Encouraged by the proliferation of distributed renewable energy systems (DRESs), the concept of blockchain based Peer-to-Peer (P2P) energy markets has been gaining momentum in recent years. This promising concept, which allows consumers and prosumers to trade electrical energy directly on a blockchain network without the need for an intermediary, have proven various benefits such as the increase in energy cost savings, improvements in main grid resiliency and more importantly, decarbonization in the long term. Since wastewater treatment systems are known to consume a significant amount of energy to treat influent wastewater such that the effluent meets national discharge standards, the application of this P2P energy trading concept in this industry could prove beneficial to all involved stakeholders. This paper presents an integration of a hierarchical day-ahead P2P energy trading model to the industrial water-energy-nexus (WEN). The first stage introduces a continuous doublesided (CDA) auction market clearing algorithm with the Vickrey-Clarke-Groves (VCG) pricing mechanism deployed on a blockchain framework. The auction mechanism takes the forecasted energy demand/generation as inputs. The next stage proposes a demand-response energy optimization management system for the involved stakeholders. Simulation results show that a P2P-enabled energy market allows consumers to decrease their daily electricity costs by 3.37% – 5.17% and allows prosumers to increase their daily electricity profits by 54.08% – 56.90%. Furthermore, aggregated load demand during peak hours have been reduced by 11.38%.
The deepening of China’s regional economic integration has posed potential impacts on climate change mitigation. This paper evaluates the impact of Changsha-Zhuzhou-Xiangtan economic integration policy on carbon emissions based on the total industrial output value, analyzes the correlation between carbon emission and total industrial output value of Changsha-Zhuzhou-Xiangtan urban agglomeration from 2000 to 2014, and calculates the carbon dioxide emission per unit of industrial added value. The results show that under the influence of economic integration, the carbon dioxide emission per unit industrial added value of Changsha-Zhuzhou-Xiangtan urban agglomeration decreases significantly, and low-carbon industry gradually occupies a dominant position. The results are helpful for the design of carbon emission reduction path and the formulation of carbon neutralization long-term policy of Changsha-Zhuzhou-Xiangtan urban agglomeration.
The charging/discharging characteristics of lithium-ion battery are mainly dependent on itself temperature which is determined by the balance both the heat generated by battery itself and the heat removed by the battery thermal management system (BTMS). Consequently, study on the heat generation behaviors of the lithium-ion battery is necessary for designing the BTMS which is capable of maintaining batteries at optimum temperature ranging from 20℃ to 40℃. In this study, the heat generation behaviors and electro-thermal characteristics of a prismatic LiFePO4 battery with a high nominal capacity of 280Ah at the charging rates of 0.5C and 1C and initial temperatures of 15℃, 25℃ and 35℃ were comprehensively explored using an electrochemical-calorimetric method. The experimental results show that the charging capacity at the end of charging is nearly independent on the above mentioned charging rates and initial temperatures, which is due to the positive effect of heat generated by the battery itself in accelerate calorimeter rate (ARC). However, it is noted that the heat generation rates during the charging process (especially for the beginning of charging) significantly increases with the growth of charging rate and the decrease of initial temperature. At the state of charge (SOC) equal to 0.1 and initial temperature of 15℃, the heat generation rates at charging rates of 0.5C and 1C are about 20.2 W and 76.6 W respectively, that is to say, the heat generation rate at high charging rate of 1C is nearly 3.8 times than that at moderate charging rate of 0.5C. These findings indicate that the battery own the excellent charging efficiency (short charging time and charging capacity nearly equal to nominal capacity) at the high charging rate of 1C, however, significant rise of heat generation rate inevitably brings the huge challenge for the BTMS. This study may also provide some guidance for the design of BTMS.
Combined cooling, heating and power (CCHP) system is a promising distributed energy system, which is usually installed close to the terminal user and satisfies the diverse energy supply. Whereas, the demand-response characteristics is critical for the system feasible and efficient operation. In this work, an alternative adjust method based on the thermochemical recuperation is developed for optimizing the CCHP production, the exhaust high-temperature gas from the prime mover is first used to drive the endothermic reaction of methanol decomposition before the absorption refrigeration, thereby the exhaust waste heat realizes the enhanced cascade utilization and improves its energy level by transited into the chemical form. Both the thermodynamic performances and the flexible demand response characteristics of the system were also comprehensively investigated. Regarding to the case studies of building application in China, two scenarios of the gas turbine and the internal combustion engine as the prime movers are considered, the system thermal efficiency for CCHP production is increased by 0.82%-13.71% accompanying with a considerable fuel saving. Furthermore, the system is able to automatically adjust the recuperation thermal ratio based on the simultaneous changed terminal energy loads, the operation flexibility of source-demand matching is thus enhanced and optimized. The reasonable operation characteristics approve this promising method to achieve efficient waste heat recovery and feasible multi-energy production.
This paper investigates a collective control problem for a parking-based large-scaled EVs. A parking under electric energy management by a virtual power plant is targeted under assumption of decentralized charging/discharging rate control of the individual EVs. A decentralized charging control strategy is proposed by solving a mean-field game problem with the cost function that balancing between the collective charging behavior and the charging level of each EV. Simulation results is finally demonstrated to validate the proposed control strategy.
In this paper, the concept of electric energy storage by a fluidized bed (EESFB) is introduced and validated. In this novel EESFB system, sand is used as the medium for energy storage. In the heating mode, sand is heated up in a fluidized bed by a group of embedded electric heating elements to a high temperature and then stored in thermally insulated tank. In the heat release mode, the stored thermal energy can be released to generate hot air, steam and electricity as necessary. Compared with other thermal energy storage technologies, EESFB is prevailing in cost-effective, environmental-friendly, high efficiency, high energy density, high flexibility to meet load fluctuations and always-ready characteristics to supply high-temperature thermal energy. It also could have a potential for massive energy storage. An experimental system with 100 kW input power was setup to study the feasibility of the novel technology. Results showed that EESFB system can be operated smoothly and sand can be efficiently heated up to a high temperature with embedded heating elements in the fluidized bed.
As energy and environmental issues become more and more serious, we need to further improve the overall energy efficiency of modern cities. The operation of the urban energy system is affected by the characteristics of human social behavior, which increases the complexity of the problem. Therefore, cities must find how to conduct a comprehensive analysis of the energy use behavior of social residents from the perspective of smart cities and energy Internet, and then carry out effective guidance and management, assist the transformation and upgrading of the urban energy system, reasonable planning, and realize the improvement of urban comprehensive energy efficiency, cleanliness, and low carbon. The social-physical behavior model of residents formed by the corresponding population mobility attributes and energy attributes can reflect economic conditions and the behavior habits of various groups, thereby assisting the investment decision-making of urban infrastructure construction, and providing a basis for urban and power grid planning.
Data generated in the cities have great potential to assist in studies on urban metabolism and urban energy transition. Several cities around the world have already adopted the open data portals to share data and increase their capabilities. However, much of these data are of low resolution, diverse formats, and mostly lack real energy measurements of buildings. In this paper, we address this issue by using an example of Energy Hub data portal “NRGYHUB”, an urban energy portal for open data for the city of Västerås, Sweden. Granular electricity, district heating and water consumption data were collected and matched to their corresponding buildings. The data are stored into a database and will be available for public through a GIS-driven interface. The challenges that were faced during the data access process are briefly described. The potential of NRGYHUB data portal as a tool to develop urban policies is discussed.
The bioenergy with CO2 capture and storage (BECCS) is an important solution to reduce CO2 emissions. This paper proposed a new method that can accurately access CO2 capture potential from a biomass-fired combined heat and power (BCHP). Chemical absorption is used as CO2 capture technology. By carefully considering the temperatures of the heat required by district heating and CO2 capture, the allocation of the available heat from flue gas condensation and extracted steam condensation for different purposes has been optimized. By using a real BCHP with a thermal capacity of 200MW as a case study, results show that the captured CO2 was 23.42t/day without any change in heat and power supply, which was 1.77% of the total released CO2.
As the increased frequency, intensity and duration of extreme weather events have significantly challenged power systems, greater attention has been focused on the development of resilient power systems. Taking a physical-cyber-human system perspective, this paper establishes a multi-criteria resilience evaluation framework for urban power systems, in which two principal elements responsible for power system function degradation are described, and fifteen (eleven objective and four subjective) power system resilience evaluation indicators are identified. Fuzzy hesitant judgement and a TOPSIS aggregation method are applied for the evaluation to minimize expert divergence and maximize group consensus. The evaluation method is then applied to four Chinese municipalities: Shanghai, Beijing and Chongqing, and Tianjin. It was found that Beijing’s resilience was the best of the four but overall the urban power system resiliencies were not enough in the face of extreme event challenges.