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- Ahlgren, Serina, et al.
(författare)
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Biofuels from agricultural biomass – Land use change in Swedish perspective
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Swedish parliament has decided that by 2045, Sweden will not be a net emitter of greenhouse gases. There is also a goal to have a fossil fuel free transport sector by 2030. However, the transport sector is still dominated by fossil fuels and many efforts are needed to lower emissions. Sweden has a relatively high share of biofuels, around 20% of the energy use in domestictransportation. However, almost 90% of these fuels are imported or produced from imported feedstock.In this study it was investigated whether and how the forecast biofuel demand for 2030 (20 TWh) can be met by biofuels produced from domestic feedstock. The scope was narrowed to biomass that does not cause land use change effects, since the European Commission has communicated that useof biofuels based on feedstock which could be used instead for food or feed will not be supported in the future. The reason for this policy decision is that increased biofuel production could stimulate direct land use change (dLUC) or indirect land use change (iLUC), leading to release ofsoil carbon and other greenhouse gases. We found that about 4-10 TWh of biofuels can be produced from iLUC-free agricultural feedstockin Sweden; the range is dependent on the assumed biofuel conversion rate. The raw material studied was (1) agricultural residues, (2) ley produced on previously unused arable land, (3) crops from arable land such as intermediate crops and (4) intensification of ley cultivation.Literature indicates that iLUC-free feedstock from other sectors (forest residues, industrial byproducts and residues, and residues from other parts of society in Sweden, marine feedstock not included) could contribute 8-11 TWh biofuel. In other words, there is good potential to reach the required 20 TWh of biofuels by 2030 based on domestic iLUC-free feedstock. Lowering domesticconsumption of meat and alcoholic beverages and lowering land use for recreational horse keeping could provide additional space for biofuel production.However, steering towards iLUC-free feedstock would mean higher production costs compared to conventional biofuel production. It is therefore of particular interest to study the potential trade-offs between greenhouse gases and economics. The production of ethanol and biogas based on wheatgrain and wheat straw was studied, where wheat grain represented the current production system and wheat straw represented an iLUC-free production system.We conclude that wheat straw-based biofuels do not compete with food production and have lower greenhouse gas emissions than those based on wheat grain, but higher production costs. The reasons for higher production costs are mainly the lower biofuel yield and more expensive pretreatment.In order to enable general conclusions on trade-offs when steering towards iLUC-free feedstock, more case studies are however needed with a larger set of studied feedstocks, biofuels and including other environmental impacts.
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- Al-Majdoub, Mahmoud, et al.
(författare)
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Treatment of Swedish Patients with Graves' Hyperthyroidism Is Associated with Changes in Acylcarnitine Levels
- 2017
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Ingår i: Thyroid : official journal of the American Thyroid Association. - : Mary Ann Liebert Inc. - 1557-9077. ; 27:9, s. 1109-1117
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Hyperthyroidism is associated with alterations in metabolism that are currently only partially understood. The objective of the study was to investigate changes in metabolism associated with reinstatement of euthyroidism in Swedish patients.METHODS: Eighty metabolites in plasma were profiled from 10 subjects with Graves' disease (GD) at baseline and after 9 and 15 months of treatment to reinstate euthyroidism. Thyroid parameters, thyrotropin (TSH), TSH receptor antibodies, free triiodothyronine, and free thyroxine were followed. Main findings were validated in plasma from 20 subjects with GD at baseline and at three, six, and nine months. The study was conducted at the endocrinology clinic in Malmö, Sweden.RESULTS: Euthyroidism was reinstated at three months, and thyroid status did not change further during the 15-month follow-up. This was paralleled by altered levels of 9/19 detected acylcarnitines (p < 0.05 after adjustment for multiple testing). Levels of short-chain acylcarnitines were decreased, intermediate-chain acylcarnitines elevated, and long-chain acylcarnitines unaltered.CONCLUSIONS: GD and treatment of the disease is associated with pronounced acyl chain length-dependent alterations in acylcarnitine levels. These changes may be impacted by ethnicity and or dietary differences.
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| 5. |
- Binzel, R.P., et al.
(författare)
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Compositional distributions and evolutionary processes for the near-Earth object population: Results from the MIT-Hawaii Near-Earth Object Spectroscopic Survey (MITHNEOS)
- 2019
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Ingår i: Icarus. - : Elsevier. - 0019-1035 .- 1090-2643. ; 324, s. 41-76
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Tidskriftsartikel (refereegranskat)abstract
- Advancing technology in near-infrared instrumentation and dedicated planetary telescope facilities have enabled nearly two decades of reconnoitering the spectral properties for near-Earth objects (NEOs). We report measured spectral properties for more than 1000 NEOs, representing >5 percent of the currently discovered population. Thermal flux detected below 2.5 microns allows us to make albedo estimates for nearly 50 objects, including two comets. Additional spectral data are reported for more than 350 Mars-crossing asteroids. Most of these measurements were achieved through a collaboration between researchers at the Massachusetts Institute of Technology and the University of Hawaii, with full cooperation of the NASA Infrared Telescope Facility (IRTF) on Mauna Kea. We call this project the MIT-Hawaii Near-Earth Object Spectroscopic Survey (MITHNEOS; myth-neos). While MITHNEOS has continuously released all spectral data for immediate use by the scientific community, our objectives for this paper are to: (1) detail the methods and limits of the survey data, (2) formally present a compilation of results including their taxonomic classification within a single internally consistent framework, (3) perform a preliminary analysis on the overall population characteristics with a concentration toward deducing key physical processes and identifying their source region for escaping the main belt. Augmenting our newly published measurements are the previously published results from the broad NEO community, including many results graciously shared by colleagues prior to formal publication. With this collective data set, we find the near-Earth population matches the diversity of the main-belt, with all main-belt taxonomic classes represented in our sample. Potentially hazardous asteroids (PHAs) as well as the subset of mission accessible asteroids (ΔV≤ 7 km/s) both appear to be a representative mix of the overall NEO population, consistent with strong dynamical mixing for the population that interacts most closely with Earth. Mars crossers, however, are less diverse and appear to more closely match the inner belt population from where they have more recently diffused. The fractional distributions of major taxonomic classes (60% S, 20% C, 20% other) appear remarkably constant over two orders of magnitude in size (10 km to 100 m), which is eight orders of magnitude in mass, though we note unaccounted bias effects enter into our statistics below about 500m. Given the range of surface ages, including possible refreshment by planetary encounters, we are able to identify a very specific space weathering vector tracing the transition from Q- to Sq- to S-types that follows the natural dispersion for asteroid spectra mapped into principal component space. We also are able to interpret a shock darkening vector that may account for some objects having featureless spectra. Space weathering effects for C-types are complex; these results are described separately by Lantz, Binzel, DeMeo. (2018, Icarus 302, 10-17). Independent correlation of dynamical models with taxonomic classes map the escape zones for NEOs to main-belt regions consistent with well established heliocentric compositional gradients. We push beyond taxonomy to interpret our visible plus near-infrared spectra in terms of the olivine and pyroxene mineralogy consistent with the H, L, and LL classes of ordinary chondrites meteorites. Correlating meteorite interpretations with dynamical escape region models shows a preference for LL chondrites to arrive from the ν6 resonance and H chondrites to have a preferential signature from the mid-belt region (3:1 resonance). L chondrites show some preference toward the outer belt, but not at a significant level. We define a Space Weathering Parameter as a continuous variable and find evidence for step-wise changes in space weathering properties across different planet crossing zones in the inner solar system. Overall we hypothesize the relative roles of planetary encounters, YORP spin-up, and thermal cycling across the inner solar system.
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| 6. |
- Björnsson, Lovisa, et al.
(författare)
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Grass biomass as biofuel feedstock –sustainable or not?
- 2017
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Ingår i: European Biomass Conference and Exhibition Proceedings, 25thEUBCE, June 2017. - 2282-5819. - 9788889407172 ; 2017, s. 39-40
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Konferensbidrag (refereegranskat)abstract
- Low carbon input due to increasing specialization, intensification and reduced use of bio-fertilizer, leads to soil organic carbon (SOC) decreases in arable land. This is an emerging problem in Europe in general, where 45% of the EU soils have low and declining SOC content. SOC losses from agricultural soils influence soil fertility, putting food security at risk, and contributes to greenhouse gas (GHG) emissions. An agricultural practice rendering loss of SOC is thus not sustainable in the long term, and measures must be taken to reverse this trend. However, existing policies for agriculture and biofuels address these issues in isolation, SOC impact is not considered when sustainability criteria for biofuels are defined in the EU renewable energy directive (RED). The aim of this study was to illustrate the relevance of SOC impact on integrated production of food and grass as energy crop for biofuel production. This diversification of current cereal dominated crop rotations proved an efficient tool to reverse SOC losses, simultaneously producing a grass-based biofuel with low climate impact. Since SOC-related aspects are excluded in EU RED, the GHG reduction calculated according to the directive does, however, not meet the 60% GHG reduction demand. This narrow perspective causes potentially interesting double benefits to be missed.
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| 9. |
- Börjesson, Pål, et al.
(författare)
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Energy Crop-Based Biogas as Vehicle Fuel: The Impact of Crop Selection on Energy Efficiency and Greenhouse Gas Performance
- 2015
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 8:6, s. 6033-6058
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Tidskriftsartikel (refereegranskat)abstract
- The production of biogas from six agricultural crops was analysed regarding energy efficiency and greenhouse gas (GHG) performance for vehicle fuel from a field-to-tank perspective, with focus on critical parameters and on calculation methods. The energy efficiency varied from 35% to 44%, expressed as primary energy input per energy unit vehicle gas produced. The GHG reduction varied from 70% to 120%, compared with fossil liquid fuels, when the GHG credit of the digestate produced was included through system expansion according to the calculation methodology in the ISO 14044 standard of life cycle assessment. Ley crop-based biogas systems led to the highest GHG reduction, due to the significant soil carbon accumulation, followed by maize, wheat, hemp, triticale and sugar beet. Critical parameters are biogenic nitrous oxide emissions from crop cultivation, for which specific emission factors for digestate are missing today, and methane leakage from biogas production. The GHG benefits were reduced and the interrelation between the crops changed, when the GHG calculations were instead based on the methodology stated in the EU Renewable Energy Directive, where crop contribution to soil carbon accumulation is disregarded. All systems could still reach a 60% GHG reduction, due to the improved agricultural management when digestate replaces mineral fertilisers.
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