kth.sePublications
Change search
Refine search result
12 1 - 50 of 55
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Ahlgren, S.
    et al.
    Röös, E.
    Di Lucia, L.
    Sundberg, Cecilia
    Hansson, P. -A
    EU sustainability criteria for biofuels: Uncertainties in GHG emissions from cultivation2012In: Biofuels, ISSN 1759-7269, E-ISSN 1759-7277, Vol. 3, no 4, p. 399-411Article in journal (Refereed)
    Abstract [en]

    Background: Cultivation of raw material represents a large proportion of biofuelś GHG emissions. The EU renewable energy directive 2009/28/EC specifies a GHG emission default value for cultivation of biofuel raw material (23 g CO2-e/MJ ethanol for wheat). The aim of this study was to quantify the uncertainty in GHG emissions for wheat cultivation in Sweden, considering uncertainty and variability in data at farm level. Results: Two levels of data collection at farm level were analyzed; simple (only yield and amount of N) and advanced (also including amounts and types of energy). The 2.5-97.5 percentile uncertainty for Swedish winter wheat was 20-27 g CO 2-e/MJ, which can be considered large in the context of the Directives threshold of 23 g (to two significant figures). Conclusion: It is concluded that quantifying GHG emissions in order to regulate biofuels is a difficult task, especially emissions from cultivation, since these are biological systems with large variability.

  • 2.
    Azzi, Elias Sebastian
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Karltun, E.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Small-scale biochar production on Swedish farms: A model for estimating potential, variability, and environmental performance2021In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 280, article id 124873Article in journal (Refereed)
    Abstract [en]

    Several small-scale pyrolysis plants have been installed on Swedish farms and uptake is increasing in the Nordic countries. Pyrolysis plants convert biomass to biochar for agricultural applications and syngas for heating applications. These projects are driven by ambitions of achieving carbon dioxide removal, reducing environmental impacts, and improving farm finances and resilience. Before policy support for on-farm pyrolysis projects is implemented, a comprehensive environmental evaluation of these systems is needed. Here, a model was developed to jointly: (i) simulate operation of on-farm energy systems equipped with pyrolysis units; (ii) estimate biochar production potential and its variability under different energy demand situations and designs; and (iii) calculate life cycle environmental impacts. The model was applied to a case study farm in Sweden. The farm's heating system achieved net carbon dioxide removal through biochar carbon sequestration, but increased its impact in several other environmental categories, mainly due to increased biomass throughput. Proper dimensioning of heat-constrained systems is key to ensure optimal biochar production, as biochar production potential of the case farm was reduced under expected climate change in Sweden. To improve the environmental footprint of future biochar systems, it is crucial that expected co-benefits from biochar use in agriculture are realised. The model developed here is available for application to other cases.

  • 3.
    Azzi, Elias Sebastian
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Karltun, Erik
    Swedish Univ Agr Sci SLU, Dept Soil & Environm, Uppsala, Sweden..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. Department of Energy and Technology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Assessing the diverse environmental effects of biochar systems: An evaluation framework2021In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 286, article id 112154Article in journal (Refereed)
    Abstract [en]

    Biochar has been recognised as a carbon dioxide removal (CDR) technology. Unlike other CDR technologies, biochar is expected to deliver various valuable effects in e.g. agriculture, animal husbandry, industrial processes, remediation activities and waste management. The diversity of biochar side effects to CDR makes the systematic environmental assessment of biochar projects challenging, and to date, there is no common framework for evaluating them. Our aim is to bridge the methodology gap for evaluating biochar systems from a life-cycle perspective. Using life cycle theory, actual biochar projects, and reviews of biochar research, we propose a general description of biochar systems, an overview of biochar effects, and an evaluation framework for biochar effects. The evaluation framework was applied to a case study, the Stockholm Biochar Project. In the framework, biochar effects are classified according to life cycle stage and life cycle effect type; and the biochar?s end-of-life and the reference situations are made explicit. Three types of effects are easily included in life cycle theory: changes in biosphere exchanges, technosphere inputs, and technosphere outputs. For other effects, analysing the cause-effect chain may be helpful. Several biochar effects in agroecosystems can be modelled as future productivity increases against a reference situation. In practice, the complexity of agroecosystems can be bypassed by using empirical models. Existing biochar life cycle studies are often limited to carbon footprint calculations and quantify a limited amount of biochar effects, mainly carbon sequestration, energy displacements and fertiliser-related emissions. The methodological development in this study can be of benefit to the biochar and CDR research communities, as well as decision-makers in biochar practice and policy.

  • 4.
    Azzi, Elias Sebastian
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Karltun, Erik
    SLU.
    Sundberg, Cecilia
    SLU.
    Life cycle assessment of urban uses of biochar and case study in Uppsala, SwedenManuscript (preprint) (Other academic)
    Abstract [en]

    Biochar is a material derived from biomass pyrolysis that is used in urban applications. The environmental impacts of new biochar products has however not been assessed. Here, the life cycle assessments of 5 biochar products were performed for 7 biochar supply-chains in 2 energy contexts. The biochar products (tree planting, green roofs, landscaping soil, charcrete, and biofilm carrier) were benchmarked against reference products and the oxidative use of biochar for steel production. Biochar demand was then estimated using dynamic material flow analysis for a new city-district in Uppsala, Sweden. In a decarbonised energy system and if biochar stability is high, all biochar products had a better climate performance than the reference, and most applications outperformed biomass use for decarbonising steel production. The climate benefits of using biochar ranged from -1.4 to -0.11 tonne CO2-eq tonne-1 biochar in a decarbonised energy system. In other environmental impact categories, biochar products had either higher or lower impacts than the reference, depending on biochar supply-chains and materials substituted, with trade-offs between sectors and impact categories. This said, several use phase effects of biochar were not included in the assessment due to knowledge limitations. In Uppsala’s new district, biochar demand was around 1700 m3 year-1 during the 25 years of construction. By 2100, 23% of the biochar accumulated in landfills, raising questions for end-of-life management of biochar-containing products. Overall, in a post-fossil economy, biochar can be a carbon dioxide removal technology with benefits, but biochar applications must be designed to maximise co-benefits.

  • 5.
    Azzi, Elias Sebastian
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Karltun, Erik
    Swedish Univ Agr Sci SLU, Dept Soil & Environm, Uppsala, Sweden..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. Swedish Univ Agr Sci SLU, Dept Energy & Technol, Uppsala, Sweden..
    Life cycle assessment of urban uses of biochar and case study in Uppsala, Sweden2022In: Biochar, ISSN 2524-7972, E-ISSN 2524-7867, Vol. 4, no 1, article id 18Article in journal (Refereed)
    Abstract [en]

    Biochar is a material derived from biomass pyrolysis that is used in urban applications. The environmental impacts of new biochar products have however not been assessed. Here, the life cycle assessments of 5 biochar products (tree planting, green roofs, landscaping soil, charcrete, and biofilm carrier) were performed for 7 biochar supply-chains in 2 energy contexts. The biochar products were benchmarked against reference products and oxidative use of biochar for steel production. Biochar demand was then estimated, using dynamic material flow analysis, for a new city district in Uppsala, Sweden. In a decarbonised energy system and with high biochar stability, all biochar products showed better climate performance than the reference products, and most applications outperformed biomass use for decarbonising steel production. The climate benefits of using biochar ranged from - 1.4 to - 0.11 tonne CO2-eq tonne(-1) biochar in a decarbonised energy system. In other environmental impact categories, biochar products had either higher or lower impacts than the reference products, depending on biochar supply chain and material substituted, with trade-offs between sectors and impact categories. However, several use-phase effects of biochar were not included in the assessment due to knowledge limitations. In Uppsala's new district, estimated biochar demand was around 1700 m(3) year(-1) during the 25 years of construction. By 2100, 23% of this biochar accumulated in landfill, raising questions about end-of-life management of biochar-containing products. Overall, in a post-fossil economy, biochar can be a carbon dioxide removal technology with benefits, but biochar applications must be designed to maximise co-benefits.

  • 6.
    Azzi, Elias Sebastian
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Karltun, Erik
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Prospective Life Cycle Assessment of Large-Scale Biochar Production and Use for Negative Emissions in Stockholm2019In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 53, no 14, p. 8466-8476Article in journal (Refereed)
    Abstract [en]

    Several cities in Sweden are aiming for climate neutrality within a few decades and for negative emissions thereafter. Combined biochar, heat, and power production is an option to achieve carbon sequestration for cities relying on biomass-fuelled district heating, while biochar use could mitigate environmental pollution and greenhouse gas emissions from the agricultural sector. By using prospective life cycle assessment, the climate impact of the pyrolysis of woodchips in Stockholm is compared with two reference scenarios based on woodchip combustion. The pyrolysis of woodchips produces heat and power for the city of Stockholm, and biochar whose potential use as a feed and manure additive on Swedish dairy farms is explored. The climate change mitigation trade-off between bioenergy production and biochar carbon sequestration in Stockholm's context is dominated by the fate of marginal power. If decarbonisation of power is achieved, building a new pyrolysis plant becomes a better climate option than conventional combustion. Effects of cascading biochar use in animal husbandry are uncertain but could provide 10-20% more mitigation than direct biochar soil incorporation. These results help design regional biochar systems that combine negative carbon dioxide emissions with increased methane and nitrous oxide mitigation efforts and can also guide the development of minimum performance criteria for biochar products.

  • 7. Cerutti, P. O.
    et al.
    Sola, P.
    Chenevoy, A.
    Iiyama, M.
    Yila, J.
    Zhou, W.
    Djoudi, H.
    Atyi, R. E.
    Gautier, D. J.
    Gumbo, D.
    Kuehl, Y.
    Levang, P.
    Martius, C.
    Matthews, R.
    Nasi, R.
    Neufeldt, H.
    Njenga, M.
    Petrokofsky, G.
    Saunders, M.
    Shepherd, G.
    Sonwa, D. J.
    Sundberg, Cecilia
    Van Noordwijk, M.
    The socioeconomic and environmental impacts of wood energy value chains in Sub-Saharan Africa: A systematic map protocol2015In: Environmental Evidence, E-ISSN 2047-2382, Vol. 4, no 1, article id 4Article in journal (Refereed)
    Abstract [en]

    Background: The vast majority of households in Sub-Saharan Africa (SSA) depend on wood energy - comprising firewood and charcoal - for their daily energetic needs. Such consumption trends are expected to remain a common feature of SSA's wood energy production and supply chains, at least in the short- to medium-terms. Notwithstanding its importance, wood energy generally has low priority in SSA national policies. However, the use of wood energy is often considered a key driver of unsustainable management and negative environmental consequences in the humid and dry forests. To date, unsystematic assessments of the socio-economic and environmental consequences of wood energy use have underplayed its significance, thus further hampering policy debates. Therefore, a more balanced approach which considers both demand and supply dynamics is needed. This systematic map aims at providing a comprehensive approach to understanding the role and impacts of wood energy across all regions and aspects in SSA. Methods: The objective of this systematic map is to collate evidence from studies of environmental and socio-economic impacts of wood energy value chains, by considering both demand and supply within SSA. The map questions are framed using a Populations, Exposure, Comparators and Outcomes (PECO) approach. We name the supply and demand of wood energy as the "exposure," composed of wood energy production, harvesting, processing, and consumption. The populations of interest include both the actors involved in these activities and the forest sites where these activities occur. The comparator is defined as those cases where the same wood energy activities occur with i) available/accessible alternative energy sources, ii) regulatory frameworks that govern the sector and iii) alternative technologies for efficient use. The outcomes of interest encompass both socioeconomic and environmental impacts that can affect more than the populations named above. For instance, in addition to the direct socioeconomic impacts felt by participants in the wood energy value chain, forest dwellers may experience livelihood changes due to forest degradation caused by external harvesters. Moreover, intensified deforestation in one area may concurrently lead to forest regeneration in another.

  • 8. Eklind, Y.
    et al.
    Sundberg, Cecilia
    Dep. of Biometry and Engineering, Swedish Univ. of Agricultural Science.
    Smårs, S.
    Steger, K.
    Sundh, I.
    Kirchmann, H.
    Jönsson, H.
    Carbon turnover and ammonia emissions during composting of biowaste at different temperatures2007In: Journal of Environmental Quality, ISSN 0047-2425, E-ISSN 1537-2537, Vol. 36, no 5, p. 1512-1520Article in journal (Refereed)
    Abstract [en]

    The effects of different process temperatures (40, 55, and 67 degrees C) during composting of source-separated household waste were studied in a 200 L compost reactor at an oxygen concentration of 16%. The overall decomposition measured as carbon mineralization, decomposition of different carbon constituents, and the dynamics of nitrogen mineralization and the microbial community, are reported. Ammonia emissions at 67 degrees C were more than double those at lower temperatures, and they were lowest at 40 degrees C. The decomposition rate, measured as CO2 emission, was highest at 55 degrees C. Decomposition of crude fat was slower at 40 degrees C than at 55 and 67 degrees C. The peak in microbial biomass was largest in the run at 40 degrees C, where substantial differences were seen in the microbial community structure and succession compared to thermophilic temperatures. Biowaste composting can be optimized to obtain both a high decomposition rate and low ammonia emissions by controlling the process at about 55 degrees C in the initial, high-rate stage. To reduce ammonia emissions it seems worthwhile to reduce the temperature after an initial high-temperature stage.

  • 9. Ericsson, N.
    et al.
    Porsö, C.
    Åhlgren, S.
    Nordberg, Å.
    Sundberg, Cecilia
    Hansson, P. -A
    Time-dependent climate impact of a bioenergy system - methodology development and application to Swedish conditions2013In: Global Change Biology Bioenergy, ISSN 1757-1693, E-ISSN 1757-1707, Vol. 5, no 5, p. 580-590Article in journal (Refereed)
    Abstract [en]

    The area of dedicated energy crops is expected to increase in Sweden. This will result in direct land use changes, which may affect the carbon stocks in soil and biomass, as well as yield levels and the use of inputs. Carbon dioxide (CO2) fluxes of biomass are often not considered when calculating the climate impact in life cycle assessments (LCA) assuming that the CO2 released at combustion has recently been captured by the biomass in question. With the extended time lag between capture and release of CO2inherent in many perennial bioenergy systems, the relation between carbon neutrality and climate neutrality may be questioned. In this paper, previously published methodologies and models are combined in a methodological framework that can assist LCA practitioners in interpreting the time-dependent climate impact of a bioenergy system. The treatment of carbon differs from conventional LCA practice in that no distinction is made between fossil and biogenic carbon. A time-dependent indicator is used to enable a representation of the climate impact that is not dependent on the choice of a specific characterization time horizon or time of evaluation and that does not use characterization factors, such as global warming potential and global temperature potential. The indicator used to aid in the interpretation phase of this paper is global mean surface temperature change (ΔTs(n)). A theoretical system producing willow for district heating was used to study land use change effects depending on previous land use and variations in the standing biomass carbon stocks. When replacing annual crops with willow this system presented a cooling contribution to ΔTs(n). However, the first years after establishing the willow plantation it presented a warming contribution to ΔTs(n). This behavior was due mainly to soil organic carbon (SOC) variation. A rapid initial increase in standing biomass counteracted the initial SOC loss.

  • 10. Ericsson, N.
    et al.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Nordberg, Å.
    Ahlgren, S.
    Hansson, P. -A
    Time-dependent climate impact and energy efficiency of combined heat and power production from short-rotation coppice willow using pyrolysis or direct combustion2017In: Global Change Biology Bioenergy, ISSN 1757-1693, E-ISSN 1757-1707, Vol. 9, no 5, p. 876-890Article in journal (Refereed)
    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.

  • 11. Ermolaev, E.
    et al.
    Jarvis, Å.
    Sundberg, Cecilia
    Swedish University of Agricultural Sciences .
    Smårs, S.
    Pell, M.
    Jönsson, H.
    Nitrous oxide and methane emissions from food waste composting at different temperatures2015In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 46, p. 113-119Article in journal (Refereed)
    Abstract [en]

    Emissions of methane (CH4) and nitrous oxide (N2O) from composting of source-sorted food waste were studied at set temperatures of 40, 55 and 67 degrees C in 10 trials performed in a controlled environment 200 L compost reactor. CH4 and N2O concentrations were generally low. In trials with 16% O-2, the mean total CH4 emission at all temperatures was 0.007% of the mineralized carbon (C), while at 67 degrees C this fraction was 0.001%. Total CH4 production was higher in the 40 degrees C trial and the limited oxygen (1% O-2) trial, with emissions of 0.029 and 0.132% of the mineralized C respectively. An early increase in N2O production was observed in trials with higher initial nitrate contents. Increased CH4 and N2O production in trials at 40 and 55 degrees C after 50% of the initial C was mineralized resulted in higher total greenhouse gas emissions. Overall, the global warming potentials in CO2-equivalents from CH4 emissions were higher than from N2O, except for composts run at 67 degrees C.

  • 12. Ermolaev, E.
    et al.
    Pell, M.
    Smårs, S.
    Sundberg, Cecilia
    Jönsson, H.
    Greenhouse gas emission from covered windrow composting with controlled ventilation2012In: Waste Management and Research, ISSN 0734-242X, Vol. 30, no 2, p. 155-160Article in journal (Refereed)
    Abstract [en]

    Data on greenhouse gas (GHG) emissions from full-scale composting of municipal solid waste, investigating the effects of process temperature and aeration combinations, is scarce. Oxygen availability affects the composition of gases emitted during composting. In the present study, two experiments with three covered windrows were set up, treating a mixture of source separated biodegradable municipal solid waste (MSW) fractions from Uppsala, Sweden, and structural amendment (woodchips, garden waste and re-used compost) in the volume proportion 1:2. The effects of different aeration and temperature settings on the emission of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) during windrow composting with forced aeration following three different control schemes were studied. For one windrow, the controller was set to keep the temperature below 40 °C until the pH increased, another windrow had minimal aeration at the beginning of the process and the third one had constant aeration. In the first experiment, CH4concentrations (CH4:CO2 ratio) increased, from around 0.1% initially to between 1 and 2% in all windrows. In the second experiment, the initial concentrations of CH4 displayed similar patterns of increase between windrows until day 12, when concentration peaked at 3 and 6%, respectively, in two of the windrows. In general, the N2O fluxes remained low (0.46 ± 0.02 ppm) in the experiments and were two to three times the ambient concentrations. In conclusion, the emissions of CH4 and N2O were low regardless of the amount of ventilation. The data indicates a need to perform longer experiments in order to observe further emission dynamics.

  • 13. Ermolaev, E.
    et al.
    Sundberg, Cecilia
    Swedish University of Agricultural Sciences.
    Pell, M.
    Jönsson, H.
    Greenhouse gas emissions from home composting in practice2014In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 151, p. 174-182Article in journal (Refereed)
    Abstract [en]

    In Sweden, 16% of all biologically treated food waste is home composted. Emissions of the greenhouse gases CH4 and N2O and emissions of NH3 from home composts were measured and factors affecting these emissions were examined. Gas and substrate in the compost bins were sampled and the composting conditions assessed 13 times during a 1-year period in 18 home composts managed by the home owners. The influence of process parameters and management factors was evaluated by regression analysis. The mean CH4 and N2O concentration was 28.1 and 5.46 ppm (v/v), respectively, above the ambient level and the CH4:CO2 and N2O:CO2 ratio was 0.38% and 0.15%, respectively (median values 0.04% and 0.07%, respectively). The home composts emitted less CH4 than large-scale composts, but similar amounts of N2O. Overall NH3 concentrations were low. Increasing the temperature, moisture content, mixing frequency and amount of added waste all increased CH4 emissions.

  • 14.
    Ermolaev, Evgheni
    et al.
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, Box 7032, SE-75007 Uppsala, Sweden..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. Swedish Univ Agr Sci SLU, Dept Energy & Technol, Box 7032, SE-75007 Uppsala, Sweden..
    Pell, Mikael
    Swedish Univ Agr Sci SLU, Dept Mol Sci, Box 7015, SE-75007 Uppsala, Sweden..
    Smars, Sven
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, Box 7032, SE-75007 Uppsala, Sweden..
    Jonsson, Håkan
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, Box 7032, SE-75007 Uppsala, Sweden..
    Effects of moisture on emissions of methane, nitrous oxide and carbon dioxide from food and garden waste composting2019In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 240, article id UNSP 118165Article in journal (Refereed)
    Abstract [en]

    Globally, waste generation is continually increasing, with landfill as the main destination for biological waste. Composting is a simple alternative for handling waste, but when poorly managed poses a risk of greenhouse gas emissions. The moisture content of substrate affects emissions of methane (CH4) and nitrous oxide (N2O) from composting, but the scale and mechanisms behind these effects are poorly understood. This study examined effects of different moisture levels (44-66%) on CH4, N2O and carbon dioxide (CO2) emissions during 20 days of composting food and garden waste under controlled conditions (55 degrees C, 16% oxygen) in a 200-L reactor. Total CO2 emissions were 400-500 g CO2-C kg(-1) initial C. Total CH4 emissions were highest, 35 g CH4-C kg(-1) initial C, for the wettest substrate (66% moisture) and decreased exponentially with declining moisture content, with the lowest total emissions, 0.04 g CH4-C kg(-1) initial C, observed with the driest substrate. Total N2O emissions were negatively correlated with moisture content, decreasing from 1.2 g N2O-N kg(-1) initial N at 44% moisture to 0.3 g N2O-N kg(-1) initial N at 59%, but the wettest substrate (66% moisture) had the highest N2O emissions, 1.4 g N2O-N kg(-1) initial N. NH4-N accumulated in the wettest material, suggesting that the increased N2O emissions were due to reduced oxygen availability. The results indicate potential to reduce greenhouse gas emissions from large-scale composting by adjusting the moisture content at different stages of composting, thus lowering its overall environmental impact. This finding can be used in guidelines for large-scale composting process to avoid moisture conditions causing large greenhouse gas emissions. Elsevier Ltd. All rights reserved.

  • 15.
    Gitau, James K.
    et al.
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, POB 2905-0065, Nairobi, Kenya.;World Agroforestry Ctr ICRAF, POB 30677-00100, Nairobi, Kenya..
    Mutune, Jane
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, POB 2905-0065, Nairobi, Kenya..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Mendum, Ruth
    Penn State Univ, Coll Agr Sci, Off Int Programs, 106 Agr Adm Bldg, University Pk, PA 16802 USA..
    Njenga, Mary
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, POB 2905-0065, Nairobi, Kenya.;World Agroforestry Ctr ICRAF, POB 30677-00100, Nairobi, Kenya..
    Implications on Livelihoods and the Environment of Uptake of Gasifier Cook Stoves among Kenya's Rural Households2019In: APPLIED SCIENCES-BASEL, ISSN 2076-3417, Vol. 9, no 6, article id 1205Article in journal (Refereed)
    Abstract [en]

    A majority of people in developing countries use biomass energy for cooking and heating due to its affordability, accessibility and convenience. However, unsustainable biomass use leads to forest degradation and climate change. Therefore, this study was carried out in Kwale County, Kenya, on the use of a biochar-producing gasifier cook stove and implications of its uptake on livelihoods and the environment. Fifty households were trained and issued with a gasifier for free. After 2-3 months of gasifier use, a survey was conducted to investigate the implications of its uptake. The direct impacts included reduced fuel consumption by 38%, reduced time spent in firewood collection, reduced expenditure on cooking fuel, diversification of cooking fuels, improved kitchen conditions and reduced time spent on cooking. The potential benefits included income generation, increased food production, reduced impacts on environment and climate change and reduced health problems. Improved biomass cook stoves can alleviate problems with current cooking methods, which include inefficient fuel use, health issues caused by smoke, and environmental problems. These benefits could contribute to development through alleviating poverty and hunger, promoting gender equality, enhancing good health and sustainable ecosystems and mitigating climate change. The study recommends the promotion of cleaner cooking stoves, particularly gasifiers, among households in rural areas while paying attention to user needs and preferences.

  • 16.
    Gitau, James K.
    et al.
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, POB 2905-0065, Nairobi, Kenya.;World Agroforestry Ctr ICRAF, POB 30677-00100, Nairobi, Kenya..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Mendum, Ruth
    Penn State Univ, Off Int Programs, Coll Agr Sci, 106 Agr Adm Bldg, University Pk, PA 16802 USA..
    Mutune, Jane
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, POB 2905-0065, Nairobi, Kenya..
    Njenga, Mary
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, POB 2905-0065, Nairobi, Kenya.;World Agroforestry Ctr ICRAF, POB 30677-00100, Nairobi, Kenya..
    Use of Biochar-Producing Gasifier Cookstove Improves Energy Use Efficiency and Indoor Air Quality in Rural Households2019In: Energies, E-ISSN 1996-1073, Vol. 12, no 22, article id 4285Article in journal (Refereed)
    Abstract [en]

    Biomass fuels dominate the household energy mix in sub-Saharan Africa. Much of it is used inefficiently in poorly ventilated kitchens resulting in indoor air pollution and consumption of large amounts of wood fuel. Micro-gasification cookstoves can improve fuel use efficiency and reduce indoor air pollution while producing char as a by-product. This study monitored real-time concentrations of carbon monoxide (CO), carbon dioxide (CO2) and fine particulate matter (PM2.5), and amount of firewood used when households were cooking dinner. Twenty-five households used the gasifier cookstove to cook and five repeated the same test with three-stone open fire on a different date. With the gasifier, the average corresponding dinner time CO, CO2, and PM2.5 concentrations were reduced by 57%, 41%, and 79% respectively compared to three-stone open fire. The gasifier had average biomass-to-char conversion efficiency of 16.6%. If the produced char is used as fuel, households could save 32% of fuel compared to use of three-stone open fire and 18% when char is used as biochar, for instance. Adoption of the gasifier can help to reduce the need for firewood collection, hence reducing impacts on the environment while saving on the amount of time and money spent on cooking fuel.

  • 17.
    Gitau, K. J.
    et al.
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, POB 2905-0065, Nairobi, Kenya.;World Agroforestry Ctr ICRAF, POB 30677-00100, Nairobi, Kenya..
    Mutune, J.
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, POB 2905-0065, Nairobi, Kenya..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. Swedish Univ Agr Sci SLU, Dept Energy & Technol, Uppsala, Sweden..
    Mendum, R.
    Penn State Univ, Off Int Programs, Coll Agr Sci, University Pk, PA 16802 USA..
    Njenga, M.
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, POB 2905-0065, Nairobi, Kenya.;World Agroforestry Ctr ICRAF, POB 30677-00100, Nairobi, Kenya..
    Factors influencing the adoption of biochar-producing gasifier cookstoves by households in rural Kenya2019In: Energy for Sustainable Development, ISSN 0973-0826, E-ISSN 2352-4669, Vol. 52, p. 63-71Article in journal (Refereed)
    Abstract [en]

    Fuel wood is the main source of cooking and heating energy in developing countries. However, it is combusted in inefficient cookstoves, leading to more fuel use and human health problems resulting from exposure to smoke. Thus new, efficient cooking systems that can address some of these problems are required. This study examined gasifier cookstove use in Kwale County, Kenya, and factors influencing adoption. Gasifier stoves were issued for free to 50 households, which were surveyed after 2-3 months of use. The results showed that the stove was used by 96% of the households at varying frequencies, 40% of them used it almost every day with 4% switching to only using the new stove. All the users appreciated it because it saved fuel, produced less smoke, and produced charcoal to use for either cooking or soil amendment. Compared with the traditional three-stone open fire, the gasifier stove was reported to be easier to clean (98% of respondents), easier to adjust the heat (88%), easier to handle (58%), caused less exposure to heat (96%) and was cleaner for pots and the kitchen (98%). Another reported benefit of the gasifier stove was that it needed no tending (i.e., adjusting wood and blowing to keep the flames burning). The gasifier stove was mainly used to cook foods that required a short cooking time and many preferred to use it to cook dinner. However, the households encountered some challenges with using the gasifier stoves. For example, fuel preparation, reloading, and lighting were reported as challenges by 42%, 77% and 19%, respectively, of the 83% of households who reported challenges. These challenges could be overcome by improving stove design and by devising innovative ways of cutting fuel into small pieces. 2019 The Authors. Published by Elsevier Inc. on behalf of International Energy Initiative.

  • 18.
    Gustafsson, Kåre
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Sustainability and Environmental Engineering. Stockholm Exergi, Stockholm, Sweden..
    Sadegh-Vaziri, Ramiar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Grönkvist, Stefan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Levihn, Fabian
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.). Stockholm Exergi, Stockholm, Sweden.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. Swedish Univ Agr Sci SLU, Dept Energy & Technol, Uppsala, Sweden.
    BECCS with combined heat and power: Assessing the energy penalty2021In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 108, article id 103248Article in journal (Refereed)
    Abstract [en]

    Bio-energy with carbon capture and storage (BECCS) is widely recognised as an important carbon dioxide removal technology. Nevertheless, BECCS has mostly failed to move beyond small-scale demonstration units. One main factor is the energy penalty incurred on power plants. In previous studies, this penalty has been determined to be 37.2 %?48.6 % for the amine capture technology. The aim of this study is to quantify the energy penalty for adding the hot potassium carbonate (HPC) capture technology to a biomass-fired combined heat and power (CHP) plant, connected to a district heating system. In this context, the energy driving the capture process is partly recovered as useful district heating. Therefore, a modified energy penalty is proposed, with the inclusion of recovered heat. This inclusion is especially meaningful if the heat has a substantial monetary value. The BECCS system is examined using thermodynamic analysis, coupled with modelling of the capture process in Aspen PlusTM. Model validation is performed with data from a BECCS test facility. The results of this study show that the modified energy penalty is in the range of 2%?4%. These findings could potentially increase the attractiveness of BECCS as a climate abatement option in a district heating CHP setting.

  • 19. Hammar, T.
    et al.
    Ericsson, N.
    Sundberg, Cecilia
    Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Hansson, P. -A
    Climate Impact of Willow Grown for Bioenergy in Sweden2014In: Bioenergy Research, ISSN 1939-1234, Vol. 7, no 4, p. 1529-1540Article in journal (Refereed)
    Abstract [en]

    Short-rotation coppice willow (SRCW) is a fast-growing and potentially high-yielding energy crop. Transition to bioenergy has been identified in Sweden as one strategy to mitigate climate change and decrease the current dependency on fossil fuel. In this study, life cycle assessment was used to evaluate and compare the climate impacts of SRCW systems, for the purpose of evaluating key factors influencing the climate change mitigation potential of SRCW grown on agricultural land in Sweden. Seven different scenarios were defined and analysed to identify the factors with the most influence on the climate. A carbon balance model was used to model carbon fluxes between soil, biomass and atmosphere under Swedish growing conditions. The results indicated that SRCW can act as a temporary carbon sink and therefore has a mitigating effect on climate change. The most important factor in obtaining a high climate change-mitigating effect was shown to be high yield. Low yield gave the worst mitigating effect of the seven scenarios, but it was still better than the effect of the reference systems, district heating produced from coal or natural gas.

  • 20. Hammar, T.
    et al.
    Hansson, P. -A
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Climate impact assessment of willow energy from a landscape perspective: A Swedish case study2017In: Global Change Biology Bioenergy, ISSN 1757-1693, E-ISSN 1757-1707, Vol. 9, no 5, p. 973-985Article in journal (Refereed)
    Abstract [en]

    Locally produced bioenergy can decrease the dependency on imported fossil fuels in a region, while also being valuable for climate change mitigation. Short-rotation coppice willow is a potentially high-yielding energy crop that can be grown to supply a local energy facility. This study assessed the energy performance and climate impacts when establishing willow on current fallow land in a Swedish region with the purpose of supplying a bio-based combined heat and power plant. Time-dependent life cycle assessment (LCA) was combined with geographic information system (GIS) mapping to include spatial variation in terms of transport distance, initial soil organic carbon content, soil texture and yield. Two climate metrics were used [global warming potential (GWP) and absolute global temperature change potential (AGTP)], and the energy performance was determined by calculating the energy ratio (energy produced per unit of energy used). The results showed that when current fallow land in a Swedish region was used for willow energy, an average energy ratio of 30 MJ MJ-1 (including heat, power and flue gas condensation) was obtained and on average 84.3 Mg carbon per ha was sequestered in the soil during a 100-year time frame (compared with the reference land use). The processes contributing most to the energy use during one willow rotation were the production and application of fertilizers (~40%), followed by harvest (~35%) and transport (~20%). The temperature response after 100 years of willow cultivation was -6·10-16K MJ-1 heat, which is much lower compared with fossil coal and natural gas (70·10-16K MJ-1 heat and 35·10-16 K MJ-1 heat, respectively). The combined GIS and time-dependent LCA approach developed here can be a useful tool in systematic analysis of bioenergy production systems and related land use effects.

  • 21. Hammar, T.
    et al.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. Swedish University of Agricultural Sciences (SLU), Sweden.
    Stendahl, J.
    Larsolle, A.
    Hansson, P. -A
    Life cycle assessment of climate impact of bioenergy from a landscape2017In: European Biomass Conference and Exhibition Proceedings 2017, ETA-Florence Renewable Energies , 2017, Vol. 2017, no 25thEUBCE, p. 1493-1497Conference 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.

  • 22.
    Hammar, Torun
    et al.
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, SE-75007 Uppsala, Sweden..
    Stendahl, Johan
    SLU, Dept Soil & Environm, SE-75007 Uppsala, Sweden..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Holmström, Hampus
    SLU, Dept Forest Resource Management, SE-90183 Umea, Sweden..
    Hansson, Per-Anders
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, SE-75007 Uppsala, Sweden..
    Climate impact and energy efficiency of woody bioenergy systems from a landscape perspective2019In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 120, p. 189-199Article in journal (Refereed)
    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.

  • 23. Henryson, K.
    et al.
    Kätterer, T.
    Tidåker, P.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. Swedish University of Agricultural Sciences (SLU), Department of Energy and Technology, P.O. Box 7032, Uppsala, 750 07, Sweden.
    Soil N2O emissions, N leaching and marine eutrophication in life cycle assessment – A comparison of modelling approaches2020In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 725, article id 138332Article in journal (Refereed)
    Abstract [en]

    Nitrogen fertilisation is an essential part of modern agriculture, providing food for a growing human population, but also causing environmental impacts when reactive nitrogen (N) is released to the environment. The amount and impact of these emissions are difficult to quantify in life cycle assessment (LCA), due to their site-dependent nature. This study compared seven models for direct soil nitrous oxide (N2O) emissions, seven models for N leaching and five characterisation models for marine eutrophication impact assessment, selected to represent medium-effort options for accounting for spatial variation in emissions and impact assessment. In a case study, the models were applied to wheat cultivation at two Swedish sites to estimate climate and marine eutrophication impact. Direct N2O emissions estimated by the models varied by up to five-fold at one of the sites and contributed 21–56% of the total climate impact. Site-dependent models gave both lower and higher N2O emissions estimates than the site-generic Tier 1 model from the Intergovernmental Panel on Climate Change (IPCC). Estimated N leaching also varied by up to fivefold at one of the sites and contributed 47–93% of the total eutrophication potential, depending on model choice. All site-dependent models estimated lower N leaching than the site-generic IPCC Tier 1 model. Marine eutrophication impact estimates varied by almost an order of magnitude depending on characterisation model choice. The large variation between models found in this study highlights the importance of model choice for N emissions and marine eutrophication impact assessment in LCA of crop cultivation. Due to the divergence of model outcomes and different limitations of some of the models, no general recommendations on choosing soil N2O emissions model, N leaching model or characterisation model for marine eutrophication could be given.

  • 24. Henryson, K.
    et al.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. Swedish University of Agricultural Sciences (SLU), Department of Energy and Technology, Sweden.
    Kätterer, T.
    Hansson, P. -A
    Accounting for long-term soil fertility effects when assessing the climate impact of crop cultivation2018In: Agricultural Systems, ISSN 0308-521X, E-ISSN 1873-2267, Vol. 164, p. 185-192Article in journal (Refereed)
    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.

  • 25.
    Henryson, Kajsa
    et al.
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, POB 7032, S-75007 Uppsala, Sweden..
    Hansson, Er-Anders
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, POB 7032, S-75007 Uppsala, Sweden..
    Katterer, Thomas
    Swedish Univ Agr Sci SLU, Dept Ecol, POB 7044, S-75007 Uppsala, Sweden..
    Tidaker, Pernilla
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, POB 7032, S-75007 Uppsala, Sweden..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Environmental performance of crop cultivation at different sites and nitrogen rates in Sweden2019In: Nutrient Cycling in Agroecosystems, ISSN 1385-1314, E-ISSN 1573-0867, Vol. 114, no 2, p. 139-155Article in journal (Refereed)
    Abstract [en]

    Nitrogen (N) fertilisation has positive and negative effects on the environmental impact of crop cultivation. The mechanisms governing these effects are highly site-dependent, a factor often ignored in assessments of the environmental impact of crop cultivation. By assessing outputs of crop rotations using a life cycle approach, this study explored how greenhouse gas emissions and marine eutrophication caused by crop cultivation (including upstream processes such as production of farm inputs) depend on fertiliser rate and the site at which the cultivation occurs. Cereal unit (CU) was used as the functional unit. The calculations were based on data from multi-site long-term field experiments in Sweden and site-dependent data and models for non-measured processes. Cultivation at three N levels was evaluated, where the highest N rate was close to current average practices and the lowest level corresponded to one-third of that. Site characteristics had a stronger influence on both greenhouse gas emissions and marine eutrophication (variations of up to 330% and 490%, respectively, within N levels) than N level (variations of up to 74% and 59%, respectively, within sites). Main sources of variation in greenhouse gas emissions were soil nitrous oxide emissions (58-810g CO2eqCU-1) and soil organic carbon changes (14-720g CO2eqCU-1), while variations in marine eutrophication were mainly explained by field-level waterborne N losses (0.9-8.2g NeqCU-1). The large variation between sites highlights the importance of considering site characteristics when assessing the environmental impact of crop cultivation and evaluating the environmental consequences of crop management practices.

  • 26.
    Henryson, Kajsa
    et al.
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, POB 7032, S-75007 Uppsala, Sweden..
    Hansson, Per-Anders
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, POB 7032, S-75007 Uppsala, Sweden..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. Swedish Univ Agr Sci SLU, Dept Energy & Technol, POB 7032, S-75007 Uppsala, Sweden.
    Spatially differentiated midpoint indicator for marine eutrophication of waterborne emissions in Sweden2018In: The International Journal of Life Cycle Assessment, ISSN 0948-3349, E-ISSN 1614-7502, Vol. 23, no 1, p. 70-81Article in journal (Refereed)
    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.

  • 27. Jarvis, Å.
    et al.
    Sundberg, Cecilia
    Swedish University of Agricultural Sciences, Sweden.
    Milenkovski, S.
    Pell, M.
    Smårs, S.
    Lindgren, P. -E
    Hallin, S.
    Activity and composition of ammonia oxidizing bacterial communities and emission dynamics of NH3 and N2O in a compost reactor treating organic household waste2009In: Journal of Applied Microbiology, ISSN 1364-5072, E-ISSN 1365-2672, Vol. 106, no 5, p. 1502-1511Article in journal (Refereed)
    Abstract [en]

    Aims: To monitor emissions of NH3 and N2O during composting and link these to ammonia oxidation rates and the community structure of ammonia oxidizing bacteria (AOB). Methods and Results: A laboratory-scale compost reactor treating organic household waste was run for 2 months. NH 3 emissions peaked when pH started to increase. Small amounts of N2O and CH4 were also produced. In total, 16% and less than 1% of the initial N was lost as NH3-N and N2O-N respectively. The potential ammonia oxidation rate, determined by a chlorate inhibition assay, increased fourfold during the first 9 days and then remained high. Initially, both Nitrosospira and Nitrosomonas populations were detected using DGGE analysis of AOB specific 16S rRNA fragments. Only Nitrosomonas europaea was detected under thermophilic conditions, but Nitrosospira populations re-established during the cooling phase. Conclusions: Thermophilic conditions favoured high potential ammonia oxidation rates, suggesting that ammonia oxidation contributed to reduced NH3 emissions. Small but significant amounts of N2O were emitted during the thermophilic phase. The significance of different AOBs detected in the compost for ammonia oxidation is not clear. Significance and Impact of Study: This study shows that ammonia oxidation occurs at high temperature composting and therefore most likely reduces NH3 emissions.

  • 28. Kimming, M.
    et al.
    Sundberg, Cecilia
    Swedish University of Agricultural Sciences, Sweden.
    Nordberg, A.
    Hansson, P. -A
    Vertical integration of local fuel producers into rural district heating systems: Climate impact and production costs2015In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 78, p. 51-61Article in journal (Refereed)
    Abstract [en]

    Farmers can use their own agricultural biomass residues for heat production in small-scale systems, enabling synergies between the district heating (DH) sector and agriculture. The barriers to entry into the Swedish heat market were extremely high as long as heat distribution were considered natural monopoly, but were recently lowered due to the introduction of a regulated third party access (TPA) system in the DH sector. This study assesses the potential impact on greenhouse gas emissions and cost-based heat price in the DH sector when farmers vertically integrate into the heat supply chain and introduce more local and agricultural crops and residues into the fuel mix. Four scenarios with various degree of farmer integration, were assessed using life cycle assessment (LCA) methodology, and by analysis of the heat production costs. The results show that full integration of local farm and forest owners in the value chain can reduce greenhouse gas emissions and lower production costs/heat price, if there is an incentive to utilise local and agricultural fuels. The results imply that farmer participation in the DH sector should be encouraged by e.g. EU rural development programmes.

  • 29. Kimming, M.
    et al.
    Sundberg, Cecilia
    Nordberg, Å.
    Baky, A.
    Bernesson, S.
    Hansson, P. -A
    Replacing fossil energy for organic milk production - Potential biomass sources and greenhouse gas emission reductions2015In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 106, p. 400-407Article in journal (Refereed)
    Abstract [en]

    There is a growing awareness of the climate impact of agricultural production, not least from cattle farms. Major sources of GHG emissions from milk production are enteric fermentation followed by fossil fuel use and manure/soil management systems. This study analyzes the potential to eliminate fossil fuel use from milk production farms in Sweden, by using residual farm resources of biomass to obtain self-sufficiency in fuel, heat and electricity. The change from a fossil-based energy system to a renewable system based on A) Biogas based on manure and straw and B) Biogas based on manure + RME were analyzed with consequential life cycle assessment (CLCA) methodology. Focus was energy use and GHG emissions and the functional unit was 1 kg of energy-corrected milk (ECM). The results show that organic milk producers can become self-sufficient in energy and reduce total GHG emissions from milk production by 46% in the Biogas system, or 32% in the Biogas + RME system compared to the Fossil system.

  • 30. Komakech, A. J.
    et al.
    Banadda, N. E.
    Kinobe, J. R.
    Kasisira, L.
    Sundberg, Cecilia
    Swedish University of Agricultural Sciences, Sweden.
    Gebresenbet, G.
    Vinnerås, B.
    Characterization of municipal waste in Kampala, Uganda2014In: Journal of the Air and Waste Management Association, ISSN 1096-2247, Vol. 64, no 3, p. 340-348Article in journal (Refereed)
    Abstract [en]

    In Kampala, Uganda, about 28,000 tons of waste is collected and delivered to a landfill every month. Kampala Capital City Authority (KCCA) records show that this represents approximately 40% of the waste generated in the city. The remaining uncollected waste is normally dumped in unauthorized sites, causing health and environmental problems. However, the organic fraction of domestic waste can provide an opportunity to improve livelihoods and incomes through fertilizer and energy production. This study characterized the municipal waste generated in Kampala and delivered to Kiteezi landfill between July 2011 and June 2012, that is, covering the dry and wet months. On each sampling day, waste was randomly selected from five trucks, sorted and weighed into different physical fractions. Samples of the organic waste from each truck were analyzed for total solids, major nutrients, and energy content. During the wet months, the waste consisted of 88.5% organics, 3.8% soft plastics, 2.8% hard plastics, 2.2% paper, 0.9% glass, 0.7% textiles and leather, 0.2% metals, and 1.0% others. During the dry months, the waste consisted of 94.8% organics, 2.4% soft plastics, 1.0% hard plastics, 0.7% papers, 0.3% glass, 0.3% textile and leather, 0.1% metals, and 0.3% others. The organic waste on average had a moisture content of 71.1% and contained 1.89% nitrogen, 0.27% phosphorus, and 1.95% potassium. The waste had an average gross energy content of 17.3 MJ/kg. It was concluded that the organic waste generated can be a suitable source of some plant nutrients that are useful especially in urban agriculture. Implications: The result of the waste characterization in Kampala was found to be significantly different from that obtained for other Sub-Saharan African (SSA) cities, showing that studies assuming average values for the waste fractions are likely to result in erroneous results. Furthermore, no reduction in organic fraction of the waste was noticed when compared with a study done two decades ago in spite of greatly improved economic status of Kampala city, a finding that is not in agreement with several other similar studies done for other SSA cities.

  • 31. Komakech, A. J.
    et al.
    Sundberg, Cecilia
    Swedish University of Agricultural Sciences, Sweden.
    Jönsson, H.
    Vinnerås, B.
    Life cycle assessment of biodegradable waste treatment systems for sub-Saharan African cities2015In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 99, p. 100-110Article in journal (Refereed)
    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.

  • 32. Kätterer, T.
    et al.
    Roobroeck, D.
    Kimutai, G.
    Karltun, E.
    Nyberg, G.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    de Nowina, K. R.
    Maize grain yield responses to realistic biochar application rates on smallholder farms in Kenya2022In: Agronomy for Sustainable Development, ISSN 1774-0746, E-ISSN 1773-0155, Vol. 42, no 4, article id 63Article in journal (Refereed)
    Abstract [en]

    Despite efforts to increase agricultural production sustainably in sub-Saharan Africa, large gaps remain between actual and potential yield of food crops. Adding biochar to degraded cropland soils in the African tropics has significant potential to enhance crop productivity. Biochar-based farming can also mitigate climate change, through soil carbon storage. This study involved six smallholder farms at sites in eastern, central, and western Kenya that are characterized by different pedo-climatic conditions. We examined the response of non-fertilized and fertilized maize monoculture to three dosages of biochar that are realistic for domestic production by farmers at each of the sites over four growing seasons. Commonly available biomass wastes in each agro-ecosystem (coconut shells, coffee husks, maize cobs) were used as feedstock for biochar, which was applied at 1, 5, and 10 Mg ha−1 at the start of the experiment. Across seasons and fertilizer treatments, maize grain yield (dry matter) showed consistently positive responses, with an average increase of 1.0, 2.6, and 4.0 Mg ha−1, respectively, above the control for the three biochar application rates. Absolute responses of maize grain yield to specific biochar doses were similar across the four investigated seasons and replicate farms within sites, and uncorrelated to yield levels in the control treatment. Here, we show for the first time that yield response to biochar decreased with increasing application rate, indicating that it may be better to spread a given amount of biochar over a large area rather than concentrating it to a smaller area, at least when biochar is applied along plant rows at rates ≥1 Mg ha−1, as in our experiment. This study demonstrated that application of biochar, locally produced from available biomass residues, is a promising approach to enhance agricultural production and carbon storage on smallholder farms under a wide range of pedo-climatic conditions in Kenya. 

  • 33. Nilsson, J
    et al.
    Tidåker, P
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Henryson, K
    Grant, B
    Smith, W
    Hansson, P. -A
    Assessing the climate and eutrophication impacts of grass cultivation at five sites in Sweden2020In: Acta Agriculturae Scandinavica - Section B, ISSN 0906-4710, E-ISSN 1651-1913Article in journal (Refereed)
    Abstract [en]

    In this study, Life Cycle Assessment (LCA) methodology was combined with the agro-ecosystem model DNDC to assess the climate and eutrophication impacts of perennial grass cultivation at five different sites in Sweden. The system was evaluated for two fertilisation rates, 140 and 200 kg N ha−1. The climate impact showed large variation between the investigated sites. The largest contribution to the climate impact was through soil N2O emissions and emissions associated with mineral fertiliser manufacturing. The highest climate impact was predicted for the site with the highest clay and initial organic carbon content, while lower impacts were predicted for the sandy loam soils, due to low N2O emissions, and for the silty clay loam, due to high carbon sequestration rate. The highest eutrophication potential was estimated for the sandy loam soils, while the sites with finer soil texture had lower eutrophication potential. According to the results, soil properties and weather conditions were more important than fertilisation rate for the climate impact of the system assessed. It was concluded that agro-ecosystem models can add a spatial and temporal dimension to environmental impact assessment in agricultural LCA studies. The results could be used to assist policymakers in optimising use of agricultural land. 

  • 34.
    Nilsson, Johan
    et al.
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, SE-75007 Uppsala, Sweden..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. Swedish Univ Agr Sci SLU, Dept Energy & Technol, SE-75007 Uppsala, Sweden..
    Tidaker, Pernilla
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, SE-75007 Uppsala, Sweden..
    Hansson, Per-Anders
    Swedish Univ Agr Sci SLU, Dept Energy & Technol, SE-75007 Uppsala, Sweden..
    Regional variation in climate impact of grass-based biogas production: A Swedish case study2020In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 275, article id 122778Article in journal (Refereed)
    Abstract [en]

    Transitioning from a fossil economy to a bio-economy will inevitably increase the demand for biomass production. One strategy to meet the demand is to re-cultivate set-aside arable land. This study investigated the climate impact and energy potential of grass-based biogas produced using fallow land in Uppsala municipality, Sweden. The assessment was performed on regional level for more than 1000 individual sites, using the agro-ecosystem model DeNitrification DeComposition (DNDC) in combination with time-dynamic life cycle assessment methodology. The results showed that the system could significantly increase biogas production within the region, which would reduce the climate impact by 9950 Mg CO2-eq per year. Compared with diesel fuel, the grass-based biogas gave a GWP reduction of 85%. However, the site-specific GWP reduction showed large spatial variability, ranging between 102 and 79% compared with diesel fuel, depending on where in the region the grass was cultivated. Two alternative scenarios were investigated, increased mineral N fertilisation and inclusion of N-fixing crops in the feedstock mixture. The highest mitigation per biogas energy produced was found for the N-fixing scenario but, because of lower yields, this scenario had lower total mitigation potential for the region than the increased fertilisation scenario. The increased fertilisation scenario had a lower climate mitigation effect per biogas energy produced, but the highest mitigation potential when the whole region was considered, because of the increased biogas production. The method applied in this study can guide land-use planning of local energy production from arable land, also for other regions.

  • 35. Njenga, M.
    et al.
    Iiyama, M.
    Jamnadass, R.
    Helander, H.
    Larsson, L.
    De Leeuw, J.
    Neufeldt, H.
    Röing De Nowina, K.
    Sundberg, Cecilia
    Gasifier as a cleaner cooking system in rural Kenya2016In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 121, p. 208-217Article in journal (Refereed)
    Abstract [en]

    Global demand for wood fuel energy is high and rising due to population increases, particularly in sub-Saharan Africa, where firewood and charcoal are the main sources of cooking energy. Inefficient cooking techniques consume large amounts of fuel and create indoor pollution, with negative health impacts particularly among women and small children. Efficient cooking stoves can potentially save fuel and reduce the health risks of smoke in the kitchen. This study compared the ease of use, energy consumption, fuel use efficiency and gas and particle emissions of a small-scale gasifier cooking stove with that of a traditional three-stone stove and an improved Hifadhi stove in a smallholder farming setting in Kenya. This was done by participatory evaluation of these cooking techniques by women on smallholder farms, assessing fuel consumption, time used in cooking and indoor air concentrations of carbon monoxide and fine particulate matter. It was found that compared with traditional and improved cooking stoves, the gasifier domestic cooking system saved 27-40% of fuel, reduced cooking time by 19-23% and reduced emissions by 40-90%. Thus the gasifier system has potential to alleviate energy and time poverty among small-scale farmers, while improving kitchen air quality. These new findings can assist in development of cleaner biomass cooking technologies in developing countries. Women who cooked using the gasifier preferred it to current cooking practices due to perceived benefits. Thus the gasifier is appropriate for rural areas; it constitutes a cleaner cooking system that saves fuel, produces charcoal for another round of cooking, cooks rapidly, and reduces indoor air pollution from cooking with biomass fuel. However, there is a need to improve the design to make it more stable and safer.

  • 36. Njenga, M.
    et al.
    Karanja, N.
    Karlsson, H.
    Jamnadass, R.
    Iiyama, M.
    Kithinji, J.
    Sundberg, Cecilia
    Additional cooking fuel supply and reduced global warming potential from recycling charcoal dust into charcoal briquette in Kenya2014In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 81, p. 81-88Article in journal (Refereed)
    Abstract [en]

    Rising demand for energy is one of the major challenges facing the world today and charcoal is a principal fuel in Kenya. Faced with energy poverty many poor households turn to briquette making. This study assessed the additional cooking fuel obtained from recycling charcoal dust into charcoal briquettes. It applied Life Cycle Assessment (LCA) to assess the global warming potential (GWP) from use of charcoal and production of briquettes from charcoal dust and cooking a traditional meal for a standard household of five people. Native vegetation of Acacia drepanolobium and a low efficiency kiln were considered the common practice, while an Acacia mearnsii plantation and a high efficiency kiln was used as an alternative scenario. Charcoal and kerosene were considered as reference fuels. Recovering charcoal dust for charcoal briquettes supplied an additional 16% cooking fuel. Wood carbonization and cooking caused the highest GWP, so there is a need for technologies to improve the efficiency at these two stages of charcoal briquettes and charcoal supply chain. Supplying energy and cooking a traditional meal in a combined system using charcoal and recovering charcoal dust for charcoal briquettes and charcoal alone accounted for 5.3-4.12 and 6.4-4.94 kg CO2 eq. per meal, respectively, assuming trees were not replanted. These amounts declined three times when the carbon dioxide from the carbonization and cooking stages was assumed to be taken up by growing biomass. This requires replanting of trees cut down for charcoal if the neutral impact of biomass energy on GWP is to be maintained. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

  • 37. Njenga, Mary
    et al.
    Mahmoud, Yahia
    Mendum, Ruth
    Iiyama, Miyuki
    Jamnadass, Ramni
    de Nowina, Kristina Roing
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. Department of Energy and Technology, Swedish University of Agricultural Sciences, Uppsala.
    Quality of charcoal produced using micro gasification and how the new cook stove works in rural Kenya2017In: Environmental Research Letters, E-ISSN 1748-9326, Vol. 12, no 9, article id 095001Article in journal (Refereed)
    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.

  • 38. Owusu, V.
    et al.
    Adjei-Addo, E.
    Sundberg, Cecilia
    Swedish Univ Agr Sci, Dept Energy & Technol, Uppsala, Sweden.
    Do economic incentives affect attitudes to solid waste source separation?: Evidence from Ghana2013In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 78, p. 115-123Article in journal (Refereed)
    Abstract [en]

    This paper examines the willingness of urban households in Ghana to accept economic incentives to participate in solid waste source separation. Low income households were less inclined to accept cash incentives than middle or high income households indicating that other factors than purely costs for waste management are important for households to participate in source-separation of waste. Perceptions on health and sorting and the availability of open space in the households were important for the willingness to accept incentives for source separation. The empirical findings indicate that household-level solid waste separation is positively influenced by gender (female) and sorting or health-related perceptions on source separation. About 80% of the households are willing to accept cash incentive of GH¢1.6374 (US$1.6347) per month to participate in source separation, and the mean cash incentive per month is GH¢1.2186 (US$1.2166). Fruitful solid waste management policy recommendations based on the empirical magnitudes and directions are made.

  • 39.
    Papageorgiou, Asterios
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Ashok, Archana
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Hashemi Farzad, Tabassom
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Climate change impact of integrating a solar microgrid system into the Swedish electricity grid2020In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 268, article id 114981Article in journal (Refereed)
    Abstract [en]

    Microgrids are small-scale electricity networks that integrate distributed electricity generation with consumers and, potentially, with storage devices. There is growing interest in these systems, as they can offer solutions for electrification of remote areas, deployment of distributed renewable energy resources, and decarbonization of electricity supply. However, the potential benefits of microgrids in terms of climate change mitigation have not yet been thoroughly assessed. In this study, Life Cycle Assessment was performed to determine the climate change impact of integrating a solar microgrid system in western Sweden into the Swedish electricity grid. To determine whether replacement of grid electricity with electricity from the microgrid can lower greenhouse gas (GHG) emissions, average and marginal GHG emission factors (EFs) for electricity use were estimated with explicit spatial and temporal resolution, using historical data on electricity generation and trade, and life cycle EFs for electricity generation technologies. The assessment, with both marginal and average EFs, showed that integration of the microgrid into the Swedish electricity grid did not provide GHG emissions abatements, as the electricity from the microgrid displaced grid electricity with lower carbon intensity. It was found that a microgrid without batteries would have lower climate change impact, but would still fail to lower overall GHG emissions. Moreover, it was demonstrated that the methodological approach used for estimation of EFs and the definition of spatial boundaries could influence the obtained results.

  • 40.
    Papageorgiou, Asterios
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Henrysson, Maryna
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Nuur, Cali
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Sustainability, Industrial Dynamics & Entrepreneurship.
    Sinha, Rajib
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Vanhuyse, F.
    Mapping and assessing indicator-based frameworks for monitoring Circular Economy development at the city-level2021In: Sustainable cities and society, ISSN 2210-6707, Vol. 75, article id 103378Article in journal (Refereed)
    Abstract [en]

    The transition towards a circular economy (CE) is increasingly recognized as a promising pathway to tackle pressing sustainability challenges at the city-level. Indicator-based frameworks, that is, integrated systems of indicators, are considered as useful tools for monitoring this transition. Yet, studies that map and assess such frameworks are scanty. This article addresses this gap by assessing 15 indicator-based frameworks applicable to measure circularity at the city-level. The identified frameworks were assessed using eight criteria (transparency, stakeholder engagement, effective communication, ability to track temporal changes, applicability, alignment with CE principles, validity and relevance to sustainable development). Additionally, 12 validity requirements were defined to assess to what extent the indicators in the frameworks reflect CE aspects. The assessment reveals a wide variation regarding the extent to which the frameworks match the criteria with none of them satisfying all. In addition, in terms of validity criterion, none includes indicators that fulfill all the validity requirements. Furthermore, most frameworks consist mainly of environmental indicators and only three include indicators reflecting aspects related to the four pillars of sustainable development (environmental, social, economic and governance). Further research could develop a standardized framework for measuring circularity at the city-level and improving existing frameworks.

  • 41.
    Papageorgiou, Asterios
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Sinha, Rajib
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Frostell, B.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    A new physical accounting model for material flows in urban systems with application to the Stockholm Royal Seaport District2019In: Journal of Industrial Ecology, ISSN 1088-1980, E-ISSN 1530-9290Article in journal (Refereed)
    Abstract [en]

    Sustainable urbanization requires streamlining of resource management in urban systems which in turn requires understanding of urban metabolism (UM). Even though various methods have been applied for UM analysis, to date there is no standardized method for comprehensive accounting of material flows in urban systems. Moreover, the accounting of material flows is rarely implemented with a bottom-up approach that can provide a thorough analysis of UM. This article presents the Urban Accounting Model (UAM) which aims to allow comprehensive accounting of urban material flows based on a bottom-up approach. The model comprises two interlinked sub-models. The first was developed by integrating a new physical input output table (PIOT) framework for urban systems into a three-dimensional structure. The second comprises a set of physical accounts for systematic accounting of material flows of each economic sector in the system in order to support the compilation of the PIOTs. The functions of the UAM were explored through its application to two urban neighborhoods in the Stockholm Royal Seaport district. The application highlighted that the UAM can describe the physical interactions between the urban system and the environment or other socioeconomic systems, and capture the intersectoral flows within the system. Moreover, its accounts provide information that allow an in-depth analysis of the metabolism of specific sectors. Overall, the UAM can function as a useful tool for UM analysis as it systematizes data collection and at the same time depicts the physical reality of the urban system.

  • 42.
    Roos, Elin
    et al.
    Swedish Univ Agr Sci, Dept Energy & Technol, Uppsala, Sweden..
    Mie, Axel
    Karolinska Inst, Dept Clin Sci & Educ, Stockholm, Sweden..
    Wivstad, Maria
    Swedish Univ Agr Sci, EPOK Ctr Organ Food & Farming, Uppsala, Sweden..
    Salomon, Eva
    Swedish Inst Agr & Environm Engn, Uppsala, Sweden..
    Johansson, Birgitta
    Swedish Univ Agr Sci, Dept Anim Environm & Hlth, Skara, Sweden..
    Gunnarsson, Stefan
    Swedish Univ Agr Sci, Dept Anim Environm & Hlth, Skara, Sweden..
    Wallenbeck, Anna
    Swedish Univ Agr Sci, Dept Anim Environm & Hlth, Skara, Sweden.;Swedish Univ Agr Sci, Dept Anim Breeding & Genet, Uppsala, Sweden..
    Hoffmann, Ruben
    Swedish Univ Agr Sci, Dept Econ, Uppsala, Sweden..
    Nilsson, Ulf
    Swedish Univ Agr Sci, Dept Ecol, Uppsala, Sweden..
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Watson, Christine A.
    Swedish Univ Agr Sci, Dept Crop Prod Ecol, Uppsala, Sweden.;Scotlands Rural Coll, SLU & Crop & Soil Syst Res Grp, Aberdeen, Scotland..
    Risks and opportunities of increasing yields in organic farming. A review2018In: Agronomy for Sustainable Development, ISSN 1774-0746, E-ISSN 1773-0155, Vol. 38, no 2, article id 14Article, review/survey (Refereed)
    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.

  • 43. Röös, E.
    et al.
    Karlsson, H.
    SLU.
    Witthöft, C.
    SLU.
    Sundberg, Cecilia
    SLU.
    Evaluating the sustainability of diets-combining environmental and nutritional aspects2015In: Environmental Science and Policy, ISSN 1462-9011, E-ISSN 1873-6416, Vol. 47, p. 157-166Article in journal (Refereed)
    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.

  • 44.
    Röös, E.
    et al.
    SLU.
    Sundberg, Cecilia
    SLU.
    Hansson, P. -A
    SLU.
    Uncertainties in the carbon footprint of food products: A case study on table potatoes2010In: The International Journal of Life Cycle Assessment, ISSN 0948-3349, E-ISSN 1614-7502, Vol. 15, no 5, p. 478-488Article in journal (Refereed)
  • 45.
    Röös, E.
    et al.
    SLU.
    Sundberg, Cecilia
    SLU, Sweden.
    Hansson, P. -A
    SLU.
    Uncertainties in the carbon footprint of refined wheat products: A case study on Swedish pasta2011In: The International Journal of Life Cycle Assessment, ISSN 0948-3349, E-ISSN 1614-7502, Vol. 16, no 4, p. 338-350Article in journal (Refereed)
    Abstract [en]

    Calculating the carbon footprint (CF) of food is becoming increasingly important in climate change communication. To design effective CF labelling systems or reduction measures, it is necessary to understand the accuracy of the calculated CF values. This study quantified the uncertainty in the CF of wheat and of a common refined wheat-based product, pasta, for different resolutions of farm-level in-data to gain an increased understanding of the origins and magnitude of uncertainties in food CFs. A 'cradle-to-retail' CF study was performed on Swedish pasta and wheat cultivated in the region of SkAyenne on mineral soils. The uncertainty was quantified, using Monte Carlo simulation, for wheat from individual farms and for the mixture of wheat used for pasta production during a year, as well as for the pasta production process. The mean pasta CF was 0.50 kg CO(2)e/kg pasta (0.31 kg CO(2)e/kg wheat before the milling process). The CF of wheat from one farm could not be determined more accurately than being in the range 0.22-0.56 kg CO(2)e/kg wheat, even though all farm-level primary data were collected. The wheat mixture CF varied much less, approximately +/- 10-20% from the mean (95% certainty) for different years. Reducing farm-level data collection to only the most influential parameters-yield, amount of N and regional soil conditions-increased the uncertainty range by between 6% and 19% for different years for the wheat mixture. The dominant uncertainty was in N2O emissions from soil, which was also the process that contributed most to the CF. The variation in the wheat mix CF uncertainty range was greater between years, due to different numbers of farms being included for the different years, than between collecting all farm-level primary data or only the most influential parameters. More precise methods for assessing soil N2O emissions are needed to decrease the uncertainty significantly. Due to the difficulties in calculating accurate values, finding other ways of differentiating between producers than calculating numerical CFs might be more fruitful and fair. When legislation requires numerical CF values, CF practitioners have little option but to continue using existing methods and data collection strategies. However, they can provide input on improvement, contribute to standardisation processes and help raise awareness and knowledge of the associated uncertainty in the data through studies like this one.

  • 46.
    Röös, E.
    et al.
    SLU.
    Sundberg, Cecilia
    SLU.
    Tidåker, P.
    SLU.
    Strid, I.
    SLU.
    Hansson, P. -A
    SLU.
    Can carbon footprint serve as an indicator of the environmental impact of meat production?2013In: Ecological Indicators, ISSN 1470-160X, E-ISSN 1872-7034, Vol. 24, p. 573-581Article in journal (Refereed)
  • 47.
    Sundberg, Cecilia
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Franke-Whittle, I. H.
    Kauppi, S.
    Yu, D.
    Romantschuk, M.
    Insam, H.
    Jönsson, Håkan
    Characterisation of source-separated household waste intended for composting2011In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 102, no 3, p. 2859-2867Article in journal (Refereed)
    Abstract [en]

    Large-scale composting of source-separated household waste has expanded in recent years in the Nordic countries. One problem can be low pH at the start of the process. Incoming biowaste at four composting plants was characterised chemically, physically and microbiologically. The pH of food waste ranged from 4.7 to 6.1 and organic acid concentration from 24 to 81mmolkg -1. The bacterial diversity in the waste samples was high, with all samples dominated by Gammaproteobacteria, particularly Pseudomonas and Enterobacteria (Escherichia coli, Klebsiella, Enterobacter). Lactic acid bacteria were also numerically important and are known to negatively affect the composting process because the lactic acid they produce lowers the pH, inhibiting other bacteria. The bacterial groups needed for efficient composting, i.e. Bacillales and Actinobacteria, were present in appreciable amounts. The results indicated that start-up problems in the composting process can be prevented by recycling bulk material and compost.

  • 48.
    Sundberg, Cecilia
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Jönsson, Håkan
    Higher pH and faster decomposition in biowaste composting by increased aeration2008In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 28, no 3, p. 518-526Article in journal (Refereed)
    Abstract [en]

    Composting of source separated municipal biowaste has at several plants in Scandinavia been hampered by low pH. In this study the hypothesis that increased aeration would improve the process was tested in full-scale experiments at two large composting plants. The O2 concentrations were high (>15%) even at the low aeration rates, so the prevailing low pH was not due to an anaerobic process environment. In spite of this, increased aeration rates at the start of the process resulted in higher microbial activity, increased pH and a more stable compost product. At one plant the decomposition rate varied in proportion to the aeration rate, to the extent that the temperatures and O2 concentrations were similar during the early processes even though aeration rates varied between 10 and 50 m3/(h, m3 compost). However, increased aeration caused severe drying of the compost, but at one plant the addition of water was adequate to prevent drying. In conclusion, by increasing the aeration rates and adding water to compensate for drying, it was possible to shorten the time needed to produce a stable compost product and thus to increase the efficiency of the composting plants.

  • 49.
    Sundberg, Cecilia
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Jönsson, Håkan
    Process inhibition due to organic acids in fed-batch composting of food waste - Influence of starting culture2005In: Biodegradation, ISSN 0923-9820, Vol. 16, no 3, p. 205-213Article in journal (Refereed)
    Abstract [en]

    Inhibition of the degradation during low pH conditions has been observed in fed-batch composting systems. To analyse this phenomenon, fed-batch composting of food waste with different amounts of starting culture was examined in laboratory reactor experiments. Changes in temperature, carbon dioxide evolution, pH, solids, ash and short chain organic acids were measured. In reactors with a daily feed rate of 24% or less of the starting culture, thermophilic temperatures occurred and the pH and carbon dioxide evolution were high and stable after a starting period of 4-5 days. In reactors with a daily feed rate of 48% or more of the starting culture the composting process failed, as the pH dropped below 6 and remained there and the temperature and carbon dioxide evolution were low. It was concluded that the use of adequate amounts of starting culture consisting of active compost can efficiently prevent low pH conditions and process inhibition in fed-batch composting of food waste.

  • 50.
    Sundberg, Cecilia
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. Swedish Univ Agr Sci, Dept Energy & Technol, Uppsala, Sweden..
    Karltun, Erik
    Swedish Univ Agr Sci, Dept Soil & Environm, Uppsala, Sweden..
    Gitau, James K.
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, Nairobi, Kenya..
    Katterer, Thomas
    Swedish Univ Agr Sci, Dept Ecol, Uppsala, Sweden..
    Kimutai, Geoffrey M.
    IITA, Nairobi, Kenya..
    Mahmoud, Yahia
    Lund Univ, Dept Human Geog, Lund, Sweden..
    Njenga, Mary
    Univ Nairobi, Wangari Maathai Inst Peace & Environm Studies, Nairobi, Kenya.;World Agroforestry ICRAF, Nairobi, Kenya..
    Nyberg, Gert
    Swedish Univ Agr Sci, Dept Forest Ecol & Management, Umeå, Sweden..
    de Nowina, Kristina Roing
    Swedish Univ Agr Sci, Dept Soil & Environm, Uppsala, Sweden.;CGIAR Syst Org, Montpellier, France..
    Roobroeck, Dries
    IITA, Nairobi, Kenya..
    Sieber, Petra
    Swedish Univ Agr Sci, Dept Energy & Technol, Uppsala, Sweden..
    Biochar from cookstoves reduces greenhouse gas emissions from smallholder farms in Africa2020In: Mitigation and Adaptation Strategies for Global Change, ISSN 1381-2386, E-ISSN 1573-1596, Vol. 25, no 6, p. 953-967Article in journal (Refereed)
    Abstract [en]

    Biochar produced in cookstoves has the potential to contribute to negative carbon emissions through sequestration of biomass carbon while also providing other benefits for sustainable development, including provision of clean renewable energy and increased yields in tropical agriculture. The aim of the reported research was to estimate effects on food production, household energy access and life cycle climate impact from introduction of biochar-producing cookstoves on smallholder farms in Kenya. Participatory research on biochar production and use was undertaken with 150 Kenyan smallholder farming households. Gasifier cookstove functionality, fuel efficiency and emissions were measured, as well as biochar effects on agricultural yields after application to soil. Cookstoves provided benefits through reduced smoke, fuel wood savings and char production, but challenges were found related to labour for fuel preparation, lighting and refilling. On-farm trials with varying rates of biochar inputs, in combination with and without mineral fertilizers, have led to a sustained increase of maize yields following one-time application. The climate impact in a life cycle perspective was considerably lower for the system with cookstove production of biochar and use of biochar in agriculture than for current cooking practices. Climate benefits from biochar production and use are thus possible on smallholder farms in sub-Saharan Africa, through reduced use of biomass in cooking, reduced emissions of products of incomplete combustion and sequestration of stable biochar carbon in soils. Biochar-producing cookstoves can be implemented as a climate change mitigation method in rural sub-Saharan Africa. Successful implementation will require changes in cooking systems including fuel supply, as well as farming systems, which, in turn, requires an understanding of local socio-cultural conditions, including power relations and gender aspects.

12 1 - 50 of 55
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf