Potential Energy Savings Research Articles

Data and Management Traffic of IEEE 802.15.4 ZigBee-Based WSN

Wireless sensor networks (WSNs) are an amalgam of wireless technologies. They are extensively utilized in numerous industries, including agriculture, medical, and military fields. In the vast majority of cases, these technologies are deployed in monitoring environmental or physical parameters including sound, pressure, and temperature. WSNs employ various technologies, including radio frequency (RF), Wi-Fi, Bluetooth, ZigBee, and Z-Wave. Zigbee in particular has greater potential for energy-savings in long-distance transmissions, and consequently has emerged as the preferred standard for use in WSNs. In Zigbee-assisted networks, the three primary data-communication devices are ZigBee coordinators, routers, and nodes. The coordinator device gathers, stores, and processes the data before forwarding it to the next appropriate node or the base-station. The system model comprises several zones with each zone containing several sensors. Each sensor node transfers data to the master node, which serves as the ZigBee coordinator. The software used for this simulated investigation is the Riverbed Modeler V17.5. This paper examines the data traffic, management traffic, and load performance of the four modelled systems. The findings demonstrate that whereas the number of coordinators has no effect on data traffic, an increase in the number of routers correspondingly increases both the amount of data sent and received. The MAC follows the same pattern.

Energy efficiency evaluation of green roofs as a passive strategy in the mediterranean climate

Green roofs are comprised of living vegetation that is installed on rooftops, serving as a sustainable architectural tool that offers numerous environmental, economic, and social advantages to the community. Green roofs have emerged as a prominent sustainable development strategy and architectural element in numerous urban centres worldwide. As for the effectiveness of green roofs in terms of boosting energy conservation in the Mediterranean climate of Amman, this research focuses on a standard medium-sized office building in Jordan. The main evaluation is carried out on the feasibility of enhancing the passive sustainability and energy performance of the building by applying extensive green roof technology. To determine the energy-saving potential, an annual energy demand in the absence of a green roof is estimated by a simulation program. In this paper, the analyses were performed in the form of parametric studies for assessing the impact of variation in soil depths on energy use, indoor temperature and carbon reduction. The study also indicates that green roofs can store heat and provide insulation enough to lessen the demand for comfortable temperature regulation indoors. The findings on energy savings indicate that energy consumption had reduced annually by up to 12 %. This means that large-scale green roofs have the real opportunity to become an efficient sustainable passive design strategy for increasing the energy performance of office building in Amman climatic conditions.

On the discrepancy of using annual or hourly emission factors for power generation to estimate CO2 reduction of building retrofitting

Buildings play a significant role in global carbon emissions, and offer substantial potential for energy savings and emission reduction. This research delves into the Emission Factor Discrepancy (EFD)—the variance in CO2 emission reduction projections obtained by employing either annual or hourly average Emission Factor (EF) for electricity generation. Through two detailed case studies in the Netherlands and incorporating emission data from the Netherlands, Sweden, and France, the study uncovers the potential magnitude and country-specific variability of the EFD.By demonstrating how the energy mix of a country influences the EFD, the research offers valuable insights into the accuracy of emission calculations for different circumstances, particularly in the context of transitioning to renewable energy sources. We have found that countries with energy sources having low load-following capability and low EFs exhibit a large EFD. Whereas, countries with high EFs and large deployment of Photovoltaics (PV) show a notably large EFD on emission reduction related to PV production. This highlights the importance of carefully selecting EFs when evaluating building retrofits in the context of smart city initiatives.This research highlights the need for establishing a uniform framework for calculating carbon emissions associated with retrofitting in buildings in conjunction with the granularity of data and the specific energy mix of a country.

Energy management strategy of series–parallel hybrid transmission integrating map information and personalized driving characteristics

The integration of multi-source intelligent and connected information during a driving trip, along with its online application to globally optimized energy management strategies, has emerged as a crucial technical approach for enhancing the energy-saving effectiveness of hybrid transmissions. However, the action mode of such information and the optimization calculation efficiency of existing dynamic programming (DP) methods limit the online application of the aforementioned strategies with global optimization capabilities. To address these problems, the present study proposes a hierarchical energy management strategy that follows the reference trajectory of the battery state of charge (SoC) and comprehensively considers the multi-source information on the driving trip. First, a global speed prediction model based on personalized driving characteristics is proposed to obtain an accurate driving cycle input for the space-domain DP method. Second, the aforementioned tasks as well as the working-mode decision of the hybrid transmission and the multi-power-source torque distribution calculation tasks are deployed in the dual-core controller. Finally, the hierarchical energy management strategy is verified via vehicle testing. Compared with the DP strategy, the proposed strategy has an energy-saving potential of 4.17% that is yet to be realized. Furthermore, compared with the charge-depleting and charge-sustaining (CD–CS) strategy, the proposed strategy reduces fuel consumption by 0.38 L per 100 km, and its energy-saving effect is significant. This study is the first to apply the DP method to the vehicle controller, thereby facilitating the online application of energy management strategies with global optimization capabilities.

Evaluation of Free Cooling Technique at the Telecom Cell Site in Ghana

Air Conditioning (AC) is the primary source of cooling in a typical Cell Site (CS) although it consumes a large quantity of electricity. Excessive energy consumption due to air conditioning increases the operational expenses of telecommunication companies. Therefore, network operators have attempted various techniques to reduce the exorbitant cost of a cell site’s high-power consumption. A Free Cooling (FC) System is one such approach. This paper uses computer modeling to investigate how the FC System will function at a CS in Ghana for 12 hours (from 6 pm to 6 am). A shelter with dimensions of 3 m × 2.47 m × 2.45 m (L × B × H) is used in the study, with three window positioning scenarios (different window heights), namely: (a) an inlet window 0.5 m high, and the outlet window 1.5 m high, (b) an inlet window and outlet window both 1.0 m high and (c) an inlet window 1.5 m high, and the outlet window 0.5 m high. The analysis revealed that the shelter with inlet and outlet windows at the same height has the most efficient heat dissipation potential. Furthermore, at a set temperature threshold of 25 °C, the annual percentage share for the two operating modes is approximately 67% for AC and 33% for FC in 2020, 76% for AC and 24% for FC in 2021, and 61% for AC and 39% for FC in 2022. However, when the set temperature threshold is increased from 25 °C to 30 °C, the annual percentage share is approximately 0.01% for AC and 99.9% for FC in 2020, 0% for AC and 100% for FC in 2021, and 1% for AC and 99% for FC in 2022. Thus, the proportion of free cooling increases as the set temperature threshold is raised, indicating potential energy savings. It could be concluded that in Ghana, installing a cell site with an FC system and setting the temperature of its control system to 30 °C or higher will result in significant energy savings.

Exploring the potential for household refrigerator replacement in Mexico City

Many studies have focused on improving the energy performance of household refrigerators and finding out their performance under different operating conditions. However, there seems to be a gap regarding the potential for electrical energy savings due to retrofitting household refrigerators. This study focuses on the replacement potential of household refrigerators eight or more years old in poor households in Mexico City. The study uses a stratified sampling methodology. The results show that it is advisable to replace 77.75% of the household refrigerators that are in operation in poor households in Mexico City. The replacement of household refrigerators with energy-efficient equipment represents 36% of the electrical energy consumption for food refrigeration in the domestic sector in Mexico City.

ANALISIS AIR CONDITIONER PADA KOMPLEK PERUMAHAN DI KOTA DENPASAR

Green building retrofit is an approach that involves modifying or enhancing existing buildings to achieve higher standards of sustainability and energy efficiency. By conducting an energy audit first, it's possible to identify potential energy savings in the housing, as well as components that need to be upgraded to reach the desired level of sustainability. Retrofit solutions may include the use of implementation of efficient HVAC systems, energy-saving lighting, and better energy management. The aim of this research is to explore the potential improvements that can be applied through Green Building Retrofit with a focus on energy efficiency and sustainability in Jadi Pesona II Barat Housing, comparing the energy consumption conditions of houses before and after the energy audit, as well as calculating the payback period for occupants after the retrofit implementation. After the energy audit and Green Building Retrofit, daily energy usage in homes in Perumahan Jadi Pesona II Barat decreased from 47.45 kWh per day to 36.91 kWh per day. This indicates a reduction of 10.54 kWh per day or approximately 22.22% from the previous conditions, and the payback period analysis results show that almost all air conditioners show values in line with the project investment feasibility parameter, which is below 4.2 years.

Optimizing energy efficiency in multi-chiller systems: A comprehensive Modelica-based approach

To achieve sustainable development of buildings, this paper investigates the energy-saving potential of multi-chiller systems by examining the interactions between sequencing optimization, load optimization, and parameter optimization in systems with varying capacities. A Modelica-based simulation platform, adaptable to various programming languages optimization engines, was developed for this purpose. The study introduces a sequencing optimization threshold function that considers both wet-bulb temperature and cooling load. Additionally, a two-stage optimization strategy that prioritizes parameter adjustments before sequencing is proposed. Case studies demonstrate that this threshold function and reversed optimization order can further enhance overall energy savings. Focusing on a system with three large chillers and one small chiller, the study reveals the energy benefits of activating the small chiller under specific conditions, improving overall system efficiency. The proposed optimization achieved a cumulative energy saving of 650,463 kWh over the summer, with sequencing contributing 5.64 %. Frequency conversion control of the water pump is identified as a significant energy-saving factor. This research provides a comprehensive approach to optimizing diverse chiller systems, highlighting substantial potential for energy conservation.

Analysis of the Energy-Saving Effect of a Novel Central Air-Conditioning System with an Internal Heat Exchanger in Summer

In this paper, a novel central air-conditioning system with an internal heat exchanger is proposed and analyzed for its energy-saving effect. Two frequently used systems are chosen as the reference systems, i.e., a conventional system with a sensible heat exchanger (Reference System I) and a conventional system with a total heat exchanger (Reference System II). Analysis models are built to simulate the performance of the system. The energy-saving effects of the proposed system and the two reference systems under different conditions are theoretically calculated using a case-studied shopping mall in Nanjing, China. The results show that the influence of indoor relative humidity (RH) on the energy-saving effect is much greater than that of the indoor design temperature. Indoor design parameters have a greater impact on energy saving than outdoor design parameters. Under the studied conditions, the maximum energy-saving rates of the proposed system, Reference System I, and Reference System II, are 52.7%, 2.3%, and 12.1%, respectively. With the decrease in fresh-air ratio from 70% to 20%, the difference in energy-saving rates between the proposed system and Reference System II (Reference System I) can increase from 5% to 23% (15% to 30%). Therefore, the proposed system has obvious energy-saving potential and advantage, especially under the condition of a lower fresh-air ratio.

Integrating solar PV systems for energy efficiency in portable cabins: A case study in Kuwait

The rapid growth of energy consumption in densely populated urban areas with limited land space, especially in hot climates, poses significant challenges. The Australian University of Kuwait conducted a study using two portable cabins to explore energy-saving techniques. One cabin integrated an off-grid solar photovoltaic (PV) system to evaluate its impact on grid electricity demands for an airconditioning (AC) cooling system over 9 months, compared to the second cabin without a PV system. The PV system utilized rooftop space with four Monofacial Go Green 350 W/24 V solar panels, an off-grid maximum power point tracker (MPPT) inverter charger 3.5kVA/100A/24 V, and two Gel deep cycle batteries 12 V/200Ah. The PV panels were oriented south at a 30-degree latitude angle, providing power through the MPPT to a 1.5-ton AC split unit for cooling. Findings showed that the cabin with solar PV panels achieved a 24.1 % energy saving and a total CO2 reduction of 129.4 kg, consuming 1,743 kWh over 237 days, compared to 2,296 kWh for the cabin without the PV system. The novelty of this study lies in the integration of off-grid solar PV systems with existing cooling technologies to evaluate potential energy savings and environmental benefits for comprehensive utilization and addressing urban and climate challenges. Enhancements can include flexible room temperature control using advanced systems, optimizing the PV system settings with more efficient AC systems, and connecting the PV system to additional loads like heating/cooling and lighting. These improvements would ensure the comprehensive utilization of captured solar energy in Kuwait and countries with similar climatic conditions throughout the year. Advancements in solar PV panel efficiency and high-intensity flexible PV panels offer opportunities for maximizing solar energy capture in dense residential buildings.

Efficient CO2 capture by non-aqueous imide/ethylene glycol solvent

Man-made CO2 emissions give rise to an important influence on climate and human survival, which has attracted widespread attention. Traditional absorbents such as aqueous amines used for CO2 capture often suffer from high regeneration energy and corrosiveness. In this regard, non-aqueous amine solutions have high energy-saving potential because organics have lower vaporization enthalpy and heat capacity than water. Herein, we explored the potential absorbent composed of ethylene glycol and imide-based bases to capture CO2. The CO2 uptake in imide-based ethylene glycol absorbent was studied, experimental results showed that succinimide/glycol-20 wt% have the highest CO2 solubility, and still maintains a high absorption capacity after 8 regeneration cycles. And the absorption mechanism has been confirmed the possible intermolecular hydrogen bonding and van der Waals forces between carbon dioxide and succinimide molecules through molecular simulation. The regeneration energy consumption is only 2.243 GJ/t CO2 through process simulation calculation, which is lower than the conventional absorbent, further indicating that the fabricated absorbent have exhibits the large potential to absorb CO2 from flue gas.

Exploring the paths of energy conservation and emission reduction in aluminum industry in Henan province, China

As the world's largest producer and consumer of aluminum, China's aluminum industry is facing enormous pressure for energy conservation and emission reduction due to its traditional high energy consumption, high emissions, and high pollution. To explore the green and low-carbon development path of the aluminum industry, an integrated modelling framework was developed, including aluminum production forecasting and scrap recycling model, energy consumption-carbon emission-air pollutant emission model, and conservation supply curve method. Five different scenarios were set up to evaluate the energy saving and emission reduction potential of Henan Province from 2023 to 2050, by adopting four measures of accelerating the recycled aluminum, promoting energy efficiency technologies, expanding the scale of electrolytic cells, and increasing the share of renewable energy. The results showed that the production of alumina and primary aluminum decreased to 9.6 and 1.8 Mt respectively in 2050, while the future production of aluminum processing products and recycled aluminum showed a continuous upward trend. By 2050, production of recycled aluminum will increase to 14.0 Mt, expanding by about 5.7 times compared to 2022. The energy-saving and emission reduction potential of the integrated scenario is the most significant, with energy consumption, CO2, SO2, NOX, PM10, PM2.5 and fluoride decreased by 54.3, 73.0, 96.5, 72.7, 82.6, 82.6, and 98.9% compared to the business-as-usual scenario, respectively. The results also indicated that accelerating the recycled aluminum and optimizing energy structure are more effective for mitigation. Finally, policy suggestions for mitigating energy consumption and pollutant emissions of the aluminum industry in Henan Province were proposed. The systematic framework of this study can be widely applicable to other provinces and the whole country, which can provide some references for the aluminum industry to achieve the carbon peak and carbon neutrality targets.

Energy characteristics of multi-chiller load distribution algorithms in a large office building

This study evaluates the energy efficiency of multi-chiller systems in large office buildings, focusing on their optimization across various climate zones as defined by ASHRAE. Using EnergyPlus for simulations, the research examines five different load distribution algorithms in multi-chiller systems that range from one to ten chillers, aiming to understand their effectiveness in 15 distinct climate zones. The primary objectives of the study include identifying the energy efficiency of multi-chiller systems in each climate zone, determining the appropriate number of chillers for each zone, and evaluating the performance of the load distribution algorithms. Based on the U.S. Department of Energy’s commercial building model, the results suggest that multi-chiller systems can significantly reduce cooling energy consumption in various climates. Among the algorithms evaluated, the Sequential Uniform Part Load Ratio (SUPLR) algorithm demonstrates notable efficiency, especially in the 4A climate zone (Baltimore), where it achieves substantial energy savings. Applying the SUPLR algorithm in a multi-chiller setup with four chillers in this zone leads to an estimated 24.5 % reduction in energy usage, equivalent to 183 MW annually. The research indicates that a range of 3 to 5 chillers is typically optimal for most climate zones. In-depth analysis in the 4A climate zone highlights the importance of minimizing operation hours at low Part Load Ratios (PLR) to ensure that chillers operate at a high Coefficient of Performance (COP). This strategy underscores the potential of well-designed multi-chiller systems to reduce cooling energy demand, particularly in climates with transitional seasons. This study provides an overview of the energy-saving potential of multi-chiller systems, applicable across a variety of climatic scenarios.

Leidenfrost spheres, projectiles, and model boats: Assessing the drag reduction by superhydrophobic surfaces

Superhydrophobic surfaces are expected to reduce drag on bluff bodies moving in water due to the introduction of a thin air layer around the solid and the resulting partial slip boundary condition. The use of Leidenfrost vapor layers, sustained on the surface of a heated metal body is a reliable method to estimate the maximum drag reduction possible due to such air layers. In the past such an approach was used to estimate the drag reduction on a free-falling heated sphere, in which case the form drag is the lead component of the drag force. Here, we extend this approach to evaluate the effect of the thin gas layers on the hydrodynamic drag of free-falling streamlined projectiles and towed model boats, where the form drag is minimal, and the skin friction drag is the lead component of the drag force. By comparing the drag for streamlined bodies with and without sustained air-layers, we see only incremental drag reductions, for the sub-critical Reynolds number tested herein. The same is true for towed model boats. These results hold both for superhydrophobic surface treatments and Leidenfrost vapor layers. Thus, we concluded that for the investigated range of sub-critical Reynolds numbers, the skin friction drag is less sensitive to the effect of the thin gas layers compared to the form drag. These novel findings have important implications for the practical potential of energy savings using gas layers sustained on superhydrophobic surfaces.

Numerical study of energy consumption in spacer-filled feed channels through 3D inverse modeling and computational fluid dynamics

This project employs advanced Computational Fluid Dynamics (CFD) simulations to investigate the complex flow field dynamics within the channel of membrane module featuring a commercially available feed spacer. Utilizing Micro-CT scanning, the intricate three-dimensional (3D) structure of the spacer is accurately captured, enhancing the precision of the simulation models. The project focuses on the effects of varying Reynolds number (Re) and Aspect Ratio (AR) on the energy consumption within the feed channel of membrane module, analyzing streamline patterns, vorticity, and flow separation angles in detail. Findings indicate that the total enstrophy identification method effectively pinpoints areas of high energy consumption, especially at lower Re levels where flow separation significantly contributes to hydraulic losses. As Re increases, the separation vortex shifts rearward, resulting in a marked decrease in the energy consumption coefficient. Furthermore, the flow separation angle consistently declines with increasing Re, stabilizing at higher levels. Significantly, a reduction in AR from 1.015 to 0.725 more than doubles the decrease in flow separation angle, highlighting substantial potential energy savings through spacer design optimization. These insights are crucial for improving the design and efficiency of spiral wound membrane modules and for refining feed spacer configurations to enhance performance.

Exergy analysis of a novel ironmaking process combining coal gasification with the smelting reduction of iron ore

The global iron and steel industry is an energy-intensive industry, and energy-saving in this industry is of great significant. A novel ironmaking process combining coal gasification with the smelting reduction of iron ore (CCGSR) is proposed, and an exergy analysis is applied to evaluate its thermodynamic performance. The results show that the exergy efficiency of the entire system is 88.15 % whereas the energy efficiency is 98.64 %. The exhaust gas of pre-reduction furnace is the main exergy output and has great energy-saving potential. The local exergy loss rates in the pyrolysis, pre-reduction, and smelting reduction furnaces are 55.81 %, 7.24 %, and 36.95 %, respectively. The pyrolysis and smelting reduction furnaces exhibit the largest exergy loss, owing to the mixing of high-temperature gas of the smelting reduction furnace and circulating gas, coke powder gasification, and heat transfer. In addition, after the exhaust gas is utilized to form a cogeneration system of iron and electricity, the exergy efficiency increases from 40.18 % to 50.06 % comparable with 600 MW ultra-supercritical coal-fired generating units. The present work also provides some suggestions for reducing exergy destruction.

Energy efficiency optimization of NB-IoT using integrated Proxy & ERAI technique

The 3rd Generation Partnership Project (3GPP) standardized the NarrowBand Internet of Things (NB-IoT) technology in Release-13, aiming to support applications requiring minimal device power consumption, efficient small data transfer, and tolerance for delays. This paper provides two major contributions: first, it characterizes the NB-IoT architecture and its enhancements in subsequent 3GPP releases; second, it introduces an energy-saving technique for NB-IoT user equipment based on semi-Markov processes. Integrating a Proxy state and an enhanced release assistant indication (ERAI), the proposed technique improves upon the traditional Discontinuous Reception (DRX) method in the NB-IoT standard. This novel approach reduces energy consumption during low data communication, distinguishing it from other power-saving methodologies. The effectiveness of this technique is assessed through the power-saving factor (PSF) under various conditions, such as different eDRX durations (T_eDRX), PSM durations (T_PSM), DRX cycle periods (T_ACTIVE+T_SLEEP), and DRX active periods (T_ACTIVE). Our findings confirm that the proposed Proxy & ERAI technique significantly boosts the power-saving capabilities of NB-IoT devices, especially for small data packet transmissions. Theoretical and simulation results indicate that the PSF can be enhanced by up to 99.4% with optimized eDRX durations (T_eDRX) and up to 99.9% with optimized PSM (T_PSM) durations. These results underscore the significant energy-saving potential of our proposed technique, making it highly effective for NB-IoT applications with low data transmission needs.

Environmental Impact, Mechanical Properties, and Productivity: Considerations on Filler Wire and Scanning Strategy in Laser Welding

Abstract Sustainability, as well as high-quality outcomes, pose significant challenges within the context of current manufacturing cycles, in alignment with European strategies aimed at decarbonization. This framework encourages a systematic evaluation of manufacturing processes in terms of their performance and carbon footprint. One sector where this is particularly relevant is the production of batteries for electric mobility, thanks to its exponential growth. Out of all the processes involved, laser welding stands out as being a critical step since it offers potential energy savings through optimization. With the dual goals of achieving mechanical strength and environmental sustainability, this study investigates alternative solutions for laser welding of aluminum sheets. Different laser welding configurations are tested to evaluate the effect of process setups on weld quality and carbon emissions across different productivity scenarios. The key findings can be summarized as follows: (1) the selection of welding setup significantly influences both quality and sustainability requirements; (2) the optimal conditions for meeting strength requirements may diverge from those aimed at minimizing environmental impact; (3) the choice of the final solution is influenced by the specific industrial scenario. The study specifically demonstrated that aluminum alloys can be welded with higher quality (porosity below 1% and equivalent ultimate strength up to 204 MPa) when filler wire is introduced alongside an active wobbling scanning strategy. Conversely, filler wire can be omitted in scenarios prioritizing high-productivity and low-carbon emissions, such as when employing a linear scanning strategy, resulting in a reduction of equivalent carbon emissions by up to 140%.

Carbon Emission Measurement of Prefabricated Buildings Based on LCA and Research on Energy Saving and Emission Reduction Strategy of Renewable Energy

In the face of diverse quantification methods for building carbon emissions, this article delves into the Life Cycle Assessment (LCA) approach to comprehensively measure the carbon emissions of prefabricated buildings throughout their lifespan. It meticulously identifies the carbon emission sources in prefabricated buildings and analyzes the measurement models relevant to their emissions in both physical and chemical stages. Prefabricated buildings hold profound implications for transforming the construction industry and advancing its sustainable development path. Examining the energy-saving characteristics and emission reduction potential of prefabricated buildings from a life-cycle perspective, this article analyzes the carbon emission measurement model during the prefabricated building transformation stage. This comprehensive analysis of the building atomization path and influential carbon emission factors lays a theoretical foundation for transitioning prefabricated buildings towards energy-saving and emission reduction strategies. Using the LCA method, carbon emissions were calculated, revealing a positive correlation with building size. Notably, through the prefabricated construction method detailed in this article, carbon emissions were significantly reduced by 30% compared to traditional construction methods.

Assessing and auditing water transport systems by applying the energy equations

ABSTRACT In improving the energy efficiency of water transport systems, two critical stages are involved: assessment (to understand the system's operation and identify potential energy savings) and auditing (to locate and break down the energy losses). Both stages are based on energy balances, which can be conducted using either the extended Bernoulli equation or the energy integral equation. Both equations can be applied, but depending on the system, data availability, and the kind of study to be performed, one is preferable over the other. This paper analyses, applies and compares both equations, with a particular focus on the less commonly used energy integral equation in the hydraulic field. This more general equation includes thermal and transient effects and it is more suitable for analyzing complex systems. In contrast, the extended Bernoulli equation, while simpler to apply, can lead to the loss of relevant information, such as the evaluation of the topographic energy. The main objective of this work is to bridge the gap between these two fundamental energy equations and recommend the most appropriate one for hydraulic problems. Real examples are presented to show their differences and validate our recommendations.