Energy Performance Research Articles

Transforming carbon-intensive coal-fired power plants into negative emission technologies via biomass-fired calcium looping retrofit

Abstract Calcium looping is a promising CO2 capture technology due to reduced energy and economic penalties compared to mature solvent scrubbing technologies. It also can enable negative CO2 emissions when biomass is used to drive the sorbent regeneration process in the calciner. However, the trade-off between the energy, economic and environmental performance under different biomass co-firing fractions in the calciner and process operating scenarios has not yet been well understood. This study examined the potential for transforming a 580 MWel coal-fired power plant into a negative CO2 emitter via retrofit of calcium looping with biomass co-firing in the calciner. High-fidelity process models were developed in Aspen Plus and used to analyse the effect of biomass co-firing fraction, CO2 capture rate in the carbonator, and the fraction of flue gas fed to the carbonator on the techno-economic performance indicators. The results revealed that co-firing 30% biomass with coal in the calciner was sufficient for the retrofitted process to achieve negative CO2 emissions (−3.9 gCO2/kWelh). In this scenario, the levelized cost of electricity was 5% lower (81.1 €/MWelh) than that in the reference retrofit scenario without biomass co-firing (85.4 €/MWelh) at a carbon tax of 100 €/tCO2. Further improvement to the techno-economic performance was achieved by reducing the amount of CO2 captured in the carbonator by reducing either the CO2 capture rate (81.1 €/tCO2) or the amount of flue gas processed (80.4 €/tCO2). Although this was achieved at the expense of the increased specific CO2 emissions to 65.2 gCO2/kWelh and 109.0 gCO2/kWelh, respectively, the net specific emissions were still about 90% lower than those of the unabated host plant (792.3 gCO2/kWelh). This study demonstrated that depending on design priorities, biomass co-firing in the calciner can transform the existing coal-fired power plants into negative CO2 emission technologies or improve the process techno-economic viability.

Balancing Energy Preservation and Performance in Energy-Harvesting Sensor Networks

Balancing Energy Preservation and Performance in Energy-Harvesting Sensor Networks

Impact of Temperature and Shading on Performance of Solar Photovoltaic Systems in Telecom Sites

Nigeria's rural mobile network boom strains its power generation. Expensive and polluting diesel generators power off-grid base stations, prompting mobile network operators to explore solar PV systems. However, real-life performance under field conditions is a major concern, as manufacturer datasheets often fall short. This study highlighted the performance of a solar PV system powering a telecommunication station in Uli, Anambra State, Nigeria. We examined temperature, irradiance and shading effect. The findings highlight the impact of shading and temperature on energy yield and performance ratio (PR). While stand-alone and solar tracking systems had similar PRs (66 to 68 percent), tracking systems generated the most energy (4.53 energy yield) due to increased solar exposure. However, this benefit came with a trade-off; higher temperature losses (1559 kWh) caused by temperature rise from direct sunlight. Additionally, the nearby structures significantly impacted tracking systems by causing shading. In conclusion, well-designed solar PV systems for telecommunication stations must consider mitigating factors like shading and temperature. This can achieve substantial advantages: lower operational expenses for operators, improved network availability for rural users, and a reduced environmental impact, aligning with UN Sustainable Development Goals.

Why the Construction Trades Have a Valuable Role in Meeting the Climate Challenge

The construction industry accounts for 18 per cent of Canada’s greenhouse gas emissions. There is extensive evidence that this can be reduced significantly by implementing aggressive net zero building practices. However, the way the industry is organized impedes this achievement because it fails to promote the development of a broadly based, highly qualified, climate-literate workforce. Successful low carbon construction requires enhancement of workers’ knowledge, skills, and competencies because it requires much higher energy performance standards than traditional construction practice. Yet the industry remains wedded to the current system of low-bid, low-quality construction to cut costs. The organization of much construction work reflects a Taylorist approach, with extensive piecework and subcontracting that relies heavily on precarious, unskilled, and semi-skilled workers. Most employers avoid investing in trades training, leaving it to governments, unions, and individual workers to fund workforce development. Committed to a deregulated market with minimal government interference in their profit-making activities, many contractors oppose tougher building and energy regulations while lobbying against higher labour standards, occupational certification requirements, and union organizing. To meet their net zero targets, governments must recognize that market forces are inadequate to create the well-trained, highly skilled workforce needed. Major policy interventions are required to force industry to make the necessary changes in vocational education and training (vet) and employment practices – changes designed to upskill the construction workforce and give workers and unions a greater voice in shaping climate-informed building practice.

Investigation of geometric structure on energy performance and flow characteristics in underwater hydraulic machinery

PurposeFor underwater hydraulic machinery, the unique structure significantly enhances the three-dimensional non-uniformity of turbulence within the flow domain and high Reynolds number turbulence introduces complex effects on the machinery. Therefore, studying the turbulent flow characteristics in underwater hydraulic machinery is crucial for system stability.Design/methodology/approachThis paper conducts a numerical analysis on a specific type of underwater hydraulic machinery. A numerical calculation model is established under stable inflow conditions to analyze the flow trends and pressure changes at different flow speeds. Subsequently, structural modifications are made to the underwater hydraulic machinery, and the characteristics of the velocity field, pressure field and vorticity distribution under different model parameters are analyzed.FindingsThe results indicate that changes in internal structure have a certain impact on flow characteristics. When the structural changes are significant, the fluid flow becomes more complex and pressure fluctuations become more intense. The research findings provide a scientific basis and theoretical guidance for the structural design of underwater hydraulic machinery and have significant research implications for controlling fluid-induced noise.Originality/valueAffected by the inherent structural characteristics of the flow channel structure, the flow direction of the high-speed water flow changes drastically in the flow channel, so it is of great significance to study its flow characteristics for the stability of the system.

Model-Based Assessment of Energy Efficiency in Industrial Pump Systems: A Case Study Approach

Outdated, oversized variable speed pump drives (VSDPs) in industry lead to sub-optimal energy efficiency and considerable energy losses. This paper proposes methods to develop 2D efficiency maps for motors, converters, and pumps using polynomial surface fitting, which enables efficiency evaluation in a wide operating range. The method was applied to an oversized VSDP in an industrial chilled water supply system, comparing the original system with five alternative VSDP combinations with high-efficiency motors and pumps. The five VSDP variants demonstrated average energy savings of around 30%, with the synchronous reluctance motor (SRM) configurations outperforming the induction motor (IM) configurations by up to 7 percentage points, particularly at low loads. The high-efficiency SRM-based 252-IE5 variant delivered the best overall energy performance, highlighting the benefits of optimised system sizing and motor selection for energy savings. The proposed method can be used in both industrial and residential applications and offers great advantages in process systems that require variable flow and pressure of water or other fluids during operation, such as HVAC, water supply and wastewater treatment, district heating, etc. The development of a VSDP drive with efficient energy optimisation is an interdisciplinary problem of mechanical and electrical engineering, and without the interaction of engineers from both fields the result will not be optimal. We try to present our method so that it can be a reliable tool for mechanical, electrical, and other engineers or researchers to assist them in finding possible energy savings, performing energy audits, and selecting the most suitable components when modernising existing or developing new systems.

Minimum-Energy Scheduling of Flexible Job-Shop Through Optimization and Comprehensive Heuristic

This study considers a flexible job-shop scheduling problem where energy cost savings are the primary objective and where the classical objective of the minimization of the make-span is replaced by the satisfaction of due times for each job. An original two-level mixed-integer formulation of this optimization problem is proposed, where the processed flows of material and their timing are explicitly considered. Its exact solution is discussed, and, considering its computational complexity, a comprehensive heuristic, balancing energy performance and due time constraint satisfaction, is developed to provide acceptable solutions in polynomial time to the minimum-energy flexible job-shop scheduling problem, even when considering its dynamic environment. The proposed approach is illustrated through a small-scale example.

Multi-Objective Optimization Design of Traditional Soil Dwelling Renovation Based on Analytic Hierarchy Process—Quality Function Deployment—Non-Dominated Sorting Genetic Algorithm II: Case Study in Tuyugou Village in Turpan, Xinjiang

As the socio-economic landscape expands and tourism flourishes, the traditional earthen dwellings of Tuyugou Village, Turpan, Xinjiang, face significant challenges, including low energy efficiency and suboptimal living comfort, necessitating data-driven and scientifically robust renovation strategies. Existing renovation methods, however, often lack empirical support and rely heavily on the subjective judgments of architects, thus hindering the effective preservation and transmission of cultural heritage. This research addresses the renovation of these traditional dwellings by employing the AHP method to systematically evaluate user requirements, with input from diverse stakeholders, including homeowners, tourists, experts, and government authorities. The study then applies the QFD method to construct the House of Quality, translating user needs into specific design attributes; this is followed by a comprehensive quantitative analysis for optimization. A novel multi-objective optimization model (MOP) is introduced, with materials as the central focus, addressing key aspects of engineering, culture, and energy conservation. The NSGA-II algorithm is utilized to generate optimal Pareto solutions, which are then further refined using the entropy-weighted VIKOR method. Among the ten pre-selected renovation solutions, the sixth design plan was identified as the optimal choice, excelling in cost control, cultural integration, and energy performance. Specifically, it achieved a unit construction cost of RMB 340.566/m2, a cultural adaptability score of 1.5364, and an energy cost of RMB 352.793/kWh, thereby demonstrating an effective balance between traditional architectural elements and modern requirements. The objective decision making enabled by the VIKOR method successfully balances cultural preservation with contemporary needs, enhancing both living standards and tourism appeal. This study offers innovative and empirically grounded renovation strategies for traditional dwellings in arid and semi-arid climates, providing a framework that effectively balances cultural preservation and modernization.

Open-Source Software for Building-Integrated Photovoltaic Tiling for Novelty Architecture

Novelty architecture buildings can be tiled with conventional rectangular solar photovoltaic (PV) modules with both close-packed cells or partially transparent modules, vastly increasing renewable energy, reducing carbon emissions, and allowing for positive energy buildings. To enable this potential, in this study, for the first time, two open-source programs were developed and integrated to provide a foundation for designing and coating real-life novelty architecture buildings and objects with solar PV modules. First, a tiling algorithm was proposed and integrated into Blender that can generate solar PV modules on the face of any 3D model, and an augmented Python version of SAM was developed to simulate the performance of the resultant irregularly shaped PV systems. The integrated open-source software was used to analyze the energy performance of seven different novelty BIPVs located across the globe. The buildings’ energy performance was compared to conventional ground-based PV systems, and the results showed that the conventional arrays generate more energy per unit power than the BIPVs. The analysis reveals that the more complex the building model geometry, the less energy the building generates; however, the novelty BIPV power and energy densities far surpass conventional ground-based PV. The real estate savings observed were substantial, reaching 170% in one case where the BIPV reached 750 m in height. The BIPVs’ energy production is optimized by orienting the building via rotation and only needs to be carried out a single time for replication anywhere globally. The results show that the energy yield of the BIPV increases as the building becomes more detailed while the total power and energy decrease, indicating the need for the careful balancing of priorities in building design. Finally, the energy simulations demonstrate the potential for net-positive energy buildings and contribute to net-zero-emission cities. The findings indicate that BIPVs are not only appropriate for conventional residential houses and commercial buildings, but also for historical building replicas or monuments in the future. Further studies are needed to investigate the structural, electrical, and socio-economic aspects of novelty-architecture BIPVs.

Structural Performance of GFRP-Wrapped Concrete Elements: Sustainable Solution for Coastal Protection

Protecting coastal regions is crucial due to high population density and significant economic value. While numerous strategies have been proposed to mitigate scouring and protect coastal structures, existing techniques have limitations. This paper introduces a novel approach, SEAHIVE®, which enhances the performance of engineered structures by utilizing hexagonal, hollow, and perforated concrete elements externally reinforced with glass fiber-reinforced polymer (GFRP). Unlike conventional steel bars, GFRP offers superior durability and requires less maintenance, making it a sustainable solution for any riverine and coastal environment. SEAHIVE® aims to provide robust structural capacity, effective energy dissipation, and preservation of natural habitats. Although some research has addressed energy dissipation and performance in riverine and coastal contexts, the structural performance of SEAHIVE® elements has not been extensively studied. This paper evaluates SEAHIVE® elements reinforced with externally bonded GFRP longitudinal strips and pretensioned GFRP transverse wraps. Testing full-size specimens under compression and flexure revealed that failure occurred when the pretensioned GFRP wraps failed in compression tests and when longitudinal GFRP strips slipped in flexure tests. Strength capacity was notably improved by anchoring the GFRP strips at both ends. These findings underscore the potential of the SEAHIVE® system to significantly enhance the durability and performance of coastal and riverine protection structures. FEM simulations provided critical insights into the failure mechanism and validated the experimental findings. In fact, by comparing FEM model results for cases before and after applying GFRP wraps under the same compression load, it was found that maximum stresses at crack locations were significantly reduced due to compression forces resulting from the presence of pretensioned GFRP wraps. Similarly, FEM model analysis on flexure samples showed that the most vulnerable regions corresponded to the locations where cracks started during testing.

Prioritizing Energy Performance Improvement Factors for Senior Centers Based on Building Energy Simulation and Economic Feasibility

This study examined energy performance improvement factors by analyzing both energy performance and the economic impacts to reduce energy costs for senior centers. A fact-finding survey was conducted on 20 senior centers in a metropolitan area, identifying key energy improvement factors. Energy simulations of the buildings were performed using ECO2, an officially certified energy assessment program in Korea, comparing the energy requirements before and after the improvements. The energy demand, energy consumption, and floor area were analyzed, with the J, K, and S standard models selected based on the median values of these factors. To assess the impact of the improvements, blower door tests were conducted on two senior centers before and after window upgrades. Based on the ECO2 simulations and the blower door test results, improvement priorities were identified in the following order: windows, exterior walls, boilers, roofs, and doors. Finally, an economic feasibility analysis applied the construction and heating costs to the standard models. Over a 40-year period, only boiler improvements generated a net profit. Without government support, this study recommends prioritizing boiler upgrades when selecting energy performance improvements.

A Comprehensive Approach to Nearly Zero Energy Buildings and Districts: Analysis of a Region Undergoing Energy Transition

This paper explores the development of positive energy communities using Eordaia, Greece, as a case study. The approach combines building and district-level energy analysis to achieve nearly zero energy performance through retrofitting, district-level storage systems, and renewable energy technologies. A parametric analysis utilizing RETSCREEN Expert and EnergyPlan software determines the optimal mix of technologies based on technical and financial parameters, with Eordaia, a region in energy transition and part of the RESPONSE Horizon project, illustrating the practical benefits. It includes a neighborhood of 105 mixed-use properties and two municipal buildings where a range of renewable energy sources and energy efficiency measures are applied. Insulation, photovoltaic systems, LED lighting, predictive thermostats, and windows coated with nanotechnology are some of the key interventions considered. The findings show considerable reductions in CO2 emissions and energy use, with payback periods ranging from 8.7 to 9.6 years. This study underscores the value of district-level strategies over individual building retrofits, highlighting cost savings and improved energy performance. These findings offer valuable insights for urban planners and policymakers aiming to transform urban areas into sustainable, positive energy districts, supporting the EU’s 2050 net-zero emissions goals.

Numerical and experimental study of dynamic gas–liquid separator with various viscosities

The gas–liquid separation process is important in various industries, such as electric power, aerospace, and petroleum. This study introduces an innovative, dynamic gas–liquid separator (DGLS) in which a cyclonic flow pattern is induced by blade rotation. This cyclonic flow enhances the efficiency of gas and liquid phase separation while also imparting energy to facilitate the transport of the separated fluid. Numerical simulations are used to analyze the internal flow dynamics, power requirements, and separation efficiency of this DGLS. A comparison with experimental results is conducted to validate the reliability of the numerical model. The effects of liquid-phase viscosity on the internal energy consumption and separation performance of the DGLS are explored at various flow rates. The simulation results indicate that for a given viscosity, the degassing rate of the separator decreases while the liquid removal rate increases as the inlet flow rate rises. Furthermore, it is observed that higher viscosity leads to poorer separation performance, with a decrease in turbulent kinetic energy near the rotating axis and an increase in turbulence intensity near the wall. At lower flow rates, the effectiveness of liquid-phase outlet pressurization improves with increasing viscosity. However, at higher flow rates, increasing viscosity leads to a substantial decline in energy performance and a reduction in liquid-phase outlet pressurization. The increment in turbulent kinetic energy is greater than the square of the mean velocity, indicating a positive correlation between turbulence intensity and turbulent kinetic energy. These findings not only provide a theoretical basis for the prediction of flow losses within a DGLS and the efficient design of these separators, but also provide guidance for industrial applications involving high-viscosity fluids.

Evaluating bioenergetic pathway contributions from single to multiple sprints

This study aims to investigate the changes in bioenergetic pathway contributions during repeated sprint exercises with an increasing number of repetitions. Twelve male amateur soccer players executed a single 20 m sprint and three repeated-sprint protocols (5 × 20 m, 10 × 20 m, 15 × 20 m with 15-second rest intervals), analyzing oxidative, glycolytic, and ATP-PCr energy pathways using the PCr-LA-O2 method. Findings revealed a significant decline in energy expenditure and performance outputs as the number of sprint repetitions increased. While the oxidative and ATP-PCr pathways’ energy contributions significantly rose with more sprints, the glycolytic pathway’s contribution notably increased only up to the 10 × 20 m protocol, then stabilized. Although the ATP-PCr pathway’s energy contribution decreased slightly from sprints 1–5 to 11–15, it remained significantly higher than the oxidative and glycolytic pathways throughout. Initially, glycolytic contribution surpassed oxidative in sprints 1–5, equaled it in sprints 6–10, and fell below in sprints 11–15. Glycolytic activity, a major energy source initially (about 36%), diminished substantially with more sprints (below 7% in the 15th sprint). This indicates that the decrease in non-mitochondrial pathway energy, particularly glycolytic, outstrips the aerobic system’s increased tolerance. These findings offer physiological insights into the relationship between performance decrement and bioenergetic metabolism in repeated sprints.

Role of synthetic process parameters of nano-sized cobalt/nickel oxide in controlling their structural characteristics and electrochemical energy performance as supercapacitor electrodes

The synthesis of nano-sized bimetallic Cobalt/Nickel oxides (Ni1.5Co1.5O4) with a 1:1 Co/Ni atomic ratio has been achieved using a surfactant-free co-precipitation/hydrothermal process. The growth mechanism of Cobalt/Nickel oxides Ni1.5Co1.5O4 is elucidated by tuning the synthesis process parameters, including co-precipitation pH and hydrothermal time. The formation of Cobalt/Nickel oxides Ni1.5Co1.5O4 oxide began with the nucleation of cobalt nickel hydroxide nanoplates through the co-precipitation process, followed by dissolution-recrystallization, stacked hexagonal nano-flakes, and a flower-like microstructure. The electrochemical performances of the oxides were evaluated, with the largest surface area observed at pH 9 being the main factor for the best super-capacitive performance. As hydrothermal time increased, the structural directing growth forward, resulted in the formation of a nano-flower structure with a larger surface area. The as-prepared cobalt nickel oxide exhibited a maximum specific capacitance value of 525.5 F g-1 at a current density of 1 A g-1 and energy and power densities of 88.2 WhKg-1 and 606 WKg-1, respectively.

Multi-objective optimization framework based on review of form-finding of architectural parametric forms

Parametric architecture has played a vital role in architectural design in recent times. Research on early form-finding of architectural forms represents a notable area of study. Despite the significance of energy performance, digital fabrication, and aesthetics as design objectives, there is a lack of a comprehensive framework that integrates them in the form-finding process. To address this gap, this research conducts a systematic review of previous studies on form-finding and optimization of architectural forms, focusing on the three aforementioned objectives. Then, based on the analysis of the selected studies, the research proposes a multi-objective optimization framework for form-finding of architectural parametric forms, considering energy performance, digital fabrication, and aesthetics. The framework comprises five phases: form generation, multi-objective optimization, aesthetic evaluation, geometry rationalization, and digital fabrication of a prototype. This framework is usable by any architect, regardless of their programming knowledge, and is applicable to any new architectural design.

Energy performance of self-powered green IoT nodes

Energy performance of self-powered green IoT nodes

Dynamic Indoor Environmental Quality Assessment in Residential Buildings: Real-Time Monitoring of Comfort Parameters Using LoRaWAN

This study addresses an identified literature gap regarding indoor environmental quality in residential buildings, where the primary focus has traditionally been on energy performance rather than comfort optimization. Leveraging the low-cost and easy-to-implement LoRaWAN protocol, this research collects and analyses real-time data on comfort parameters, including temperature, CO2 levels, humidity, lighting, atmospheric pressure, and total volatile organic compounds (TVOC) across various buildings within the INCUBE EU project. The results highlight the dynamic nature of the parameters and emphasize the importance of continuous monitoring to enhance comfort and energy efficiency in smart residential buildings. The findings advocate for integrating technologies like LoRaWAN to optimize indoor environmental quality, ultimately improving residential comfort and occupant well-being.

Procedure of developing more energy efficient and electrified hydraulic systems for loader cranes

This work presents a process for the requirement management and conceptual design phases of hydraulic systems. The aim is to provide a foundation for developing more energy efficient systems for the working hydraulics of construction machines. A framework is developed and applied in a case study of a loader crane. An important part of the framework is to evaluate and compare different designs based on customer usage of the machine. Emphasis has also been put on incorporating the knowledge and experience of both industry and academia. A large number of different designs are evaluated during a concept exploration phase. The design space is then narrowed down to the system design analysis phase. Losses from simultaneous operation are significant, systems with two and four pumps respectively are therefore selected for analysis by demonstrators. In order to reach equal energy performance, two-pump systems need to be more complex, i.e., they require a more sophisticated control and more components, than four-pump systems. When comparing demonstrator results, the conclusion is that for two-pump systems, it is more challenging to reach the theoretical performance, both in terms of energy efficiency and of drivability, than for the less complex systems made possible with four-pumps.

Road to net zero: Greenness of Leadership in Energy and Environmental Design and California Green Building Standards Code in the multifamily sector

AbstractThis study evaluates the effectiveness of Leadership in Energy and Environmental Design (LEED) and California Green Building Standards Code (CALGreen) sustainability programs in reducing greenhouse gas (GHG) emissions in multifamily buildings. We find that CALGreen effectively reduces GHG emissions by 7.2%–11.6%. However, among properties completed during the CALGreen period (on or after 2015), LEED‐certified properties exhibit 14.1%–20.8% higher GHG emissions compared to non‐LEED‐certified buildings. We attribute this result to the emphasis on theoretical design versus actual energy performance of those programs. Furthermore, our research reveals that LEED‐certified buildings completed before the implementation of CALGreen command a rent premium of 4.7%–5.4%. However, this LEED premium diminishes during the CALGreen period. Non‐LEED properties completed during the CALGreen period show limited evidence of rent premiums.