include cleaner and more sustainable wood based cooking systems.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
charcoal, gasifier cook stove, indoor air pollution, woodfuel cooking systems
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-214320 (URN)10.1088/1748-9326/aa7499 (DOI)000408262300001 ()
Note

QC 20170914

Available from: 2017-09-14 Created: 2017-09-14 Last updated: 2017-11-29Bibliographically approved
Ericsson, N., Sundberg, C., Nordberg, Å., Ahlgren, S. & Hansson, P.-A. -. (2017). Time-dependent climate impact and energy efficiency of combined heat and power production from short-rotation coppice willow using pyrolysis or direct combustion. Global Change Biology Bioenergy, 9(5), 876-890
Open this publication in new window or tab >>Time-dependent climate impact and energy efficiency of combined heat and power production from short-rotation coppice willow using pyrolysis or direct combustion
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2017 (English)In: Global Change Biology Bioenergy, ISSN 1757-1693, E-ISSN 1757-1707, Vol. 9, no 5, p. 876-890Article in journal (Refereed) Published
Abstract [en]

A life cycle assessment of a Swedish short-rotation coppice willow bioenergy system generating electricity and heat was performed to investigate how the energy efficiency and time-dependent climate impact were affected when the feedstock was converted into bio-oil and char before generating electricity and heat, compared with being combusted directly. The study also investigated how the climate impact was affected when part of the char was applied to soil as biochar to act as a carbon sequestration agent and potential soil improver. The energy efficiencies were calculated separately for electricity and heat as the energy ratios between the amount of energy service delivered by the system compared to the amount of external energy inputs used in each scenario after having allocated the primary energy related to the inputs between the two energy services. The energy in the feedstock was not included in the external energy inputs. Direct combustion had the highest energy efficiency. It had energy ratios of 10 and 36 for electricity and heat, respectively. The least energy-efficient scenario was the pyrolysis scenario where biochar was applied to soils. It had energy ratios of 4 and 12 for electricity and heat, respectively. The results showed that pyrolysis with carbon sequestration might be an option to counteract the current trend in global warming. The pyrolysis system with soil application of the biochar removed the largest amount of CO2 from the atmosphere. However, compared with the direct combustion scenario, the climate change mitigation potential depended on the energy system to which the bioenergy system delivered its energy services. A system expansion showed that direct combustion had the highest climate change mitigation potential when coal or natural gas were used as external energy sources to compensate for the lower energy efficiency of the pyrolysis scenario.

Place, publisher, year, edition, pages
Blackwell Publishing Ltd, 2017
Keywords
biochar, climate impact metrics, land use change, LCA, pyrolysis, Salix, soil organic carbon, SRC, willow
National Category
Biological Sciences
Identifiers
urn:nbn:se:kth:diva-207331 (URN)10.1111/gcbb.12415 (DOI)2-s2.0-85013447108 (Scopus ID)
Note

QC 20170607

Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2017-06-07Bibliographically approved
Waldenström, C., Ferguson, R., Sundberg, C., Tidåker, P., Westholm, E. & Åkerskog, A. (2016). Bioenergy From Agriculture: Challenges for the Rural Development Program in Sweden. Society & Natural Resources, 1-16
Open this publication in new window or tab >>Bioenergy From Agriculture: Challenges for the Rural Development Program in Sweden
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2016 (English)In: Society & Natural Resources, ISSN 0894-1920, E-ISSN 1521-0723, p. 1-16Article in journal (Refereed) Published
Abstract [en]

This article addresses the challenges for the EU Rural Development Program (RDP) to promote sustainable bioenergy production from agriculture. Drawing on the Swedish example, we identify opportunities for farmers and discuss agricultural-based bioenergy production in relation to the program objectives for agricultural competitiveness, sustainability and climate effects, and rural development. The sustainability and climate effects of agricultural-based bioenergy can be ascertained only through contextual analysis, and research indicates that rural development may be best promoted through local collaborative energy systems. Contrasting two ideal-type roles farmers may assume in bioenergy production, we discuss Swedish institutional contexts of energy production. In Sweden, the national energy policy tends to favor large-scale energy solutions and farmers taking on the roles as suppliers of primary products in large-scale energy systems. For RDP objectives to be realized, this tendency needs to be countered, local solutions need to be supported, and a national three-tiered energy policy integration needs to be furthered.

Place, publisher, year, edition, pages
Routledge, 2016
Keywords
Agriculture and the environment, energy policy, environmental management, policy and politics, rural and agricultural development, sustainable development
National Category
Environmental Sciences related to Agriculture and Land-use
Identifiers
urn:nbn:se:kth:diva-187208 (URN)10.1080/08941920.2016.1150538 (DOI)000386680900006 ()2-s2.0-84962127947 (Scopus ID)
Note

QC 20161129

Available from: 2016-05-18 Created: 2016-05-18 Last updated: 2018-01-10Bibliographically approved
Röös, E., Karlsson, H., Witthöft, C. & Sundberg, C. (2015). Evaluating the sustainability of diets-combining environmental and nutritional aspects. Environmental Science and Policy, 47, 157-166
Open this publication in new window or tab >>Evaluating the sustainability of diets-combining environmental and nutritional aspects
2015 (English)In: Environmental Science and Policy, ISSN 1462-9011, E-ISSN 1873-6416, Vol. 47, p. 157-166Article in journal (Refereed) Published
Abstract [en]

This study examined two methods for jointly considering the environmental impact and nutritional quality of diets, which is necessary when designing policy instruments promoting sustainable food systems. Both methods included energy content and 18 macro- and micronutrients in the diet, the climate impact, land use and biodiversity damage potential. In Method 1, the content of different nutrients in the diet was normalised based on recommended intake or upper levels for average daily intake and presented together with the environmental impacts, which were normalised according to estimated sustainable levels. In Method 2, the nutritional quality of different diets was considered by calculating their nutrient density score, and the environmental impact was then expressed per nutrient density score. Three diets were assessed; a diet corresponding to Nordic recommendations, the current average Swedish diet and a lifestyle Low Carbohydrate-High Fat (LCHF) diet. Method 1 clearly showed that the climate impact was far beyond the sustainable level for all diets, while land use was within the sustainability limit for the recommended diet, but not the other two. Comparisons based on nutrient density scores depended on the score used, but the current and LCHF diets had more impact than the recommended diet (less livestock products) for all but one score. Over- and under-consumption of nutrients were clearly shown by Method 1 but not possible to distinguish with Method 2, as normalisation was not possible, making it difficult to evaluate the absolute scale of the impacts when nutrient density scores were used. For quantitative information on the environmental and nutritional impacts of diets as support in decision-making processes, it is important that data presentation is transparent. There is limited value in reducing results to a low number of indicators that are easy to read, but difficult to interpret, e.g. nutrient density score. Method 1 allows combined assessment of diets regarding environmental impact and nutritional intake and could be useful in dietary planning and in development of dietary recommendations and other policy instruments to achieve more sustainable food systems.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Sustainable diets, Climate, Land use, Biodiversity, Nutrient density score, Nutrition
National Category
Food Science
Identifiers
urn:nbn:se:kth:diva-182622 (URN)10.1016/j.envsci.2014.12.001 (DOI)000349581400015 ()2-s2.0-84919791227 (Scopus ID)
Note

QC 20160608

Available from: 2016-06-02 Created: 2016-02-22 Last updated: 2017-11-30Bibliographically approved
Komakech, A. J., Sundberg, C., Jönsson, H. & Vinnerås, B. (2015). Life cycle assessment of biodegradable waste treatment systems for sub-Saharan African cities. Resources, Conservation and Recycling, 99, 100-110
Open this publication in new window or tab >>Life cycle assessment of biodegradable waste treatment systems for sub-Saharan African cities
2015 (English)In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 99, p. 100-110Article in journal (Refereed) Published
Abstract [en]

Most of the waste collected in sub-Saharan African cities is biodegradable but it is usually dumped in landfills, creating environmental and health challenges for residents. However, there are biodegradable waste treatment methods that could mitigate these challenges. This study analysed anaerobic digestion, composting, vermicomposting and fly larvae waste treatments using life cycle assessment (LCA). The impact categories assessed were energy use, global warming and eutrophication potential. The results showed that anaerobic digestion performed best in all impact categories assessed. However, management of the anaerobic digestion process is critical and methane losses must be kept very small, as otherwise they will cause global warming.

National Category
Other Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-182614 (URN)10.1016/j.resconrec.2015.03.006 (DOI)000356735500010 ()2-s2.0-84928975070 (Scopus ID)
Note

QC 20160316

Available from: 2016-02-22 Created: 2016-02-22 Last updated: 2017-11-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5979-9521

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