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  • 101.
    Lönnqvist, Tomas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Energi och klimatstudier, ECS.
    Silveira, Semida
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Energi och klimatstudier, ECS.
    Enhancing the biogas potential from residues and energy crops in Sweden2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Gas has played a marginal role in the Swedish energy system not only because Sweden lacks fossil gas resources but also due to the lack of specific policies to develop the segment. This contrasts with the present situation in many other European countries where gas grids and markets are well developed. More recently, changing demand patterns in the transport sector and stringent environmental policies have triggered the development of biogas and provided a strong incentive for the development of infrastructure for biomethane in many Swedish towns. On-going initiatives often combine public and private efforts mainly at the municipal level. They build upon new opportunities in the transport sector and, thus, the biogas is upgraded to biomethane to fulfil the standard requirements of vehicle engines. However, biomethane production and infrastructural efforts have not always been in phase with the rapid expansion of the vehicle fleet.Only a small part of the practical production potential for biogas has been realized in Sweden so far. There is considerable potential for further expansion based on agricultural, urban and industrial residues, but also energy crops. However, assessments regarding the potential for energy crops in Sweden are rather divergent. This paper provides a comparison between different Swedish assessments and also European ones and further discusses the practical potential for biogas generation in Sweden. Immediate opportunities for biogas generation are identified. The study results from a collaboration between the division of Energy and Climate Studies at KTH and Fortum Värme.

  • 102.
    Ma, Charlie
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Aspects of Ash Transformations in Pressurised Entrained-Flow Gasification of Woody Biomass: Pilot-scale studies2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Pressurised entrained-flow gasification (PEFG) of woody biomass has the potential to produce high purity syngas for the production of vital chemicals, e.g., biofuels. However, ash-related issues such as reactor blockages and refractory corrosion need to be addressed before this potential can be realised from a technical perspective. These undesirable consequences can be brought about by slag formation involving inorganic ash-forming elements and the chemical transformations that they undergo during fuel conversion. The objective of this study was to elucidate the ash transformations of the major ash-forming elements and the slag formation process. A pilot-scale PEFG reactor was used as the basis of the study, gasifying different woody biomass-based fuels including wood, bark, and a bark/peat mixture. Different ash fractions were collected and chemically analysed. Reactor slags had elemental distributions differing from that of the fuel ash, indicating the occurrence of fractionation of ash material during fuel conversion. Fly ash particles from a bark campaign were also heterogeneous with particles exhibiting differing compositions and physical properties; e.g., molten and crystalline formations. Si was consistently enriched in the reactor slags compared to other major ash-forming elements, while analyses of other ash fractions indicated that K was likely volatilised to a significant extent. In terms of slag behaviour, near-wall temperatures of approximately 1050-1200 °C inside the reactor were insufficient to form flowing ash slag for continuous extraction of ash material during firing the woody biomass fuels alone. However, fuel blending of a bark fuel with a silica-rich peat changed the chemical composition of the reactor slags and bulk slag flow behaviour was evident. Thermochemical equilibrium calculations supported the importance of Si in melt formation and in lowering solidus and liquidus temperatures of Ca-rich slag compositions that are typical from clean wood and bark. Viscosity estimations also showed the impact that solids have upon slag flow behaviour and corresponded qualitatively to the experimental observations. Corrosion of reactor refractory was observed. The mullite-based refractory of the reactor formed a slag with the fuel ash slag, which caused the former to flux away. Reactor blockages were also resultant because of the high viscosity of this slag near the outlet.  A preliminary study into the corrosion of different refractories was also carried out, based on firing a bark/peat mixture.  Alumina-rich refractories consisting of corundum, hibonite, mullite, and andalusite tended to form anorthite and exhibited varying degrees of degradation. Infiltration of slag was evident for all the samples and was a severe mode of degradation for some refractories. For fused-cast periclase and spinel-based refractories, slag infiltration was limited to voids and no extensive signs of refractory dissolution were found. This is also supported by a thermochemical equilibrium calculations mimicking slag infiltration that incorporated viscosity estimations. The findings from this thesis contribute towards the development of woody biomass PEFG by highlighting issues concerning ash fractionation, slag behaviours and ash\slash refractory interaction that should be investigated further.

  • 103. Ma, Charlie
    et al.
    Carlborg, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Hedman, Henry
    Wennebro, Jonas
    Weiland, Fredrik
    Wiinikka, Henrik
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Ohman, Marcus
    Ash Formation in Pilot-Scale Pressurized Entrained-Flow Gasification of Bark and a Bark/Peat Mixture2016Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, nr 12, s. 10543-10554Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pressurized entrained-flow gasification (PEFG) of bark and a bark/peat mixture (BPM) was carried out in a pilot scale reactor (600 kW(th), 7 bar(a)) with the objective of studying ash transformations and behaviors. The bark fuel produced a sintered but nonflowing reactor slag, while the BPM fuel produced a flowing reactor slag. Si was enriched within these slags compared to their original fuel ash compositions, especially in the bark campaign, which indicated extensive ash matter fractionation. Thermodynamically, the Si contents largely accounted for the differences in the predicted solidus/liquidus temperatures and melt formations of the reactor slags. Suspension flow viscosity estimations were in qualitative agreement with observations and highlighted potential difficulties in controlling slag flow. Quench solids from the bark campaign were mainly composed of heterogeneous particles resembling reactor fly ash particles, while those from the BPM campaign were flowing slags with likely chemical interactions with the wall refractory. Quench effluents and raw syngas particles were dominated by elevated levels of K that, along with other chemical aspects, indicated KOH(g) and/or K(g) were likely formed during PEFG. Overall, the results provide information toward development of woody biomass PEFG and indicate that detailed understanding of the ash matter fractionation behavior is essential.

  • 104. Ma, Charlie
    et al.
    Weiland, Fredrik
    Hedman, Henry
    Boström, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Ohman, Marcus
    Characterization of Reactor Ash Deposits from Pilot-Scale Pressurized Entrained-Flow Gasification of Woody Biomass2013Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, nr 11, s. 6801-6814Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pressurized entrained-flow gasification of renewable forest residues has the potential to produce high-quality syngas suitable for the synthesis of transport fuels and chemicals. The ash transformation behavior during gasification is critical to the overall production process and necessitates a level of understanding to implement appropriate control measures. Toward this end, ash deposits were collected from inside the reactor of a pilot-scale O-2-blown pressurized entrained-flow gasifier firing stem wood, bark, and pulp mill debarking residue (PMDR) in separate campaigns. These deposits were characterized with environmental scanning electron microscopy equipped with energy-dispersive X-ray spectrometry and X-ray diffractometry. The stem wood deposit contained high levels of calcium and was comparatively insubstantial. The bark and PMDR fuels contained contaminant sand and feldspar particles that were subsequently evident in each respective deposit. The bark deposit consisted of lightly sintered ash aggregates comprising presumably a silicate melt that enveloped particles of quartz and, to a lesser degree, feldspars. Discontinuous layers likely to be composed of alkaline-earth metal silicates were found upon the aggregate peripheries. The PMDR deposit consisted of a continuous slag that contained quartz and feldspar particles dispersed within a silicate melt. Significant levels of alkaline-earth and alkali metals constituted the silicate melts of both the bark and PMDR deposits. Overall, the results suggest that fuel contaminants (i.e., quartz and feldspars) play a significant role in the slag formation process during pressurized entrained-flow gasification of these woody biomasses.

  • 105.
    Mander, Sarah
    et al.
    Univ Manchester, Tyndall Ctr Climate Change Res, Manchester M13 4PL, Lancs, England..
    Anderson, Kevin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Naturresurser och hållbar utveckling. Univ Manchester, Tyndall Ctr Climate Change Res, Manchester M13 4PL, Lancs, England.
    Larkin, Alice
    Univ Manchester, Tyndall Ctr Climate Change Res, Manchester M13 4PL, Lancs, England..
    Gough, Clair
    Univ Manchester, Tyndall Ctr Climate Change Res, Manchester M13 4PL, Lancs, England..
    Vaughan, Naomi
    Univ East Anglia, Tyndall Ctr Climate Change Res, Norwich NR4 7TJ, Norfolk, England..
    The role of bio-energy with carbon capture and storage in meeting the climate mitigation challenge: A whole system perspective2017Inngår i: 13Th International Conference on Greenhouse Gas Control Technologies, Ghgt-13 / [ed] Dixon, T Laloui, L Twinning, S, Elsevier, 2017, s. 6036-6043Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper explores the role and implications of bio-energy with carbon capture and storage (BECCS) for addressing the climate change mitigation challenge. Framed within the context of the latest emissions budgets, and their associated uncertainty, we present a summary of the contribution of BECCS within the Integrated Assessment Model (IAM) scenarios used by the climate change community. Within this discussion we seek to shed light on two important areas. Firstly, that BECCS is a central, but often hidden element of many of the modelling work that underpins climate policy from the global to the national scale. The second area we address are the assumptions for BECCS embedded within IAM models, and the wider system consequences of these implied levels of deployment. In light of these challenges, we question whether BECCS can deliver what is anticipated of it within existing climate change policy. (C) 2017 The Authors. Published by Elsevier Ltd.

  • 106.
    Manzetti, Sergio
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Beräkningsbiologi och bioinformatik. Fjordforsk AS, Nanofactory, Inst Sci & Technol, N-6894 Midtun, Vangsnes, Norway..
    Andersen, Otto
    Western Norway Res Inst, Postboks 163, N-6851 Sogndal, Norway..
    A molecular dynamics study of nanoparticle-formation from bioethanol-gasoline blend emissions2016Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 183, s. 55-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aerosol components and nanoparticles deriving from fuel combustion represent a class of exhaust emissions with critical relevance to environmental studies. In particular, the formation of nanoparticles is an important theme for environmental assessments of new fuel blends. Here, a set of computer simulations is carried out to study the behaviour of acetaldehyde-phenanthrene nanoparticles in relation to the influences to the three major atmospheric components CO2, O-2, N-2. The results show that phenanthrene and acetaldehyde quickly generate nanoparticles with dimensions of 2-5 nm in vacuum. The formed particles are stable in atmospheric conditions and interestingly absorb CO2 from the atmosphere-gas simulations but not O-2 and N-2. The probability of absorption of CO2 in the formed nanoparticles results as 10-20-fold compared to N-2 and O-2. Furthermore, acetaldehyde appears to localize on the surface of the formed nanoparticles, and seemingly acts with the planar geometry of phenanthrene as a facilitator for CO2 absorption. The results provided show also the properties of formed nanoparticle with higher concentrations of acetaldehyde and lower of phenanthrene, where phenanthrene forms the core of the nanoparticle, while acetaldehyde interacts with the surface and subsurface area in making their chemistry hydrophilic with a dense aromatic core. The study is important for further assessing bioethanol and fuel blends, and also introduces a methodology for studying interactions of gases and particles at the molecular level, with macroscopic significance. The study reports on growth of nanoparticles by CO2 absorption, introduces a new issue for blending fuels, with implications towards pollution profiles.

  • 107. Marques, W. L.
    et al.
    Mans, R.
    Henderson, R. K.
    Marella, E. R.
    Horst, J. T.
    Hulster, E. D.
    Poolman, B.
    Daran, J. -M
    Pronk, J. T.
    Gombert, A. K.
    van Maris, Antonius J. A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Combined engineering of disaccharide transport and phosphorolysis for enhanced ATP yield from sucrose fermentation in Saccharomyces cerevisiae2018Inngår i: Metabolic engineering, ISSN 1096-7176, E-ISSN 1096-7184, Vol. 45, s. 121-133Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Anaerobic industrial fermentation processes do not require aeration and intensive mixing and the accompanying cost savings are beneficial for production of chemicals and fuels. However, the free-energy conservation of fermentative pathways is often insufficient for the production and export of the desired compounds and/or for cellular growth and maintenance. To increase free-energy conservation during fermentation of the industrially relevant disaccharide sucrose by Saccharomyces cerevisiae, we first replaced the native yeast α-glucosidases by an intracellular sucrose phosphorylase from Leuconostoc mesenteroides (LmSPase). Subsequently, we replaced the native proton-coupled sucrose uptake system by a putative sucrose facilitator from Phaseolus vulgaris (PvSUF1). The resulting strains grew anaerobically on sucrose at specific growth rates of 0.09 ± 0.02 h−1 (LmSPase) and 0.06 ± 0.01 h−1 (PvSUF1, LmSPase). Overexpression of the yeast PGM2 gene, which encodes phosphoglucomutase, increased anaerobic growth rates on sucrose of these strains to 0.23 ± 0.01 h−1 and 0.08 ± 0.00 h−1, respectively. Determination of the biomass yield in anaerobic sucrose-limited chemostat cultures was used to assess the free-energy conservation of the engineered strains. Replacement of intracellular hydrolase with a phosphorylase increased the biomass yield on sucrose by 31%. Additional replacement of the native proton-coupled sucrose uptake system by PvSUF1 increased the anaerobic biomass yield by a further 8%, resulting in an overall increase of 41%. By experimentally demonstrating an energetic benefit of the combined engineering of disaccharide uptake and cleavage, this study represents a first step towards anaerobic production of compounds whose metabolic pathways currently do not conserve sufficient free-energy.

  • 108.
    Martin, Michael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Industrial Symbiosis in the Biofuel Industry: Quantification of the Environmental Performance and Identification of Synergies2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The production of biofuels has increased in recent years, to reduce the dependence on fossil fuels and mitigate climate change. However, current production practices are heavily criticized on their environmental sustainability. Life cycle assessments have therefore been used in policies and academic studies to assess the systems; with divergent results. In the coming years however, biofuel production practices must improve to meet strict environmental sustainability policies.

    The aims of the research presented in this thesis, are to explore and analyze concepts from industrial symbiosis (IS) to improve the efficiency and environmental performance of biofuel production and identify possible material and energy exchanges between biofuel producers and external industries.

    An exploration of potential material and energy exchanges resulted in a diverse set of possible exchanges. Many exchanges were identified between biofuel producers to make use of each other’s by-products. There is also large potential for exchanges with external industries, e.g. with the food, energy and chemical producing industries. As such, the biofuel industry and external industries have possibilities for potential collaboration and environmental performance improvements, though implementation of the exchanges may be influenced by many conditions.

    In order to analyze if concepts from IS can provide benefits to firms of an IS network, an approach was created which outlines how quantifications of IS networks can be produced using life cycle assessment literature for guidelines and methodological considerations. The approach offers methods for quantifying the environmental performance for firms of the IS network and an approach to distribute impacts and credits for the exchanges between firm, to test the assumed benefits for the firms of the IS network.

    Life cycle assessment, and the approach from this thesis, have been used to quantify the environmental performance of IS networks by building scenarios based on an example from an IS network of biofuel producers in Sweden. From the analyses, it has been found that exchanges of material and energy may offer environmental performance improvements for the IS network and for firms of the network. However, the results are dependent upon the methodological considerations of the assessments, including the reference system, functional unit and allocation methods, in addition to important processes such as the agricultural inputs for the system and energy systems employed.

    By using industrial symbiosis concepts, biofuel producers have possibilities to improve the environmental performance. This is done by making use of by-products and waste and diversifying their products, promoting a transition toward biorefinery systems and a bio-based economy for regional environmental sustainability.

  • 109.
    Martin, Michael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Using LCA to quantify the environmental performance of an industrial symbiosis network: Application in the Biofuels IndustryManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    It is generally assumed that industrial symbiosis creates economic and environmental benefits for all firms involved, though few quantifications have been produced. The environmental performance of an industrial symbiosis network will be quantified using an approach from previous literature. Additionally, the benefits provided by exchanges have partitioned to firms taking part in the industrial symbiosis network, which may have implications for tax incentives, marketing, expansion and environmental awareness. The current industrial symbiosis network has been found to have benefits compared to reference scenarios produced. However, methodological choices, such as the choice of reference scenario and allocation methods may significantly influence the results of the environmental performance.

  • 110.
    Martin, Michael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Parsapour, Amin
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Upcycling wastes with biogas production:: An exergy and economic analysis2012Inngår i: Venice 2012: International Symposium on Energy from Biomass and Waste, Venice, Italy, 2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The massive consumption of finite resources creates high economical and environmental costs due to material dispersion and waste generation. In order to overcome this, by-products and wastes may be used, to avoid the use of virgin materials and benefit from the useful inherent energy of the material. By adding value to the material, economic and environmental performance can be improve, which is called upcycling. In this paper, an exergy and economic analysis of a biogas process is examined. In order to investigate if biogas production from wastes can upcycle materials, biogas production from a by-product from the brewing process is examined. From the analysis, the process is found to upcycle the by-product with an increase in exergy and economic benefit due to the generation of biomethane and biofertilizer. This analysis thus shows that by using by-products as such, the sustainability of the system may improve.

  • 111.
    Martin, Michael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Svensson, Niclas
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Eklund, Mats
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Who gets the benefits? An approach for assessing the environmental performance of industrial symbiosis2015Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 98, s. 263-271Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Industrial symbiosis networks are generally assumed to provide economic and environmental benefits for all firms involved, though few quantifications have been produced in the literature, and the methods for these quantifications have varied. This paper provides an approach to quantify the environmental performance of industrial symbiosis networks using guidance from the literature of life cycle assessment. Additionally, an approach to distribute credits due to exchanges for firms in the industrial symbiosis network is outlined. From the approach, influential methodological considerations used for the quantifications are discussed, including e.g. the production of reference systems, allocation methods, system boundaries and functional unit. The implications of such an approach may be beneficial for the industrial symbiosis community and provide information crucial for taxes, subsidies, business relations, expansion possibilities for the network, marketing and other issues related to the environmental performance of firms in the industrial symbiosis network.

  • 112.
    Martin, Michael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Svensson, Niclas
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Fonseca, Jorge
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Eklund, Mats
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Quantifying the environmental performance of integrated bioethanol and biogas production2014Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 6, s. 109-116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As the production of biofuels continues to expand worldwide, criticism about, e.g. the energy output versus input and the competition with food has been questioned. However, biofuels have the possibility to be optimized in order to improve the environmental performance. This could be accomplished through the use of concepts from industrial symbiosis. This paper provides a quantification of the environmental performance of industrial symbiosis in the biofuel industry through integration of biogas and ethanol processes using a life cycle approach. Results show that although increasing integration is assumed to produce environmental benefits, not all impact categories have achieved this and the results depend upon the allocation methods, energy system and assumptions chosen.

  • 113.
    Martin, Michael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Svensson, Niclas
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Fonseca, Jorge
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Eklund, Mats
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska högskolan.
    Who gets the benefits?: An approach for assessing the environmentalperformance of industrial symbiosis2012Inngår i: Greening of Industry Network: Support your future today! Turning environmental challenges into business opportunities, 2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    It is generally assumed that industrial symbiosis creates economic and environmental benefits for all firmsinvolved, though only a few quantifications have been produced in the literature. An approach to quantifyenvironmental performance of industrial symbiosis using life cycle assessment has been provided,outlining the choice of functional unit, system boundaries, impact assessment and allocation as well as thedistribution of benefits among firms in the symbiotic activity. The implications of such an approach maybe beneficial for the industrial symbiosis and life cycle assessment communities and provide informationcrucial for taxes, subsidies, business relations, marketing and other issues related to the environmentalperformance of firms in the industrial symbiosis network.

  • 114.
    Martinez, Cristina A.
    et al.
    University of Murcia, Spain; IMIB Arrixaca, Spain.
    Nohalez, Alicia
    University of Murcia, Spain; IMIB Arrixaca, Spain.
    Parrilla, Inmaculada
    University of Murcia, Spain; IMIB Arrixaca, Spain.
    Motas, Miguel
    University of Murcia, Spain; IMIB Arrixaca, Spain.
    Roca, Jordi
    University of Murcia, Spain; IMIB Arrixaca, Spain.
    Romero, Inmaculada
    CSIC, Spain.
    Garcia-Gonzalez, Diego L.
    CSIC, Spain.
    Cuello, Cristina
    University of Murcia, Spain; IMIB Arrixaca, Spain.
    Rodriguez-Martinez, Heriberto
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för barns och kvinnors hälsa. Linköpings universitet, Medicinska fakulteten.
    Martinez, Emilio A.
    University of Murcia, Spain; IMIB Arrixaca, Spain.
    Gil, Maria A.
    University of Murcia, Spain; IMIB Arrixaca, Spain.
    The overlaying oil type influences in vitro embryo production: differences in composition and compound transfer into incubation medium between oils2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikkel-id 10505Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The oil overlay micro-drop system is widely used for cultures of mammalian gametes and embryos. We evaluated hereby the effects of two unaltered commercial oils-Sigma mineral oil (S-MO) and Nidoil paraffin oil (N-PO)-on in vitro embryo production (IVP) outcomes using a pig model. The results showed that while either oil apparently did not affect oocyte maturation and fertilization rates, S-MO negatively affected embryo cleavage rates, blastocyst formation rates, and, consequently, total blastocyst efficiency of the system. No differences in the oxidation state were found between the oils or culture media incubated under S-MO or N-PO. Although both oils slightly differed in elemental composition, there were no differences in the concentrations of elements between fresh media and media incubated under oils. By contrast, we demonstrated clear oil-type differences in both the composition of volatile organic compounds (VOC) and the transfer of some of these VOCs (straight-chain alkanes and pentanal and 1,3-diethyl benzene) to the culture medium, which could have influenced embryonic development.

  • 115. Martinsson, J
    et al.
    Eriksson, A C
    Nielsen, I Elbaek
    Berg Malmborg, V
    Ahlberg, E
    Andersen, C
    Lindgren, R
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nyström, Robin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nordin, E Z
    Brune, W H
    Svenningsson, B
    Swietlicki, E
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Pagels, J H
    Impacts of Combustion Conditions and Photochemical Processing on the Light Absorption of Biomass Combustion Aerosol2015Inngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 49, nr 24, s. 14663-14671Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim was to identify relationships between combustion conditions, particle characteristics, and optical properties of fresh and photochemically processed emissions from biomass combustion. The combustion conditions included nominal and high burn rate operation and individual combustion phases from a conventional wood stove. Low temperature pyrolysis upon fuel addition resulted in "tar-ball" type particles dominated by organic aerosol with an absorption Angstrom exponent (AAE) of 2.5-2.7 and estimated Brown Carbon contributions of 50-70% to absorption at the climate relevant aethalometer-wavelength (520 nm). High temperature combustion during the intermediate (flaming) phase was dominated by soot agglomerates with AAE 1.0-1.2 and 85-100% of absorption at 520 nm attributed to Black Carbon. Intense photochemical processing of high burn rate flaming combustion emissions in an oxidation flow reactor led to strong formation of Secondary Organic Aerosol, with no or weak absorption. PM1 mass emission factors (mg/kg) of fresh emissions were about an order of magnitude higher for low temperature pyrolysis compared to high temperature combustion. However, emission factors describing the absorption cross section emitted per kg of fuel consumed (m(2)/kg) were of similar magnitude at 520 nm for the diverse combustion conditions investigated in this study. These results provide a link between biomass combustion conditions, emitted particle types, and their optical properties in fresh and processed plumes which can be of value for source apportionment and balanced mitigation of biomass combustion emissions from a climate and health perspective.

  • 116.
    Matsakas, Leonidas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Nitsos, Christos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Vörös, Dimitrij
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    High-Titer Methane from Organosolv-Pretreated Spruce and Birch2017Inngår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, nr 3, artikkel-id 263Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The negative impact of fossil fuels and the increased demand for renewable energy sources has led to the use of novel raw material sources. Lignocellulosic biomass could serve as a possible raw material for anaerobic digestion and production of biogas. This work is aimed at using forest biomass, both softwood (spruce) and hardwood (birch), as a raw material for anaerobic digestion. We examined the effect of different operational conditions for the organosolv pretreatment (ethanol content, duration of treatment, and addition of acid catalyst) on the methane yield. In addition, we investigated the effect of addition of cellulolytic enzymes during the digestion. We found that inclusion of an acid catalyst during organosolv pretreatment improved the yields from spruce, but it did not affect the yields from birch. Shorter duration of treatment was advantageous with both materials. Methane yields from spruce were higher with lower ethanol content whereas higher ethanol content was more beneficial for birch. The highest yields obtained were 185 mL CH4/g VS from spruce and 259.9 mL CH4/g VS from birch. Addition of cellulolytic enzymes improved these yields to 266.6 mL CH4/g VS and 284.2 mL CH4/g VS, respectively.

  • 117.
    Mellin, Pelle
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Kantarelis, Efthymios
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    CFD approach to investigate fast pyrolysis by pre-heated steam, in a fluidized bed reactor2012Konferansepaper (Annet vitenskapelig)
  • 118.
    Mellin, Pelle
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Zhang, Qinglin
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Kantarelis, Efthymios
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Zhou, Chunguang
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Accuracy and Potential Use of a Developed CFD-pyrolysis Model for Simulating Lab-scale Bio Oil Production2012Inngår i: The 20th EU BC&E Online Proceedings 2012, 2012, s. 953-959Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The paper describes development of a CFD¬pyrolysis model using an Eularian-Eularian framework with an implemented pyrolysis reaction model. The CFD¬pyrolysis model is used to simulate the bubbling fluidized bed reactor integrated in a new experimental fast pyrolysis process for bio oil production. The model is compared to experiments in aspect of outlet gas composition, temperature and bed height. Tar behavior and yield of bio oil are illustrated and a parametric study investigates impact of flow rate and temperature on bio oil yield. The results show a tolerable fit compared to measurements and reasonable tendencies in the parametric study.

  • 119.
    Menya, E.
    et al.
    Makerere Univ, Coll Engn Design Art & Technol, Dept Mech Engn, POB 7062, Kampala, Uganda.;Gulu Univ, Dept Biosyst Engn, POB 166, Gulu, Uganda..
    Olupot, P. W.
    Makerere Univ, Coll Engn Design Art & Technol, Dept Mech Engn, POB 7062, Kampala, Uganda..
    Storz, H.
    Thuenen Inst Agr Technol, Bundesallee 47, D-38116 Braunschweig, Germany..
    Lubwama, M.
    Makerere Univ, Coll Engn Design Art & Technol, Dept Mech Engn, POB 7062, Kampala, Uganda..
    Kiros, Yohannes
    KTH, Tidigare Institutioner (före 2005), Kemiteknik.
    Characterization and alkaline pretreatment of rice husk varieties in Uganda for potential utilization as precursors in the production of activated carbon and other value-added products2018Inngår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 81, s. 104-116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, 13 rice husk (RH) varieties from 4 agro-ecological zones in Uganda were characterized, NaOH-pretreated, and evaluated for their potential utilization as precursors for production of bio-oil, ash, char, and activated carbon for selected applications. RH varieties were characterized through particle size analysis, bulk density, proximate and ultimate analyses, specific surface area, pore volume, as well as lignocellulosic and inorganic compositions. Selected RH varieties were subsequently pretreated at NaOH concentrations of 1-4%w/v, using pretreatment ratios of 5 g RH: 40 mL NaOH. Properties varied among RH varieties, suiting them as feedstocks for different applications. Upland rice husk varieties are more suited precursors for production of bio-oil, and activated carbon due to their relatively lower ash content, higher specific surface area, as well as higher volatile matter and fixed carbon contents. Upland rice husks could as well be employed in the preparation of electrodes for electrochemical devices, due to their relatively higher specific surface area. A high ash content (21-32% dry basis) of lowland rice husks presents good prospects for their calcination, since larger amounts of rice husk ash could be obtained, and employed in different applications. Lowland rice husk varieties could also be more suited precursors for production of char for soil amendment, due to their relatively higher ash content, which subsequently increases their char yields. However, alkaline pretreatment of rice husks using 2-4%w/v NaOH can reduce the ash content by as much as 74-93%, depending on the rice husk variety, which paves way for utilizing rice husks with a high ash content in different applications. Aside from ash reduction, the enhanced specific surface area (1.2-1.7 m(2) g(-1)), volatile matter (68-79%db) and fixed carbon (19-24%db) contents of NaOH-pretreated rice husks suggests they are more suited feedstocks than when employed in their raw form, for production of bio-oil, as well as activated carbon.

  • 120.
    Molin, Elin
    et al.
    Dalarna Univ, Energy Technol, SE-79188 Falun, Sweden.;PPAM Solkraft AB, Corp Res, SE-59072 Ljungsbro, Sweden..
    Stridh, Bengt
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Molin, Andreas
    PPAM Solkraft AB, Corp Res, SE-59072 Ljungsbro, Sweden.;Linkoping Univ, Dept Management & Engn, Div Energy Syst, SE-58183 Linkoping, Sweden..
    Waeckelgard, Ewa
    Dalarna Univ, Energy Technol, SE-79188 Falun, Sweden..
    Experimental Yield Study of Bifacial PV Modules in Nordic Conditions2018Inngår i: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 8, nr 6, s. 1457-1463Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study reports on the first full-year field study in Sweden using bifacial photovoltaic modules. The two test sites are located on flat roofs with a low albedo of 0.05 in Linkoping (58 degrees N) and were studied fromDecember 2016 to November 2017. Site 1 has monofacial and bifacial modules with a 40 degrees tilt facing south, which is optimal for annual energy yield for monofacial modules at this location. Site 2 has monofacial 40 degrees tilt south-facing modules and bifacial vertical east-west orientated modules. The annual bifacial energy gain (BGE) was5% at site 1 and1% at site 2 for albedo 0.05. The difference in power temperature coefficients between bifacial and monofacial modules was estimated to influence BG(E) by + 0.4 and + 0.1 percentage points on site 1 and 2, respectively. A higher albedo could be investigated on a sunny day with fresh snow for the bifacial east-west modules. The specific yield was 7.57 kWh/kW(p), which was a yield increase of 48% compared with tar paper at similar solar conditions.

  • 121.
    Momayez, Forough
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi. Isfahan University of Technology.
    Karimi, Keikhosro
    Isfahan University of Technology.
    Karimi, Shiva
    Isfahan University of Technology.
    Sárvári Horváth, Ilona
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Efficient hydrolysis and ethanol production from rice straw by pretreatment with organic acids and effluent of biogas plant2017Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 80, s. 50537-50545Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effluent of biogas production plant was used for the pretreatment of rice straw for the improvement of ethanol production. In addition, the organic active ingredients of the effluent, i.e., acetic, butyric, lactic and propionic acids (1-4%), as well as water were employed for the pretreatment at 100 and 140 °C. The results indicated that pretreatment at 100 °C had no significant effect on the performance of subsequent enzymatic hydrolysis and ethanol production by simultaneous saccharification and fermentation (SSF). Among different types of organic acids presented in the effluent, lactic acid showed a better performance. The highest concentration of glucose and ethanol were achieved after 72 h enzymatic hydrolysis and SSF from the straw pretreated at 140 °C with 4% lactic acid. Applying the effluent for the straw pretreatment at 140 °C resulted in an increase in glucose and ethanol concentrations by 42.4 and 47.5%, respectively, compared to those from untreated samples. SEM, FTIR, BET, BJH, and compositional analyses were used to characterize the changes in the structure and composition of rice straw by the pretreatment. Changes in the straw swelling, cellulose crystallinity, pore size distribution, and composition were responsible for the acquired improvements.

  • 122. Moradian, Farzad
    et al.
    Tchoffor, Placid A.
    Davidsson, Kent O.
    Pettersson, Anita
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Thermodynamic equilibrium prediction of bed agglomeration tendency in dual fluidized-bed gasification of forest residues2016Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 154, s. 82-90Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dual fluidized-bed (DFB) gasification is one of the recently developed technologies for production of heat, power, transportation fuels and synthetic chemicals through steam gasification of biomass. Bed agglomeration is a serious ash-related problem that should be taken into account when biomass-based fuels are selected for fluidized bed gasification and combustion. This study developed a thermodynamic equilibrium model to assess the risk of bed agglomeration in gasification and combustion reactors of a DFB gasifier using biomass (forest residues) as feedstock. The modelling approach combined thermodynamic equilibrium calculations with chemical fractionation technique to predict the composition and melting behaviour of the fuel-derived ash as well as bed particles coating layer in the gasification and combustion reactors. FactSage was employed for the thermodynamic equilibrium calculations. The modelling results were then compared with experimental data obtained from a full-scale DFB gasifier to estimate the reliability and validity of the predictive model. In general, a good agreement was found between the modelling results and experimental observations. For the forest residues as feedstock and olivine as bed material, the modelling results indicate a low risk of bed agglomeration in the DFB gasifier, as long as the dominant temperature in the combustion zone is below 1020 degrees C. In contrast, quartz as bed material in the DFB gasifier was shown to significantly increase the risk of bed agglomeration through coating-induced agglomeration mechanism. 

  • 123.
    Morgalla, Mario
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Lin, Leteng
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Seemann, Martin
    Chalmers.
    Strand, Michael
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Characterization of particulate matter formed during wood pellet gasification in an indirect bubbling fluidized bed gasifier using aerosol measurement techniques2015Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 138, s. 578-587Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study characterizes particulate matter, organic compounds, and inorganic compounds formed in an atmospheric indirect bubbling fluidized bed gasifier at two different steam-to-fuel ratios using wood pellets as fuel. The sampling and conditioning system consisted of a high-temperature dilution probe to quench aerosol dynamics and condense inorganic vapors, a primary thermodenuder to adsorb tar components, and a secondary thermodenuder to investigate the volatility/thermal stability of the remaining aerosol. Both online and offline instruments were used to characterize the aerosol in terms of number size distribution, mass size distribution, particle mass concentration, particle number concentration, morphology, and elemental analysis. Size distributions with three distinct modes were established. The fine and intermediate modes were mainly formed by tar and alkali vapors that had condensed in the sampling and conditioning systems. The coarse mode mainly consisted of the original particles, which are char, fly ash, and fragmented bed material. At the higher steam-to-fuel ratio, tar components seem to be reduced and more coarse-mode particles emitted compared to the low steam case. Furthermore, a possibility for online monitoring of heavy tar is suggested. (C) 2015 Elsevier B.V. All rights reserved.

  • 124.
    Morgalla, Mario
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Lin, Leteng
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Strand, Michael
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Benzene conversion in a packed bed loaded with biomass char particles2018Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, nr 1, s. 554-560Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigates the conversion of benzene in a packed bed containing fine char particles. Benzene and steam were simultaneously supplied to a tubular ceramic reactor that was heated electrically. Fragmented char particles were suspended and continuously supplied via a separate supply line. A packed bed of crushed alumina balls was positioned in the reactor to retain the char particles. The benzene conversion in the hot char bed was investigated by varying the bed temperature (900–1100 °C), steam concentration (0–27 vol %), and char concentration (5–50 g Nm–3). The highest conversions achieved in the experiments were approximately 75%. At comparable char concentrations, similar benzene conversions occurred at 900 and 1000 °C. Increasing the temperature to 1100 °C or increasing the steam concentration reduced the benzene conversion. The results indicate that the reduced conversion was due to enhanced char gasification reactions at elevated temperatures and steam concentrations and thus to reduced char mass in the packed bed.

  • 125.
    Morgalla, Mario
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Lin, Leteng
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Strand, Michael
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Decomposition of benzene using char aerosol particles dispersed in a high-temperature filter2017Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 118, s. 1345-1352Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study the tar-removal suitability of char particles finely dispersed in a high-temperature filter was investigated. Benzene was selected as the model tar. An aerosol-based method was designed and used to investigate the benzene decomposition behaviour. Two types of char were used: commercially available activated charcoal and pine char prepared in the laboratory. The conversion behaviour of both chars was investigated in the temperature range between 750 and 900 °C using steam as the gasification medium. During the experiments, different benzene concentrations, amounts of deposited char and gas residence times were tested. The results indicate that both activated carbon and pine char reduced the benzene concentration. Activated carbon generally produced higher and more stable benzene conversions compared to the pine char particles. Decreasing the benzene concentration or increasing the gas residence time or char mass improved the benzene conversion. It was concluded that the char gasification rate became slower while benzene was simultaneously converted. The aerosol-based method was also used to investigate benzene decomposition behaviour while continuously supplying fresh char particles together with steam at 1000 °C. In that way, the deactivated and gasified char particles were steadily replaced, preventing the benzene conversion from decreasing over time.

  • 126.
    Muraleedharan, Madhu Nair
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Depolymerization of Lignocellulose by Lytic Polysaccharide MonoOxygenases2018Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Lignocellulose biomass is considered as one of the most potential and sustainable sources for the production of value-added chemicals and fuels while replacing the traditional petroleum resources. In a biorefinery, by employing biochemical conversion processes,cellulose present in the biomass is broken down into monomeric sugars which can belater converted into fuels or chemicals. This process is done with the help of different cellulose digesting enzymes (cellulases), isolated from natural cellulolytic organisms suchas saprophytic fungi.

    Lytic polysaccharide monooxygenases (LPMOs) are considered as one of the vital classesof enzymes in the bio-conversion of lignocellulose. They are copper active enzymes present naturally in cellulose degrading fungi. Unlike the traditional cellulases, they havea unique way of breaking cellulose using molecular oxygen or hydrogen peroxide as cosubstratein the presence of a reducing agent. Their ability to enhance the action of other cellulases in depolymerizing the cellulose, make them an integral part of today’s commercial cellulase cocktails.

    This thesis comprises the study about the action of lytic polysaccharide monooxygenaseson various cellulose substrates, both model and natural. The first part of the thesis focuses on the ability of an LPMO (MtLPMO9) and a traditional cellulase (MtEG5A), to act insynergism. The evaluation was done based on the release of oxidized and non-oxidized sugars and also on the ability to liquefy the substrates. It was observed that together, these two enzymes resulted in enhanced release of oxidized and non-oxidized sugars. Both were able to reduce viscosity of the substrates but no further synergistic effect was observed when added together.

    The second part focuses on the ability of LPMOs to accept electrons from lignins for their action of breaking cellulose chains. Three LPMOs, MtLPMO9, PcLPMO9D and NcLPMO9C, lignins from agricultural and forest biomass pretreated by various pretreatment methods were selected. It was demonstrated that lignins, both in isolatedand substrate bound form were able to act indirectly as reducing agents, by releasingsoluble low-molecular-weight molecules that act as mediators between enzyme and bulklignins. The structural and compositional properties of lignins also affected their ability toact as electron donors. In addition, the effect of biomass pretreatment methods on the lignin properties was also studied. The lignins from acid catalyzed organosolv pretreatment were found as the best candidates in supplying electrons to the enzymes.Interestingly, NcLPMO9C was not able to utilize lignins as electron donors requiring further investigation on their mechanism both in vivo and in vitro.

  • 127.
    Muraleedharan, Madhu Nair
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zouraris, Dimitrios
    National Technical University of Athens.
    Karantonis, Antonis
    National Technical University of Athens.
    Topakas, Evangelos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sandgren, Mats
    Swedish University of Agricultural Sciences.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Karnaouri, Anthi C.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Effect of structural properties of lignin isolated from different sources on its efficiency to serve as electron donor of fungal Lytic Polysaccharide Monooxygenases2018Inngår i: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834Artikkel i tidsskrift (Fagfellevurdert)
  • 128. Mäkelä, Mikko
    et al.
    Wai Kwong, Chi
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Yoshikawa, Kunio
    Hydrothermal treatment of grape marc for solid fuel applications2017Inngår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 145, s. 371-377Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The treatment and disposal of grape marc, a residue from grape processing, represents a significant economic and environmental challenge for the winemaking industry. Hydrothermal treatment of grape marc could be an efficient way for producing solid fuels on-site at the wineries. In this work the effects of treatment temperature and liquid pH on grape marc char and liquid properties were determined based on laboratory experiments and the combustion characteristics of char were assessed through thermogravimetric analysis and fuel ash classification. The results showed that hydrothermal treatment increased the energy and carbon contents and decreased the ash content of grape marc. The effect of liquid pH was statistically significant (p < 0.05) only for the determined carbon yield of liquid samples. The energy yield from grape marc was maximized at lower treatment temperatures, which also decreased the content of less thermally stable compounds in the attained char. Higher treatment temperatures decreased grape marc solid, carbon and energy yields and led to an increase in thermally labile compounds compared to lower temperatures likely due to the condensation of liquid compounds or volatiles trapped in the pores of char particles. The alkali metal contents of char ash were reduced coupled with an increase in respective phosphorus. Overall the results support the use of hydrothermally treated grape marc in solid fuel applications, if elevated levels of ash phosphorus can be tolerated.

  • 129.
    Nair, Ramkumar B
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Eh-Hser Nay, Theimya
    Lennartsson, Patrik R.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Taherzadeh, Mohammad J
    Högskolan i Borås, Akademin för textil, teknik och ekonomi. Biotechnology.
    Waste Bread Valorization Using Edible Filamentous Fungi2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The present study is the first of its kind to use industrial waste bread for ethanol and food-grade filamentous fungal biomass production, with an ‘integrated-biorefinery’ approach for the existing wheat-based ethanol facilities. Four different food-grade fungi such as Neurospora intermedia, Aspergillus oryzae, belonging to ascomycetes and Mucor indicus, Rhizopus oryzae, belonging to zygomycetes, were screened. Initial screening for fungal cultures (without external enzyme saccharification) showed an ethanol yield maximum of 47.8 ±1.1 to 67.3 ±2.1, and 38.7 ±1.1 to 67.7±1.8 mg per g dry substrate loading from whole-grain bread and white-bread respectively, post the enzymatic liquefaction. Scale-up of the N. intermedia fermentation achieved using bench scale airlift reactor showed an ethanol yield maximum of 91.6 ±2.1 and 87.5 ±1.9 mg per g dry substrate loading for whole-grain bread and white-bread respectively.

  • 130.
    Nair, Ramkumar B
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Kalif, Mahdi
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Ferreira, Jorge A.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Taherzadeh, Mohammad J
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Lennartsson, Patrik R.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Mild-temperature dilute acid pretreatment for integration of first and second generation ethanol processes2017Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 245, s. 145-151Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of hot-water (100 °C) from the 1st generation ethanol plants for mild-temperature lignocellulose pretreatment can possibly cut down the operational (energy) cost of 2nd generation ethanol process, in an integrated model. Dilute-sulfuric and -phosphoric acid pretreatment at 100 °C was carried out for wheat bran and whole-stillage fibers. Pretreatment time and acid type influenced the release of sugars from wheat bran, while acid-concentration was found significant for whole-stillage fibers. Pretreatment led up-to 300% improvement in the glucose yield compared to only-enzymatically treated substrates. The pretreated substrates were 191–344% and 115–300% richer in lignin and glucan, respectively. Fermentation using Neurospora intermedia, showed 81% and 91% ethanol yields from wheat bran and stillage-fibers, respectively. Sawdust proved to be a highly recalcitrant substrate for mild-temperature pretreatment with only 22% glucose yield. Both wheat bran and whole-stillage are potential substrates for pretreatment using waste heat from the 1st generation process for 2nd generation ethanol.

  • 131.
    Nair, Ramkumar B
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Ravula, Vamsikrishna
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Lennartsson, Patrik R.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Taherzadeh, Mohammad J
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Neurospora intermedia pellets for enhanced ethanol and fungal biomass production from wheat straw2017Inngår i: Proceedings of 39th Symposium on Biotechnology for Fuels and Chemicals, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recent studies at our research group have described an ‘integrated-biorefinery’ model for the existing 1st generation wheat-based ethanol facilities, by using edible filamentous fungus, Neurospora intermedia. The process focuses on the production of 2nd generation ethanol together with fungal biomass (for animal or aquaculture feed applications) from wheat straw. A final ethanol yield of 94% (theoretical maximum based on substrate glucan content) was obtained with N. intermedia fermentation in dilute phosphoric acid pretreated (0.7%w/v acid, 7min at 201±4°C) and enzymatically hydrolyzed (10FPU cellulase/g substrate) straw. Fungal cultivation in liquid straw hydrolysate resulted in a maximum of 3.71±0.11g/L dry fungal biomass. Considering the industrial significance of the fungal process, attempts were made to manipulate N. intermedia to grow as pellet forms in the straw hydrolysate, for the first time. Of the various culture conditions screened, stable pellet morphology was obtained at pH 3.0 to 5.5, resulting in uniform pellets with size ranging from 2.5 to 4.25mm. Fermentation using N. intermedia pellets in the liquid straw hydrolysate, resulted in about 31% increase in the ethanol yield, with an improved glucose assimilation by the pellets (82% reduction) as opposed to filamentous forms (51% reduction), at similar culture conditions. The growth of fungal pellets in presence of inhibitors (at different concentrations of acetic acid and furfural) resulted in about 11% to 45% increase in ethanol production as compared to filamentous forms, at similar growth conditions in the liquid straw hydrolysate. Detailed results on N. intermedia pelletization in liquid straw hydrolysate will be discussed in this presentation.

  • 132.
    Naqvi, Muhammad
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013). Department of Energy, Building, and Environment, Mälardalen University, Sweden.
    Dahlquist, E.
    Department of Energy, Building, and Environment, Mälardalen University, Sweden.
    Yan, J.
    Department of Energy, Building, and Environment, Mälardalen University, Sweden & Department of Chemical Engineering, Royal Institute of Technology (KTH), Sweden.
    Naqvi, S. R.
    School of Chemical & Materials Engineering, NUST, Pakistan.
    Nizami, A. S.
    Center of Excellence in Environmental Studies, King Abdulaziz University, Saudi Arabia.
    Salman, C. A.
    Department of Energy, Building, and Environment, Mälardalen University, Sweden.
    Danish, M.
    State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, ECUST, China.
    Farooq, U.
    State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, ECUST, China.
    Rehan, M.
    Center of Excellence in Environmental Studies, King Abdulaziz University, Saudi Arabia.
    Khan, Z.
    Systems Power and Energy, School of Engineering, University of Glasgow, UK.
    Qureshi, A. S.
    Institute of Biotechnology and Genetic Engineering, University of Sindh, Pakistan.
    Polygeneration system integrated with small non-wood pulp mills for substitute natural gas production2018Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 224, s. 636-646Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study aims to examine the potential substitute natural gas (SNG) production by integrating black liquor gasification (BLG) island with a small wheat straw-based non-wood pulp mills (NPM), which do not employ the black liquor recovery cycle. For such integration, it is important to first build knowledge on expected improvements in an overall integrated non-wood pulp mill energy system using the key performance indicators. O2-blown circulating fluidized bed (CFB) gasification with direct causticization is integrated with a reference small NPM to evaluate the overall performance. A detailed economic analysis is performed together with a sensitivity analysis based on variations in the rate of return due to varying biomass price, total capital investment, and natural gas prices. The quantitive results showed considerable SNG production but significantly reduced electricity production. There is a substantial CO2 abatement potential combining CO2 capture and CO2 mitigation from SNG use replacing compressed natural gas (CNG) or gasoline. The economic performance through sensitivity analysis reflects significant dependency on both substitute natural gas production and natural gas market price. Furthermore, the solutions to address the challenges and barriers for the successful commercial implementation of BLG based polygeneration system at small NPMs are discussed. The system performance and discussion on the real application of integrated system presented in this article form a vital literature source for future use by large number of small non-wood pulp industries.

  • 133.
    Nayak, Maneesh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för biologisk grundutbildning. IBG.
    Metabolic engineering of Synechocystis PCC 6803 with the aim to enhance isobutanol/1-butanol production using CRISPR interference2017Independent thesis Advanced level (degree of Master (Two Years)), 30 poäng / 45 hpOppgave
    Fulltekst tilgjengelig fra 2019-09-23 09:18
  • 134. Nielsen, Ingeborg E.
    et al.
    Eriksson, Axel C.
    Lindgren, Robert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Martinsson, Johan
    Nyström, Robin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nordin, Erik Z.
    Sadiktsis, Ioannis
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nojgaard, Jacob K.
    Pagels, Joakim
    Time-resolved analysis of particle emissions from residential biomass combustion: Emissions of refractory black carbon, PAHs and organic tracers2017Inngår i: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 165, s. 179-190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Time-resolved particle emissions from a conventional wood stove were investigated with aerosol mass spectrometry to provide links between combustion conditions, emission factors, mixing state of refractory black carbon and implications for organic tracer methods. The addition of a new batch of fuel results in low temperature pyrolysis as the fuel heats up, resulting in strong, short-lived, variable emission peaks of organic aerosol-containing markers of anhydrous sugars, such as levoglucosan (fragment at m/z 60). Flaming combustion results in emissions dominated by refractory black carbon co-emitted with minor fractions of organic aerosol and markers of anhydrous sugars. Full cycle emissions are an external mixture of larger organic aerosol-dominated and smaller thinly coated refractory black carbon particles. A very high burn rate results in increased full cycle mass emission factors of 66, 2.7, 2.8 and 1.3 for particulate polycyclic aromatic hydrocarbons, refractory black carbon, total organic aerosol and m/z 60, respectively, compared to nominal burn rate. Polycyclic aromatic hydrocarbons are primarily associated with refractory black carbon-containing particles. We hypothesize that at very high burn rates, the central parts of the combustion zone become air starved, leading to a locally reduced combustion temperature that reduces the conversion rates from polycyclic aromatic hydrocarbons to refractory black carbon. This facilitates a strong increase of polycyclic aromatic hydrocarbons emissions. At nominal burn rates, full cycle emissions based on m/z 60 correlate well with organic aerosol, refractory black carbon and particulate matter. However, at higher burn rates, m/z 60 does not correlate with increased emissions of polycyclic aromatic hydrocarbons, refractory black carbon and organic aerosol in the flaming phase. The new knowledge can be used to advance source apportionment studies, reduce emissions of genotoxic compounds and model the climate impacts of refractory black carbon, such as absorption enhancement by lensing. 

  • 135.
    Niklasson, Fredrik
    et al.
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Energi och cirkulär ekonomi.
    Gustavsson, Lennart
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Energi och cirkulär ekonomi.
    Ryde, Daniel
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Energi och cirkulär ekonomi.
    Johansson, Mathias
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Energi och cirkulär ekonomi.
    Persson, Henrik
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Energi och cirkulär ekonomi.
    Schüßler, Ingmar
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Energi och cirkulär ekonomi.
    Branschgemensam forskning för småskaliga biobränslepannor inför ekodesign2018Rapport (Annet vitenskapelig)
    Abstract [sv]

    Nytillverkade småskaliga biobränslepannor måste uppfylla ekodesignkraven senast år 2020. I en marknadsundersökning från 2014 klarade ingen av 11 testade pelletspannor alla ställda krav, vilket tydligt visar på ett utvecklingsbehov. Föreliggande projekt har haft som syfte att panntillverkare och forskningsinstitut branschgemensamt ska bemöta de förbränningstekniska utmaningar som tillverkarna står inför.

    För pelletspannor är den största utmaningen med ekodesigndirektivet att prestanda till största delen beräknas från drift vid partiell last (låg last). Tidigare har prestanda bara fastställts vid nominell last och designen optimerats därefter. I detta projekt har tester körts med två moderna pelletspannor som har olika typer av pelletsbrännare: en med horisontellt brännarrör och en med undermatad brännarkopp. Resultaten visar att tillräckligt god förbränning kunde upprätthållas vid partiell last med båda brännartyperna. Dock uppvisade rörbrännaren betydligt lägre emissioner vid partiell last, troligtvis beroende på att förbränningszonen i denna brännare är skyddad från värmestrålningsutbyte med kylande pannväggar. Ett ganska omfattande arbete lades ned på att förse koppbrännaren med en skyddande krage som skulle skydda förbränningszonen. Det resulterade dock inte in någon betydande förbättring, antagligen beroende på att tillförseln av sekundärluft inte blev optimal. Ett mer omfattande arbete krävs för att utveckla en optimal brännardesign av denna typ.

    För vedpannor är det en utmaning att klara ekodesigndirektivets NOx-krav på 200 mg/Nm³. En mängd temperaturmätningar i en vedpanna för villabruk resulterade i att termisk NOx-bildning kunde uteslutas. Pannan förseddes med ett system för rökgasåterföring, men det minskade inte NOx-emissionen. Därefter provades olika vedsorter. NOx-emissionen kunde minskas till att klara gränsvärdet med avbarkad björkved. Kemiska analyser visade att björkbarken innehöll 0,49% kväve jämfört med 0,09% i stamveden. Även granved gav låga NOx-emissioner, men det bränslet medförde ökade emissioner av CO och OGC. För att vedpannor ska klara kraven på CO, OGC och stoft krävs optimering med avseende på vedens slutförbränningsfas. I det skedet är emissionerna som högst, vilket beror på att värmeeffekten avtar och luftflödet tenderar att kyla ned rökgasen innan de brännbara gaserna brunnit ut. Den optiska partikelmätningen visade tydlig korrelation mellan stoft och CO i rökgasen. Om pannan uppfyller gränsvärdet för CO så finns goda chanser att även kravet på partiklar uppfylls.

    Verkningsgraden som anges i ekodesigndirektivet beräknas utgående från bränslets övre värmevärde. Dessutom subtraheras vissa förlustfaktorer. Detta innebär att pannan inte får ha några onödigt stora värmeförluster eller omotiverat hög elförbrukning för att klara satta krav. Mätningar visade att den största förlusten sker via värmen i rökgasen. Den näst största förlustposten är värmetransport från pannkroppen. För verkningsgraden ökar betydelsen av en välisolerad pannkropp vid partiell last. De två pelletspannor som användes inom projektet låg väl till för att kunna uppfylla ekodesigndirektivets krav på verkningsgrad.

  • 136.
    Niklasson, Fredrik
    et al.
    SP Energiteknik, Borås.
    Persson, Tomas
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Marknadspotential för bio- och solvärmesystem2008Rapport (Annet vitenskapelig)
    Abstract [sv]

    I denna rapport analyseras marknaden för kombinerade sol- och pelletsystem, medfokus på småhus. Syftet är att presentera antalet objekt inom olika kategorier av husoch värmesystem som kan vara intressanta för konvertering till bio-sol system samtatt ge en uppskattning av årliga uppvärmningsbehov inom respektive kategori.

    Energistatistik från Statistiska centralbyrån (SCB) har använts i kombination medtidigare studier av byggnadsbestånd och byggnadsutformning. Dessutom harinformation inhämtats från olika branschorganisationer.

    Från föreliggande genomgång står det klart att den största potentialen för bio-solsystem finns på villamarknaden både för helt nya system och för kompletteringar tillbefintliga system. År 2006 fanns det 775 000 småhus med vattenburen värme varav ca183 000 hade vattenburen el. Uppskattningsvis fanns 109 000 småhus med bådevattenburen el och lokaleldstad för biobränsle och ca 118 000 hus bedöms ha haftmöjlighet till oljeeldning (denna grupp har troligtvis minskat ytterligare efter 2006).Bland de elvärmda husen finns också ca 102 000 småhus med frånluftvärmepumpareller luft/vattenvärmepumpar. 365 000 av husen hade en biobränslepanna. Därtillkommer 504 000 hus med direktelvärme, varav ca 292 000 med lokaleldstad.

    Medelförbrukningen för uppvärmning och varmvatten för hus som enbart värms medolja är ca 27 MWh/år, medan motsvarande värde för småhus med vattenburen el är ca15 MWh/år. Småhusen med direktel använder ca 12 MWh/år för uppvärmning ochvarmvatten. Det betyder att ekonomin blir betydligt sämre vid konvertering avelvärmda hus jämfört med oljekonvertering, eftersom energibehovet är lägre samt attinstallationskostnaden kan vara högre.

    En uppskattning av antalet komponenter som inom 10 år kan komma att installeras idessa hus är 213 000 solfångare, 108 000 ackumulatortankar, 106 000 skorstenar,84 000 luftburna pelletkaminer och varmvattenberedare, 40 000 vattenmantladekaminer och 28 000 pannrumspannor. Dessutom tillkommer en utbytesmarknad,kanske speciellt bland husen med biobränslepanna, där gamla pannor byts ut elleräldre människor som tidigare orkat elda med ved till slut byter till pelleteldning.

    Av nybyggda villor uppvärms ca 30 % med el i kombination med biobränsle(troligtvis lokaleldstad) och ungefär lika stor andel värms med enbart vattenburen el(antagligen ofta kompletterat med frånluftvärmepump). Det borde vara av intresse attredan vid nybyggnationen få in integrerade solfångare och pelleteldning i störreutsträckning i nya hus och det kan bli lättare efter att byggreglerna ändras den 1:ajanuari 2010 med en skärpning av kraven för nybyggda hus som använder el föruppvärmning, alltså även el till värmepumpar.

    Potentialen för bio-solsystem till flerbostadshus och lokaler är begränsad då 86 % avflerbostadshusen och nära 70 % av lokalerna värms med fjärrvärme. Det fanns år2006 ca 6200 lokaler med oljeeldning, 4600 lokaler med vattenburen elvärme och5700 lokaler med direktverkande elvärme. I lokalerna som redovisas av SCB ingårinte tillverkande industri. För lägenheter i flerbostadshus gäller att ca 42 000lägenheter värms med enbart olja, 44 000 lägenheter med olja och värmepump,48 000 lägenheter använder direktel och 31 000 lägenheter vattenburen el.

  • 137.
    Niklasson, Fredrik
    et al.
    SP Energiteknik, Borås.
    Persson, Tomas
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Marknadspotential för sol- och biovärmesystem2010Rapport (Annet vitenskapelig)
    Abstract [sv]

    I denna rapport analyseras marknaden för kombinerade sol- och pelletsystem, med fokus påsmåhus. Syftet är att presentera antalet objekt inom olika kategorier av hus och värmesystemsom kan vara intressanta för konvertering till bio-sol system samt att ge en uppskattning avårliga uppvärmningsbehov inom respektive kategori.

    Energistatistik från Statistiska centralbyrån (SCB) har använts i kombination med tidigarestudier av byggnadsbestånd och byggnadsutformning. Dessutom har information inhämtatsfrån olika branschorganisationer.

    Från föreliggande genomgång står det klart att den största potentialen för bio-sol systemfinns på villamarknaden både för helt nya system och för kompletteringar till befintliga system.År 2006 fanns det 775 000 småhus med vattenburen värme varav ca 183 000 hade vattenburenel. Uppskattningsvis fanns 109 000 småhus med både vattenburen el och lokaleldstadför biobränsle och ca 118 000 hus bedöms ha haft möjlighet till oljeeldning (dennagrupp har troligtvis minskat ytterligare efter 2006). Bland de elvärmda husen finns också ca102 000 småhus med frånluftvärmepumpar eller luft/vattenvärmepumpar. 365 000 av husenhade en biobränslepanna. Därtill kommer 504 000 hus med direktelvärme, varav ca 292 000med lokaleldstad.

    Medelförbrukningen för uppvärmning och varmvatten för hus som enbart värms med olja ärca 27 MWh/år, medan motsvarande värde för småhus med vattenburen el är ca 15 MWh/år.Småhusen med direktel använder ca 12 MWh/år för uppvärmning och varmvatten. Det betyderatt ekonomin blir betydligt sämre vid konvertering av elvärmda hus jämfört med oljekonvertering,eftersom energibehovet är lägre samt att installationskostnaden kan vara högre.En uppskattning av antalet komponenter som inom 10 år kan komma att installeras i dessahus är 213 000 solfångare, 108 000 ackumulatortankar, 106 000 skorstenar, 84 000 luftburnapelletkaminer och varmvattenberedare, 40 000 vattenmantlade kaminer och 28 000 pannrumspannor.Dessutom tillkommer en utbytesmarknad, kanske speciellt bland husen medbiobränslepanna, där gamla pannor byts ut eller äldre människor som tidigare orkat elda medved till slut byter till pelleteldning.

    Av nybyggda villor uppvärms ca 30 % med el i kombination med biobränsle (troligtvis lokaleldstad)och ungefär lika stor andel värms med enbart vattenburen el (antagligen oftakompletterat med frånluftvärmepump). Det borde vara av intresse att redan vid nybyggnationenfå in integrerade solfångare och pelleteldning i större utsträckning i nya hus och det kanbli lättare efter att byggreglerna ändras den 1:a januari 2010 med en skärpning av kraven förnybyggda hus som använder el för uppvärmning, alltså även el till värmepumpar.

    Potentialen för bio-solsystem till flerbostadshus och lokaler är begränsad då 86 % av flerbostadshusenoch nära 70 % av lokalerna värms med fjärrvärme. Det fanns år 2006 ca 6200lokaler med oljeeldning, 4600 lokaler med vattenburen elvärme och 5700 lokaler med direktverkandeelvärme. I lokalerna som redovisas av SCB ingår inte tillverkande industri. Förlägenheter i flerbostadshus gäller att ca 42 000 lägenheter värms med enbart olja, 44 000lägenheter med olja och värmepump, 48 000 lägenheter använder direktel och 31 000 lägenhetervattenburen el.

  • 138.
    Niklasson, Johanna
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik.
    Bergquist Skogfors, Linnea
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik.
    Can organic waste fuel the buses in Johannesburg?: A study of potential, feasibility, costs and environmental performance of a biomethane solution for public transport2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Like many large cities, Johannesburg faces several sustainability challenges such as unsustainable use of natural resources, emissions contributing to environmental- and waste related problems. The city is a provincial transport centre, and the transport sector is responsible for a large share of the city’s energy demand and emissions. To approach several of these challenges simultaneously the City of Johannesburg considers the possibilities to use renewable, waste-based, fuel for public transport and has shown a great interest in how Sweden produce and use biogas. 

    In this study an early assessment of the potential, feasibility, economic costs and environmental performance of a waste-based biomethane solution in Johannesburg is performed, with the purpose to fuel a public transport bus fleet. This has been done by developing and using a multi-criteria analysis (MCA). The MCA consists of four categories: potential, feasibility, economic costs and environmental performance. These categories consist of 17 key areas with corresponding key questions and indicators with relating scales used for scoring the indicators. The indicators and scales help identify what information is necessary to collect for the assessment. Furthermore, an Excel tool and a questionnaire are provided to serve as a help when performing the assessment. The feasibility assessment is conducted both for the city as a whole as well as for individual feedstocks. Information for the studied case was gathered from a literature study and interviews in Johannesburg with local experts and potential stakeholders. 

    The identified feedstocks in Johannesburg are landfill gas, waste from a fruit and vegetable market, organic household waste, abattoir waste, waste from the food industry, waste management companies and sewage sludge from the wastewater treatment plants (WWTP). The identified biomass potential is 230,000 tonnes of dry matter/year, generating a total biomethane potential of 91,600,000 Nm3/year, which is enough to fuel almost 2700 buses. In the process of producing biogas, digestate is created. The digestate can be used as biofertilizer and recycle nutrients when used in agriculture. The complete biomass potential in Johannesburg was not identified meaning there is additional potential, from e.g. other food industries, than examined in this study. 

    Assuming that all feedstocks except for landfill gas and WWTP sludge are processed in one biogas plant, the investment cost for this biogas plant is 28 million USD and the total operation and maintenance cost is 1.4 million USD per year. The investment cost and yearly operating cost for the upgrading plant is 43 million USD and 2.4 million USD respectively. Finally, the distribution costs were calculated, including compression and investment in vessels. The investment and operational costs for compression is 7.4 million USD and 220,000 USD/year respectively. The investment cost for the vessels was calculated to 15 million USD and the operational costs of the distribution 16 million USD/year. Consideration should be given to the fact that the numbers used when calculating these costs comes with uncertainties.

    Most indicators in the feasibility assessment of the city as a whole were given the score Poor, but some indicators were scored Satisfactory or Good. The assessment of the individual feedstocks led to a ranking of the most to the least feasible feedstocks where the waste from the fruit and vegetable market and the municipal household waste are considered being in the top. This assessment also shows the feedstocks are in general quite suitable for biomethane production. The issue is the lack of economic and legislative support and strategies not working in favour of biomethane. These are areas that can be improved by the local or national government to give better conditions for production of biomethane in the future. Some examples of this are a proposed landfill tax or landfill ban as well as a closing of the landfills due to the lack of new land. This could all contribute to better conditions for biomethane solutions in the future. Main identified hinders are electricity generation from biogas as a competitor with biomethane, and a general lack of knowledge about biogas and biomethane, from the high-level decision makers to a workforce lacking skills about construction and operation of biogas plants. 

  • 139.
    Nilsson, Håkan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Cournac, Laurent
    Rappaport, Fabrice
    Messinger, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lavergne, Jerome
    Estimation of the driving force for dioxygen formation in photosynthesis2016Inngår i: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1857, nr 1, s. 23-33Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photosynthetic water oxidation to molecular oxygen is carried out by photosystem II (PSII) over a reaction cycle involving four photochemical steps that drive the oxygen-evolving complex through five redox states S-i (i = 0, ... , 4). For understanding the catalytic strategy of biological water oxidation it is important to elucidate the energetic landscape of PSII and in particular that of the final S-4 --> S-0 transition. In this short-lived chemical step the four oxidizing equivalents accumulated in the preceding photochemical events are used up to form molecular oxygen, two protons are released and at least one substrate water molecule binds to the Mn4CaO5 cluster. In this study we probed the probability to form S-4 from S-0 and O-2 by incubating YD-less PSII in the S-0 state for 2-3 days in the presence of O-18(2) and (H2O)-O-16. The absence of any measurable O-16,18(2) formation by water-exchange in the S-4 state suggests that the S-4 state is hardly ever populated. On the basis of a detailed analysis we determined that the equilibrium constant K of the S-4 --> S-0 transition is larger than 1.0 x 10(7) so that this step is highly exergonic. We argue that this finding is consistent with current knowledge of the energetics of the S-0 to S-4 reactions, and that the high exergonicity is required for the kinetic efficiency of PSII.

  • 140.
    Niska, John
    et al.
    Swerea MEFOS, Heating and Metalworking Department.
    Grip, Carl-Erik
    Luleå University of Technology, Division of Energy Science.
    Mellin, Pelle
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Investigating Potential Problems and Solutions of Renewable Fuel Use in Steel Reheating Furnaces2013Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Implementing renewable fuels in steel reheating furnaces can reduce carbon dioxide emissions from fossil fuels, so the steel industry is interested in finding the optimal method of implementation. The relatively low cost of solid biofuels from forest products make them an attractive candidate, but there is a risk of reaction between pellets ash and furnace brick. Therefore a test was conducted with wood pellets ash on a furnace brick to test the sensitivity to pellets ash. One problem is the formation of a glassy phase due to the interaction of furnace refractories with pellets ash. The risk for the formation of a glassy phase depends on the composition of the refractory, composition of the ash and the furnace conditions, for example, a glassy phase was found to form on a chamotte refractory furnace brick when a pellets ash and the brick were heated to 1200°C.

    One method to analyze the risk for volatile and low melting point compounds from solid biofuels is to use a tertiary phase diagram to divide various components in the ash. Oxides and compounds rich in the alkali metals (Na and K) tend to form volatile compounds. These alkali metal oxides together with silica can give low melting point phases for compositions near the bottom of this diagram. Ash compositions near the top of the diagram which are rich in CaO and MgO tend to have higher melting points. The wood pellets ash investigated was analysed and found to contain a large percentage of Ca, Si and Mg, expressed as CaO (44.4%), SiO2 (14.6%) and MgO (10.1%) and relatively modest amounts of the alkali metals Na and K expressed as Na2O (3.5%) and K2O (6.2%). This mostly stem wood pellets ash could give concern with the formation of a glassy phase, so biofuels with more twigs, leaves and bark with a higher concentration of alkali metals could give even greater concerns. Therefore alternatives like gasification should be considered.

    Gasification of solid biofuels is one way to avoid ash-forming compounds in reheating furnaces. A survey was performed to evaluate different gasification technologies, as well as existing applications of syngas in other high-temperature industries.

  • 141.
    Nordlander, Eva
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    System studies of Anaerobic Co-digestion Processes2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Production of biogas through anaerobic digestion is one pathway to achieving the European Union (EU) goals of reducing greenhouse gas emissions, increasing the share of renewable energy, and improving energy efficiency. In this thesis, two different models (Anaerobic Digestion Model No. 1 and an artificial neural network) are used to simulate a full-scale co-digester in order to evaluate the feasibility of such models. This thesis also includes models of two systems to study the inclusion of microalgae in biogas plants and wastewater treatment plants. One of the studies is a life-cycle assessment in which replacement of the ley crop with microalgae is evaluated. The other study concerns the inclusion of microalgae in case studies of biological treatment in three wastewater treatment plants. Finally, the co-digestion between microalgae and sewage sludge has been simulated to evaluate the effect on biogas and methane yield. The results showed that Anaerobic Digestion Model No.1 and the artificial neural network are suitable for replicating the dynamics of a full-scale co-digestion plant. For the tested period, the artificial neural network showed a better fit for biogas and methane content than the Anaerobic Digestion Model No. 1. Simulations showed that co-digestion with microalgae tended to reduce biomethane production. However, this depended on the species and biodegradability of the microalgae. The results also showed that inclusion of microalgae could decrease carbon dioxide emissions in both types of plants and decrease the energy demand of the studied wastewater treatment plants. The extent of the decrease in the wastewater treatment plants depended on surface volume. In the biogas plant, the inclusion of microalgae led to a lower net energy ratio for the methane compared to when using ley crop silage. Both studies show that microalgae cultivation is best suited for use in summer in the northern climate.

  • 142.
    Nordlander, Eva
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Eva, Thorin
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yan, JinYue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH-Royal Institute of Technology, Stockholm, Sweden.
    Investigating the possibility of applying an ADM1 based model to a full-scale co-digestion plant2017Inngår i: Biochemical engineering journal, ISSN 1369-703X, E-ISSN 1873-295X, Vol. 120, s. 73-83Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigated the possibility of using a model based on the anaerobic digestion model no. 1 (ADM1) on a full-scale 4000 m3 digester in order to understand how such theoretical models can be applied to a real industrial process. The industrial scale digester co-digests the organic fraction of municipal solid waste, grease trap sludge, and ley crop silage with varying feed rates and amounts of volatile solids. A year of process data was collected. Biogas flow, methane content/flow, and ammonia nitrogen were the variables that the model was best at predicting (index of agreement at 0.78, 0.61/0.77, and 0.68, respectively). The model was also used to investigate the effect of increasing the volatile solids (VS) concentration entering the digester. According to simulation results, increasing the influent VS concentration will increase biogas and methane outflow (from 1.5 million Nm3 methane to more than 2 million Nm3 methane), but decrease the amounts of biogas/methane per unit of volatile solids (from about 264 Nm3methane per tonne VS to below 215 Nm3 methane per tonne VS).

  • 143.
    Nordlander, Eva
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Thorin, Eva
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Yan, Jinyue
    KTH.
    Modeling of a full-scale biogas plant using a dynamic neural network2013Konferansepaper (Fagfellevurdert)
  • 144. Norheim, Arnstein
    et al.
    Lindberg, Daniel
    Hustad, Johan E
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Equilibrium calculations of the composition of trace compounds from biomass gasification in the solid oxide fuel cell operating temperature interval2009Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, nr 2, s. 920-925Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The solid oxide fuel cell (SOFC), due to its high operating temperature and high fuel flexibility, may be fueled by biomass gasification producer gases. Based on the main gas components of typical producer gases (CO, CO(2), H(2), H(2)O, N(2), and light hydrocarbons), the expected SOFC performance will be in the range of cells that use, for example, reformed natural gas as fuel. However, other minor components such as compounds of S, Cl, Na, and K may form species that degrade the SOFC fuel electrode and thus have a negative influence on SOFC performance. Knowledge of the composition of the minor components and the expected level of these compounds is therefore of great importance to be able to perform a detailed experimental study and thus evaluate the expected SOFC performance. The present work comprises results from equilibrium calculations of the composition of biomass gasification gases from two types of biomass gasifiers, one that uses air as gasifying agent and one that uses steam, in the SOFC operating temperature interval (750-1000 degrees C). The major trace components present in biomass gasification producer gases have been identified for several levels of sulfur, potassium, chlorine, and sodium in the SOFC operating temperature interval. Sulfur is present mainly as H(2)S(g), whereas potassium is mainly present as KOH(g) and to some extent K(g), depending mainly on temperature. High chlorine content in the fuel favors KCl(g) production. In the temperature interval between 750 and 900 degrees C there are, in the cases investigated here, small amounts of carbonate-rich liquid phase and solid carbonates in equilibrium with the gasifier gas.

  • 145.
    Nyström, Robin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lindgren, Robert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Avagyan, Rozanna
    Westerholm, Roger
    Lundstedt, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Influence of Wood Species and Burning Conditions on Particle Emission Characteristics in a Residential Wood Stove2017Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, nr 5, s. 5514-5524Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Emissions from small-scale residential biomass combustion are a major source of indoor and outdoor particulate matter (PM) air pollution, and the performance of stoves, boilers, and fireplaces have been shown to be influenced both by fuel properties, technology, and user behavior (firing procedures). Still, rather scarce information is available regarding the relative importance of these variables for the particle characteristics and emissions of different particulate components, e.g., soot, polycyclic aromatic hydrocarbons (PAHs), oxy-PAH, and metals. In particular, the behavior of different wood fuels under varying firing procedures and combustion conditions has not been studied thoroughly. Therefore, the objective of this work was to elucidate the influence of wood species and combustion conditions on particle emission characteristics in a typical Nordic residential wood stove. The emissions from four different wood species were investigated at two controlled combustion conditions, including nominal and high burn rates, with a focus on physical and chemical properties of the fine particulate matter. Considerably elevated carbonaceous particle emissions (soot and organics) were found during high burn rate conditions, which were associated with a shift in particle number size distribution toward a higher fraction of larger particles. In some cases, as here seen for pine, the specific fuel properties can affect the combustion performance and thereby also influence particle and PAH emissions. For the inorganic ash particles, the content in the fuel, and not burning conditions, was found to be the main determining factor, as seen by the increased emissions of alkali salts for aspen. Wood stove emission data on 11 specific oxy-PAHs, together with 45 PAHs, were combined with controlled variations of burning conditions and fuels. The oxy-PAH/PAH ratio during a high burn rate was observed to increase, suggesting an enrichment of particulate oxy-PAH. Accordingly, the main influence on emission performance and particle characteristics was seen between different burn rates, and this study clearly illustrates the major importance of proper operation to avoid unfavorable burning condition, regardless of the wood species used.

  • 146.
    Nyström, Robin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lindgren, Robert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Avagyan, Rozanna
    Westerholm, Roger
    Lundstedt, Staffan
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Influence of wood species and burning conditions on particle emission characteristics in a residential wood stoveManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Emissions from small scale residential biomass combustion are a major source of indoor and outdoor particulate matter (PM) air pollution, and the performance of stoves, boilers and fireplaces have been shown to be influenced both by fuel properties, technology and user behaviour (firing procedures). Still, rather scarce information is available regarding the relative importance of these variables for the particle characteristics and emissions of different particulate components, e.g. soot, PAH, oxy-PAH, and metals. In particular, the behaviour of different wood fuels under varying firing procedures and combustion conditions, has not been studied thoroughly. The objective of this work was therefore to elucidate the influence of wood species and combustion conditions on particle emission characteristics in a typical Nordic residential wood stove. The emissions from four different wood species were investigated at two controlled combustion conditions including nominal and high burn rates, with focus on physical and chemical properties of the fine particulate matter. Considerably elevated carbonaceous particle emissions (soot and organics) was found during high burn rate conditions, associated with a shift in particle number size distribution towards a higher fraction of larger particles. In some cases, as here seen for pine, the specific fuel properties can affect the combustion performance and thereby also influence particle and PAH emissions. For the inorganic ash particles, the content in the fuel, and not burning condition, was found to be the main determining factor as seen by the increased emissions of alkali salts for aspen. For the first time, wood stove emission data on 11 specific oxy-PAHs together with 45 PAH was combined with controlled variations of burning conditions and fuels. The oxy-PAH/PAH ratio during high burn rate was found to increase, suggesting an enrichment of particulate oxy-PAH, information that can be of relevance when assessing the toxicological properties of the PM. Accordingly, the main influence on emission performance and particle characteristics was seen between different burn rates, and this study clearly illustrates the major importance of proper operation to avoid unfavorable burning condition regardless of the wood species used.

  • 147.
    Nzayisenga, Jean Claude
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Eriksson, Karolina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Sellstedt, Anita
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Mixotrophic and heterotrophic production of lipids and carbohydrates by a locally isolated microalga using wastewater as a growth medium2018Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 257, s. 260-265Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The biomass production and changes in biochemical composition of a locally isolated microalga (Chlorella sp.) were investigated in autotrophic, mixotrophic and heterotrophic conditions, using glucose or glycerol as carbon sources and municipal wastewater as the growth medium. Both standard methods and Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) analysis of data acquired by Fourier-transform IR (FTIR) spectrometry showed that autotrophic and mixotrophic conditions promoted carbohydrate accumulation, while heterotrophic conditions with glycerol resulted in the highest lipid content and lowest carbohydrate content. Heterotrophic conditions with glycerol as a carbon source also resulted in high oleic acid (18:1) contents and low linolenic acid (18:3) contents, and thus increasing biodiesel quality. The results also show the utility of MCR-ALS for analyzing changes in microalgal biochemical composition.

  • 148.
    Olofsson, Martin
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Del Pino, Victoria
    NECTON Company, Portugal.
    Lamela, Teresa
    NECTON Company, Portugal.
    Bergé, Jean Pascal
    Ifremer Nantes, France.
    Nilsson, Emmelie
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Legrand, Catherine
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Are algal oil yield estimations dependent on seasonal variation?2011Inngår i: Algae: The sustainable biomass for the future. Perspectives from the submariner project algae cooperation event Trelleborg, Sweden - September 28-29, 2011 / [ed] Cecilia Torres, Berlin, Germany: s.Pro-sustainable projects GmbH , 2011, s. 44-45Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 149.
    Olofsson, Martin
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Lamela, Teresa
    Necton SA, Olhao, Portugal.
    Nilsson, Emmelie
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Bergé, Jean-Pascal
    IFREMER, Nantes, France.
    del Pino, Victória
    Necton SA, Olhao, Portugal.
    Uronen, Pauliina
    Neste Oil, Ctr Technol, Porvoo, Finland.
    Legrand, Catherine
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata 2014Inngår i: Marine Drugs, ISSN 1660-3397, E-ISSN 1660-3397, Vol. 12, nr 4, s. 1891-1910Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Instead of sole nutrient starvation to boost algal lipid production, we addressed nutrient limitation at two different seasons (autumn and spring) during outdoor cultivation in flat panel photobioreactors. Lipid accumulation, biomass and lipid productivity and changes in fatty acid composition of Nannochloropsis oculata were investigated under nitrogen (N) limitation (nitrate:phosphate N:P 5, N:P 2.5 molar ratio). N. oculata was able to maintain a high biomass productivity under N-limitation compared to N-sufficiency (N:P 20) at both seasons, which in spring resulted in nearly double lipid productivity under N-limited conditions (0.21 g L−1 day−1) compared to N-sufficiency (0.11 g L−1 day−1). Saturated and monounsaturated fatty acids increased from 76% to nearly 90% of total fatty acids in N-limited cultures. Higher biomass and lipid productivity in spring could, partly, be explained by higher irradiance, partly by greater harvesting rate (~30%). Our results indicate the potential for the production of algal high value products (i.e., polyunsaturated fatty acids) during both N-sufficiency and N-limitation. To meet the sustainability challenges of algal biomass production, we propose a dual-system process: Closed photobioreactors producing biomass for high value products and inoculum for larger raceway ponds recycling waste/exhaust streams to produce bulk chemicals for fuel, feed and industrial material.

  • 150.
    Olofsson, Martin
    et al.
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Lamela, Teresa
    Necton SA, Olhao, Portugal.
    Nilsson, Emmelie
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Bergé, Jean-Pascal
    IFREMER, Nantes, France.
    del Pino, Victória
    Necton SA, Olhao, Portugal.
    Uronen, Pauliina
    Neste Oil, Ctr Technol, Porvoo, Finland.
    Legrand, Catherine
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata 2014Inngår i: Marine Drugs, ISSN 1660-3397, E-ISSN 1660-3397, Vol. 12, nr 4, s. 1891-1910Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Instead of sole nutrient starvation to boost algal lipid production, we addressed nutrient limitation at two different seasons (autumn and spring) during outdoor cultivation in flat panel photobioreactors. Lipid accumulation, biomass and lipid productivity and changes in fatty acid composition of Nannochloropsis oculata were investigated under nitrogen (N) limitation (nitrate:phosphate N:P 5, N:P 2.5 molar ratio). N. oculata was able to maintain a high biomass productivity under N-limitation compared to N-sufficiency (N:P 20) at both seasons, which in spring resulted in nearly double lipid productivity under N-limited conditions (0.21 g L−1 day−1) compared to N-sufficiency (0.11 g L−1 day−1). Saturated and monounsaturated fatty acids increased from 76% to nearly 90% of total fatty acids in N-limited cultures. Higher biomass and lipid productivity in spring could, partly, be explained by higher irradiance, partly by greater harvesting rate (~30%). Our results indicate the potential for the production of algal high value products (i.e., polyunsaturated fatty acids) during both N-sufficiency and N-limitation. To meet the sustainability challenges of algal biomass production, we propose a dual-system process: Closed photobioreactors producing biomass for high value products and inoculum for larger raceway ponds recycling waste/exhaust streams to produce bulk chemicals for fuel, feed and industrial material.

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