| 1. |
- Ding, Y., et al.
(författare)
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Economical flexibility options for integrating fluctuating wind energy in power systems : The case of China
- 2018
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 228, s. 426-436
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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.
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| 2. |
- Guziana, Bozena, et al.
(författare)
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Policy Based Scenarios for Waste-to-Energy Use : Swedish Perspective
- 2014
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Ingår i: Waste and Biomass Valorization. - : Springer Science and Business Media LLC. - 1877-2641 .- 1877-265X. ; 5:4, s. 679-688
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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.
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| 3. |
- Guziana, Bozena, 1963-, et al.
(författare)
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SCENARIOS FOR WASTE-TO-ENERGY USE - SWEDISH PERSPECTIVE.
- 2011
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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.
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| 4. |
- Guziana, Bozena, 1963-, et al.
(författare)
-
Waste-to-energy in a Polish perspective
- 2012
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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.
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| 5. |
- Han, Song, et al.
(författare)
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A dynamic model to optimize a regional energy system with waste and crops as energy resources for greenhouse gases mitigation
- 2012
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 46:1, s. 522-532
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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.
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| 6. |
- Han, Song, 1978-, et al.
(författare)
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Annual performance analysis and comparison of pellet production integrated with an existing combined heat and power plant
- 2011
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 102:10, s. 6317-6325
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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.
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| 7. |
- Han, Song, 1978-, et al.
(författare)
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Influence of drying process on the biomass-based polygeneration system of bioethanol, power and heat
- 2012
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 90:1, s. 32-37
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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.
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| 8. |
- Han, Song
(författare)
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Regional Energy Systems with Retrofitted Combined Heat and Power (CHP) Plants
- 2012
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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.
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| 9. |
- Han, Song, 1978-
(författare)
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Retrofitting CHP Plant and Optimization of Regional Energy System
- 2011
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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.
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| 10. |
- Han, Song, et al.
(författare)
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Techno-economic analysis of an integrated biorefinery system for poly-generation of power, heat, pellets and bioethanol
- 2014
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 38:5, s. 551-563:38, s. 551-563
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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.
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