Low Power Generation Research Articles

Electrical power supply consumption in education sector and energy audit: Case study of University of Jos


 
 
 Electricity supply has been identified as the key constraint to industrialization and economic development in Nigeria. The unbundling of the power sector was aimed at boosting electricity supply, this effort has yielded some appreciable results, but not very significant. As a result of the low power generation and distribution, Nigeria’s federal government is working towards solving the prevailing problems of inadequate power in some key sectors by building power generating plants in some of the institutions of learning in the country. This paper looks at the determinants of electrical energy consumption and electrical energy audit, a case study of the University of Jos. The load profiles demand survey, load demand forecast and other important factors were investigated. The result revealed that there is available power of 22–23 hours from the national grid and the balance 1–2 hours of power is supplied by the generating sets, good savings in the cost of diesel and maintenance. An annual excess of 2,199,900 kWH is enjoyed by the university over the national per capita power consumption.
 
 

Synergistically Improving Flexibility and Thermoelectric Performance of Composite Yarn by Continuous Ultrathin PEDOT:PSS/DMSO/Ionic Liquid Coating.

Combining fabrics with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) coating is the most promising method to fabricate wearable thermoelectric (TE) devices. However, the high modulus, low strain, and low TE performance of PEDOT:PSS coating lead to poor flexibility and low power generation efficiency. In this study, dimethyl sulfoxide (DMSO) and ionic liquids (ILs) were selected as a modifier to enhance the flexibility and TE performance of PEDOT:PSS. Different from the penetrating structure and coil conformation of pristine PEDOT:PSS coating, a flexible continuous ultrathin layer of PEDOT:PSS/DMSO/1-ethyl-3-methylimidazolium dicyanamide (P/D/ED) with a linear conformation forms on the surface of cotton yarn. The morphology and structure of PEDOT:PSS and P/D/ED coating were characterized by FESEM, XPS, and Raman spectroscopy. Compared with the pristine PEDOT:PSS film, the P/D/ED film shows significantly reduced modules and enhanced strain and bending stability. Moreover, the TE performance of P/D/ED-coated yarn is significantly enhanced with nearly half mass loading. Based on this, a large-area wearable TE fabric with enhanced flexibility and TE performance was prepared. The output power density is 136.1 mW/m2 at ΔT = 40.8 K, which is a typically high value compared with the former reported composite TE fabrics. This study provides a new way to synergistically enhance the flexibility and TE performance of composite yarn, and the prepared TE fabric has great potential as a wearable power source.

Investigation of Si-based thermoelectrochemical cells (TECs) towards semiconductor fabrication and processing

Thermoelectrochemical cells (TECs) are an alternative with potential for micro-power generator applications but is rarely fabricated using semiconductor processes or micro-fabrication technology. This study initiates fabrication of a Si-based TEC cell device using micro-fabrication technology. The iodide/triiodide poly(vinyl alcohol) hydrogel polymer electrolyte, and citric acid as supporting electrolyte, is selected as the TEC material. A platinum electrode sputtered on a silicon substrate is used as the hot and cold electrode. The TEC voltage generation that is based on Soret diffusion and the Seebeck effect shows good repeatability and stability. The magnitude of the power density shows dependence on the device electrode separation and temperature difference. At 10 mm electrode separation and a temperature difference of 30 K, the Si substrate TEC is able to produce 310 µW m−2; thus, it shows high potential as a low heat waste Si-based TEC power generator.

Inertia and primary frequency modulation strategy for a doubly fed induction generator based on supercapacitor energy storage control

ABSTRACT Doubly fed wind turbines cannot respond to changes in grid frequency under maximum power point tracking control. The traditional deloading frequency control suffers from problems, such as low power generation efficiency, small speed adjustment range, and frequent starting of pitch angle control. An inertia and primary frequency modulation (FM) strategy for a doubly fed wind turbine based on supercapacitor energy storage control is proposed in this study. Virtual inertia and primary frequency adjustments are realized by supercapacitor control. Changing or increasing the additional control of the wind turbine is unnecessary. The proposed strategy can improve the disturbance resistance and self-stabilization of a single wind turbine. The capacity of the energy storage unit is optimally configured in accordance with the cost and charging/discharging efficiency of the actual supercapacitor module. Comparing and evaluating the economics of the primary FM scheme of an active power reserve provide a powerful economic advantage. Simulations and experiments show that inertial support, primary frequency adjustment capability, and power generation benefits are significantly improved compared with those in the conventional primary frequency control. This study provides new ideas for the modified inertia and primary FM function of a doubly fed wind turbine.

Effect of Different Mediators on Bio-Energy Generation and Palm Oil Mill Effluent Treatment in an Air-Cathode Microbial Fuel Cell-Adsorption System

Palm oil mill effluent (POME) discharged without treatment into watercourses can pollute the water source. Microbial fuel cell (MFC) has gained high attention as a green technology of converting organic wastewater into bio-energy. As an approach to overcome the limitations of the existing POME treatment methods, air-cathode MFC-Adsorption system is introduced as an innovative technology to treat POME and generate bio-electricity simultaneously. However, the use of conventional MFC with proton exchange membrane in large scale applications is restricted by the high cost and low power generation. Addition of mediator in MFC is essential in order to increase the electron transfer efficiency, hence enhancing the system performance. This study therefore aims to investigate the effect of different type of mediators i.e. congo red (CR), crystal violet (CV) and methylene blue (MB) on the performance of an affordable air-cathode MFC-Adsorption system made from earthen pot with POME as the substrate. The addition of different mediators altered the pH of the MFC-Adsorption system, in which more alkaline system showed better performance. The voltage generated in the system with CR, CV and MB mediator was 120.58 mV, 168.63 mV and 189.25 mV whereas the current generated was 2.41 mA, 3.37 mA and 3.79 mA, respectively. The power density of 290.79 mW/m3, 568.72 mW/m3 and 716.31 mW/m3 was produced in the MFC-Adsorption system with CR, CV and MB mediator, respectively. The highest POME treatment efficiency was achieved in MFC-Adsorption system with MB mediator, which resulted in biochemical oxygen demand, chemical oxygen demand, total suspended solids, turbidity and ammoniacal nitrogen removal of 75.3%, 84.8%, 91.5%, 86.1% and 23.31%, respectively. Overall, the air-cathode MFC-Adsorption system with addition of MB mediator was feasible for POME treatment and simultaneous bio-energy generation.

Review on ZnO-based piezotronics and piezoelectric nanogenerators: aspects of piezopotential and screening effect

Among various piezoelectric materials, ZnO has attracted a great deal of attention due to facile preparations and exceptional semiconductor characteristics compared to other conventional piezoceramics or organic piezoelectric materials. One of the issues hindering ZnO from progressing into applications is the screening effect, where the intrinsic piezopotential generated upon mechanical deformations is screened and becomes waned or even diminished by the presence of intrinsic free carriers in ZnO. Consequently, ZnO-based piezoelectric devices often suffer from low output voltages, resulting in low total output power generation even though the output current could be larger than those made of insulating piezoelectric materials, such as PZT, polyvinylidene fluoride, and barium titanate. It is therefore vital to fully understand the impact of the screening effect and produce strategies to handle this issue in the context of piezotronics and piezoelectric nanogenerators (PENG). Therefore, this article presents a comprehensive review of growth methodologies for various ZnO nanostructures, structure modifications, effects of free carriers on the screening effect and strategies for device applications, including strain-gated transistors, PENG and piezotronic sensors for gas, humidity and bio-molecules etc.

Performance analysis of ORC low temperature waste heat power generation system

For 90~180°C low temperature waste heat resources, three different types of organic working fluids, benzene, isopentane and R245fa are selected from the perspectives of safety, environmental protection and physical properties of working fluid. The mathematical models of the system are established through MATLAB and REFPROP and the influence of the evaporation temperature on the performance of the ORC low temperature waste heat power generation system is studied. The results show that the thermal efficiency and net output power of the system increase with the increase of evaporation temperature; the evaporation pressure of CFC-type working fluids is relatively low; the net output power and thermal efficiency of HFC and HC-type working fluids are generally relatively low. The evaporator has the largest irreversible loss in the system, followed by the condenser and expander while the working fluid pump has the smallest irreversible loss.

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

An overview of biofuel power generation on policies and finance environment, applied biofuels, device and performance

The prices of fossil fuels, the gap between energy supply and demand, energy security, environmental issues, and the reduction of greenhouse gas emissions commonly promote the development of biomass power generation in China. Compared to direct biomass combustion power generation and biogas power generation, liquid biofuel power generation has better application potential. Policies and finance environment of countries and organizations have promoted the extensive application of biofuel power generation in recent years, especially in China. Evaluation of internal combustion engine, gas turbine and fuel cell on the stationary power station and mobile generation shows that gas turbine is the main generator-set, the fuel cell is the fastest-growing and future generator-set, while the engine is the first choice in transport and low power generation field. As the second, third and fourth generation biofuels, biomethanol, bioethanol, biodiesel and others have been researched and widely used in power generation. In addition, power generation performance and emissions have been improved to some extent after biofuels supplying. For the future, combined heat and power (CHP) generation and integrated gasification combined cycle (IGCC) is imperative development trends of power generation for higher energy and exergy efficiency. CHP based on the various generating facilities will be the next choice and direction of energy use trends for transport.

Three stages in the co-transformation of the energy and mobility sectors

Renewable electricity sources such as wind and solar power have shown a remarkable development in terms of efficiency, costs and availability, but system integration still remains a challenge. Realizing a fully renewable electricity supply will require large scale storage technologies and flexible users to overcome long periods of low power generation. At the same time, other sectors such as mobility and industry must be electrified to replace fossil fuels. Power-to-methane is a promising technology as it enables large-scale energy storage and sector coupling using existing infrastructures. In this work, we analyze the co-transformation of the German electricity, mobility and industry sectors, taking into account the recent decision to phase out coal by 2038. We evaluate the necessary capacities of renewables and sizes for storage options, as well as system costs and associated emissions using a techno-economic optimization model with a high technological and temporal resolution in the open-source framework OSeMOSYS. We find three rather different stages of the transformation driven by the decreasing emissions cap and the coal phase-out. Solar power is expanded vastly up to 2030, whilst coal is replaced mainly by fossil natural gas by 2040. Emissions caps become very challenging after 2040 to the extent that all flexibility options are greatly expanded: storage, curtailment and flexible power-to-methane.

A low energy consumption de-carbonization natural gas combined cycle power generation system based on LiBr/H2O absorption heat transformer

An integrated system of natural gas combined cycle (NGCC) with monoethanolamine-based (MEA-based) CO2 capture was proposed in this study aiming to reduce the efficiency penalty of CO2 mitigation. In the proposed system, three measures were adopted: (1) utilizing absorption heat transformer (AHT) and ejector to recover the waste heat as well as providing suitable steam for solvent regeneration; (2) recirculating part of reboiler condensate to fully utilize the superheat degree of the extracted steam, and (3) injecting reboiler condensate into the regenerative system of power cycle to reuse the surplus heat of reboiler condensate. Thermodynamic benefits and economic viability of the proposed system were compared with the de-carbonization NGCC power plant without integration. Results indicated the efficiency penalty of CO2 capture in the proposed system decreased by 2.67 percentage points. Meanwhile, the cost of electricity and the cost of CO2 avoided were reduced by 4.73% and 15.08%, respectively, while the adopted additional devices caused an increase of the investment by 19.12 M$.

Screening of Energy-Saving Technologies for Cement Production Based on Boston Consulting Group Matrix

Based on the analysis of the development situation of China’s cement industry and the BCG Matrix method, this paper classifies and screens 31 energy-saving technologies in China's cement production, and puts forward guiding suggestions for the application of energy-saving technologies for cement enterprises. The screening results show that the “Energy-efficient powder separation technology” and “New low-calcium cement clinker and production technology” are “double-high” technologies with excellent on both screening indicators. The investment energy saving rates are 17.5 tce/10,000 yuan (tons of standard coal equivalent per 10,000 yuan) and 10 tce/10,000 yuan. The promotion ratio increments are 35% and 25%. “Cement clinker energy-saving nitrogen reduction firing technology”, “Fan drive mode adopts high voltage frequency conversion speed control technology”, “Pure low temperature waste heat power generation technology for cement kiln” are “single-high” technologies with excellent on one of screening indicators. The investment energy saving rates are 0.3tce/10,000 yuan, 4.1tce/10,000 yuan, 3.9tce/10,000 yuan respectively. The promotion ratio increments are 19%, 35%, 31.5% respectively.

Adaptive rapid neural optimization: A data-driven approach to MPPT for centralized TEG systems

Thermoelectric generation (TEG) system is designed to recover waste heat generated in industrial production and daily life with disadvantage of low power generation efficiency. Since non-uniform temperature distribution (NTD) easily gives rise to multiple local maximum power points (LMPPs) for centralized TEG systems, conventional maximum power point tracking (MPPT) methods is likely to lead to a low-quality LMPP. Hence, a novel adaptive rapid neural optimization (ARNO) approach is proposed to capture maximum power point (MPP). Particularly, generalized regression neural network (GRNN) is devoted to construct a proper mapping between control input of duty cycle and power output of TEG system, thus ARNO can implement an efficient search for MPP. In order to reduce possible instability caused by manual tuning, Bayesian optimization (BO) is adopted to adaptively select optimal parameters of GRNN. Compared to conventional MPPT methods, four simulations are carried out to verify the feasibility and advantages of ARNO, start-up experiment, step temperature variation, stochastic change of temperature, and sensitivity analysis included. Further, dSpace platform based hardware-in-the-loop experiments are performed to verify the feasibility of the proposed method.

Influence of topology and diode characteristics of AC-DC converters for low power piezoelectric energy harvesting

Most often, piezoelectric generators are connected to an AC-DC converter, also called rectifier, to obtain a continuous energy which can be regulated and stored. In the case of low power generators, the choice of the rectifier is critical since the losses into this circuit are not negligible and should be as low as possible.In this paper, different topologies of rectifier using different diode references are studied to rectify the output voltage of a piezoelectric generator. We show that the differences between the fullwave rectifier and a voltage doubler are quite small in terms of output power. The main differences are visible on the final voltage value and the optimal load. On the contrary, the choice of diodes is critical, especially the reverse leakage current which must be limited since it largely affects the output power for low power generators.The internal capacitance of the generator also plays an important role since it changes the capability of the generator to provide current. We show that low threshold voltage diodes are more appropriate for generators presenting a high internal capacitance while low leakage current are preferable for generators presenting a low internal capacitance value.

Distributed placement of wind farms to minimize the impact of power fluctuations on the electric power system

The problem of the influence of power fluctuations of wind farms due to the variability of the wind speed on the electric power system is considered. With high wind energy penetration, an increase in the operating reserve in electric power systems is required to cover possible sudden power fluctuations. One of the ways to reduce the stochastic nature of the wind farms power generation is their geographically distributed location. A method is proposed for the selection of capacity and distributed placement of wind farms, taking into account the factor of the variability of the total generated power. In each of the prospective areas for wind farm placement, the simulation of electricity generation by a single wind turbine with hour-by-hour breakdown is carried out using the developed WindMCA software based on long-term ground-based weather stations data. Optimization of wind farms capacity and their distributed placement in areas is carried out using a genetic algorithm in the MATLAB environment. The target function is the coefficient of variation of the power generated by all wind farms in the areas under consideration, depending on the number of wind turbines therein. Power duration curves are used in the final comparison of wind farms siting options. The application of the method is carried out on the example of the wind farms placement in the Zabaykalsky Krai. A solution has been obtained that provides a minimum coefficient of variation of the wind farms generated power and a relatively high capacity utilization factor. With a distributed location of wind farms, the duration of the period with the maximum output is reduced, however, the duration of low power generation is significantly increased. With an increase in the number of wind farms connected to various nodes of the electric power system, a certain guaranteed level of power generation can be obtained, which, ultimately, will reduce the required amount of the reserve of generating capacities.

New bracket and motion control system for distributed photovoltaic power stations

In view of the existing solar panel blackout, affecting the ecological environment, unreasonable spatial distribution, low power generation efficiency, high failure rate, difficult to operate and other issues, design a mechanical uniform solar power bracket: weather conditions, temperature, light strength and other multi-factor evaluation of the way to monitor the state of photovoltaic panels to adjust. According to the latitude and longitude and terrain of photovoltaic plate installation, the periodic movement trajectory is automatically planned, the operation is monitored centrally, and the failure point is located quickly and the operational efficiency is improved by comparing with big data speculation.

DESIGNING, PROTOTYPING AND TESTING OF TURBINES WHICH TO BE PLACED IN TO WATER PIPELINES TO PROVIDE ELECTRIC POWER GENERATION

Gün geçtikçe elektrik çoğu alanda kullanımı artmaktadır. Son zamanlarda gelişen araba teknolojisi ile elektrikli araçlar kullanımı artmaya başlamıştır. Bu nedenle elektrik üretimi önemi gün geçtikçe artmaktadır. Elektrik üretilmesi birçok yöntemi vardır. Bunlardan bazıları düşük maliyetli iken bazıları maliyeti yüksek olmaktadır. Düşük maliyetli olan yenilenebilir olan enerji türleridir. Bu amaçla mevcut derelerimizden akan nehirden veya evlerimize gelen şebeke borularından elektrik üretilmesi hedeflenmiştir. Şebeke boru üzerinde yerleştirilecek türbin ile elektrik üretilmesi hedeflenmiştir. Bu amaçla türbin tasarımı yapılmış ve prototip üretimi yapılarak testler yapılması hedeflenmiştir.

Review of Installation Status and Major Environmental Issues of Floating Photovoltaic Power Plants (FPVs)

Objectives : After investigation of types, characteristics, and domestic and overseas installation cases of floating photovoltaic power plants (FPVs), both power generation capacity and coverage ratio of the FPVs were analyzed, and the major environmental issues impacting on water quality and aquatic ecosystem were reviewed.Methods : Both information and data of the FPVs extracted from existing literature and provided by the FPVs installation companies were statistically analyzed.Results and Discussion : FPVs divided into three types such as pontoon type, frame type, and solar tracking type are installed in various ways by country and region. As of the second half of 2018, the global power generation capacity of FPVs is 1.3 GWp, and FPVs have been intensively installed in China, Japan, Korea, Taiwan, and UK. While the pontoon type has been mainly installed in other countries except Korea, the frame type was mainly installed in Korea. Among various water resources, FPVs installed in agricultural water resources have various power generation capacity and coverage ratio whereas FPVs installed in industrial, rainwater storage, and other water resources have relatively high power generation capacity and coverage ratio. Compared to FPVs installed in other water resources, FPVs installed in drinking water resources have relatively low power generation capacity and coverage ratio. After reviewing the major environmental issues related to FPVs (i.e., leaching of hazardous substances, deterioration of water quality and aquatic ecosystem, changes in water temperature and illumination, and disturbance of aquatic ecosystem), the impacts of the FPVs on water environment are found to be insignificant, and the positive effects (i.e., mitigation of green tide and restoration of the aquatic ecosystem) are confirmed.Conclusions : Although the impacts of the FPVs on water environment (water quality and aquatic ecosystem) are found to be insignificant, additional experiments reflecting extreme conditions and long-term continuous monitoring of water quality and aquatic ecosystem in terms of coverage ratio, array and type of FPVs are required.

Vector spatiotemporal solitons in cold atomic gases with linear and nonlinear PT symmetric potentials.

Realizing vector spatiotemporal solitons that are stable in high dimensions is a long-standing goal in the study of nonlinear optical physics. Here, a scheme is proposed to generate three-dimensional (3D) vector spatiotemporal solitons in a cold atomic system with linear and nonlinear parity-time (PT) potentials by utilizing electromagnetically induced transparency (EIT). We investigate the existence and stability of these vector 3D semilunar solitons (SSs) and vortex solitons (VSs) supported by the linear and nonlinear PT potentials. The results show that these solitons have extremely low generation power and very slow propagation velocity and can stably propagate with constant total energy in this system. The frontal head-on collisions of two vector solitons feature quasi-elastic collisions. The dynamics characteristics of these solitons depend on the linear and nonlinear PT-symmetric potential parameters, in particular, the imaginary part of PT potentials. Our study provides a new route for manipulating high-dimensional nonlinear vector optical signals via the controlled optical linear and nonlinear potentials in cold atomic gases.

Circulation of anodic effluent to the cathode chamber for subsequent treatment of wastewater in photosynthetic microbial fuel cell with generation of bioelectricity and algal biomass

Synthetic wastewater containing 1500 mg L−1 of COD was treated in the anode chamber for 5, 10, and 20 d. An anode chamber was conducted under anaerobic conditions with mixed culture bacteria inoculum attached to the anode. Anodic effluent was transferred to the cathode chamber for further treatment for 5, 10, and 20 d as the growth medium of Chlorella vulgaris. The microalgal photosynthesis process provided oxygen for the cathodic reaction. In 5 d of anodic hydraulic retention time (HRT), the effluent contained high COD, resulting in low power generation in the P-MFC due to the heterotrophic metabolism carried out by microalgae diminishing photosynthesis. However, high biomass productivity up to 0.649 g L−1 d−1 was obtained in the subsequent treatment of 5 d in the cathode chamber. An anodic HRT of 10 d resulted in higher power generation (0.0254 kWh kg−1 COD), and higher COD removal efficiency up to 60%. A further 10 d treatment in the cathode chamber increased the COD removal efficiency up to 74%. Anode and cathode chambers combined removed 79% of NH4+–N concentration from the original synthetic wastewater within 20 d. This study demonstrated that the anodic effluent of the P-MFC can be utilized in the cathode chamber as a growth medium for microalgae if conducted with appropriate HRT in the anode. P-MFC provides a promising sustainable solution for wastewater treatment while generating electricity and algal biomass as by-products.