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  • 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. 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, ISSN 2047-2382, 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.

  • 3. 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.

  • 4. 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.

  • 5. 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.

  • 6. 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.

  • 7. 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.

  • 8. 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.

  • 9. 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.

  • 10. 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.

  • 11. 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.

  • 12. 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.

  • 13. 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.

  • 14. 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.

  • 15. 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.

  • 16. 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.

  • 17. 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.

  • 18. 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. © 2016 Elsevier Ltd. All rights reserved.

  • 19. 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/).

  • 20. 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, ISSN 1748-9326, 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.

  • 21. Owusu, V.
    et al.
    Adjei-Addo, E.
    Sundberg, C.
    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.

  • 22.
    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.

  • 23. 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.

  • 24.
    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)
  • 25.
    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.

  • 26.
    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)
  • 27.
    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.

  • 28.
    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.

  • 29.
    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.

  • 30.
    Sundberg, Cecilia
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Navia, Rodrigo
    Is there still a role for composting?2014In: Waste Management & Research, ISSN 0734-242X, E-ISSN 1096-3669, Vol. 32, no 6, p. 459-460Article in journal (Refereed)
  • 31.
    Sundberg, Cecilia
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Smårs, Sven
    Jönsson, Håkan
    Low pH as an inhibiting factor in the transition from mesophilic to thermophilic phase in composting2004In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 95, no 2, p. 145-150Article in journal (Refereed)
    Abstract [en]

    During composting of household waste, the acidity of the material affects the process during the initial phase of rising temperature. In this study, the effects of temperature (36-46°C) and pH (4.6-9.2) on the respiration rate during the early phase of composting were investigated in two different composts. A respiration method where small compost samples were incubated at constant temperature was used. The respiration rate was strongly reduced at 46°C and pH below 6, compared to composts with a higher pH or lower temperature. The combination of high temperature and low pH is a possible adverse factor in large-scale composting of food waste.

  • 32.
    Sundberg, Cecilia
    et al.
    Swedish University of Agricultural Sciences.
    Yu, D.
    Franke-Whittle, I.
    Kauppi, S.
    Smårs, S.
    Insam, H.
    Romantschuk, M.
    Jönsson, H.
    Effects of pH and microbial composition on odour in food waste composting2013In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 33, no 1, p. 204-211Article in journal (Refereed)
    Abstract [en]

    A major problem for composting plants is odour emission. Slow decomposition during prolonged low-pH conditions is a frequent process problem in food waste composting. The aim was to investigate correlations between low pH, odour and microbial composition during food waste composting. Samples from laboratory composting experiments and two large scale composting plants were analysed for odour by olfactometry, as well as physico-chemical and microbial composition. There was large variation in odour, and samples clustered in two groups, one with low odour and high pH (above 6.5), the other with high odour and low pH (below 6.0). The low-odour samples were significantly drier, had lower nitrate and TVOC concentrations and no detectable organic acids. Samples of both groups were dominated by Bacillales or Actinobacteria, organisms which are often indicative of well-functioning composting processes, but the high-odour group DNA sequences were similar to those of anaerobic or facultatively anaerobic species, not to typical thermophilic composting species. High-odour samples also contained Lactobacteria and Clostridia, known to produce odorous substances. A proposed odour reduction strategy is to rapidly overcome the low pH phase, through high initial aeration rates and the use of additives such as recycled compost.

  • 33. Tidåker, P.
    et al.
    Sundberg, Cecilia R.
    Öborn, I.
    Kätterer, T.
    Bergkvist, G.
    Rotational grass/clover for biogas integrated with grain production - A life cycle perspective2014In: Agricultural Systems, ISSN 0308-521X, E-ISSN 1873-2267, Vol. 129, p. 133-141Article in journal (Refereed)
    Abstract [en]

    Rotational perennial grass/clover has multiple effects in cropping systems dominated by cereals. This study evaluated the environmental impact of rotational grass/clover ley for anaerobic digestion in a cereal-dominated grain production system in Sweden. Life cycle assessment (LCA) methodology was used to compare two scenarios: (i) a cropping system including only spring barley and winter wheat; and (ii) a cropping system including 2-year grass/clover ley in combination with spring barley and winter wheat. The functional unit was one tonne of grain. The two main functions of the grass/clover crop were to provide feedstock for biogas production and to act as an organic fertiliser for allocation among the cereal crops in the rotation. Special consideration was given to nitrogen (N) management and the rotational effects of the grass/clover ley. In total, 73% of the N requirement of cereals in the ley scenario was met through symbiotic N fixation. Replacing diesel with biogas and mineral fertiliser with digested grass/clover biomass (digestate) reduced the use of fossil fuels substantially, from 1480. MJ per tonne in the reference scenario to -2900. MJ per tonne in the ley scenario. Potential eutrophication per tonne grain increased in the ley scenario, mainly owing to significantly higher ammonia emissions from spreading digestate and the larger area required for producing the same amount of grain. Potential acidification also increased when N mineral fertiliser was replaced by digestate. Crops relying on symbiotic N fixation are a promising feedstock for reducing the use of non-renewable energy in the production chain of farm-based bioenergy, but careful handling of the N-rich digestate is required. Replacing cereals intended for feed or food with bioenergy crops leads to indirect land use changes (iLUC) when the displaced crops must be produced elsewhere and the benefits obtained when biofuels replace fossil fuels may thereby be outweighed. In this study, the iLUC factor assumed had a critical effect on global warming potential in the ley scenario. However, carbon sequestration and the higher yield potential of subsequent cereal crops can mitigate greenhouse gas emissions from iLUC to a varying extent. We recommend that crop sequences rather than single crops be considered when evaluating the environmental impact of production systems that include perennial legumes for food, feed and bioenergy.

  • 34. Waldenström, C.
    et al.
    Ferguson, R.
    Sundberg, Cecilia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology. Swedish University of Agricultural Sciences, Sweden.
    Tidåker, P.
    Westholm, E.
    Åkerskog, A.
    Bioenergy From Agriculture: Challenges for the Rural Development Program in Sweden2016In: Society & Natural Resources, ISSN 0894-1920, E-ISSN 1521-0723, p. 1-16Article in journal (Refereed)
    Abstract [en]

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

1 - 34 of 34
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