Electricity Generation Efficiency Research Articles

Sustainable All-Day Thermoelectric Power Generation From the Hot Sun and Cold Universe.

Energy conversion from the environment into electricity is the most direct and effective electricity source to sustainably power off-grid electronics, once the electricity requirement exceeds the capability of traditional centralized power supply systems. Normally photovoltaic cells have enabled distributed power generation during the day, but do not work at night. Thus, efficient electricity generation technologies for a sustainable all-day power supply with no necessity for energy storage remain a challenge. Herein, an innovative all-day power generation strategy is reported, which self-adaptively integrates the diurnal photothermal and nocturnal radiative cooling processes into the thermoelectric generator (TEG) via the spectrally dynamic modulated coating, to continuously harvest the energy from the hot sun and the cold universe for power generation. Synergistic with the optimized latent heat phase change material, the electricity generation performance of the TEG is dramatically enhanced, with a maximum power density exceeding 1000mWm-2 during the daytime and up to 25mWm-2 during the nighttime, corresponding to an improvement of 123.1% and 249.1%, compared with the conventional strategy. This work maximizes the utilization of ambient energy resources to provide an environmentally friendly and uninterrupted power generation strategy. This opens up new possibilities for sustained power generation both daytime and nighttime.

Well‐to‐wheels analysis of greenhouse gas emissions for passenger vehicles in Middle East and North Africa

AbstractBattery electric vehicles (BEVs) are widely considered a pathway to achieve low carbon mobility. BEVs emit zero emissions from the tailpipe, but their life cycle carbon reduction compared to gasoline vehicles varies based on primary energy sources, electricity generation, and use efficiency. The Middle East and North Africa (MENA) region is an area rich in fossil fuels, meriting a detailed comparison between the emissions from BEV and other powertrains. We developed a MENA‐specific life cycle model that estimates well‐to‐wheel (WTW) greenhouse gas (GHG) emissions from passenger transport with internal combustion engine vehicles (ICEVs), hybrid electric vehicles (HEVs), plug‐in hybrid electric vehicles, and BEVs. MENA's average WTW GHG emissions for all supply chain steps including combustion emissions from vehicle operation are 767 g/kWh and 84 g CO2eq/MJ for electricity and gasoline, respectively, but are highly variable due to heterogeneity in upstream supply chains. The use of hybrid gasoline ICEVs provides the largest emission reduction opportunity for existing vehicle fleets in 9 of the 16 MENA countries. For these nine countries, replacing gasoline ICEVs with HEVs could, on average, reduce country‐level life cycle GHG emissions by 47%. There is a similar emission reduction opportunity for 14 of the 16 MENA countries when normalizing vehicle efficiencies irrespective of the powertrain shares and other trends in existing vehicle fleets. Future scenario analysis shows that BEVs would have the lowest WTW GHG emissions among all powertrains in most MENA countries only if significantly reduced electricity transmission losses and cleaner grid mix are realized, although a high cost of infrastructure developments is expected.

Efficient hydrogen production and electricity generation in solar-driven single-photoelectrode photocatalytic fuel cell

Efficient hydrogen production and electricity generation in solar-driven single-photoelectrode photocatalytic fuel cell

Performance improvement of building-integrated photovoltaic panels using a composite phase change material-carbon foam heat sink: An experimental study

Building-integrated photovoltaic (BIPV) panels are important for enhancing building self-power generation, promoting sustainable energy practices, and reducing dependence on the grid. Nevertheless, the efficiency and output power of these panels are negatively affected by the temperature increase caused by incident solar radiation. Thus, the present study introduces an innovative paraffin/carbon foam composite phase change material for efficient thermal management of building-integrated photovoltaic panels. Through indoor and outdoor experimental tests, the study evaluated and compared the performance of the proposed system. This system integrates a PV panel with an RT-55 phase change material and carbon foam structure (BIPV-PCM-CF) and was compared to three other cases, including a naturally cooled free PV panel, a building wall integrated PV panel to simulate conventional building-integrated photovoltaic system (BIPV), and a PV panel integrated with only RT-55 paraffin wax as the phase change material (BIPV-PCM). The study found that integrating the PV cell into building walls (BIVP) increased its temperature by 9.61 °C and decreased generated power and efficiency by 5.11 % and 10.95 %, respectively, compared to the free PV panel. On the other hand, the BIPV-PCM panel reduced module temperature by 18.1 °C but could not solidify the needed amount of PCM during the nighttime. The BIPV-PCM-CF panel, which incorporated carbon foam with PCM, outperformed the other systems, producing a cooling performance of 22.94 °C and increasing electricity generation and system efficiency by an average of 12.64 % and 27.35 %, respectively, compared to the free PV panel. These findings highlight effective strategies to promote sustainable energy practices, improve the electric performance of BIPV panels, and reduce dependence on non-renewable energy sources in buildings.

Solar photothermal self-deicing composite films based on fluorinated polyimide and phosphorene nanoflakes for passive anti-icing of photovoltaic panels

Snow and ice coverage greatly deteriorates the power output of photovoltaic (PV) solar cells due to sunlight obstruction and thus makes a great impact on their electricity generation. To address this problem, we design a type of passive self-deicing composite films based on colorless fluorinated polyimide as a polymeric matrix and phosphorene (PR) nanoflakes as a light absorber for the photothermal deicing of PV panels driven by solar energy. The composite films were successfully fabricated through in situ polycondensation, followed by temperature-programmed thermal imidization. The resultant composite films exhibit a colorless transparent feature along with high transmittance and high absorptivity. The presence of PR nanoflakes enhances the absorption of solar light and conversion of photothermal energy by the composite films, resulting in good photothermal self-deicing effectiveness for solar PV panels. There is an accelerated melting process occurring in the ice covering on the surface of the composite films under solar illumination. The composite film containing 2.0 wt % PR nanoflakes exhibits an optimal photothermal self-deicing performance under a high photothermal conversion efficiency of 92.9 %. The use of this composite film can promote a rapid recovery of the output voltage to an ideal value for the snow- or ice-covered PV panels through fast photothermal self-deicing. This study provides a novel approach for the development of passive self-deicing materials to enhance the power output and electricity generation efficiency of solar PV panels in the snowy and icy weather.

Maximizing the Energy Scavenging Capability of Droplet Triboelectric Nanogenerators through Surface Engineering

Recent advancements in energy harvesting have led to innovative methods for converting droplet motion into electricity, such as droplet triboelectric nanogenerators (D-TENGs). However, enhancing their power generation capacity and efficiency remains a challenge. We present a novel surface engineering approach that significantly boosts the electrical outputs of the D-TENGs. By grafting perfluorodecyltrimethoxysilane (PFDTMS) onto polydimethylsiloxane (PDMS) surfaces pre-treated with sandpaper, we achieve a dual effect: fluoridation and increased contact area between droplets and PDMS. This modification, when applied to a droplet-based TENG, yields a remarkable 10-20 fold increase in power metrics such as current, charge, and voltage as compared to untreated counterparts, resulting in an energy conversion efficiency of 17.1% under a 30 MΩ load. Our enhanced D-TENG efficiently harvested energy from falling tap water droplets, producing a current of ~2mA. Remarkably, a single droplet impact could illuminate 400 LED lights. Furthermore, when coupled with capacitors, the device powered a hygrometer and 3W light bulbs, demonstrating substantial potential for real-world applications. This breakthrough in surface engineering for energy harvesters represents a significant step forward in the efficient and powerful generation of electricity from droplet motions.

Can operational efficiency in the Portuguese electricity sector be improved? Yes, but...

Efficiency has long been an issue of concern in the electricity sector. Most existing studies relate technical efficiency in electricity generation to policy factors while that in transmission and distribution is associated with environmental factors. Although firm operation is also a relevant perspective on this topic, its explicit impact upon technical efficiency has rarely been studied. In order to analyze the evolution and operational determinants of productive and cost efficiency in the Portuguese electricity sector (including generation from different sources, trade, transmission and distribution), this study estimates Stochastic Frontier models using firm-level panel data from 2006 to 2019, covering the period of liberalization of the Portuguese electricity market. The evidence indicates efficiency improvement through time, which is likely to slow down and needs to be consolidated. Results on the inefficiency determinants suggest that it is possible to improve productive technical efficiency by encouraging investment in fixed assets, higher average hourly wage and moderate average working hours. In addition, based on the results, we advocate deepening the integration of the Iberian electricity market and stimulating competition in the renewable energy sector.

Harnessing overlapped temperature-salinity gradient in solar-driven interfacial seawater evaporation for efficient steam and electricity generation

Solar-driven interfacial water evaporation (SIWE) offers a superb way to leverage concentrated solar heat to minimize energy dissipation during seawater desalination. It also engenders overlapped temperature-salinity gradient (TSG) between water-air interface and adjacent seawater, affording opportunities of harnessing electricity. However, the efficiency of conventional SIWE technologies is limited by significant challenges, including salt passivation to hinder evaporation and difficulties in exploiting overlapped TSG simultaneously. Herein, we report self-sustaining hybrid SIWE for not only sustainable seawater desalination but also efficient electricity generation from TSG. It enables spontaneous circulation of salt flux upon seawater evaporation, inducing a self-cleaning evaporative interface without salt passivation for stable steam generation. Meanwhile, this design enables spatial separation and simultaneous utilization of overlapped TSG to enhance electricity generation. These benefits render a remarkable efficiency of 90.8% in solar energy utilization, manifesting in co-generation of solar steam at a fast rate of 2.01 kg m−2 h−1 and electricity power of 1.91 W m−2 with high voltage. Directly interfacing the hybrid SIWE with seawater electrolyzer constructs a system for water-electricity-hydrogen co-generation without external electricity supply. It produces hydrogen at a rapid rate of 1.29 L h−1 m−2 and freshwater with 22 times lower Na+ concentration than the World Health Organization (WHO) threshold.

Transparent integrated pyroelectric-photovoltaic structure for photo-thermo hybrid power generation

Thermal losses in photoelectric devices limit their energy conversion efficiency, and cyclic input of energy coupled with pyroelectricity can overcome this limit. Here, incorporating a pyroelectric absorber into a photovoltaic heterostructure device enables efficient electricity generation by leveraging spontaneous polarization based on pulsed light-induced thermal changes. The proposed pyroelectric-photovoltaic device outperforms traditional photovoltaic devices by 2.5 times due to the long-range electric field that occurs under pulse illumination. Optimization of parameters such as pulse frequency, scan speed, and illumination wavelength enhances power harvesting, as demonstrated by a power conversion efficiency of 11.9% and an incident-photon-to-current conversion efficiency of 200% under optimized conditions. This breakthrough enables reconfigurable electrostatic devices and presents an opportunity to accelerate technology that surpasses conventional limits in energy generation.

Expansion-flow-modulated 3D printing of vertically aligned graphene photofuel cell

Channel-aligned regulation of photoelectrode within the bulk structure to generate eminent light absorbance and high-level pollutant adsorption is pivotal but challenging for realizing high-performance photofuel cell (PFC) system. Herein, we demonstrated an effective and scalable expansion-flow-modulated direct ink writing (DIW) 3D printing strategy for controllably constructing microlattice photoelectrode, with multiscale well-interconnected oriented channels built by layer-by-layer highly-regular assembly of filaments and vertical alignment of graphene nanosheets within filaments as well as uniform coupling of abundant photoactive nanoparticles to highly ordered channel walls. The unique architectural features enabled high-speed and effective diffusion/trapping of wastewater pollutants throughout the entire photoelectrode, and meanwhile facilitated ready spreading of incident light into the photoelectrode interior to yield high light absorption. As a result, an integrated 3D-printed vertically-aligned PFC (3DP VAPFC) assembled with as-fabricated photoelectrode exhibited its powerful capability for efficiently converting wastewater pollutants into electric energy under sunlight, with remarkable cycling stability and maximum power density of 0.11 mW cm−2. This work opens a promising route for architecting advanced photoelectrode toward PFC devices with highly efficient degradation and electricity generation of pollutants.

Achieving Ultrahigh Voltage Over 100 V and Remarkable Freshwater Harvesting Based on Thermodiffusion Enhanced Hydrovoltaic Generator

AbstractEvaporative hydrovoltaic generators hold significant potential for alleviating water‐energy crisis, but low output voltage configurations due to the slow phase transition rate of water molecules and the intricate nature of integration limit their applications. Herein, a lotus‐inspired interfacial evaporation‐driven hydrovoltaic generators (IEHVG) is developed for efficient generation of water vapor and electricity from seawater instead of freshwater and achieves an ultrahigh voltage output higher than 100‐volt level through forested IEHVG integration. The biomimetic hydrogel is developed with specific liquid transport channels, graphene quantum dots/MXene nanocomposites, and gradient hydrophobic interface for highly enhanced photothermal evaporation and electricity generation by mimicking the transpiration process of a “stems‐leaves of lotus”. The synergistic thermodiffusion effect leads to the output power density of IEHVG reaches up to 45.6 µW cm−2 and can power electronic devices or charge commercial supercapacitors. The freshwater‐electricity cogeneration integrated system consisting of 192 IEHVG units can harvest a record‐breaking voltage reaching 105 V and a high freshwater harvesting rate up to 2.0 L m−2 h−1 from seawater in a well‐lit outdoor area. This work demonstrates that IEHVG offers a novel concept for modular freshwater and high‐voltage power sources access on offshore work platforms.

Interface Engineering to Operate Reversible Protonic Ceramic Electrochemical Cells Below 500 °C

AbstractThe low‐temperature (<500 °C) operation of reversible protonic ceramic electrochemical cells (PCECs) is desirable in achieving efficient and sustainable electricity generation, as well as green hydrogen production. However, significant interfacial resistance, which contributes to both ohmic and polarization resistance, remains a hurdle in lowering the operating temperature. In this study, PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) and BaZr0.4Ce0.4Y0.1Yb0.1O3‐δ (BZCYYb) mono‐grain composite interlayers are introduced, which significantly extend the electrode/electrolyte interface and increase the concentration of vertically aligned oxygen vacancies along the heterointerface. This unique design achieves the lowest ohmic and polarization resistances among previously reported values in solid electrolyte‐based electrochemical cells. As a result, the PCEC can operate at extremely low temperature of 350 °C with an exceptional peak power density of 0.50 W cm−2 in fuel cell mode and current density of 0.25 A cm−2 at 1.3 V in electrolysis cell mode. Furthermore, it demonstrates high energy conversion efficiency and excellent stability under static and dynamic operating conditions.

Dual Attention Graph Convolutional Network optimized with the Sun Flower Optimization for Differential Privacy Protection Mechanism for Smart Grid against Security Attacks

A smart grid combines information and communication technology with the conventional power system to provide efficient and dependable electricity generation, transmission, distribution, and control. Utilities and users share information and electricity in a smart grid. This manuscript presents a Dual Attention Graph Convolutional Network (DAGCN) optimized with the Sun Flower Optimization Algorithm (SFO) predicting the differential privacy protection mechanism for smart grid (DPSG-DAGCN-SFO). Initially, the data is collected from NSL-KDD datasets. Afterward, the data is fed to an Adaptive Robust Cubature Kalman Filter (ARCKF) based preprocessing process. Then the preprocessed data’s are fed to Adaptive and Concise Empirical Wavelet Transform (ACEWT)for extracting features such as authentication, integrity and trusted authority. The extracted features are fed to Dual Attention Graph Convolutional Network (DAGCN)to classify the privacy protection in smart grid such as stealthy attack and no attack. The weight parameters of DAGCN are optimized using SFO. The proposed DPSG-DAGCN-SFO is implemented in python, effectiveness assessed by several performance metrics such as accuracy, error rate, precision, sensitivity, F1-score and recall. The proposed method error rate attains 2% stealthy attack and4% no attack of the of the privacy protection in smart grid. The proposed method shows better results in all existing systems like Bayesian Clustering Algorithm (BCA), Self-Adaptive Grid-Partitioning Algorithm (SGNA) and Elliptic Curve Digital Signature Algorithm (ECDSA).From the result it is concludes that the proposed DPSG-DAGCN-SFO method based error rate lower than the existing methods.

Analysis of hydraulic losses in the series from 1990 to 2022 at the Retiro small hydroelectric power plant

Hydraulic losses are a crucial variable in hydroelectric ventures as they can cause significant reductions in power generation. This article analyses the impact of hydraulic losses on the Retiro Small Hydroelectric Power Plant (SHPP), investigating their effect on monthly average power and, consequently, the efficiency of electricity generation. This study examines the historical series of load losses at the Retiro SHPP from 1990 to 2022. The calculations are based on flow data available in HidroWeb. The study considered the maximum and minimum flow rates in the historical flow series as constraints for hydropower generation. We used a multivariable function to calculate the efficiency of the hydraulic turbine, relating the turbine flow rate and the net water head. We developed mathematical relationships for head losses that occur in the grid, at the water intake, and due to friction from the intake to the turbine of the Retiro SHPP. The article presents a comparison between the actual monthly average power of the Small Hydroelectric Power Plant (SHPP) and the simulated monthly average power. We normalized the data for turbine flow and load loss to conduct statistical analysis. Kernel probability density was applied to understand the distribution shape of the data. Findings show that average monthly capacity is lowest in September, at approximately 0.81 MW. In March, the highest power occurs, approximately 14.19 MW. During the high flow period, the simulated average power, which accounts for load losses, closely matched the actual average power generated at the Retiro SHPP. In the months from July to October, despite being the period with the lowest head losses, it is the time when there is a greater opportunity to maximize energy generation at the power plant. An inefficient power generation system experiences significant load losses during specific periods of the year. To minimize this effect, it is crucial to understand the behavior of hydraulic losses and consider implementing mitigating measures.

Numerical investigation of electricity generation potential by water circulating through three horizontal wells at Fengshun geothermal field in China

Fengshun geothermal field is the first medium and low temperature geothermal area in China, which is used for electricity generation. At present only vertical wells are employed to extract heat energy. After about 40 years of exploitation, the production temperature and rate are all declined. In this work, based on the hydrogeological data of the study area, the deep reservoir temperature and corresponding circulation depth of underground hot water are predicted with a silica thermometer. To fully develop the deep heat reservoir, we proposed a new heat exploitation scheme through three horizontal wells, computed the electricity generation potential and efficiency, and analyzed the main factors affecting heat production. The results indicate that under the reference conditions, the three horizontal well system attaches an electric power of 2.70–1.5 MW, a reservoir impedance of 0.13–0.27 MPa/(kg/s), a pump power of 0.29–1.16 MW, and energy efficiency of 7.34–1.30 during the reservoir lifetime of 43.6 years. Thus, this three-horizontal-well system has significant development potential in Fengshun deep geothermal reservoir. Sensitivity analysis indicates that water production rate, injection temperature and initial reservoir temperature have a significant impact on heat production performance. Reducing the water production rate and injection temperature within a certain range can improve energy efficiency. For the precise design of power generation systems and the accurate evaluation of production performance, field logging data is necessary.

Hybrid axis wind turbine profile design

Wind offers vast opportunities in terms of energy potential. Previous studies have shown that wind power can meet all the world's energy needs by using effective wind turbines. However, the efficiency of wind turbines is not at the expected level, and they are not widely used due to various reasons. In this sense, it is substantial to yield airfoils with better aerodynamic properties. Geometrically, wind turbines are divided into two types as horizontal and vertical axes. Within the scope of this study, it was aimed to design a modified airfoil including both horizontal and vertical axes properties. Accordingly, a hybrid design was made in terms of the airfoil axis obtained by the modification of the NACA4412 profile. In terms of the method of the study, the electric generation efficiency of hybrid airfoils with different inclinations was measured under constant distance and air flow. As a result of the study, it was attained that the modified airfoil curved at an angle of 30° was about 12% more efficient in terms of electricity generation than the unmodified one.

Simultaneous production of electricity and potable water underwater by integrating concentrating photovoltaic with air gap membrane distillation

This paper combines underwater concentrating photovoltaic and air gap membrane distillation, enabling the simultaneous production of electricity and potable water in underwater environments. Given its submerged nature and absence of land occupation, it proves particularly advantageous for land-deficient regions with limited access to electricity and potable water, such as islands and Coastal cities. It primarily comprises innovatively designed underwater solar concentrators featuring extensive light interception angles, photovoltaic modules, and membrane distillation units. It utilizes exhausted heat from photovoltaic modules to separate clean water from seawater via membrane distillation process. Furthermore, it is engineered to prevent any contact between metal materials and seawater, thereby mitigating the risk of corrosion. An experimental setup with photovoltaic cells’ areas of 0.006 m2 is developed and tested in the laboratory and under real weather conditions to assess its performance. The steady-state experimental findings indicate that as solar irradiation increases from 500 W/m2 to 900 W/m2, its electricity generation efficiency ranges from 9.0% to 9.7%, while the water yield efficiency ranges from 32.8% to 35.1%. Besides, outdoor experiments demonstrate that its power output during normal incidence ranges from 38.89 W/m2-85.56 W/m2, with an average electrical efficiency of 10.5%. Its average potable water yield reaches 0.537 kg/m2/h and average water production efficiency reaches 48.3%.

Bioelectrocatalytic reduction by integrating pyrite assisted manganese cobalt-doped carbon nanofiber anode and bacteria for sustainable antimony catalytic removal

A novel manganese cobalt metal–organic framework based carbon nanofiber electrode (MnCo/CNF) was prepared and used as microbial fuel cell (MFC) anode. Pyrite was introduced into the anode chamber (MnCoPy_MFC). Synergistic function between pyrite and MnCo/CNF facilitated the pollutants removal and energy generation in MnCoPy_MFC. MnCoPy_MFC showed the highest chemical oxygen demand removal efficiency (82 ± 1%) and the highest coulombic efficiency (35 ± 1%). MnCoPy_MFC achieved both efficient electricity generation (maximum voltage: 658 mV; maximum power density: 3.2 W/m3) and total antimony (Sb) removal efficiency (99%). The application of MnCo/CNF significantly enhanced the biocatalytic efficiency of MnCoPy_MFC, attributed to its large surface area and abundant porous structure that provided ample attachment sites for electroactive microorganisms. This study revealed the synergistic interaction between pyrite and MnCo/CNF anode, which provided a new strategy for the application of composite anode MFC in heavy metal removal and energy recovery.

Energy, economic, and environmental analysis: A study of operational strategies for combined heat and power system based on PEM fuel cell in the East China region

This study introduces a combined heat and power (CHP) system primarily based on proton exchange membrane (PEM) fuel cells, which can provide electricity and heat for residential buildings in the East China region under two operating strategies. The analysis and discussion focus on the impact of parameters such as current density and gas inlet pressure on the system's output power and efficiency. The results indicate that excessively high current density decreases the system's electricity generation efficiency, while a moderate increase in hydrogen inlet pressure contributes to greater heat generation. Considering energy, economic, and environmental factors, the system operates with the thermal-led strategy in parallel with the grid, resulting in a substantial 73.3 % reduction in fuel costs. The annual greenhouse gas (GHG) emissions and the amount of emission reduction are lowered to 6.96 × 107 g and 3.39 × 107 g, respectively.

Key issues to consider toward an efficient constructed wetland-microbial fuel cell: the idea and the reality.

The research on constructed wetland (CW) and microbial fuel cell (MFC) has been separate studies worldwide with crucial achievements being made in both fields. Due to environmentally friendly feature (of CW) and rich microbial population and excellent electrode catalytic activity (of MFC), CW and MFC have their own anticipated application prospect in wastewater purification and biological electricity generation. More significantly, the idea of embedding MFC into CW to form CW-MFC expands the scope for both of them and this has received much interest in recent years due to its striking features of sewage treatment efficiency, electricity generation, sustainability, and environmental friendliness. The increasing interest and the lack of soul of CW-MFC emerging to the new researchers reflect the need to recall the idea and summarize its development with regard to achieving its reality via some key issues This forms the basis of the paper. The paper also includes how to enhance the efficiency of electricity generation and supplement energy consumption, the degradation of emerging pollutants, and the degradation mechanism as well as the potential joint application of CW-MFC with other treatment technique. A mass of CW-MFC design parameters has been synthesized from the literature. Challenges and potential directions of CW-MFC in the future are prospected. It is expected that the paper can serve as a linkage for bridging knowledge gaps for further studies of CW-MFC.