| 1. |
- Chen, B., et al.
(author)
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Pathways for sustainable energy transition
- 2019
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In: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 228, s. 1564-1571
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Journal article (peer-reviewed)abstract
- Energy transitions are ongoing processes all over the world. While sustainable solutions are envisioned for the future, many societies are still under high-carbon and high-pollution energy regime borne by fossil fuels. How to design pathways towards sustainable energy transition has attracted worldwide concerns. Understanding the possible transition pathways of the energy system requires the integration of new energy technologies, environmental sciences, economics and management. This Special Issue of Journal of Cleaner Production targets to collect the latest research results on sustainable energy systems, discover innovative avenues and inspiring models and share knowledge on energy system modelling and management. In this paper, we identify 4 themes on sustainable energy transition pathways including: (1)Sustainable energy economics and management; (2)Renewable energy generation and consumption; (3)Environmental impacts of energy systems; and (4)Electric vehicle and energy storage. Theories, technologies, innovative models, and successful experiences are discussed accordingly. It is suggested that creative, robust and audacious strategies in governance, management and education are needed to boost sustainable energy transition across various scales and sectors.
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| 2. |
- Gustafsson, Marcus, 1987-, et al.
(author)
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Techno-economic analysis of energy renovation measures for a district heated multi-family house
- 2016
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In: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 177, s. 108-116
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Journal article (peer-reviewed)abstract
- Renovation of existing buildings is important in the work toward increased energy efficiency and reduced environmental impact. The present paper treats energy renovation measures for a Swedish district heated multi-family house, evaluated through dynamic simulation. Insulation of roof and façade, better insulating windows and flow-reducing water taps, in combination with different HVAC systems for recovery of heat from exhaust air, were assessed in terms of life cycle cost, discounted payback period, primary energy consumption, CO2 emissions and non-renewable energy consumption. The HVAC systems were based on the existing district heating substation and included mechanical ventilation with heat recovery and different configurations of exhaust air heat pump.Compared to a renovation without energy saving measures, the combination of new windows, insulation, flow-reducing taps and an exhaust air a heat pump gave up to 24% lower life cycle cost. Adding insulation on roof and façade, the primary energy consumption was reduced by up to 58%, CO2 emissions up to 65% and non-renewable energy consumption up to 56%. Ventilation with heat recovery also reduced the environmental impact but was not economically profitable in the studied cases. With a margin perspective on electricity consumption, the environmental impact of installing heat pumps or air heat recovery in district heated houses is increased. Low-temperature heating improved the seasonal performance factor of the heat pump by up to 11% and reduced the environmental impact.
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| 3. |
- Lindroth [formerly Tyrberg], Simon, 1979-
(author)
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Buoy and Generator Interaction with Ocean Waves : Studies of a Wave Energy Conversion System
- 2011
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Doctoral thesis (other academic/artistic)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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| 4. |
- Thomas, Jean-Baptiste, et al.
(author)
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A comparative environmental life cycle assessment of hatchery, cultivation, and preservation of the kelp Saccharina latissima
- 2021
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In: Ices Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 78:1, s. 451-467
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Journal article (peer-reviewed)abstract
- Seaweed cultivation and processing industries could contribute to sustainable blue growth and the European bioeconomy. This article contributes a case study evaluation of environmental sustainability of preserved brown seaweed Saccharina latissima by means of environmental life cycle assessment of a pilot facility in Sweden. The study accounts for nutrient bioremediation and carbon capture and includes two alternative hatchery processes, a 2-ha longline cultivation, and four alternative preservation methods (hang-drying outdoors, heated air-cabinet drying, ensiling, and freezing). The study found that as a result of carbon capture and nitrogen and phosphorus uptake (bioremediation) by seaweed, more CO2 and PO4 equivalents are (temporarily) absorbed than emitted by the supply chain. The extent of emissions is most affected by preservation methods undertaken. Impact profiles of the supply chain show that the greatest impact shares result from freezing and air-cabinet drying, both the two most energy-intensive processes, followed by the cultivation infrastructure, highlighting strategic optimization opportunities. Hatchery processes, harvesting, and the low-energy ensilage and hang-drying outdoors were found to have relatively small impact shares. These findings presage the environmentally friendliness of seaweed-based products by documenting their potential to mitigate eutrophication and climate change, even when taking a life cycle perspective.
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| 5. |
- Mathern, Alexandre, 1986, et al.
(author)
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Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends
- 2021
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In: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 14:7
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Research review (peer-reviewed)abstract
- Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.
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| 6. |
- Herre, Lars, 1990-, et al.
(author)
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Simplified model of integrated paper mill for optimal bidding in energy and reserve markets
- 2020
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In: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 279
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Journal article (peer-reviewed)abstract
- Due to the increased use of variable renewable energy sources, more capacity for reserves is required. Non-generating resources such as large industrial consumers can arbitrage energy prices and provide reserve capacity by exploiting the inherent flexibility in selected industrial processes. A large enough industrial consumer can capitalize on this flexibility through optimized bidding in electricity markets. In this work, the day-ahead cost minimization of a risk-averse pulp and paper mill is formulated as a two-stage stochastic problem, considering thermodynamic and electrical constraints. The bids in the energy and reserve markets are jointly optimized subject to price uncertainty as well as uncertainty of frequency realization. The results of a case study in Sweden display a significant economic benefit in exploiting the flexibility of integrated pulp and paper mills with electric boilers. The expected cost of the pulp and paper mill resulting from different strategies are compared and the risk-aversion of the pulp and paper mill is investigated. Reserve offers are mainly facilitated by fast-acting electric boilers and supported by flexibility in the steam network. We show that reserve offers can significantly improve the profitability of the pulp and paper mill.
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| 7. |
- Svensson, Olle, 1967-
(author)
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Experimental results from the Lysekil Wave Power Research Site
- 2012
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Doctoral thesis (other academic/artistic)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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| 8. |
- Johansson, Björn, 1975, et al.
(author)
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Power Level Sampling of Metal Cutting Machines for Data Representation in Discrete Event Simulation
- 2015
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In: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 53:23, s. 7060-7070
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Journal article (peer-reviewed)abstract
- An extension to the application area for discrete event simulation (DES) has been ongoing since the last decade and focused only on economic aspects to include ecologic sustainability. With this new focus, additional input parameters, such as electrical power consumption of machines, are needed. This paper aim at investigating how NC machine power consumption should be represented in simulation models of factories. The study includes data-sets from three different factories. One factory producing truck engine blocks, one producing brake disc parts for cars and one producing forklift components. The total number of data points analysed are more than 2,45,000, where of over 1,11,000 on busy state for 11 NC machines. The low variability between busy cycles indicates that statistical representations are not adding significant variability. Furthermore, results show that non-value-added activities cause a substantial amount of the total energy consumption, which can be reduced by optimising the production flow using dynamic simulations such as DES.
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| 9. |
- Jiao, Yang, et al.
(author)
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Analysis of two hybrid energy storage systems in an off-grid photovoltaic microgrid : A case study
- 2020
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In: Proceedings IEEE PES Innovative Smart Grid Technologies Conference Europe. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 554-558
-
Conference paper (peer-reviewed)abstract
- In recent years, driven by global environmental issues, a growing number of renewable energy sources (RESs) have been developed. Microgrids have been confirmed as an important part in the increasing penetrations of renewable energy and the shift from a centralized paradigm to decentralized electricity production. The energy storage system (ESS) is a critical component that affects the development of microgrids. Combining advantages from different energy storage technologies, a hybrid energy storage system (HESS) can satisfy multiple requirements in microgrids. This paper compares the single battery system with the battery-supercapacitor (SC) HESS and the battery-flywheel HESS in an isolated photovoltaic (PV) power microgrid. Results show that both the SC and the flywheel distinctly reduce the battery charging and discharging powers and the required capacity of the battery. Therefore, the stresses and the needed size of the battery are reduced and the battery lifetime is extended.
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| 10. |
- Lindahl, Niklas, 1981, et al.
(author)
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Early stage techno-economic and environmental analysis of aluminium batteries
- 2023
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In: Energy Advances. - : Royal Society of Chemistry (RSC). - 2753-1457. ; 2:3, s. 420-429
-
Journal article (peer-reviewed)abstract
- For any proper evaluation of next generation energy storage systems technological, economic, and environmental performance metrics should be considered. Here conceptual cells and systems are designed for different aluminium battery (AlB) concepts, including both active and passive materials. Despite the fact that all AlBs use high-capacity metal anodes and materials with low cost and environmental impact, their energy densities differ vastly and only a few concepts become competitive taking all aspects into account. Notably, AlBs with high-performance inorganic cathodes have the potential to exhibit superior technological and environmental performance, should they be more reversible and energy efficient, while at the system level costs become comparable or slightly higher than for both AlBs with organic cathodes and lithium-ion batteries (LIBs). Overall, with continued development, AlBs should be able to complement LIBs, especially in light of their significantly lower demand for scarce materials. Several aluminium battery concepts are evaluated at material, cell and system levels for technical, economic and environmental performance, which enables them to complement lithium-ion batteries in the future.
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| 11. |
- von Platten, Jenny, et al.
(author)
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Renovating on unequal premises : A normative framework for a just renovation wave in swedish multifamily housing
- 2021
-
In: Energies. - : MDPI. - 1996-1073. ; 14:19
-
Journal article (peer-reviewed)abstract
- While the energy transition of the EU housing stock is now being intensified with the launch of the Renovation Wave, economic inequalities are increasing in many OECD countries, which has effects on housing-related inequalities and the demand of affordable housing. The Renovation Wave is thus an opportunity to improve housing quality for low-income households, but also entails risks for increased rents. In Sweden, the standard of housing is relatively high and energy poverty in multifamily housing is rare, meaning that there are limited social benefits to be achieved from extensive energy retrofitting; moreover, Sweden lacks a social housing sector, which limits protection of the worst-off residents. This paper thus explores whether the limited social benefits of the Renovation Wave weigh up against the risks that it entails for the worst-off in the Swedish context. This is done within a normative framework for just energy transitioning that is developed within the context of the Renovation Wave and increasing economic inequalities, consisting of four ordered principles: (1) The equal treatment principle; (2) The priority principle; (3) The efficiency principle; and (4) The principle of procedural fairness. Analysis showed that to be considered just according to our framework, the Swedish energy transition of housing should, in contradistinction to what is suggested in the Renovation Wave, limit the imposition of extensive energy retrofitting in low-income areas. Finally, having identified a mismatch between the most effective approaches in terms of energy savings and the most acceptable approaches in terms of social justice, we offer policy recommendations on how to bridge this mismatch in a Swedish context. © 2021 by the authors.
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| 12. |
- Galkin, Nikolai, et al.
(author)
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On Modelling of Edge Datacentre Microgrid for Participation in Smart Energy Infrastructures
- 2022
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In: IEEE Open Journal of the Industrial Electronics Society. - : Institute of Electrical and Electronics Engineers Inc.. - 2644-1284. ; 3, s. 50-64
-
Journal article (peer-reviewed)abstract
- Datacentres are becoming a sizable part of the energy system and are one of the biggest consumers of the energy grid. The so-called “Green Datacentre” is capable of not only consuming but also producing power, thus becoming an important kind of prosumers in the electric grid. Green datacentres consist of a microgrid with a backup uninterrupted power supply and renewable generation, e.g., using photovoltaic panels. As such, datacentres could realistically be important participants in demand/response applications. However, this requires reconsidering their currently rigid control and automation systems and the use of simulation models for online estimation of the control actions impact. This paper presents such a microgrid simulation model modelled after a real edge datacentre. A case study consumption scenario is presented for the purpose of validating the developed microgrid model against data traces collected from the green edge datacentre. Both simulation and real-time validation tests are performed to validate the accuracy of the datacentre model. Then the model is connected to the automation environment to be used for the online impact estimation and virtual commissioning purposes.
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| 13. |
- Zhang, Yang, et al.
(author)
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Planning and operation of an integrated energy system in a Swedish building
- 2019
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In: Energy Conversion and Management. - : Elsevier. - 0196-8904 .- 1879-2227. ; 199
-
Journal article (peer-reviewed)abstract
- More flexibility measures are required due to the increasing capacities of variable renewable energies (VRE). In buildings, the integration of energy supplies forms integrated energy systems (IES). IESs can provide flexibility and increase the VRE penetration level. To upgrade a current building energy system into an IES, several energy conversion and storage components are needed. How to decide the component capacities and operate the IES were investigated separately in studies on system planning and system operation. However, a research gap exists that the system configuration from system planning is not validated by actual operation conditions in system operation. Meanwhile, studies on system operation assume that IES configurations are predetermined. This work combines system planning and system operation. The IES configuration is determined by mixed integer linear programming in system planning. Actual operation conditions and forecast errors are considered in system operation. The actual operation profiles are obtained through year-round simulations of different energy management systems. The results indicate that the system configuration from system planning can meet energy demands in system operation. Among different energy management systems, the combination of robust optimization and receding horizon optimization achieves the lowest yearly operation cost. Meanwhile, two scenarios that represent high and low forecast accuracies are studied. Under the high and low forecast accuracy scenarios, the yearly operation costs are about 4% and 6% higher than that obtained from system planning.
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| 14. |
- Shahroozi, Zahra, 1992-
(author)
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Survivability control using data-driven approaches and reliability analysis for wave energy converters
- 2024
-
Doctoral thesis (other academic/artistic)abstract
- Wave energy, with five times the energy density of wind and ten times the power density of solar, offers a compelling carbon-free electricity solution. Despite its advantages, ongoing debates surround the reliability and economic feasibility of wave energy converters (WECs). To address these challenges, this doctoral thesis is divided into four integral parts, focusing on optimizing the prediction horizon for power maximization, analyzing extreme waves' impact on system dynamics, ensuring reliability, and enhancing survivability in WECs.Part I emphasizes the critical importance of the prediction horizon for maximal power absorption in wave energy conversion. Using generic body shapes and modes, it explores the effect of dissipative losses, noise, filtering, amplitude constraints, and real-world wave parameters on the prediction horizon. Findings suggest achieving optimal power output may be possible with a relatively short prediction horizon, challenging traditional assumptions.Part II shifts focus to WEC system dynamics, analyzing extreme load scenarios. Based on a 1:30 scaled wave tank experiment, it establishes a robust experimental foundation, extending into numerical assessment of the WEC. Results underscore the importance of damping to alleviate peak forces. Investigating various wave representations highlights conservative characteristics of irregular waves, crucial for WEC design in extreme sea conditions.Part III explores the computational intricacies of environmental design load cases and fatigue analyses for critical mechanical components of the WEC. The analysis is conducted for hourly sea state damage and equivalent two-million-cycle loads. Finally, a comparison of safety factors between the ultimate limit state and fatigue limit state unfolds, illustrating the predominant influence of the ultimate limit state on point-absorber WEC design.Part IV, centers on elevating survivability strategies for WECs in extreme wave conditions. Three distinct controller system approaches leverage neural networks to predict and minimize the line force. Distinct variations emerge in each approach, spanning from rapid detection of optimal damping to integrating advanced neural network architectures into the control system with feedback. The incorporation of a controller system, refined through experimental data, showcases decreases in the line force, providing a practical mechanism for real-time force alleviation.This thesis aims to contribute uniquely to the goal of advancing wave energy conversion technology through extensive exploration.
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| 15. |
- Behzadi, Amirmohammad, et al.
(author)
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A Green and Energy-Efficient Smart Building Driven by Photovoltaic Thermal Panels Connected to the Grid
- 2023
-
In: International Conference on Smart Cities and Green ICT Systems, SMARTGREENS - Proceedings. - : Science and Technology Publications, Lda. - 9789897586514 ; , s. 106-112
-
Conference paper (peer-reviewed)abstract
- The present paper introduces a new smart building system driven by photovoltaic thermal panels. The concept is to improve the contribution of renewable energy in the local matrix for peak load shaving by having a two-way connection with the local electricity network via a rule-based energy monitoring control design. Besides, the feasibility of removing the electrical storage unit with high investment cost is studied by establishing a dynamic interaction between the energy production and usage components to reduce the energy costs over the year. The system has intelligent thermal energy storage integrated with an electrically-driven coil, heat exchanger, pumps, and several smart valves and control units. The transient system simulation (TRNSYS) package is implemented to assess the practicality of the suggested intelligent model for a building complex in Malmo, Sweden. According to the parametric outcomes, by raising the panel area, while the generated electricity increases, the solar utilization factor falls, indicating conflictive changes among performance metrics. The results also show that the renewable resource covers the building's heating and electricity demands for the majority of the year and that a significant amount of energy is sold to the neighbourhood electricity grid, demonstrating the viability of the introduced intelligent model.
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| 16. |
- Lv, Zhihan, Dr. 1984-, et al.
(author)
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Towards carbon Neutrality : Prediction of wave energy based on improved GRU in Maritime transportation
- 2023
-
In: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 331
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Journal article (peer-reviewed)abstract
- Efficient use of renewable energy is one of the critical measures to achieve carbon neutrality. Countries have introduced policies to put carbon neutrality on the agenda to achieve relatively zero emissions of greenhouse gases and to cope with the crisis brought about by global warming. This work analyzes the wave energy with high energy density and wide distribution based on understanding of various renewable energy sources. This study provides a wave energy prediction model for energy harvesting. At the same time, the Gated Recurrent Unit network (GRU), Bayesian optimization algorithm, and attention mechanism are introduced to improve the model's performance. Bayesian optimization methods are used to optimize hyperparameters throughout the model training, and attention mechanisms are used to assign different weights to features to increase the prediction accuracy. Finally, the 1-hour and 6-hour forecasts are made using the data from China's NJI and BSG observatories, and the system performance is analyzed. The results show that, compared with mainstream prediction algorithms, GRU based on Bayesian optimization and attention mechanism has the highest prediction accuracy, with the lowest MAE of 0.3686 and 0.8204, and the highest R2 of 0.9127 and 0.6436, respectively. Therefore, the prediction model proposed here can provide support and reference for the navigation of ships powered by wave energy.
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| 17. |
- Kersten, Anton, 1991
(author)
-
Modular Battery Systems for Electric Vehicles based on Multilevel Inverter Topologies - Opportunities and Challenges
- 2021
-
Doctoral thesis (other academic/artistic)abstract
- Modular battery systems based on multilevel inverter (MLI) topologies can possibly overcome some shortcomings of two-level inverters when used for vehicle propulsion. The results presented in this thesis aim to point out the advantages and disadvantages, as well as the technical challenges, of modular vehicle battery systems based on MLIs in comparison to a conventional, two-level IGBT inverter drivetrain. The considered key aspects for this comparative investigation are the drive cycle efficiency, the inverter cost, the fault tolerance capability of the drivetrain and the conducted electromagnetic emissions. Extensive experiments have been performed to support the results and conclusions. In this work, it is shown that the simulated drive cycle efficiency of different low-voltage-MOSFET-based, cascaded seven-level inverter types is improved in comparison to a similarly rated, two-level IGBT inverter drivetrain. For example, the simulated WLTP drive cycle efficiency of a cascaded double-H-bridge (CDHB) inverter drivetrain in comparison to a two-level IGBT inverter, when used in a small passenger car, is increased from 94.24% to 95.04%, considering the inverter and the ohmic battery losses. In contrast, the obtained efficiency of a similar rated seven-level cascaded H-bridge (CHB) drivetrain is almost equal to that of the two-level inverter drivetrain, but with the help of a hybrid modulation technique, utilizing fundamental selective harmonic elimination at lower speeds, it could be improved to 94.85%. In addition, the CDHB and CHB inverters’ cost, in comparison to the two-level inverter, is reduced from 342€ to 202€ and 121€, respectively. Furthermore, based on a simple three-level inverter with a dual battery pack, it is shown that MLIs inherently allow for a fault tolerant operation. It is explained how the drivetrain of a neutral point clamped (NPC) inverter can be operated under a fault condition, so that the vehicle can drive with a limited maximum power to the next service station, referred to as limp home mode. Especially, the detection and localization of open circuit faults has been investigated and verified through simulations and experiments. Moreover, it is explained how to measure the conducted emissions of an NPC inverter with a dual battery pack according to the governing standard, CISPR 25, because the additional neutral point connection forms a peculiar three-wire DC source. To separate the measured noise spectra into CM, line-DM and phase-DMquantities, two hardware separators based on HF transformers are developed and utilized. It is shown that the CM noise is dominant. Furthermore, the CM noise is reduced by 3dB to 6dB when operating the inverter with three-level instead of two-level modulation.
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| 18. |
- Ghaviha, Nima, et al.
(author)
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Review of Application of Energy Storage Devices in Railway Transportation
- 2017
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In: Energy Procedia. - : Elsevier BV. - 1876-6102.
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Conference paper (peer-reviewed)abstract
- Regenerative braking is one of the main reasons behind the high levels of energy efficiency achieved in railway electric traction systems. During regenerative braking, the traction motor acts as a generator and restores part of the kinetic energy into electrical energy. To use this energy, it should be either fed back to the power grid or stored on an energy storage system for later use. This paper reviews the application of energy storage devices used in railway systems for increasing the effectiveness of regenerative brakes. Three main storage devices are reviewed in this paper: batteries, supercapacitors and flywheels. Furthermore, two main challenges in application of energy storage systems are briefly discussed. © 2017 The Authors.
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| 19. |
- Rusu, Cristina, et al.
(author)
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Challenges for Miniaturised Energy Harvesting Sensor Systems
- 2018
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In: 2018 10th International Conference on Advanced Infocomm Technology (ICAIT). - : Institute of Electrical and Electronics Engineers Inc.. - 9781538679364 ; , s. 214-217
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Conference paper (peer-reviewed)
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| 20. |
-
Chalmers Environmental Initiative Progress Report 2001
- 2001
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Editorial collection (peer-reviewed)abstract
- The Board of the Chalmers University of TechnologyFoundation decided in 1999 to invest SEK 100million in a strategic investment in the environmentwith a special focus on environmental systems analysis.This investment was entitled The ChalmersEnvironmental Initiative (CEI). Through thisenvironmental initiative Chalmers has acquired aprominent international position within environmentalsystems analysis.CEI is the result of the active research and educationthat has taken place at Chalmers over the past 10years. A broad base in combination with leadingedge technology presented the opportunity to createa very strong research programme based oninteraction between the various schools at Chalmers.As CEI is integrated into undergraduate anddoctoral programmes at Chalmers, engineers,architects and doctoral students have access, withinthe framework of their studies, to research-basedenvironmental education with a focus on asustainable society. CEI also co-operates with otherparties, such as industry, politicians, various organisationsand the general public, as a further means ofcontributing to sustainable development in society.Within CEI, seven new professors have beenappointed within the following areas:Management for SustainabilityRolf Wolff, 1 June 2000Environmental Systems TechnologyAnne-Marie Tillman, 1 September 2000Sustainable Industrial MetabolismChristian Azar, 1 September 2000Global Environmental MeasurementsDonal Murtagh, 1 November 2000Green ChemistryWilliam J. Frederick Jr, 1 August 2001Sustainable Energy SystemsFilip Johnsson, preliminary 1 October 2001Design for Sustainable Urban DevelopmentVacant: interviews during April 2001The four professors appointed in 2000 are presentedin this report as well as their declaration of intentfor the next few years. At present, the CEI professorsare involved with approximately 40 universities,institutes and industrial partners in the form ofproject co-operation and joint publications. The fourprofessors have the greater proportion of theirenvironmental research funded through externalgrants, compared to CEI. The proportion of facultyfunds and other internal Chalmers funds is at presentvery low. A summary of the financing structureis also included in this report.During 2001, various forms of co-operation wereinitiated between the professors, such as joint projectplans, doctoral students, courses and graduateschools. During autumn 2001, a residential seminaris planned for discussions within CEI as well as anopen presentation of the project and the professors.This major in-house focus on environmental researchhas attracted attention externally and contributedto the opening up of new potential in combinationwith increased expectations. Since May 1, 2000,Chalmers has been a member of the Alliance forGlobal Sustainability (AGS), an association of someof the world’s foremost universities in theenvironmental field. AGS and other platforms formthe basis for international research collaboration.CEI and other environmental activities have led tospin-off effects and contributed to increased interestin Chalmers as an environmental university.Chalmers and Göteborg University were, forexample, jointly awarded the King Carl XVI Gustafvisiting professorship in environmental science for2001-2002 and Margot Wallström received anhonorary doctorate from Chalmers in 2001. A largenumber of well-known environmental researchershave also visited Chalmers to take part inconferences and seminars, including the winners ofthe Volvo Environmental Award for 2000 and thewinner of the City of Göteborg InternationalEnvironmental Award for 2000.
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| 21. |
- PAPPIS, IOANNIS, 1989-
(author)
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Trade-offs and conflicting objectives of decision-making investments in low-carbon technology portfolios for sustainable development : National and continental insights offered by applying energy system models
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Energy infrastructure and appropriate energy policies are crucial for sustainable development and to meet Sustainable Development Goals (SDGs). Limiting global warming potential below 1.5oC would require “rapid and far-reaching” transitions and unprecedented changes in all aspects of society. Several factors influence investment decisions on energy conversion technologies and their specific locations. The choice, timing, and location of energy investments affect the total system cost, socio-economic development, the environment (e.g., emissions, water use), and a nation's energy security. However, existing national energy modelling initiatives only investigate a subset of these pillars for achieving sustainability.This thesis examines the challenges associated with the energy transition of low-and middle-income countries (Paraguay, Ethiopia, Africa). This work considers national and global policies, focusing on achieving SDG7 and SDG13. The dissertation includes a cover essay and four appended papers. The research conducted in this Thesis examines how energy-systems models can assist in understanding an energy system's complex interactions for sustainable development.Specifically, the results highlight hydropower and solar PV as key technologies to achieve climate change targets, energy security and energy access goals. Hydropower and other renewable electricity can be exported to bolster energy security for the exporting country, although export revenues are eroded by local demand growth and low export prices. The benefits of low-cost electricity provided by cross-border hydropower should be balanced against energy security concerns for the importing country. The research demonstrates the benefits of regional coordination, with trade enabling renewable resources to be harnessed and the electricity transmitted to demand centres. Although RET decreases carbon dioxide emissions and water use compared to fossil-fuel plants and creates more jobs, they require high up-front capital costs offset by the lower operating fuel costs in the long term. Thus, increasing the ambition of climate targets while achieving electricity access results in lower cumulative costs. Also, although hydropower and renewable technologies build climate resilience, hydropower operation depends on climate variability affecting energy security. Thus, mitigation strategies should consider the associated challenges of climate change in hydropower investments.Hydropower and renewables are primarily grid-connected technologies, so off-grid and mini-grid systems are key complements to national-grid expansion when pushing for universal energy access. They also impact energy security, total system costs and socio-economic development. This Thesis's outcomes can support governments in strategic energy planning to identify future renewable energy projects and ensure their financial viability. Energy systems in their transition need to be affordable, reliable and sustainable (e.g., energy secured, combat climate change) by being climate-resilient. The thesis findings demonstrate that nations need integrated energy planning, accounting for the geospatial characteristics of energy technologies, and water resources management to achieve SDG7 and build climate-resilient (SDG13). A broad portfolio of renewable technologies, interconnectors and a decentralized power generation system providing electricity closer to the end-user demand is needed to enhance energy security, decrease environmental pressures and provide affordable electricity for a nation.
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| 22. |
- Malmgren, Elin, 1992, et al.
(author)
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The environmental performance of a fossil-free ship propulsion system with onboard carbon capture – a life cycle assessment of the HyMethShip concept
- 2021
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In: Sustainable Energy & Fuels. - : Royal Society of Chemistry (RSC). - 2398-4902. ; 5:10, s. 2753-2770
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Journal article (peer-reviewed)abstract
- The climate impact caused by the shipping industry has increased over the past decades despite attempts toimprove the energy efficiency of vessels and lower induced emissions. A tool in reducing climate and otherenvironmental impacts is new low emissions propulsion technologies. These new technologies need toreduce harmful emissions not only in the tailpipe but also over the entire life cycle. This study uses lifecycle assessment to investigate the life cycle environmental impact of a propulsion concept currentlyunder development: the HyMethShip concept. The HyMethShip concept combines electro-methanolenergy storage, an onboard pre-combustion carbon capture system, and a dual fuel internal combustionengine. The concept aims for an almost closed CO2 loop by installing CO2 capture onboard.The CO2 isunloaded in port and converted into electro-methanol which is used to fuel the ship again. This is madepossible by a pre-combustion process converting electro-methanol to hydrogen and CO2. Theassessment is conducted from well-to-propeller and focuses on ship operation in the North Sea in 2030.The results indicate that this technology could be an alternative to reduce the climate impact fromshipping.The results show a lower impact on acidification, climate change, marine eutrophication,particulate matter, photochemical ozone formation, and terrestrial eutrophication compared to internalcombustion engines run on either marine gas oil (0.1% sulphur content), biogenic methanol, fossilmethanol, or electro-methanol. Electricity with low climate and environmental impact is likely requiredto achieve this, and low NOx emissions from combustion processes need to be maintained. A potentialtrade-off is higher toxicity impacts from the HyMethShip concept compared to most other options, dueto metal needs in wind power plants.
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| 23. |
- Timmons, D., et al.
(author)
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Cost minimization for fully renewable electricity systems : A Mauritius case study
- 2019
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In: Energy Policy. - : Elsevier Ltd. - 0301-4215 .- 1873-6777. ; 133
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Journal article (peer-reviewed)abstract
- Climate change is the world's most prominent environmental problem, and fossil-fuel combustion is its primary cause. To set carbon reduction goals, policy makers require information on feasibility and cost of renewable energy systems. In this study, we describe an economic approach to modeling a national electricity system based entirely on renewable sources, using the island-nation of Mauritius as a case study. Many renewable electricity studies consider levelized costs of electricity (LCOE), which represents average cost of electricity, but cost minimization requires equalizing marginal costs. With variable sources, marginal costs change over time. Minimizing cost thus requires a model incorporating variability at high time resolution (daily or hourly), with the objective of minimizing the levelized cost of electricity for an entire electricity system (LCOES). In Mauritius, the minimum-cost renewable electricity portfolio includes roughly equal proportions of solar, wind, and biomass electricity, along with electricity storage. Policy issues include setting renewable energy targets, selecting policy instruments to incentivize optimum renewable energy portfolios, incorporating energy efficiency, determining appropriate discount rates, ensuring land availability, and accounting for non-cost considerations. Many of the economic and policy issues identified apply universally, and methods demonstrated in this study could be used anywhere in the world.
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| 24. |
- Garciá-Carmona, L., et al.
(author)
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Biohybrid systems for environmental intelligence on living plants : WatchPlant project
- 2021
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In: GoodIT 2021 - Proceedings of the 2021 Conference on Information Technology for Social Good. - New York, NY, USA : Association for Computing Machinery (ACM). ; , s. 210-215
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Conference paper (peer-reviewed)abstract
- New challenges such as climate change and sustainability arise in society influencing not only environmental issues but human's health directly. To face these new challenges IT technologies and their application to environmental intelligent monitoring become into a powerful tool to set new policies and blueprints to contribute to social good. In the new H2020 project, WatchPlant will provide new tools for environmental intelligence monitoring by the use of plants as "well-being"sensors of the environment they inhabit. This will be possible by equipping plants with a net of communicated wireless self-powered sensors, coupled with artificial intelligence (AI) to become plants into "biohybrid organisms"to test exposure-effects links between plant and the environment. It will become plants into a new tool to be aware of the environment status in a very early stage towards in-situ monitoring. Additionally, the system is devoted to be sustainable and energy-efficient thanks to the use of clean energy sources such as solar cells and a enzymatic biofuel cell (BFC) together with its self-deployment, self-awareness, adaptation, artificial evolution and the AI capabilities. In this concept paper, WatchPlant will envision how to face this challenge by joining interdisciplinary efforts to access the plant sap for energy harvesting and sensing purposes and become plants into "biohybrid organisms"to benefit social good in terms of environmental monitoring in urban scenarios.
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| 25. |
- Ringsberg, Jonas, 1971, et al.
(author)
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Comparison of mooring solutions and array systems for point absorbing wave energy devices
- 2018
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In: Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE. - 9780791851326 ; 11A, s. 1-11
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Conference paper (peer-reviewed)abstract
- Most of the ocean energy technologies are considered to be ina pre-commercial phase and need technical development. Thisstudy focuses on design of mooring solutions and comparesarray systems of a specific floating point-absorbing waveenergy converter (WEC) developed by the companyWaves4Power. A full-scale prototype of the WEC is installedin Runde (Norway) where it is moored with three polyestermooring lines, each having one floater and one gravity anchor.Based on this reference installation, the method of systemsengineering was used to propose twenty-two conceptualmooring solutions for different array systems. They werecompared and reduced to four top concepts in a systematicelimination procedure using Pugh and Kesselring matrices. Thetop concepts were assessed in detail by means of LCOE(levelised cost of energy), LCA (life cycle analysis) and riskanalyses. The fatigue life of the mooring lines and the energycapture were calculated using results obtained from coupledhydrodynamic and structure response analyses in the DNV-GLDeepC software. Two final concepts were proposed for thewater depths 75 and 200 m.
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