Abstract

The urgent need to combat global warming has highlighted the significance of transitioning towards environmentally friendly energy sources. Acknowledged by the European Commission as a valuable approach for facilitating this transition, the energy community model offers promise to districts and cities seeking sustainable solutions. This paper focuses on the district of Sätra in Västerås, Sweden, and explores the potential of operating as an energy community. The study considers Sätra’s economic, social, and technical circumstances, as well as Sweden’s regulatory framework. The methodology consists mainly of interviews with specialists and urban actors, as well as reviewing the literature and relevant documents. The findings highlight various political, technical, social, and economic barriers that hinder the establishment of an energy community in Sätra, such as the absence of a clear definition for energy communities, intermittency of renewable energy sources, low awareness among residents and marginalization of some social groups, and insufficient funding for initiatives. To address these barriers, the study proposes several incentives and mitigation strategies. These include developing a comprehensive definition of “energy community”, establishing an umbrella organization to coordinate efforts, raising awareness among stakeholders, and securing adequate funding. The valuable insights provided by the current study on the establishment of an energy community in Sätra and the proposed incentives and mitigation strategies serve as a basis for further exploration and implementation, paving the way for a sustainable and resilient energy future in the district and the country.

Abstract

Currently, the main types of methanol steam reforming (MSR) reactors used in vehicles are fixed bed reactors and microchannel reactors. However, these two-dimensional reactors have limitations such as restricted radial diffusion, catalyst coating peeling off easily, and high pressure drop. In this study, a new type of three-dimensional porous Cu/ZnO catalyst was developed using 3D printing combined with dealloying technology. The internal mass and heat transfer characteristics of the three catalyst structures, Cylindrical microchannel, Diamond, and Gyroid, were revealed using computational fluid dynamics (CFD) simulation. The simulation results showed that the Gyroid structure with its curved and smooth flow channels enhanced radial mass and heat transfer while having the advantage of low pressure drop. Performance tests showed that the Gyroid structure catalyst exhibited high activity and good stability.

Abstract

Flexible operation of enhanced geothermal system (EGS) can not only address the peak modulation of geothermal power generation, but also actually improve the utilization of geothermal resource. Thus, an inversion investigation is presented to explore the effect of the flexible operation of EGS on reservoir lifespan using a pinnate horizontal well in present work. A nested iterative program is developed to fit the relationship between the generation capacity and operation time first, and injection flow rate second, by incorporating the non-linear least squares and Levenberg-Marquardt method. Particle swarm optimization (PSO) with self- adaptive inertia weight algorithm is employed to inverse the flexible operation strategy according to the surrogate model and the data of power consumption in demand side. The result indicates that the generation capacity and production temperature of EGS with pinnate horizontal well are strongly associated only with the injection mass flow rate. According to the power consumption in demand side, the geothermal power plant proposed should be launched at spring or autumn to avoid the geothermally seismic activity that caused by the larger injection flow rate. The flexible operation strategy of EGS with pinnate horizontal well should be implemented 11.25 days earlier than expected. Compared with the optimum operation strategy, the application of flexible operation strategy delays the thermal breakthrough time by 1.28 years, but causes a higher pump consumption.

Abstract

In dengsi gas reservoir, Anyue gas field, Sichuan Basin, It’s diagenetic process of ultra-deep carbonate sedimentation is complex. At present, the structural characteristics of the pore throat are not enough. In this paper, I use the real reservoir core of the gas reservoir as the research object, and study the types and characteristics of the pore throat of the reservoir by using the method of cast thin section analysis and nuclear magnetic resonance testing.Studying the nuclear magnetic resonance spectroscopy characteristics of the three types of pore cores after different pressure imbibition of saturated water. The results show that the main peaks of T2 spectrum of pore type I, II and III cores are distributed around 1-10ms, 10-100ms and 1ms, and the high-speed conductivity of fractures can improve the overall imbibition degree of pore type II cores. Increasing saturation pressure has the greatest effect on the imbibition saturation degree of pore type II cores, and the best effect on the cores with permeability between 0.001-0.01mD. Because it is difficult for water to enter the pore type III core with too low permeability, the influence of increasing saturation pressure on the pore type III core is low. The research can provide a theoretical basis for the study of water invasion mechanism in the production process of target gas reservoir and the drainage gas production in the later stage.

Abstract

In order to promote the green, energy-efficient and sustainable development of data centers, this study introduces a hybrid cooling system that incorporates the full-day radiative cooling technology into data centers and couples it within a heat pipe integrated cooling system, which efficiently operates alongside mechanical refrigeration and natural cold sources. The radiative cooling performance and regional adaptability in 12 major cities in China were analyzed using Energy Plus and mathematical modeling. Moreover, a 40-day test was conducted in Hebei to validate the practical operation of the radiative cooling system. The results demonstrated that during the summer, the average maximum net radiative cooling power can reach 40-50 W/m2. The study also reveals the potential of combining the radiative cooling system with traditional air conditioning, leading to an average annual energy savings rate of 28% for data centers. The research provides valuable guidance for the design and implementation of radiative cooling systems in data centers.

Abstract

Coal-fired power plants integrated with post-combustion carbon capture technology are selected as an effective way to meet the demand for electricity, and to ameliorate the environmental pollution caused by the burning of fossil fuels. However, there is energy loss in the coal-fired power plants integrated with large-scale carbon capture systems. To obtain the optimal system parameter of coal- fired power plants integrated with large-scale carbon capture systems, the inlet temperature of the stripper and the irreversibility of the system is first analyzed, followed by waste heat utilization. As renewable power generation deployment grows, fossil fuel plants, including coal-fired units with coupled carbon capture systems, are being forced to operate more flexibly. The performance of coal-fired power plants integrated with large-scale carbon capture systems under load-cycling operation conditions is analyzed. It turns out that the exergy efficiency of CPCC under 30%THA is the lowest, only 2.9%. The structures should be restructured under low load ratio.

Abstract

To obtain a better understanding of the characteristics of large-scale seasonal borehole thermal energy storage (BTES), a demonstration project was developed in Chifeng, China. In the project, combined heat sources of industrial waste heat and solar energy were adopted for 500000 m3 borehole thermal energy storage. In this study, the long-term thermal and economic performance of the demonstration project was analyzed based on the operation data of the demonstration project. First, actual system energy and economic performance of the demonstration project were analyzed. After that, a system simulation model was established and calibrated with the long-term system measured data from the demonstration project. The system simulation model was integrated into the LCCA model for assessing system long-term economic performance with different system design parameters and operation strategies. Then a multi-object optimization based on Non-dominated Sorting Genetic Algorithm II (NSGA-II) was conducted for finding the optimal design configuration and system performance.
The results of this study showed that, the annualized cost of borehole thermal energy storage of the studied system around 4-6 US$/GJ, and it could be further reduced to 2.7 $/GJ in China by reducing the borehole drilling cost and returning water temperature of the district heating network. Which emphasized that borehole thermal energy storage has a good application prospect in future urban distributed energy systems.

Abstract

Conventional ice-skating rinks require an intensive refrigeration load and continuous use of chiller which results in a substantial energy consumption. Therefore, novel, and sustainable alternatives are required to make more energy efficient ice-skating rinks. In this study, we propose a novel first-of-a-kind PCM (Phase Change Material) based ice skating rink and report the development of computational tool based on CFD (Computational Fluid Dynamics) to study various design aspects of such innovative system. The overall results show the significance of this model in providing a powerful tool to select suitable PCM, test operating parameters such as inlet temperature and flow rate, as well as predict the ice rink performance under different scenarios.

Abstract

The wastewater sector represents a significant contributor to greenhouse gas (GHG) emissions, and the issue of GHG emissions from wastewater infrastructures in the Qinghai-Tibet Plateau (QTP) has been overlooked. This study constructed a unified accounting framework based on the emission factors approach to quantify GHG emissions from wastewater infrastructures on the QTP, and identified the influencing factors of GHG emissions changes through Logarithmic Mean Divisia Index (LMDI). Within our accounting framework, we took into account the temperature coefficient to accurately represent the low water temperatures prevalent on the QTP. Furthermore, we revised the emission factor for electricity consumption by considering the local energy structure based on the development of clean energy. Spatial and temporal differences were analyzed using the GHG emissions accounting results spanning from 2014 to 2018. The results show that total GHG emissions from QTP’s wastewater infrastructures increased from 0.25 Mt CO2e to 0.43 Mt CO2e between 2014 and 2018, with the cities along the edge in the east exhibiting noticeably higher GHG emissions. The development of clean energy on the QTP has led to a reduction in the electricity emission factor, thereby slowing down the growth of GHG emissions by 18.7%. The increase in sludge yield and electricity intensity of WWTPs contributed 10.3% and 9.6% to the overall growth of GHG emissions, and reducing these two influencing factors can effectively decelerate the upward trajectory of GHG emissions in the wastewater sector.

Abstract

Liquid air energy storage is a promising large-scale energy storage technology with high energy density for increasingly weather-dependent power grids, with no geographical constraints. The round-trip efficiency of a standalone liquid air energy storage system is predicted to be between 40 % and 67 %. An attractive way to increase the economic viability of the liquid air energy storage system is to couple the system with additional heat sources. Incorporating concentrated solar power has recently been proposed to increase the temperature at the inlet of the air turbines, and thus boosting the discharging power output and round-trip efficiency. This paper aims to find the optimal system design based on concentrated solar power temperature, considering both energy storage and power production metrics. The analyzed liquid air energy storage system is based on the Linde cycle, two tank thermal oil system for compression heat storage, and a two tank, two stage cold recovery system using methanol and liquid propane. A heliostat system with two-tank direct molten salt thermal energy storage is used as an additional heat source. A supercritical organic Rankine cycle system is used for excess heat recovery with R32 as working fluid. Novel ways of integrating the organic Rankine cycle system for multiple-source excess heat utilization were analyzed. Effects of charging and discharging pressures, number of air compressors and turbines and solar heat transfer fluid temperatures on the optimal organic Rankine cycle design and round-trip exergy ratio were studied. The results suggest that a maximum round-trip exergy ratio of 62.2 % can be achieved. The paper provides a basis for further optimization of design and operation of the solar aided liquid air energy storage systems, especially in off-design conditions for low sun availability.