Abstract

Flexible devices with remote monitoring and control availabilities, integrated behind-the-meter or last mile of electricity (grid edge) have significantly become widespread in the past decade. There are emerging distributed energy resource (DER) management solutions that give DER more active roles in power system and energy market operation. DER coordination incorporates inherent uncertainties related to distributed generation from intermittent renewables, non-flexible loads and dynamic prices. Consideration of uncertainties in optimum energy scheduling in community microgrids with a large number of electric vehicles can provide considerable benefits. This study presents a cloud-based optimal energy scheduling approach that considers diverse uncertainties in EV charging coordination as part of community microgrid energy scheduling. A case study is conducted for a representative community microgrid to investigate the benefits and challenges in uncertainty considered optimal energy scheduling.

Abstract

The solar power tower (SPT) is regarded as the most promising technology used for the next-generation concentrated solar-thermal power (CSP) plant. However, the degraded solar-thermal conversion performance of the solar tower receiver in the SPT system significantly reduces its power generation efficiency and capacity. In the previous study carried out by the authors, an unperceived negative thermal-flux phenomenon was discovered in the tower receiver, which is one of the main reasons for the degradation of the tower receiver’s thermal performance. Aiming to eliminate the negative thermal-flux phenomenon, this study proposes a novel optimization method by depositing the unique solar selective-absorbing coatings on the negative thermal-flux regions to improve the solar-thermal conversion performance of these regions. Four kinds of solar selective-absorbing coatings (SSCs) with different spectral selectivities, namely, silver coating, black chrome coating, and ideal coatings with cutoff wavelengths of 2.5 μm and 1.5 μm, are employed to investigate the effects on the heat transfer characteristics of the negative thermal-flux region and overall thermal performance of the tower receiver. Besides, the economic metrics of the above four kinds of novel tower receivers with different solar selective coatings are also evaluated in this study. The results show that the optimization method by SSC substitution at negative thermal-flux regions exerts an excellent role in eliminating the adverse effects of the negative thermal-flux region. The efficiency of the novel tower receiver with an ideal coating could be significantly improved by 12.03 %. In addition, the annual power output of an SPT plant with the novel receiver is effectively improved by 5.0 %, and the levelized cost of energy is reduced by 4.9 %.

Abstract

The increasing use of renewable energy and the spread of smart energy services require detailed studies of the system load. The data from the advanced metering infrastructure assist these requirements by providing detailed picture of electricity consumption patterns and profiles. However, high resolution electricity data can cause computational challenges and privacy concerns. As a result, the data are often spatially aggregated. This paper investigates the impact of data aggregation on the data understanding and the electricity load characteristics. The study looks at the similarity among different groups combinations within the same aggregation level, the variation in the load diversity and peaks occurrences, and on the hourly electricity variations between the individual customer and its aggregated group. The study concludes that the individual customers’ behaviors are lost with the increasing levels of aggregation, and that the similarity among groups on the same aggregation level increases with the aggregation level.

Abstract

Stratified Flames have gained prominence in the combustion research applications due to its improved stability and lower emission characteristics. In the present study, stratified jet flames are studied in a dual annular combustor. The static stability and the flame macrostructure have been presented and discussed. Stratification by making the inner annulus mixture rich was found to significantly improve the static stability limits. Furthermore, stratification by making the inner annulus rich was found to lead to attached flame at lower equivalence ratios of 0.22-0.38. Thus, stratification is more helpful at lower equivalence ratios.

Abstract

By combing a supercritical CO2 (sCO2) Brayton cycle and a direct contact membrane distillation (DCMD) block, an energy-efficient water and electricity cogeneration is proposed. Two layouts of the hybrid system are designed. Thermodynamic analysis for the hybrid system is carried out by considering the effects of the operation conditions and the membrane properties. With the on-design parameters input, the energy efficiency of the layout 1 and layout 2 is 38.48% and 37.52%, respectively. By optimizing the parameters, the energy efficiency can be further improved. Although the layout 1 has higher energy efficiency, the layout 2 has larger variation ranges of the parameters due to the less limitation of the pinch point temperature difference in the intermediate heat exchanger (IHX).

Abstract

In this paper, we present an approach and results of integrating climate impacts and climate adaptation measures in the energy and agriculture sectors in a macroeconomic top-down model. By integrating climate projections from dynamically downscaled regional climate models, we assess the impacts of changing precipitation patterns and rising temperatures on sectoral outcomes such as crop production and electricity generation, as well as on other macroeconomic socioeconomic factors such as employment and government spending for Ethiopia and Burkina Faso. The results show that neglecting climate impacts when developing long-term scenarios overestimates the evolution of economic growth in both countries. On the other hand, climate adaptation measures and adequate entitlement levels can largely offset the adverse effects of climate change in both sectors.

Abstract

Ammonia is a promising energy vector and storage means for hydrogen. Power to ammonia (P2A) processes employ renewable energy to split water to provide the hydrogen for the Haber-Bosch ammonia synthesis. The fluctuating nature of the renewables requires a good dynamic behavior of these cycles. Employing the software Aspen Plus Dynamics®, this paper investigates the dynamic behavior of a novel containerized P2A solution, which is going to be tested at the University of Genova in 2023. The simulation results of the start-up, various load changes and the shutdown of the process suggest that the control architecture can handle all cases in a satisfactory way. However, there seems to be room for improvement regarding the parameters of some controls.

Abstract

Hydrogen is the most fascinating renewable energy source. Hydrogen fuel cells have facilitated the capture of hydrogen and converted power into useful energy. In this work, carbon cloth-based electrodes were used to develop miniaturized hydrogen fuel cells (HFC) using 3D-printed sealing parts. Cobalt (II) Oxide (Co3O4), synthesized from Cobalt (II) chloride hexahydrate and reduced Graphene Oxide (rGO) based nanoparticles, was used to advance the catalytic activity at the anode, and Platinum-Carbon (Pt/C) coated carbon cloth serves as the cathode. A 4.5 mg of aluminum foil embedded inside the carbon cloth was utilized for hydrogen generation. The cell discharge analysis was observed to be stable up to 4h 60 minutes, as during this time aluminum foil produced hydrogen. This compact 3D-printed HFC device was capable of producing an open circuit potential of 480 mV and a peak power density of 25.6 µW cm2 when the Sodium Hydroxide (NaOH) alkaline electrolyte was introduced into the HFC. Furthermore, the series and parallel combination of devices produced higher voltage and power output. This cell design can be used as the power source for devices with small power applications.

Abstract

Analyses of voltage stability in the presence of STATCOM has been premeditated, focusing on the relationship between voltage stability collapse and power system voltage stability. STATCOM and its allocation expected to improve the power system’s voltage stability. To boost the voltage profile of the system, a circular optimization approach is employed to determine the best sizing of STATCOM. On IEEE 14 bus test bed, simulation results are confirmed using several STATCOMs in various circumstances.

Abstract

This study presents an innovative de-coupling cooling technology where latent cooling load and sensible cooling load are handled separately by a desiccant coated heat exchanger (DCHE) based dehumidifier and a dew-point evaporative cooler (DEC). Their performances are investigated numerically by analyzing the heat and mass transfer. Simulation has been carried out for DCHE and examined the output states of the process air, namely the dry-bulb temperature and humidity ratio. Key results revealed that moisture removal capacity (MRC), latent cooling capacity (QL) for DCHE are largely affected by varying air dry-bulb and air wet-bulb temperatures while the almost constant COPth was observed regardless of the variation of temperatures. For the DEC, the higher dew-point effectiveness and wet-bulb effectiveness were observed at the higher dry-bulb temperature and higher humidity ratio while the higher sensible cooling capacity was observed at the higher dry-bulb temperature and lower humidity ratio.