| 1. |
- Lindroth [formerly Tyrberg], Simon, 1979-
(författare)
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Buoy and Generator Interaction with Ocean Waves : Studies of a Wave Energy Conversion System
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- On March 13th, 2006, the Division of Electricity at Uppsala University deployed its first wave energy converter, L1, in the ocean southwest of Lysekil. L1 consisted of a buoy at the surface, connected through a line to a linear generator on the seabed. Since the deployment, continuous investigations of how L1 works in the waves have been conducted, and several additional wave energy converters have been deployed. This thesis is based on ten publications, which focus on different aspects of the interaction between wave, buoy, and generator. In order to evaluate different measurement systems, the motion of the buoy was measured optically and using accelerometers, and compared to measurements of the motion of the movable part of the generator - the translator. These measurements were found to correlate well. Simulations of buoy and translator motion were found to match the measured values. The variation of performance of L1 with changing water levels, wave heights, and spectral shapes was also investigated. Performance is here defined as the ratio of absorbed power to incoming power. It was found that the performance decreases for large wave heights. This is in accordance with the theoretical predictions, since the area for which the stator and the translator overlap decreases for large translator motions. Shifting water levels were predicted to have the same effect, but this could not be seen as clearly. The width of the wave energy spectrum has been proposed by some as a factor that also affects the performance of a wave energy converter, for a set wave height and period. Therefore the relation between performance and several different parameters for spectral width was investigated. It was found that some of the parameters were in fact correlated to performance, but that the correlation was not very strong. As a background on ocean measurements in wave energy, a thorough literature review was conducted. It turns out that the Lysekil project is one of quite few projects that have published descriptions of on-site wave energy measurements.
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| 2. |
- Svensson, Olle, 1967-
(författare)
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Experimental results from the Lysekil Wave Power Research Site
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents how experimental results, from wave power research performed offshore at the Lysekil research site, were obtained. The data were used to verify theoretical models as well as evaluate the feasibility of wave power as a future sustainable energy source.The first experiments carried out at the research site was the measurement of the force in a line where one end was connected to a buoy with a diameter of 3 m and the other end to a set of springs with limited stroke length. The system is exposed to high peak forces compared to average forces. The maximum measured force in the line, when the buoy motion is limited by a stiff stopper rope is ten times the average force in that particular sea state.The experiment performed on the first wave energy converter tested at the Lysekil Research Site is described. The infrastructure of the site is presented where the central connection point is the measuring station. The key finding is that it is possible to transform the motions of ocean waves into electrical energy and distribute it to land.Many wave energy converters must be interconnected if large amounts of energy are to be harvested from the waves. The first submerged substation intended for aggregation of energy from wave power converters is described, with focus on the measurement and control system placed inside the substation. During this experiment period the generators were equipped with many different sensors; these measurements are explained in the thesis.The system that aggregates power from the studied wave energy converter is regularly exposed to peak power of up to 20 times the maximum average output from the converter.Vertical and horizontal movement of the buoy has been measured in different ways. The result is that the vertical displacement of the buoy can be measured with a simple accelerometer circuit but it is much more complicated to measure the horizontal displacement. A special method for measuring the horizontal displacement has been implemented by measuring the strain in the enclosure and the force in the line.
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| 3. |
- Acuña, José, 1982-
(författare)
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Distributed thermal response tests : New insights on U-pipe and Coaxial heat exchangers in groundwater-filled boreholes
- 2013
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Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- U-pipe Borehole Heat Exchangers (BHE) are widely used today in ground source heating and cooling systems in spite of their less than optimal performance. This thesis provides a better understanding on the function of U-pipe BHEs and Investigates alternative methods to reduce the temperature difference between the circulating fluid and the borehole wall, including one thermosyphon and three different types of coaxial BHEs.Field tests are performed using distributed temperature measurements along U-pipe and coaxial heat exchangers installed in groundwater filled boreholes. The measurements are carried out during heat injection thermal response tests and during short heat extraction periods using heat pumps. Temperatures are measured inside the secondary fluid path, in the groundwater, and at the borehole wall. These type of temperature measurements were until now missing.A new method for testing borehole heat exchangers, Distributed Thermal Response Test (DTRT), has been proposed and demonstrated in U-pipe, pipe-in-pipe, and multi-pipe BHE designs. The method allows the quantification of the BHE performance at a local level.The operation of a U-pipe thermosyphon BHE consisting of an insulated down-comer and a larger riser pipe using CO2 as a secondary fluid has been demonstrated in a groundwater filled borehole, 70 m deep. It was found that the CO2 may be sub-cooled at the bottom and that it flows upwards through the riser in liquid state until about 30 m depth, where it starts to evaporate.Various power levels and different volumetric flow rates have been imposed to the tested BHEs and used to calculate local ground thermal conductivities and thermal resistances. The local ground thermal conductivities, preferably evaluated at thermal recovery conditions during DTRTs, were found to vary with depth. Local and effective borehole thermal resistances in most heat exchangers have been calculated, and their differences have been discussed in an effort to suggest better methods for interpretation of data from field tests.Large thermal shunt flow between down- and up-going flow channels was identified in all heat exchanger types, particularly at low volumetric flow rates, except in a multi-pipe BHE having an insulated central pipe where the thermal contact between down- and up-coming fluid was almost eliminated.At relatively high volumetric flow rates, U-pipe BHEs show a nearly even distribution of the heat transfer between the ground and the secondary fluid along the depth. The same applies to all coaxial BHEs as long as the flow travels downwards through the central pipe. In the opposite flow direction, an uneven power distribution was measured in multi-chamber and multi-pipe BHEs.Pipe-in-pipe and multi-pipe coaxial heat exchangers show significantly lower local borehole resistances than U-pipes, ranging in average between 0.015 and 0.040 Km/W. These heat exchangers can significantly decrease the temperature difference between the secondary fluid and the ground and may allow the use of plain water as secondary fluid, an alternative to typical antifreeze aqueous solutions. The latter was demonstrated in a pipe-in-pipe BHE having an effective resistance of about 0.030 Km/W.Forced convection in the groundwater achieved by injecting nitrogen bubbles was found to reduce the local thermal resistance in U-pipe BHEs by about 30% during heat injection conditions. The temperatures inside the groundwater are homogenized while injecting the N2, and no radial temperature gradients are then identified. The fluid to groundwater thermal resistance during forced convection was measured to be 0.036 Km/W. This resistance varied between this value and 0.072 Km/W during natural convection conditions in the groundwater, being highest during heat pump operation at temperatures close to the water density maximum.
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| 4. |
- Davidsson, Simon, et al.
(författare)
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A review of life cycle assessments on wind energy systems
- 2012
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Ingår i: The International Journal of Life Cycle Assessment. - : Springer Science and Business Media LLC. - 0948-3349 .- 1614-7502. ; 17:6, s. 729-742
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Forskningsöversikt (refereegranskat)abstract
- PurposeSeveral life cycle assessments (LCA) of wind energy published in recent years are reviewed to identify methodological differences and underlying assumptions.MethodsA full comparative analysis of 12 studies were undertaken (10 peer-reviewed papers, 1 conference paper, 1 industry report) regarding six fundamental factors (methods used, energy use accounting, quantification of energy production, energy performance and primary energy, natural resources, and recycling). Each factor is discussed in detail to highlight strengths and shortcomings of various approaches.ResultsSeveral potential issues are found concerning the way LCA methods are used for assessing energy performance and environmental impact of wind energy, as well as dealing with natural resource use and depletion. The potential to evaluate natural resource use and depletion impacts from wind energy appears to be poorly exploited or elaborated on in the reviewed studies. Estimations of energy performance and environmental impacts are critically analyzed and found to differ significantly.Conclusions and recommendationsA continued discussion and development of LCA methodology for wind energy and other energy resources are encouraged. Efforts should be made to standardize methods and calculations. Inconsistent use of terminology and concepts among the analyzed studies are found and should be remedied. Different methods are generally used and the results are presented in diverse ways, making it hard to compare studies with each other, but also with other renewable energy sources.
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| 5. |
- Johansson, Björn, 1975, et al.
(författare)
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Evaluation and Calculation of Dynamics in Environmental Impact Assessment
- 2013
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Ingår i: IFIP Advances in Information and Communication Technology. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1868-4238 .- 1868-422X. - 9783642403514 ; 397:1, s. 135-141
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Konferensbidrag (refereegranskat)abstract
- In ten years customers will select products not only based on price and quality but also with strong regard to the product value environmental footprint, including for example the energy consumed. Customers expect transparency in the product realization process, where most products are labeled with their environmental footprint. Vigorous companies see this new product value as an opportunity to be more competitive. In order to effectively label the envi-ronmental impact of a product, it is pertinent for companies to request the envi-ronmental footprint of each component from their suppliers. Hence, companies along the product lifecycle require a tool, not only to facilitate the computing of the environmental footprint, but also help reduce/balance the environmental impact during the lifecycle of the product. This paper proposes to develop a procedure that companies will use to evaluate, improve and externally advertise their product’s environmental footprint to customers.
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| 6. |
- Kilkiş, Şiir
(författare)
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A net-zero building application and its role in exergy-aware local energy strategies for sustainability
- 2012
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 63:SI, s. 208-217
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Tidskriftsartikel (refereegranskat)abstract
- Based on two case studies, this paper explores the nexus of exergy, net-zero targets, and sustainable cities as a means of analyzing the role of exergy-aware strategies at the building and district level. The first case study is a premier building in Ankara that is ready to meet the net-zero exergy target. It is also the first building in Turkey to receive the highest Platinum rating in Leadership in Energy and Environmental Design. A net-zero exergy building (NZEXB) is a building that has an annual sum of net-zero exergy transfer across the building-district boundary. This new target is made possible by lowered annual exergy consumption, (AEXC), and increased on-site production from a bundle of sustainable energy technologies. The modeled results of the building indicate that the reduced AEXC of 60 kW h/m 2 yr is met with on-site production of 62 kW h/m 2 yr. On-site production includes PV and building integrated PV, a micro-wind turbine, combined heat and power, GSHP, and solar collectors. Diversified thermal energy storage tanks further facilitate the exergy supply to meet with the exergy demand. The results of this case study provide key lessons to structure an energy value chain that is more aware of exergy, which are up-scalable to the district level when the bundle of sustainable energy technologies is zoomed out across a larger spatial area. These key lessons are then compared with the second case study of two districts in the south heating network of the city of Stockholm, which was the European Green Capital in 2010. The levels of exergy match in these districts of Stockholm, namely the districts of Högdalen and Hammarby, is found to be 0.82 and 0.84, respectively. However, there remain several bottlenecks for these districts to reach net-zero targets at the community level. The paper concludes that the NZEXB case study has much to offer as a "building block" to reform the way energy is converted and managed and in this way, to structure an exergy-aware energy value chain for greater sustainability in green cities of the future.
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| 7. |
- Grip, Carl-Erik, et al.
(författare)
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Possibilities and problems in using exergy expressions in process integration
- 2011
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Ingår i: Proceedings of the World Renewable Energy Congress 2011 (WREC 2011), 9-13 May, Linköping.. - Linköping : Linköping University Electronic Press. ; , s. 1605-1612
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Konferensbidrag (refereegranskat)abstract
- Industrial energy systems are complicated networks, where changes in one process influence its neighboring processes. Saving energy in one unit does not necessarily lead to energy savings for the total system. A study has been carried out on the possibility to use the exergy concept in the analysis of industrial energy systems. The exergy concept defines the quality of an amount of energy in relation to its surrounding, expressing the part that could be converted into work. The study consists of literature studies and general evaluations, an extensive case study and an interview study. In the latter it was found that non technical factors are major obstacles to the introduction of exergy.
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| 8. |
- Ackermann, Thomas
(författare)
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Introduction
- 2012
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Ingår i: Wind Power in Power Systems, Second Edition. - : Wiley. ; , s. 1-5
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Bokkapitel (refereegranskat)
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| 9. |
- Vikström, Hanna, 1985-, et al.
(författare)
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Lithium availability and future production outlooks
- 2013
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 110:10, s. 252-266
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Tidskriftsartikel (refereegranskat)abstract
- Lithium is a highly interesting metal, in part due to the increasing interest in lithium-ion batteries. Several recent studies have used different methods to estimate whether the lithium production can meet an increasing demand, especially from the transport sector, where lithium-ion batteries are the most likely technology for electric cars. The reserve and resource estimates of lithium vary greatly between different studies and the question whether the annual production rates of lithium can meet a growing demand is seldom adequately explained. This study presents a review and compilation of recent estimates of quantities of lithium available for exploitation and discusses the uncertainty and differences between these estimates. Also, mathematical curve fitting models are used to estimate possible future annual production rates. This estimation of possible production rates are compared to a potential increased demand of lithium if the International Energy Agency’s Blue Map Scenarios are fulfilled regarding electrification of the car fleet. We find that the availability of lithium could in fact be a problem for fulfilling this scenario if lithium-ion batteries are to be used. This indicates that other battery technologies might have to be implemented for enabling an electrification of road transports.
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| 10. |
-
Systems Perspectives on Electromobility 2013
- 2013
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Samlingsverk (redaktörskap) (refereegranskat)abstract
- The transportation of goods and people is at the heart of the industrial society.Yet transportation relies heavily upon oil – a scarce fossil fuel that contributes toclimate change and local air pollution. The term ‘electromobility’ refers to an alternativetransportation system based on vehicles propelled by electricity. Electromobilityis increasingly seen as favourable in that it could circumvent problems relatedto both oil and biofuels whilst meeting our mobility needs and desires. However,the virtue of electromobility is not uncontested and a range of issues come to thefore. Are electric vehicles energy efficient? Are they safe? How much greenhousegas is emitted in the production of electricity and advanced vehicle components?Will battery production lead to new resource problems? Will electromobilitypromote or hinder the diffusion of renewable energy? Will driving patterns shapeor be shaped by new types of vehicles? Is electromobility suitable for cars but notfreight transport? How is technical knowledge for electromobility produced andby whom? Is the automotive industry up to the challenge? Is there a need for newbusiness models and governmental policy support (or both) to stimulate marketdemand for electric vehicles?There is no simple answer to these questions. However, studying electromobilityfrom different systems perspectives can help to resolve these complex issues.Systems Perspectives on Electromobility 2013 is composed of fifteen chaptersthat address different topics related to the immensely important issue of whether– and to what extent – our transport systems can and should be energised byelectricity. The book is far from complete, but we hope it may be a useful startingpoint for future discussions and debates.
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| 11. |
- Mosteiro-Romero, Martín, et al.
(författare)
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Relative importance of electricity sources and construction practices in residential buildings: A Swiss-US comparison of energy related life-cycle impacts
- 2014
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788. ; 68:PARTA, s. 620-631
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Tidskriftsartikel (refereegranskat)abstract
- Comparisons of buildings in similar climates built in accordance with different regional constructionpractices and building rating systems can provide useful insights in sustainable design practices. Theobjectives of this study were: (1) to perform energy related life cycle assessments of a typical LEED-H(Leadership in Energy and Environmental Design for Homes) single-family home in New Jersey (US), and atypical Minergie-P single-family home in Chur, Switzerland; and (2) to assess the effect of rating systemsand construction practices on the buildings’ environmental impacts. Inventory data was obtained fromthe Ecoinvent 2.2 database with a replacement of the Western European electricity mix with the US orNew Jersey electricity mix for the New Jersey home. The Swiss building performed better regarding nonrenewableenergy consumption, Global Warming Potential and Acidification Potential mainly due to thegeothermal heat pump and the Swiss electricity mix while there was less of a difference regarding OzoneLayer Depletion Potential and Eutrophication Potential. The influence of electricity sources exceeded theeffects of longer building life time or the removal of the Swiss basement. Regional building practices, localcodes and environmental policies should take the electricity mix into account because it is so important.
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| 12. |
- Mahapatra, Krushna, et al.
(författare)
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Energy advice service as perceived by Swedish homeowners
- 2011
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Ingår i: International Journal of Consumer Studies. - : Wiley. - 1470-6423 .- 1470-6431. ; 35:1, s. 104-111
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Tidskriftsartikel (refereegranskat)abstract
- External actors can influence potential adopters to adopt energy efficiency measures. In Sweden municipality energy advisers are one such actor group who provides energy advice and information to the end users. The success of energy advice service for improvement of energy efficiency of detached houses depends on homeowners' perception towards it. In this context, we conducted a national survey of about 3000 owners of detached houses through stratified random sampling method in the summer of 2008. We found that majority of owners of detached houses consider energy advisers as an important source of information. Furthermore, many homeowners who contacted energy advisers for advice had implemented the suggestions. However, only a few homeowners had contacted an energy adviser. Our findings suggest that it is beneficial to continue the energy advice service, but more efforts are needed to increase homeowners' awareness of and satisfaction with such services.
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| 13. |
- Gustavsson, Leif, 1954-, et al.
(författare)
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Implementering av energieffektiviseringsåtgärder i befintlig bebyggelse : Report prepared for the Swedish Energy Agency
- 2010
-
Rapport (populärvet., debatt m.m.)abstract
- There is great potential to improve energy efficiency in existing Swedish residential buildings. However, the successful implementation of efficiency measures depends on economical and technical factors, as well as on the attitudes and perceptions of the relevant actors. A better understanding of their attitudes and perceptions may influence the design of suitable policy measures that increase the adoption of energy efficiency measures. In this context, we conducted mail-in surveys completed by owners of detached houses, chairmen of co-operative housing associations (bostadsrättsförening) and municipality energy advisers in Sweden. We also interviewed window sellers/installers in Jämtland.Results show that it was important for the majority of homeowners to reduce their household energy use, with most undertaking no-cost measures (e.g., switching off lights). However, 70–90% of the responding homeowners had no intention of adopting building envelope measures over the next 10 years. The main reason for non-adoption was that homeowners were satisfied with the physical condition and thermal performance of their existing building envelope components. Homeowners who thought their energy cost was high were more likely to adopt an investment measure compared to those who thought their energy cost was low. Investment costs and annual energy cost savings were the most important factors in adoption of energy efficient building envelope measures. Therefore, economic incentives may induce homeowners to adopt energy efficiency investment measures. However, a large percentage (64%) of homeowners was unaware of the existence of government support for reducing household energy use. Information campaigns announcing the availability of economic incentives and the cost advantages of energy efficiency measures may be helpful in the adoption decision.Homeowners‘ considered interpersonal sources, builders, installers and energy advisers as important sources of information for their adoption of energy efficiency measures. Though a large percentage of respondents considered energy advisers as an important source of information, only 14% of homeowners had contacted an energy adviser in the past. Our findings suggest that the energy advice service is important for homeowners, but more efforts are needed to increase homeowners‘ awareness of and satisfaction with such services. The majority of municipal energy advisers were of the opinion that more training in technical aspects of energy issues and increased financial support could improve their performance.Installers and material suppliers are important actors in homeowners‘ adoption of energy efficiency measures. For example, approximately 53% of responding homeowners to a survey in Jämtland/Västernorrland stated that the window seller/installer from whom they had bought windows had recommended a particular type of window, and 97% had installed the windows that were recommended. The window sellers/installers in Jämtland prefer a window that is ―reasonably‖ energy efficient. They believe that windows with a U-value of 1.2 W/m2K are good and there is no reason to further improve the energy efficiency. The majority did not recommend windows with U-value <1.2 W/m2K. They were concerned about the condensation issues and high prices of such windows. This may influence the diffusion of very energy efficient windows in Swedish detached houses.About 80-95% of chairmen in co-operative housing associations who responded to our survey had no intention of adopting building envelope measures over the next 10 years. They were satisfied with the existing building envelope components, which may be one of the reasons for this lack of intention. As in the case of owners of detached houses, economic factors, like annual energy cost savings and investment costs, guide the implementation of energy efficiency investment measures in co-operative housing associations. However, about 66% of the responding chairmen did not consider financial constraint as a barrier to implementing investment intensive energy efficiency measures. For 54% of the respondents limited in-house competency to evaluate the benefits of energy efficiency measures was the main barrier.The majority of owners of detached houses (80%) and chairmen of co-operative housing associations (70%) perceived that economic policy instruments, such as investment subsidies and tax deductions, would encourage them to implement energy efficiency measures. Other policy instruments, especially information instruments, were perceived as less effective. Among various information policies, increasing the frequency of meter reading received the highest approval with 38% of homeowners, whereas approximately 41% of housing association chairmen thought that individual metering of heating and hot water use could be effective. Approximately 30% of homeowners and housing association chairmen thought that energy declaration was effective.
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| 14. |
- Frodeson, Stefan, 1968-, et al.
(författare)
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The Potential of Using Two-Step Drying Techniques for Improving Energy Efficiency and Increasing Drying Capacity in Fuel Pellet Industries
- 2013
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Ingår i: Drying Technology. - : Taylor & Francis. - 0737-3937 .- 1532-2300. ; 31:15, s. 1863-1870
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Tidskriftsartikel (refereegranskat)abstract
- The use of wood fuel pellets has increased worldwide in recent years, and pellet producers conclude that the lack of drying capacity is a barrier to increased production. In this study, we develop a concept of two different dryers called the two-step drying technique. The aim is to show the potential for increasing the drying capacity and improving energy efficiency when introducing a second dryer into the pellet plant. The study is theoretical and based on an industrial packed moving bed dryer. It shows that the drying capacity increased by 22% when a pneumatic second dryer was used.
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| 15. |
- Grip, Carl-Erik, et al.
(författare)
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Application of Pinch Analysis in an Integrated Steel Plant in Northern Sweden
- 2013
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Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 53:7, s. 1202-1210
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Tidskriftsartikel (refereegranskat)abstract
- The energy system in a modern integrated steel plant is a complicated network of units exchangingenergy and matter with each other. System studies using process integration tools are important to avoidsub-optimization. At the steel plant in Luleå such studies have been carried out using a MILP-based mathematicalprogramming tool (reMIND), mainly because of its inherent flexibility for handling combinedflows and reactions of both matter and chemical, thermal and mechanical energy. There are, however,areas where the energy system is dominated by creation, transport and exchange of thermal energy, andwhere pinch analysis can be expected to be a valuable tool. For this reason a pinch targeting study wascarried out for the plant site of the integrated steel plant in Luleå. The coke plant and the iron making/steelmaking plant were both studied with three ambition levels of possible improvements. The study confirmedthat pinch analysis is a powerful tool for targeting energy savings in areas where thermal energyflows dominate the local energy system, e.g., the gas cleaning area at the coke plant. The study also indicatedthat a connection between the energy systems in the coke plant and the iron making/steelmakingwould be valuable. This is not 100% feasible because of distance, but, a common steam net could add adegree of flexibility.
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| 16. |
- Åberg, Anna, 1978-
(författare)
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A Gap in the Grid : Attempts to introduce natural gas in Sweden 1967-1991
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis follows the process of introducing natural gas in Sweden and the construction of a Northern European gas grid from 1967 to 1991. Natural gas is a relatively unnoticed fuel in Sweden today, but this relative anonymity stands in contrast to an extensive historical activity that has taken place behind the scenes of Swedish energy policy. The single pipeline constructed between Denmark and Sweden in the early 1980s was both preceded and followed by many other attempts to construct a larger natural gas pipeline in the region made in the last 50 years. Åberg traces these attempts while discussing the complex and messy process of constructing and managing a transnational energy infrastructure.Åberg follows actors in Sweden and other countries in their attempts to negotiate and construct a natural gas infrastructure, and puts this process into a national as well as transnational context. The perceived risks and opportunities surrounding natural gas are examined, together with factors that have influenced the development of natural gas in a broader sense. By seeing the changing and messy natural gas projects as arenas where different actors construct and negotiate risks and opportunities, as well as contexualize the projects, Åberg shows how the natural gas sector in Sweden has evolved and taken shape.The study shows that natural gas in Sweden has suffered from unstable actor coalitions on different levels, a difficult market situation, and a changeful political context, especially with regard to energy policy. The import status of the fuel and the consequential transnationality of the natural gas infrastructure have also made the process of constructing a pipeline more complex. However, natural gas was introduced in Sweden, showing that when a strong enough actor coalition agreed that there was enough reason to warrant a natural gas introduction and was ready to join this endeavor, a connection could be achieved. This puts into question to what degree general explanations in terms of finance and policy drive energy decisions, and makes a case for showing how these explanations are adapted into their social and historical contexts in sometimes surprising ways.
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| 17. |
- Strömstedt, Erland, 1972-
(författare)
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Submerged Transmission in Wave Energy Converters : Full Scale In-Situ Experimental Measurements
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Different wave power technologies are in development around the world in different stages of prototype testing. So far only a few devices have been deployed offshore at full scale for extended periods of time. Little data is published about how these different devices perform.This thesis presents results from experiments with the full-scale offshore wave energy converters at the Lysekil research site on the Swedish west coast. The theories, experiments, measurements, performance evaluations and developments of the submerged transmission in the direct driven permanent magnet linear generator are in focus. The reciprocating submerged transmission fulfills the purpose of transmitting the absorbed mechanical wave energy through the capsule wall into the generator, while preventing the seawater from entering the capsule and reducing the life time of the converter.A measuring system with seven laser triangulation sensors has been developed to measure small relative displacements between piston rod and seal housing in the submerged transmission with excellent accuracy for the purpose of evaluating both functional behavior and successive wear in-situ. A method for calculating relative tilt angles, azimuth angles, differential tilt angles, and successive wear in the submerged transmission has been developed. Additional sensors systems have been installed in the converter enabling correlation and a thorough investigation into the operating conditions of the transmission and the converter. The thesis presents unique results from the measurements. A data acquisition system transmits the signals from the converter on the seabed to an onshore measuring station. Results are presented in time-, frequency- and the time-frequency domain.The results have given important information for further development of the submerged transmission, which is important to the survivability of the system. The thesis describes the status of research, and is a step that may influence future designs of wave energy devices for reaching survivability and a cost-effective renewable energy system.
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| 18. |
- Wetterlund, Elisabeth, et al.
(författare)
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Optimal use of forest residues in Europe under different policies-second generation biofuels versus combined heat and power
- 2013
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Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; 3:1, s. 3-16
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Tidskriftsartikel (refereegranskat)abstract
- The European Union has set a 10 % target for the share of renewable energy in the transportation sector for 2020. To reach this target, second generation biofuels from, for example, forest residues are expected to replace around 3 % of the transport fossil fuel consumption. However, forest residues could also be utilised in the heat and electricity sectors where large amounts of fossil fuels can be replaced, thus reducing global fossil CO2 emissions. This study investigates the use of forest residues for second generation biofuel (ethanol or methanol) or combined heat and power (CHP) production at the European level, with focus on the influence of different economic policy instruments, such as carbon cost or biofuel policy support. A techno-economic, geographically explicit optimisation model is used. The model determines the optimal locations of bioenergy conversion plants by minimising the cost of the entire supply chain. The results show that in order to reach a 3 % second generation biofuel share, a biofuel support comparable to today's tax exemptions would be needed. With a carbon cost applied, most available forest residues would be allocated to CHP production, with a substantial resulting CO2 emission reduction potential. The major potential for woody biomass and biofuel production is found in the region around the Baltic Sea, with Italy as one of the main biofuel importers.
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| 19. |
- Kyprianidis, Konstantinos G.
(författare)
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Multi-Disciplinary Conceptual Design of Future Jet Engine Systems
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes various aspects of the development of a multi-disciplinary aero engine conceptual design tool, TERA2020 (Techno-economic, Environmental and Risk Assessment for 2020), based on an explicit algorithm that considers: engine performance, engine aerodynamic and mechanical design, aircraft design and performance, emissions prediction and environmental impact, engine and airframe noise, and production, maintenance and direct operating costs.As part of this research effort, a newly-derived semi-empirical NOx correlation for modern rich-burn single-annular combustors is proposed. The development of a numerical methods library is also presented, including an improved gradient-based algorithm for solving non-linear equation systems. Common assumptions made in thermo-fluid modelling for gas turbines and their effect on caloric properties are investigated, while the impact of uncertainties on performance calculations and emissions predictions at aircraft system level is assessed. Furthermore, accuracy limitations in assessing novel engine core concepts as imposed by current practice in thermo-fluid modelling are identified.The TERA2020 tool is used for quantifying the potential benefits from novel technologies for three low pressure spool turbofan architectures. The impact of failing to deliver specific component technologies is quantified, in terms of power plant noise and CO2 emissions. To address the need for higher engine thermal efficiency, TERA2020 is again utilised; benefits from the potential introduction of heat-exchanged cores in future aero engine designs are explored and a discussion on the main drivers that could support such initiatives is presented. Finally, an intercooled core and conventional core turbofan engine optimisation procedure using TERA2020 is presented. A back-to-back comparison between the two engine configurations is performed and fuel optimal designs for 2020 are proposed.Whilst the detailed publications and the work carried out by the author, in a collaborative effort with other project partners, is presented in the main body of this thesis, it is important to note that this work is supported by 20 conference and journal papers.
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| 20. |
- Yan, Jinyue, et al.
(författare)
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Recent progress in sustainable energy systems
- 2013
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 37:15, s. 1937-1938
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 21. |
- Heeren, Niko, et al.
(författare)
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Towards a 2000 Watt society – assessing building-specific saving potentials of the Swiss residential building stock
- 2012
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Ingår i: International Journal of Sustainable Building Technology and Urban Development. - 2093-7628 .- 2093-761X. ; 3:1, s. 43-49
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Tidskriftsartikel (refereegranskat)abstract
- Switzerland declared the notion of the 2000 Watt society as their leitmotif towards a sustainable development in terms of energy and greenhouse gas emissions. This implies that worldwide, no more than 17,520 kWh of total primary energy and 1 ton CO2-equivalent are to be consumed per capita and year for all services. Thus, in order to meet the targets of the 2000 Watt society, it is necessary to reduce primary energy demand by 44% and greenhouse gas emissions by 77%. The building stock model, described in this paper, assisted the government of Zurich to identify the necessary steps in order to achieve the goals with regard to the city's residential, school, and office buildings. The objective of this paper is to investigate the role of energy demand reduction in residential buildings on the way towards the goals of a 2000 Watt society.In order to illustrate the mechanisms within the building stock and to identify the effects of construction activity, the model works with different scenarios. Specific measures were isolated and analysed individually. All three measures act directly on the building stock; each have comparable reduction potential in terms of primary energy demand (ca. 15%) and greenhouse gas emissions (ca. 40%). In order to further cut back greenhouse gas emissions, measures to reduce the carbon intensity of fuels and electricity need to be considered.
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| 22. |
- Wikström, Fredrik, 1964-, et al.
(författare)
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Potential environmental gains from reducing food losses through development of new packaging – a life cycle model.
- 2010
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Ingår i: Packaging technology & science. - Chichester : John Wiley & Sons. - 0894-3214 .- 1099-1522. ; 23:7, s. 403-411
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Tidskriftsartikel (refereegranskat)abstract
- The environmental concern and development issues regarding packaging has for 20 years to a high extent been on packaging when it has become waste. To reduce the environmental impact from the whole food packaging system it is also important to develop the packaging’s ability to reduce food waste. In some cases it may be necessary to increase the environmental impact of packaging in order to reduce food waste. In this paper, the environmental impact of packaging and food losses and the balance between the two has been examined for five different food items. The results show that packaging’s that reduce food waste can be an important tool to reduce the total environmental impact, even if there is an increase in impact from the packaging itself. This is especially true for food items where the environ- mental impact of the food is high relative the packaging, for example cheese, and for food items with high losses, for example bread. It is important to analyse the risk of increasing food losses when pack- aging design changes, for example, when the aim is less packaging material, which is the main intention of the packaging and packaging waste directive of the European Union.
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| 23. |
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| 24. |
- Bengtsson, Selma, 1984, et al.
(författare)
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Environmental Assessment of Two Pathways Towards the Use of Biofuels in Shipping
- 2012
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Ingår i: Energy Policy. - : Elsevier BV. - 0301-4215. ; 44, s. 451-463
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Tidskriftsartikel (refereegranskat)abstract
- The goal of this study is to evaluate the life cycle performance of two alternative pathways to biofuels in the shipping industry: the 'diesel route' and the 'gas route'. The diesel route comprises of a shift from heavy fuel oil to marine gas oil and then a gradual shift to biodiesel, whereas the gas route comprises of a shift to liquefied natural gas and then a gradual shift to liquefied biogas. The two routes are assessed in a case study for the ferry traffic between the Swedish mainland and the island Gotland. Life cycle assessment (LCA) is used to evaluate the environmental performance with the functional unit chosen to be one year of ro-pax ferry service, including both passenger and goods transportation. The gas route is indicated to have better overall environmental performance than the diesel route. Furthermore, use of biofuels is illustrated as one possible measure to decrease the global warming impact from shipping, but to the expense of greater environmental impact for some other impact categories. As an example, the global warming potential (GWP(100)) was shown to decrease with the use of biofuels in this study, while the eutrophication potential and the primary energy use increased.
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| 25. |
- Mahapatra, Krushna, et al.
(författare)
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Swedish energy advisers' perceptions regarding and suggestions for fulfilling homeowner expectations
- 2011
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Ingår i: Energy Policy. - : Elsevier BV. - 0301-4215 .- 1873-6777. ; 39:7, s. 4264-4273
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Tidskriftsartikel (refereegranskat)abstract
- Municipality energy advice services were re-introduced in Sweden in 1998 as a way of advising end-users, mainly owners of detached houses, on energy issues. In this paper, we investigate Swedish energy advisers' perceptions of homeowners' awareness of the energy advice service and their perceived ability to fulfil homeowners' expectations. Our study is based on a mail-in questionnaire survey conducted in 2009 and distributed to municipality energy advisers in all municipalities in Sweden. About 66% of the energy advisers responded. The results show that 43% of the energy advisers thought that fewer than 50% of the homeowners were aware of the service and that mass media advertisements and presentations at different organisations could improve homeowner awareness. Energy adviser attitudes, job satisfaction, and the perception that the advisers possessed up-to-date and good knowledge and sufficient financial resources to execute their duties had a significant influence on their perceived ability to fulfil homeowner expectations. Increased training in technical aspects of energy measures and increased financial support were the two measures most widely suggested as a means to improve energy advisers' performance.
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