| 1. |
- Ding, Y., et al.
(författare)
-
Economical flexibility options for integrating fluctuating wind energy in power systems : The case of China
- 2018
-
Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 228, s. 426-436
-
Tidskriftsartikel (refereegranskat)abstract
- The inherent stochastic nature of wind power requires additional flexibility during power system operation. Traditionally, conventional generation is the only option to provide the required flexibility. However, the provision of the flexibility from the conventional generation such as coal-fired generating units comes at the cost of significantly additional fuel consumption and carbon emissions. Fortunately, with the development of the technologies, energy storage and customer demand response would be able to compete with the conventional generation in providing the flexibility. Give that power systems should deploy the most economic resources for provision of the required operational flexibility, this paper presents a detailed analysis of the economic characteristics of these key flexibility options. The concept of “balancing cost” is proposed to represent the cost of utilizing the flexible resources to integrate the variable wind power. The key indicators are proposed respectively for the different flexible resources to measure the balancing cost. Moreover, the optimization models are developed to evaluate the indicators to find out the balancing costs when utilizing different flexible resources. The results illustrate that exploiting the potential of flexibility from demand side management is the preferred option for integrating variable wind power when the penetration level is below 10%, preventing additional fuel consumption and carbon emissions. However, it may require 8% of the customer demand to be flexible and available. Moreover, although energy storage is currently relatively expensive, it is likely to prevail over conventional generation by 2025 to 2030, when the capital cost of energy storage is projected to drop to approximately $ 400/kWh or lower.
|
|
| 2. |
- Guziana, Bozena, et al.
(författare)
-
Policy Based Scenarios for Waste-to-Energy Use : Swedish Perspective
- 2014
-
Ingår i: Waste and Biomass Valorization. - : Springer Science and Business Media LLC. - 1877-2641 .- 1877-265X. ; 5:4, s. 679-688
-
Tidskriftsartikel (refereegranskat)abstract
- The use of waste for energy purposes becomes increasingly interesting with respect to waste management and the energy systems. The decisions on alternative uses of waste for energy are mainly influenced by different policies, waste management, energy supply and use, as well as technologies. Two important issues, namely, a clear priority of waste prevention in waste management within EU and the growing concern for food losses and food waste at global and national level, shall be carefully considered and addressed. This paper proposes policy based scenarios for waste-to-energy systems with a focus on Sweden and with a broader EU approach. As baseline for the scenario development an inventory of waste-to-energy related policies and goals on international, national, regional and local level as well as inventory of existing scenarios and reports with future trends is made. The main substitute for fossil fuels and the possibilities for renewable energy export are basic elements that define scenarios. Biofuels and electricity are identified as main substitutes for the fossil fuels. A low waste availability level is recommended to be included in sensitivity analysis for scenarios. This paper assumes relative decoupling in Low Waste scenario in 2030, and absolute decoupling first in 2050.
|
|
| 3. |
- Guziana, Bozena, 1963-, et al.
(författare)
-
SCENARIOS FOR WASTE-TO-ENERGY USE - SWEDISH PERSPECTIVE.
- 2011
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The use of waste for energy purposes becomes increasingly interesting both with respect to waste management and for the energy systems. The decisions on alternative uses of waste for energy are mainly influenced by different policies, waste management, energy supply and use, as well as technologies. Two important issues, namely, a clear priority of waste prevention in waste management within EU and the growing concern for food losses and food waste at global and at national level, shall be carefully considered and addressed. This paper proposes scenarios for waste to energy systems with focus on Sweden and with a broader EU approach is applied: Biofuels Sweden, Electric vehicles and Bioenergy Europe. As baseline for the scenario development inventory of waste-to-energy related policies and goals on international, national, regional and local level as well as inventory of existing scenarios and reports with future trends is made. A low waste availability level is recommended to be included in sensitivity analysis for scenarios.
|
|
| 4. |
- Guziana, Bozena, 1963-, et al.
(författare)
-
Waste-to-energy in a Polish perspective
- 2012
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Energy recovery from waste becomes increasingly interesting both with respect to waste management and for the sustainable energy supply. The REMOWE (Regional Mobilizing of Sustainable Waste-to-Energy Production) project, seeks to facilitate the implementation of sustainable systems for waste-to-energy in the project regions. Based on investigations done within the REMOWE project this paper discusses increased waste-to-energy utilization in Poland with focus on a comparison with the current state in Sweden. There are big differences between Sweden and Poland, and between Lower Silesia Voivodship in Poland and Västmanland County in Sweden. The REMOWE project through its outputs and discussions during meetings support transfer of technology, knowledge and best practice. Procedural justice and early involvement of public can increase social acceptance and successful implementation of projects regarding incineration, biogas production and separate collection of biodegradable waste.
|
|
| 5. |
- Han, Song, et al.
(författare)
-
A dynamic model to optimize a regional energy system with waste and crops as energy resources for greenhouse gases mitigation
- 2012
-
Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 46:1, s. 522-532
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A dynamic model of a regional energy system has been developed to support sustainable waste treatmentwith greenhouse gases (GHG) mitigation, addressing the possibility for development towardsa regional fossil fuel-free society between 2011 and 2030. The model is based on conventional mixedinteger linear programming (MILP) techniques to minimize the total cost of regional energy systems. TheCO2 emission component in the developed model includes both fossil and biogenic origins whenconsidering waste, fossil fuels and other renewable sources for energy production. A case study for thecounty of Västmanland in central Sweden is performed to demonstrate the applicability of the developedMILP model in five distinct scenarios. The results show significant potential for mitigating CO2 emissionby gradually replacing fossil fuels with different renewable energy sources. The MILP model can be usefulfor providing strategies for treating wastes sustainably and mitigating GHG emissions in a regionalenergy system, which can function as decision bases for formulating GHG reduction policies andassessing the associated economic implications.
|
|
| 6. |
- Han, Song, 1978-, et al.
(författare)
-
Annual performance analysis and comparison of pellet production integrated with an existing combined heat and power plant
- 2011
-
Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 102:10, s. 6317-6325
-
Tidskriftsartikel (refereegranskat)abstract
- Three optional pellet production processes integrated with an existing biomass-based CHP plant using different raw materials (wood chips and solid hydrolysis residues) are studied. The year is divided into 12 periods, and the integrated biorefinery systems are modeled and simulated for each period. The annual economic performance of three integrated biorefinery systems is analyzed based on the simulation results. The option of pellet production integrated with the existing CHP plant with the exhaust flue gas and superheated steam as drying mediums has the lowest specific pellet production cost of 105 epsilon/t(pellet), the shortest payback time of less than 2 years and the greatest CO2 reduction of the three options. An advantage in common among the three options is a dramatic increase of the total annual power production and significant CO2 reduction in spite of a small decrease of power efficiency.
|
|
| 7. |
- Han, Song, 1978-, et al.
(författare)
-
Influence of drying process on the biomass-based polygeneration system of bioethanol, power and heat
- 2012
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 90:1, s. 32-37
-
Tidskriftsartikel (refereegranskat)abstract
- One of the by-products from bioethanol production using woody materials is lignin solids, which can be utilized as feedstock for combined heat and power (CHP) production. In this paper, the influence of integrating a drying process into a biomass-based polygeneration system is studied, where the exhaust flue gas is used to dry the lignin solids instead of direct condensation in the flue gas condenser (FGC). The evaporated water vapor from the lignin solids is mixed with the drying medium for consequent condensation. Thus, the exhaust flue gas after the drying still has enough humidity to produce roughly the same amount of condensation heat as direct condensation in the existing configuration. The influence of a drying process and how it interacts with the FGC in CHP production as a part of the polygeneration system is analyzed and evaluated. If a drying process is integrated with the polygeneration system, overall energy efficiency is only increased by 3.1% for CHP plant, though the power output can be increased by 5.5% compared with the simulated system using only FGC.
|
|
| 8. |
- Han, Song
(författare)
-
Regional Energy Systems with Retrofitted Combined Heat and Power (CHP) Plants
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fossil fuel depletion, economic development, urban expansion and climate change present tough challenges to municipal- and regional-scale energy systems. Regional energy system planning, including waste treatment, renewable energy supply, energy efficiency, and climate change, are considered essential to meet these challenges and move toward a sustainable society. This thesis includes studies on energy system from municipal waste, potential for a fossil fuel-independent regional energy system with increased renewable energy products using waste as one of energy sources, and the performance of biomass-fired combined heat and power (CHP) plants. A top-down method is adopted to organize the studies, from national waste-to-energy (WtE) scenarios to individual energy plants.The first study considers the overall potential contribution of WtE to energy supply and greenhouse gas (GHG) emissions mitigation in Sweden until 2050 under several different scenarios. Depending on WtE scenario considered, the study shows that WtE can supply energy between 38 and 186 TWh and mitigate between CO2 of 1 and 12 Mt per year by 2050 based on the baseline of year 2010.At a regional level, static and dynamic optimization models with a focus on WtE are developed for two regions in Sweden and Finland. The former is used to investigate the possibilities of optimal positioning of new energy plants, retrofitting existing energy plants and planting energy crops. The latter case study is on regional heat and power production using biogas generated from agricultural and livestock wastes. Centralized biogas production units perform better than distributed production regarding energy and carbon balance though the net energy output is negligible. However, a significant GHG emission can be reduced compared to the present status.Retrofitting existing conventional CHP plants is another option for improving regional energy system. The study shows that integrating heat-demanded processes such as drying, bioethanol and pellet production with existing CHP plants can improve overall energy efficiency and power output, increase annual operation time and reduce production cost as well as mitigate GHG emissions. It is recommended that building new WtE/energy plants at optimum sites, upgrading the existing energy plants, expanding the agricultural/forestry waste/residues output (biomass) and planting more energy crops shall be taken into considerations for the future regional energy systems.
|
|
| 9. |
- Han, Song, 1978-
(författare)
-
Retrofitting CHP Plant and Optimization of Regional Energy System
- 2011
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of biomass-based combined heat and power (CHP) plants is considered by the EU administration to be an effective way to increase the use of renewables in the energy system, to reduce greenhouse gas emissions and to alleviate the dependency on imported fossil fuels. At present in Sweden, most of the CHP plants are operated in part-load mode because of variations in heat demand. Further use of the potential heat capacity from CHP plants is an opportunity for integration with other heat-demanding processes. Retrofitting the conventional CHP plants by integration with bioethanol and pellet production processes is considered a feasible and efficient way to improve the plants’ performances. Modeling and simulation of the CHP plant integrated with feedstock upgrading, bioethanol production and pellet production is performed to analyze the technical and economic feasibility. When integrating with bioethanol production, the exhaust flue gas from the CHP plant is used to dry the hydrolysis solid residues (HSR) instead of direct condensation in the flue gas condenser (FGC). This drying process not only increases the overall energy efficiency (OEE) of the CHP plant but also increases the power output relative to the system using only a FGC. Furthermore, if steam is extracted from the turbine of the CHP plant and if it is used to dry the HSR together with the exhaust flue gas, pellets can be produced and the bioethanol production costs can be reduced by 30% compared with ethanol cogeneration plants. Three optional pellet production processes integrated with an existing biomass-based CHP plant using different raw materials are studied to determine their annual performance. The option of pellet production integrated with the existing CHP plant using exhaust flue gas and superheated steam for drying allows for a low specific pellet production cost, short payback time and significant CO2 reduction. A common advantage of the three options is a dramatic increase in the total annual power production and a significant CO2 reduction, in spite of a decrease in power efficiency. The retrofitted biomass-based CHP plants play a crucial role in the present and future regional energy system. The total costs are minimized for the studied energy system by using wastes as energy sources. Analyses of scenarios for the coming decades are performed to describe how to achieve a regional fossil fuel-free energy system. It is possible to achieve the target by upgrading and retrofitting the present energy plants and constructing new ones. The conditions and obstacles have also been presented and discussed through optimizing the locations for proposed new energy plants and planting energy crops.
|
|
| 10. |
- Han, Song, et al.
(författare)
-
Techno-economic analysis of an integrated biorefinery system for poly-generation of power, heat, pellets and bioethanol
- 2014
-
Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 38:5, s. 551-563:38, s. 551-563
-
Tidskriftsartikel (refereegranskat)abstract
- Bioethanol is an alternative to fossil fuels in the transportation sector. The use of pellet for heating is also an efficient way to mitigate greenhouse gas emissions. This paper evaluates the techno-economic performance of a biorefinery system in which an existing combined heat and power (CHP) plant is integrated with the production of bioethanol and pellet using straw as feedstock. A two-stage acid hydrolysis process is used for bioethanol production, and two different drying technologies are applied to dry hydrolysis solid residues. A sensitivity analysis is performed on critical parameters such as the bioethanol selling price and feedstock price. The bioethanol production cost is also calculated for two cases with either 10 year or 15 year payback times. The results show that the second case is currently a more feasible economic configuration and reduces production costs by 36.4%-77.3% compared to other types of poly-generation plants that are not integrated into existing CHP plants.
|
|
| 11. |
- Han, Song, et al.
(författare)
-
WASTE-TO-ENERGY SCENARIOS ANALYSIS BASED ON ENERGY SUPPLY AND DEMAND IN SWEDEN
- 2012
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Energy recovery from waste treatment is of great significance for the waste management and sustainable energy supply. Sweden has proposed an ambitious vision of zero net greenhouse gases emissions by 2050, which makes most possible use of resources that the waste represents necessary. This paper is to study how the waste-to-energy (WtE) can interact with other forms of renewable energy to affect the energy supply and demand in Sweden. Based on an assumption of waste generation-treatment balance in 2050 with two cases, power preference and motor fuels preference, are investigated under diverse WtE scenarios. The results indicate that WtE production can contribute to the primary energy supply by 38 to 186 TWh, amounting to 6% to 47% of the total. The power production can be ranged from 7 to 35 TWh and motor fuels from 2 to 34 TWh through under different WtE scenarios. Furthermore, the final mitigation of CO2 emission is estimated to be from 1 to 12 Mt in 2050 compared to base year of 2010, really depending on which WtE scenario is considered.
|
|
| 12. |
- Hui, Hongxun, et al.
(författare)
-
5G network-based Internet of Things for demand response in smart grid : A survey on application potential
- 2020
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 257
-
Forskningsöversikt (refereegranskat)abstract
- Demand response (DR) has been widely regarded as an effective way to provide regulation services for smart grids by controlling demand-side resources via new and improved information and communication technologies. Emerging 5G networks and 5G-based Internet of Things (IoTs) can doubtless provide better infrastructure for DR, owing to 5G's advantages of fast transfer speed, high reliability, robust security, low power consumption, and massive number of connections. However, nearly none of the existing studies have applied 5G technology to DR, which will be the subject surveyed in this paper. First, the concept of DR and recent practical advances are investigated, especially the application of communication technologies to DR. Then, a comprehensive review of the cyber security, consumer privacy, and reliability of DR is presented. These topics received little attention in the past, but they will be among the most crucial factors in the future. In addition, the essential features and typical application scenarios of 5G communication are investigated. On this basis, the advantages, methods, recent advances, and implementation planning of 5G on DR are studied. Finally, the future work that must urgently be conducted in order to achieve the application of 5G to DR is discussed. This paper's application survey of 5G on DR is carried out before 5G technology enters the large-scale commercial stage, so as to provide references and guidelines for developing future 5G networks in the smart grid paradigm.
|
|
| 13. |
- Hui, H., et al.
(författare)
-
Probabilistic integrated flexible regions of multi-energy industrial parks : Conceptualization and characterization
- 2023
-
Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 349
-
Tidskriftsartikel (refereegranskat)abstract
- Multi-energy industrial parks, composed of the district energy supply system and terminal industrial loads, are dominant energy consumers with over 50% occupation of total energy consumption. Considering the energy conversion in the district energy supply system and adjustment of production subtasks in terminal industrial loads, the industrial parks could provide considerable flexibility for utility multi-energy systems to deal with contingencies. However, industrial parks may have multiple uncertainties originating from the production subtasks' variability, distributed renewable energy's fluctuation, and random failures of equipment. These uncertainties could make the flexibility assessment of industrial parks unreliable, which may further exacerbate utility system risks. To address the problem, this paper innovatively proposes the concept of probabilistic integrated flexible regions and corresponding characterization approaches, which can effectively describe the credible multi-energy adjustment ability of industrial parks. First, the energy-material flows in the industrial park are modeled considering multiple uncertainties while subject to constraints such as operating limits of equipment, energy and material balancing, and production targets. Then, the modeling and calculation methods of probabilistic integrated flexible regions are given. These regions are labeled with certain probability requirements and visualized in the input multi-energy space. Using a real-world test system that produces air conditioning equipment in China, the results show that the proposed model can effectively reflect the probability characteristics of the integrated flexibility under multiple uncertainties. For this test system, the area of a highly credible integrated flexibility, represented by the probabilistic integrated flexible region with 99% probability, is about half of that obtained by the deterministic model. That is, half of the integrated flexibility evaluated by the deterministic method in the test system may not be practically utilized considering the impacts of uncertainties. Therefore, the proposed method could provide a credible and comprehensive evaluation of the multi-energy industrial park's flexibility considering multiple uncertainties.
|
|
| 14. |
- Huo, Yanda, et al.
(författare)
-
Data-Driven Adaptive Operation of Soft Open Points in Active Distribution Networks
- 2021
-
Ingår i: IEEE Transactions on Industrial Informatics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1551-3203 .- 1941-0050. ; 17:12, s. 8230-8242
-
Tidskriftsartikel (refereegranskat)abstract
- The integration of soft open point (SOP) effectively improves the flexibility of active distribution networks (ADNs). However, in practical operation, accurate network parameters are difficult to obtain and the operation state changes rapidly with distributed generators (DGs). With the development of information technologies, massive operation data can be acquired in ADNs. How to utilize multisource data has become the key to realize the intelligent operation of ADNs. This article proposes a data-driven operation strategy of SOP based on model-free adaptive control (MFAC). First, considering the inaccurate parameters and frequent change of operation states, a data-driven framework is formulated for the real-time operation of SOP. Then, the operation strategies of multiple SOPs are further improved with interarea coordination. The results of case studies show that driven by the measurement data, the potential benefits of SOPs are explored to adaptively respond to system state changes and improve the operational performance of ADNs.
|
|
| 15. |
- Ji, H., et al.
(författare)
-
Robust operation for minimizing power consumption of data centers with flexible substation integration
- 2022
-
Ingår i: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 248
-
Tidskriftsartikel (refereegranskat)abstract
- The rapid development of digital economy has led to a dramatic increasement of internet data centers (IDCs), which consume a large amount of electricity. The diverse data-processing demands, high power consumption and workload uncertainty put forward a high requirement for the economical and secure operation of IDCs. As information technology (IT) devices are driven by direct current (DC), flexible substation (FS) has been gradually utilized to provide DC power for IDCs. This paper proposes robust operation strategies for minimizing IDC power consumption with FS integration. First, the linearized IDC power consumption model based on the technology of dynamic voltage and frequency scaling (DVFS) is proposed to describe the operating state of IT devices. Then, considering the FS-based coordinated operation of IDC, photovoltaic (PV) station and energy storage system (ESS), the deterministic power consumption minimization model of IDCs is established. Considering the workload uncertainty, the operation strategies based on distributionally robust optimization (DRO) for IDCs are further proposed. Finally, the effectiveness of proposed method is validated on a modified practical network with IDCs integrated. Results show that through the dispatch of workload and power flow regulation of FS, the power consumption and dropping workload of IDCs are effectively reduced.
|
|
| 16. |
- Jian, J., et al.
(författare)
-
Multi-stage supply restoration of active distribution networks with SOP integration
- 2022
-
Ingår i: Sustainable Energy, Grids and Networks. - : Elsevier Ltd. - 2352-4677. ; 29
-
Tidskriftsartikel (refereegranskat)abstract
- Supply restoration from outages is essential for improving the reliability of active distribution networks (ADNs) after fault isolation. Soft open point (SOP) can adjust the power flow among feeders and provide voltage support for power outage areas. Considering the sequential coordination of switching operation and SOP control mode selection, a multi-stage supply restoration method with SOPs is proposed for ADNs. First, the sequential energization is formulated, in which the impact of SOP control mode on restoration sequence is analyzed. By providing voltage support, the coordination of SOPs will rapidly energize the outage area and improve the voltage profile. Then, a multi-stage restoration model with SOPs is proposed, in which reconfiguration of switches and control mode selection of SOPs are coordinated in sequence to maximize the load recovery level of ADNs. Through the switching action-time mapping, secure operation is ensured during the entire supply restoration process. Finally, the effectiveness of the proposed method is validated on a modified IEEE 33-node distribution system and practical distribution networks with four-terminal SOP. Results show that the proposed method can fully exploit the potential benefits of SOPs and effectively enhance the load recovery level of ADNs.
|
|
| 17. |
|
|
| 18. |
- Li, Peiran, et al.
(författare)
-
Understanding rooftop PV panel semantic segmentation of satellite and aerial images for better using machine learning
- 2021
-
Ingår i: Advances in Applied Energy. - : Elsevier BV. - 2666-7924. ; 4, s. 100057-100057
-
Tidskriftsartikel (refereegranskat)abstract
- The photovoltaic (PV) industry boom and increased PV applications call for better planning based on accurate and updated data on the installed capacity. Compared with the manual statistical approach, which is often time-consuming and labor-intensive, using satellite/aerial images to estimate the existing PV installed capacity offers a new method with cost-effective and data-consistent features. Previous studies investigated the feasibility of segmenting PV panels from images involving machine learning technologies. However, due to the particular characteristics of PV panel semantic-segmentation, the machine learning tools need to be designed and applied with careful considerations of the issue formulation, data quality, and model explainability. This paper investigated the characteristics of PV panel semantic-segmentation from the perspective of computer vision. The results reveal that the PV panel image data has several specific characteristics: highly class-imbalance and non-concentrated distribution; homogeneous texture and heterogenous color features; and the notable resolution threshold for effective semantic-segmentation. Moreover, this paper provided recommendations for data obtaining and model design, aiming at each observed character from the viewpoints of recent solutions in computer vision, which can be helpful for future improvement of the PV panel semantic-segmentation.
|
|
| 19. |
- Liu, Z., et al.
(författare)
-
Effect of soil moisture content on thermal performance of ground source heat exchangers : An electromagnetism topology-based analysis
- 2023
-
Ingår i: Energy Reports. - : Elsevier Ltd. - 2352-4847. ; 10, s. 3914-3928
-
Tidskriftsartikel (refereegranskat)abstract
- Ground source heat pump (GSHP) technology has gained significant attention as a viable solution for the heating, ventilation, and air conditioning (HVAC) of buildings. One of the factors that can impact the performance of GSHP systems is the soil moisture content. In this study, an innovative approach, referred to as soil impedance topology, is introduced as an alternative to traditional methods for measuring soil moisture content in geothermal heat pump systems. This method is inspired by pipeline grid utilizes impedance measurement, which provides a direct measurement of soil moisture content without the need for sensors. The study also proposes a changing rule of impedance with varying moisture content, where capacitance increases and resistance decreases when the soil moisture content is less than 20% but stabilizes beyond a water content of 20%. The accuracy of the topological mechanism prediction method is high, as demonstrated through the verification of the Smith circle and measured data. However, it is noted that the performance may be insufficient in the high frequency band and high soil moisture content. The use of impedance topology provides a more accurate and reliable method for measuring soil moisture content as well as for modeling and predicting heat transfer rates and system performance. This technology has strong potential to improve efficiency, reduce energy costs, and enhance the environmental sustainability of geothermal heat pump systems.
|
|
| 20. |
- Mu, Cuicui, et al.
(författare)
-
Ecosystem CO2 Exchange and Its Economic Implications in Northern Permafrost Regions in the 21st Century
- 2023
-
Ingår i: Global Biogeochemical Cycles. - 0886-6236. ; 37:11
-
Tidskriftsartikel (refereegranskat)abstract
- Climate warming increases carbon assimilation by plant growth and also accelerates permafrost CO2 emissions; however, the overall ecosystem CO2 balance in permafrost regions and its economic impacts remain largely unknown. Here we synthesize in situ measurements of net ecosystem CO2 exchange to assess current and future carbon budgets across the northern permafrost regions using the random forest model and calculate their economic implications under the Shared Socio-economic Pathways (SSPs) based on the PAGE-ICE model. We estimate a contemporary CO2 emission of 1,539 Tg C during the nongrowing season and CO2 uptake of 2,330 Tg C during the growing season, respectively. Air temperature and precipitation exert the most control over the net ecosystem exchange in the nongrowing season, while leaf area index plays a more important role in the growing season. This region will probably shift to a carbon source after 2,057 under SSP5-8.5, with a net emission of 17 Pg C during 2057–2100. The net economic benefits of CO2 budget will be $4.5, $5.0, and $2.9 trillion under SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. Our results imply that a high-emission pathway will greatly reduce the economic benefit of carbon assimilation in northern permafrost regions.
|
|
| 21. |
- Qi, L., et al.
(författare)
-
Techno-economic assessment of implementing photovoltaic water villas in Maldives
- 2023
-
Ingår i: iScience. - : Elsevier Inc.. - 2589-0042. ; 26:5
-
Tidskriftsartikel (refereegranskat)abstract
- Solar energy is considered to be an effective measure to alleviate the shortage of power supply in the Maldives. In this paper, a roof photovoltaic (PV) system integrated into water villas in the Maldives was investigated. Three islands—Ayada Maldives, Angaga Island Resort, and JA Manafaru, located in the southern, central, and northern parts of Maldives—were selected for a case study. The potential of PV installations in Ayada Maldives, Angaga Island Resort, and JA Manafaru reaches 1,410, 445, and 742 kW, with corresponding annual power generation of 2.04, 0.64, and 1.12 GWh, respectively. The profits over the life cycle of 25 years of the above three studied islands are 4.86, 1.52, and 2.90 million USD, respectively, with payback periods in the range of 6–7 years.
|
|
| 22. |
|
|
| 23. |
- Song, J., et al.
(författare)
-
Parameter optimization analysis of rotary electromagnetic vibration energy harvester for performance enhancement under free vibration
- 2023
-
Ingår i: iScience. - : Elsevier Inc.. - 2589-0042. ; 26:10
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, three new important aspects of rotary electromagnetic vibration energy harvesting technology (RE-VEH) are concerned and investigated: (i) vibro-electric coupling mechanism of the RE-VEH system is studied through theoretical modeling; (ii) quantitative analysis of system parameters based on numerical simulation method is carried out for the optimal design of RE-VEH; and (iii) dynamic power output performance of the RE-VEH system in free vibration is discussed. The parameter adjusting methods of the RE-VEH system in free vibration mode are obtained through theoretical analysis and numerical simulation. The experimental results show that the power output performance of RE-VEH in free vibration mode matches the numerical simulation results. The simulation and experimental results show that the maximum voltage output and power output of the RE-VEH with different structure parameters under free vibration can be up to the level of 100∼101 V/watt. The above results indicate that RE-VEH in a free vibration environment has significant energy output performance.
|
|
| 24. |
- Sun, H., et al.
(författare)
-
Methane hydrate re-formation and blockage mechanism in a pore-level water-gas flow process
- 2023
-
Ingår i: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 263
-
Tidskriftsartikel (refereegranskat)abstract
- Hydrate re-formation increases blockage risk and further reduces gas production efficiency. Considering the huge water production and gas migration, it is essential to determine the key parameters that control hydrate re-formation and blockage in the two-phase flow process. However, little research reveals the mechanism of hydrate re-formation in the water-dominated two-phase flow system. In this study, two-phase flow in hydrate sediment is simulated by controlling the water-gas flow rate, and the effect of effective sectional velocity on hydrate re-formation characteristics is analyzed. The experimental results showed that temperature and pressure followed a three-stage change trend in the water-dominated two-phase flow process: including hydrate re-formation induction stage I, mass hydrate re-formation and agglomeration stage II, and pore gas consumption stage III. Moreover, a lower effective sectional velocity of water (WESV) would reduce the gas concentration gradient between water and hydrate to enhance the hydrate re-formation process. Meanwhile, the gas phase impeded the mass transfer on the water-hydrate interface and acted as the nucleation site to promote hydrate re-formation. Furthermore, it was noticed that the relationship between the onset time of flow blockage and WESV was linearly positive, however, the amount of hydrate re-formation reduced with increasing WESV.
|
|
| 25. |
- Zhang, Haoran, et al.
(författare)
-
1.6 Million transactions replicate distributed PV market slowdown by COVID-19 lockdown
- 2021
-
Ingår i: Applied Energy. - : ELSEVIER SCI LTD. - 0306-2619 .- 1872-9118. ; 283
-
Tidskriftsartikel (refereegranskat)abstract
- Solar PV has seen a spectacular market development in recent years and has become a cost competitive source of electricity in many parts of the world. Yet, prospective observations show that the coronavirus pandemic could impact renewable energy projects, especially in the distributed market. Tracking and attributing the economic footprint of COVID-19 lockdowns in the photovoltaic sector poses a significant research challenge. Based on millions of financial transaction records and 44 thousand photovoltaic installation records, we tracked the spatiotemporal sale network of the distributed photovoltaic market and explored the extent of market slowdown. We found that a two-month lockdown duration can be assessed as a high-risk threshold value. When the lockdown duration exceeds the threshold value, the monthly value-added loss reaches 67.7%, and emission reduction capacity is cut by 64.2% over the whole year. We show that risks of a slowdown in PV deployment due to COVID19 lockdowns can be mitigated by comprehensive incentive strategies for the distributed PV market amid market uncertainties.
|
|
| 26. |
- Zhang, Haoran, et al.
(författare)
-
Epidemic versus economic performances of the COVID-19 lockdown : A big data driven analysis
- 2022
-
Ingår i: Cities. - : Elsevier BV. - 0264-2751 .- 1873-6084. ; 120
-
Tidskriftsartikel (refereegranskat)abstract
- Lockdown measures have been a “panacea” for pandemic control but also a violent “poison” for economies.Lockdown policies strongly restrict human mobility but mobility reduce does harm to economics. Governmentsmeet a thorny problem in balancing the pros and cons of lockdown policies, but lack comprehensive andquantified guides. Based on millions of financial transaction records, and billions of mobility data, we trackedspatio-temporal business networks and human daily mobility, then proposed a high-resolution two-sidedframework to assess the epidemiological performance and economic damage of different lockdown policies. Wefound that the pandemic duration under the strictest lockdown is less about two months than that under thelightest lockdown, which makes the strictest lockdown characterize both epidemiologically and economicallyefficient. Moreover, based on the two-sided model, we explored the spatial lockdown strategy. We argue thatcutting off intercity commuting is significant in both epidemiological and economical aspects, and finally helpedgovernments figure out the Pareto optimal solution set of lockdown strategy.
|
|
| 27. |
- Zhang, Haoran, et al.
(författare)
-
Urban power load profiles under ageing transition integrated with future EVs charging
- 2021
-
Ingår i: Advances in Applied Energy. - : Elsevier BV. - 2666-7924. ; 1, s. 100007-100007
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding ageing transition caused fine-grained changes of electricity profile is the significant insight for coping with future threatens in grid flexibility management. The research gaps for the hourly-basis knowledge exist due to challenges in microanalysis on user-side behavior. Based on billions of users’ behavior data, we investigated the changes on the load profiles due to population aging. We found that owing to ageing transition, the participation population in high electricity-density activities decreases by about 8%. The corresponding shift in driving behavior rises the 14% difference between peak charging load and valley. We concluded that population aging will dramatically change both the magnitude and shape of future dynamic-load profiles. Therefore, we further suggested a new solution with comprehensive and quantitative management for PVs development and the smart charging market with smooth operation of the grid in coupling the potential challenges caused by the ageing issue.
|
|
