| 1. |
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| 2. |
- Daianova, Lilia, et al.
(författare)
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Evaluation of a regional bioenergy system with local production of biofuel for transportation, integrated with a CHP plant
- 2012
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 92, s. 739-749
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Tidskriftsartikel (refereegranskat)abstract
- The share of renewable liquid fuels (ethanol, fatty acid methyl ester, biogas, and renewable electricity) in the total transportation fuel in Sweden, has increased by the end of 2009 to such level that e.g. domestic bioethanol production is unable to satisfy current ethanol fuel demand. Regional small-scale ethanol production can assist the region in covering the regional needs in transport fuel supply. Current case study system includes the production of ethanol, biogas, heat and power from locally available cereals straw. A mixed integer programming (MIP) model is developed for cost optimization of regional transport fuel supply (ethanol, biogas and petrol). The model is applied for two cases, one when ethanol production plant is integrated with an existing CHP plant (polygeneration), and one with a standalone ethanol production plant. The optimization results show that for both cases the changes in ethanol production costs have the biggest influence on the costs for supplying regional passenger car fleet with transport fuel. Petrol fuel price and straw production costs have also a significant effect on costs for supplying cars with transport fuel for both standalone ethanol production and integrated production system. By integrating the ethanol production process with a CHP plant, the costs for supplying regional passenger car fleet with transport fuel can be cut by 31%, from 150 to 104 (sic)/MW h fuel, which should be compared with E5 costs of 115 E/MW h (excl VAT).
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| 3. |
- Eriksson, Ola
(författare)
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A Systems perspective of Waste and Energy - Strengths and Weaknesses of the ORWARE Model
- 2000
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Waste management of today in Sweden is a complex phenomenonthat demands for a scientific and systematic approach. Thecomplexity is a result of a wide variety of actors,technologies, and impact on the environment, health, and theeconomy. Waste management also has a high relevance withrespect to energy. There are direct connections as e.g. energyrecovery from waste, but also indirect as the systemscomplexity and the environmental and economical impacts.Helpful tools in the planning of waste management aredifferent types of models of which ORWARE is one. Based onprinciples from Life Cycle Analysis (LCA) and complemented witha simple Cost Benefit Analysis (CBA) ORWARE can provide somehelp in finding environmentally sound solutions for wastemanagement systems. The model does not answer all questionsraised by practitioners but can still be used for advisorypurposes. The model does not include sociological or politicalaspects but it covers the area of physical flows with impactson environment, society and economy. Other impacts have to beconsidered with other methods.The experiences from using ORWARE in Swedish municipalitiesduring more than a half decade clearly shows the advantages anddisadvantages of the tool. The model is very flexible when itcomes to the possibility of site-specific adjustments of inputdata and process functions. With help of the model thecomplexity of the studied system can be illustrated by e.g. amap of the number of connections between different types ofinformation. In this way ORWARE supports dialogue betweendifferent stakeholders and collects knowledge in a unique way.On the other hand, modelling such an extensive and complexsystem often leads to errors that takes time to find andcorrect. The model can not be considered as user friendly anddoes not cover all aspects wanted by the society. There arealso educational problems with different time frames and spaceboundaries in the analysis that make the results hard tointerpret.As there are many similarities between waste management andenergy management, experiences from systems analysis of wastemanagement can be used for planning of more sustainablesolutions in the energy management. That is why it isinteresting to develop the methodology used in ORWARE and adaptit to a partly new area like e.g. energy management. Oneexample of improving the methodology is to extend the number ofimpact categories. Another example is to put the functionsdelivered in focus. ORWARE focuses at the waste managementsystem, and thus "treating waste from a certain area" is onefundamental functional unit. Translated to energy that wouldmean to build a model of the energy supply system. But tooptimise the whole system that delivers a function ought to bea more efficient way to head for sustainability than to studythe supply system and the applications separately. That wouldmean to put the end user functions provided by some kind ofenergy transformation in focus instead.In systems analysis it is also important to consider thealternatives to different options of technologies or systemdesigns. In order to understand and assess the influence frome.g. waste management and energy on the environment and thesocio-technical system called society, a systems perspective isthus very important. The systems perspective should work at alldecision levels and with a life cycle perspective on thefunction.
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| 4. |
- Eriksson, Ola
(författare)
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Environmental and Economic Assessment of Swedish Municipal Solid Waste Management in a Systems Perspective
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Waste management is something that affects most people. Thewaste amounts are still increasing, but the waste treatment ischanging towards recycling and integrated solutions. In Swedenproducers’responsibility for different products, a taxand bans on deposition of waste at landfills implicates areorganisation of the municipal solid waste management. Plansare made for new incineration plants, which leads to that wastecombustion comes to play a role in the reorganisation of theSwedish energy system as well. The energy system is supposed toadapt to governmental decisions on decommission of nuclearplants and decreased use of fossil fuels.Waste from private households consists of hazardous waste,scrap waste, waste electronics and wastes that to a largeextent are generated in the kitchen. The latter type has beenstudied in this thesis, except for newsprint, glass- and metalpackages that by source separation haven’t ended up in thewaste bin. Besides the remaining amount of the above mentionedfractions, the waste consists of food waste, paper, cardboard-and plastic packages and inert material. About 80-90 % of thismixed household waste is combustible, and the major part ofthat is also possible to recycle.Several systems analyses of municipalsolid waste managementhave been performed. Deposition at landfill has been comparedto energy recovery, recycling of material (plastic andcardboard) and recycling of nutrients (in food waste).Environmental impact, fuel consumption and costs are calculatedfor the entire lifecycle from the households, until the wasteis treated and the by-products have been taken care of.To stop deposition at landfills is the most importantmeasure to take as to decrease the environmental impact fromlandfills, and instead use the waste as a resource, therebysubstituting production from virgin resources (avoidingresource extraction and emissions). The best alternative tolandfilling is incineration, but also material recycling andbiological treatment are possible.Recycling of plastic has slightly less environmental impactand energy consumption than incineration. The difference issmall due to that plastic is such a small part of the totalwaste amount, and that just a small part of the collectedamount is recycled. Cardboard recycling is comparable toincineration; there are both advantages and disadvantages.Source separation of food waste may lead to higher transportemissions due to intensified collection, but severalenvironmental advantages are observed if the waste is digestedand the produced biogas substitutes diesel in busses.Composting has no environmental advantages compared toincineration, mainly due to lack of energy recovery. Therecycling options are more expensive than incineration. Theincreased cost must be seen in relation to the environmentalbenefits and decreased energy use. If the work with sourceseparation made by the households is included in the analysis,the welfare costs for source separation and recycling becomesnon-profitable. It is however doubted how much time is consumedand how it should be valuated in monetary terms.In systems analyses, several impacts are not measured.Environmental impact has been studied, but not allenvironmental impact. As the parts of the system are underconstant change, the results are not true forever. Recyclingmay not be unambiguously advantageous today, but it can be inthe future.Despite the fact that systems analysis has been developedduring 10 years in Sweden, there are still many decisions takenregarding waste management without support from systemsanalysis and use of computer models. The minority of users ispleased with the results achieved, but the systems analysis isfar from easy to use. The adaptation of tools and models to thedemands from the potential users should consider thatorganisations of different sizes have shifting demands andneeds.The application areas for systems analysis and models arestrategic planning, decisions about larger investments andeducation in universities and within organisations. Systemsanalysis and models may be used in pre-planning procedures. Apotential is a more general application (Technology Assessment)in predominantly waste- and biofuel based energy processes, butalso for assessment of new technical components in a systemsperspective. The methodology and systems approach developedwithin the systems analysis has here been transformed to anassessment of environmental, economic and technical prestandaof technical systems in a broad sense.
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| 5. |
- Kapoor, Manali, et al.
(författare)
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Impact of Conditioning Prior to Dilute Acid Deconstruction of Biomass for the Production of Fermentable Sugars
- 2017
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 5:5, s. 4285-4292
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Tidskriftsartikel (refereegranskat)abstract
- Cost of cellulases is a major impediment in commercialization of cellulosic ethanol. To reduce the enzyme doses for the production of fermentable sugars from rice straw (RS), a series of alkali conditioning experiments were conducted prior to dilute acid (DA) pretreatment. This approach resulted in removal of a majority of extractives, ash, acetic acid, and part lignin, and thus resulted in lowering pseudolignin formation thereby increasing enzymatic hydrolysis yields. Glucan hydrolysis of 69.8%, 74.0%, and 83.5% was obtained at 10 wt % water insoluble solid (WIS) using 8 FPU enzyme/g WIS of biomass conditioned using 0.2, 0.4, and 0.5 wt % alkali prior to pretreatment, which is 14–37% higher than the control (61.0%). The overall sugar recovery in these experiments were 69.2%, 70.2%, and 68.5% at 15 wt % WIS resulting in a sugar concentration greater than 120 g/L, which in turn can produce approximately 5–6% w/v ethanol concentration in fermentation broth. It was found that this approach resulted in a decrease of the enzyme consumption vis-a-vis the conventional process by 46.4% to recover the same amount of sugars. This lowering of enzyme consumption has resulted in net savings, after taking into account the cost of alkali used in the conditioning steps.
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| 6. |
- Malmqvist, Tove, et al.
(författare)
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A Swedish environmental rating tool for buildings
- 2011
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 36:4, s. 1893-1899
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Tidskriftsartikel (refereegranskat)abstract
- In 2003, a joint effort between the Swedish government, a number of companies in the building and construction sectors, some municipalities, insurance companies and banks set a target that by 2009, all new buildings and 30% of existing Swedish buildings should be rated using a voluntary environmental rating tool. In a major research programme finished in 2008, a tool was developed to be used in this context. The tool covers three assessment areas: Energy, Indoor environment and Material & Chemicals. These areas are split into 11 aspects with one or a few indicators. Rating criteria are specified for each indicator, stipulating requirements for a rating Gold, Silver, Bronze and Rated. Indicator results can then be aggregated to aspect, area and a single raring for building level for enhanced result communication. The tool builds on previous experiences regarding environmental building rating tools and therefore includes some special characteristics which aim to tackle some of the criticism directed towards the first generation of such tools. At the time of writing, the first buildings have received official ratings and an independent stakeholder group is promoting broader implementation of the tool. (C) 2010 Elsevier Ltd. All rights reserved.
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| 7. |
- Rönnander, Jonas, et al.
(författare)
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Biotransformation of vanillin into vanillyl alcohol by a novel strain of Cystobasidium laryngis isolated from decaying wood
- 2018
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Ingår i: AMB Express. - : Springer Science and Business Media LLC. - 2191-0855 .- 2191-0855. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Vanillin is an aromatic aldehyde found as a component of lignocellulosic material, and in the cured pods of orchidaceae plants. Like other phenolic substances, vanillin has antimicrobial activity and can be extracted from lignin either by a thermo-chemical process or through microbial degradation. Vanillin, can serve as a model monomer in biodegradation studies of lignin. In the present study, a yeast isolated from decaying wood on the Faroe Islands, was identified as Cystobasidium laryngis strain FMYD002, based on internal transcribed spacer sequence analysis. It demonstrated the ability to convert vanillin to vanillyl alcohol, as detected by ultra-high performance liquid chromatography–quadrupole-time-of-flight. Structural analysis of vanillyl alcohol was carried out by using gas chromatography–mass spectrometry and 1H NMR spectroscopy, and further verified by synthesis. The reduction of vanillin to vanillyl alcohol has been documented for only a few species of fungi. However, to our knowledge, this biotransformation has not yet been reported for basidiomycetous yeast species, nor for any representative of the subphylum Pucciniomycotina. The biotransformation capability of the present strain might prove useful in the industrial utilisation of lignocellulosic residues.
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| 8. |
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| 9. |
- Wang, Zhao, 1984-
(författare)
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A weighted correlation approach of the density functional theory for an inhomogeneous fluid at an interface
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This doctoral thesis presents a newly developed density functional theory (DFT), i.e., the weighted correlation approach (WCA), to study the structural and thermodynamic properties of an inhomogeneous fluid at an interface. The WCA approach provides a generic formulation to evaluate the change of the single-particle direct correlation function in terms of a series of pair direct correlation functions weighted by different correlation-weight functions with adjustable correlation-weight factors. When applied practically, however, an approximation of the pair direct correlation function has to be made, together with appropriate definitions of the weighted densities and the choices of the correlation-weight functions. Despite this seeming complexity, it is shown that the WCA approach can be regarded as a generalization of the classic density functional approaches and this enables us to develop and apply DFT methods in different ways. For demonstration purposes, several implementations of the WCA approach are proposed and applied to predict the density distribution of an inhomogeneous fluid at an interface. The WCA approach is also employed with a novel pressure expression to investigate the inhomogeneous fluid-mediated interaction pressure for different cases. The WCA calculations from the above applications suggest that it is a successful approach for describing the structural and thermodynamic properties of an inhomogeneous fluid at an interface, as compared to the published results of the Monte Carlo simulations, density functional methods and experimental data.
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| 10. |
- Wang, Zhao, et al.
(författare)
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The weighted correlation approach for density functional theory : a study on the structure of the electric double layer
- 2011
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 23:17, s. 175002-
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Tidskriftsartikel (refereegranskat)abstract
- Within the framework of density functional theory, a weighted correlation approach is developed in order to obtain the density distributions of an inhomogeneous fluid. It results in a formally exact expression, by means of the concept of a weighted pair correlation function, used to evaluate the change of the single-particle direct correlation function of the system relative to that of a reference state. When applying the approach for practical use, however, an approximation of the pair correlation function has to be made, along with an appropriate definition of a weight function. Noticeably, combining this approach with fundamental measure theory gives rise to a new method, which we call the FMT/WCA-k(2) approach, for studying the structural and thermodynamic properties of a charged hard-sphere fluid subjected to a spatially varying external potential. Application of the FMT/WCA-k(2) approach in a range of electrolyte concentrations and surface charge densities, against the Monte Carlo simulations, shows that it is superior to the typical approaches of density functional theory in predicting the ionic density profiles of both counter-ions and co-ions near a highly charged surface. It is capable of capturing the fine features of the structural properties of the electric double layers, to well reproduce the layering effect and the charge inversion phenomenon, also in strongly coupled cases where divalent counter-ions are involved. In addition, it is found that the FMT/WCA-k(2) approach even has an advantage over the anisotropic, hyper-netted chain approaches in giving better agreement with the Monte Carlo results.
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