Annual Average Power Research Articles

WIND ENERGY POTENTIAL IN YOBE, NORTHEASTERN NIGERIA: AN AIDED TECHNIQUE THROUGH GEOGRAPHIC INFORMATION SYSTEM AND REMOTE SENSING

The role of wind energy and other renewable energy sources in combating climate change cannot be overemphasized. Many countries including Nigeria have so far implemented policy measures to promote renewable energy. Moreover, the most important step to be taken in order to effectively harness renewable energy is to estimate their potentials in terms of viability and sustainability. This study was focused on evaluate the wind energy potential zones in Yobe State, northeast Nigeria, using integrated multiple criteria decision-making analysis (MCDA), Geographical Information System and Remote Sensing (GIS-RS), and Analytic Hierarchy Process (AHP) methods. Weibull distribution statistical method was applied to validate the GIS-RS based analysis. The study revealed a wind speed variation ranged from 1.48 to 7.15 m/s and an average annual wind power density of about 80 W/m2. About 90 % of study area has about 90 % wind power density of about 85 W/m2 and below while the remaining 10 % is covered by wind power density ranged between 85 and 616.89 W/m2. The results of the study showed that the area is viable for wind power generation and distribution. Furthermore, the wind energy resource will yield favorable economic gain for the study area. Thus the study concluded that Yobe is a suitable area for wind power generation both at medium scale generation, and standalone connection system.

Estimating the spatial distribution of solar photovoltaic power generation potential on different types of rural rooftops using a deep learning network applied to satellite images

Rooftop photovoltaic (PV) power generation is an important form of solar energy development, especially in rural areas where there is a large quantity of idle rural building roofs. Existing methods to estimate the spatial distribution of PV power generation potential are either unable to obtain spatial information or are too expensive to be applied in rural areas. Herein, we propose a novel approach to estimate the spatial distribution of the general potential of rural rooftop power from publicly available satellite images. We divide rural building roofs into three categories based on their orientation and roof angle and propose a revised U-Net deep learning network to extract roof images from satellite images at the macro level. Based on the rooftop detection, a calculation method for the potential area of the installed PV panel at the micro level was developed, considering different types of PV panels and their maintenance methods. By combining the above results and setting the solar radiation parameters and PV system efficiency, we can obtain the spatial distribution of the rooftop PV power generation potential in rural areas. This method is applied in northern China on a village and a town scale, and the overall accuracy of the revised U-Net model can reach over 92%. The spatial distribution information was analyzed and displayed. The annual average PV power generation potential ranges from 26.5 to 36.2 MWh per household and from 7.3 to 10 GWh per village.

Recovery of liquefied natural gas cold energy in a clean cogeneration system utilizing concentrated photovoltaics

Natural gas must be liquefied for long distance transport, so a lot of energy is lost during the liquefaction and regasification process. The innovative system proposed in this study recovers the cold exergy of liquefied natural gas (LNG) regasification process and also uses this potential for concentrated photovoltaics (CPV) cooling. The system uses cascades of organic Rankine cycles (ORC) whose boilers' high-temperature sources are supplied by thermal management of the CPV and low-temperature sides are in thermal contact with LNG flow. In the proposed system, the ORC's organic working fluid cools the CPV heat sink directly to reduce exergy destructions. An analytical thermodynamic and heat transfer model is developed which focuses on the heat transfer within the CPV heat sinks. The proposed system is examined in the ambient conditions of the top five LNG importing countries in the world. The results indicate that the proposed approach can deliver up to 24 MW electrical power, which is improved up to 180% in comparison with using the seawater-driven ORCs. The system produces up to 223 kg/s of cooling water in 7 °C, and its exergetic efficiency is up to 31%. From the CPV cooling point of view, the proposed system in 1000 × solar radiation concentration can keep the CPV temperature below 87 °C. Among studied regions, the best annual average of 2nd law efficiency can be achieved in India, about 28.3%. Utilizing the proposed system in a 100 kg/s LNG regasification unit can result in 26–32 MW of annual average power production, depending on the region it is used.

Photovoltaic distributed generation integrated electrical distribution system for development of sustainable energy using reliability assessment indices and levelized cost of electricity

AbstractReliability assessment index is one of the main performance indicator for analyzing the impact of distributed energy generation system in the utility distribution system and minimize the costs associated with energy interruptions. In this study, sustainable energy development by using integrated photovoltaic distributed generation (DG) system considering reliability assessment indices and levelized cost of energy are presented. Electrical transient and analysis program simulation software are used for evaluation and assessment of the reliability indices based on the failure rate, average annual power interruption/outage time and repair time. The analytical method are used to evaluate the expected interruption cost (ECOST) of the system. HelioScope software is a photovoltaic simulation tool are used to design and calculate the energy generation (kWh) as well as global horizontal irradiation (kWh/m2) of the photovoltaic system. Experimental test system is a radial distribution network consisting of an 11.0 kV feeder emanating from 132.0 kV distribution grid station Satiana. According to the reliability evaluation and assessment of experimental test system before integration of photovoltaic distributed energy generation, the average service availability index (ASAI) is 0.9648 per unit. Then, the expected energy not supplied (EENS) is 772.0308 MWh per year and ECOST is 386,652,468.18 PKR per year. After integration of Photovoltaic DG, ASAI is 0.9741 per unit, then the EENS is 563.8584 MWh per year and integration ECOST is 227,087,143.39 PKR per year. The results showed that integrated PV DG system improve the reliability of conventional energy distribution systems.

REGARDING THE CHARACTERISTICS OF THE WIND IN NORTHERN REGION DISTRICTS OF THE REPUBLIC OF MOLDOVA

The study is focused on three districts in the northern region of the Republic of Moldova – Briceni, Edinet and Ocnita. The maps were calculated and presented in terms of average annual wind speed and wind power density at a height of 100 m above ground level, wind rose and Weibull wind speed distribution. In the calculations performed for the three analyzed districts it was found that the average annual wind speed is between 6.84 and 7.35 m / s, and the wind power density – between 450 and 593 W / m2. The highest annual average speed equal to 7.35 m / s was identified in Ocnita district. At the same time, having the maps of the wind speed and the power density, the convenient locations for the construction of the wind farms can be selected. For each district involved in the study, a location with a pronounced wind potential was identified, recommended for the location of any wind farms.

Numerical heat transfer modeling and climate adaptation analysis of vacuum-photovoltaic glazing

Vacuum-photovoltaic (VPV) glazing has attracted much attention due to its excellent thermal insulation performance and its ability to utilize solar energy. However, few simulation models have been established based on actual products and rarely have been validated by experiments. In this paper, a four-layer CdTe-based VPV glazing was developed and the corresponding numerical heat transfer model was established with the integration of a dynamic power generation model. The numerical model was then validated against both the results from the WINDOW program and a guarded hot box experiment. Afterward, the validated model was employed to analyze the energy and power generation performance of the VPV glazing in diverse climate zones in China with Harbin, Beijing, Changsha, Guangzhou, and Kunming used as representative cities. The numerical simulation results indicate that the U-value of the proposed VPV glazing is 0.89 W/(m2⋅K), which is in good agreement with the experimental results. Compared with a normal double glazing, the average energy reductions achieved with VPV glazing in air conditioning seasons are 128 kWh/m2, 23 kWh/m2, 45 kWh/m2, and 52 kWh/m2 in Harbin, Beijing, Changsha, and Guangzhou, respectively. In addition, the average annual power outputs of VPV glazing in Harbin, Beijing, Changsha, Guangzhou, and Kunming are 47 kWh/m2, 48 kWh/m2, 34 kWh/m2, 36 kWh/m2, and 45 kWh/m2, respectively. The numerical model developed in this study can be used for energy-saving potential analysis and optimization of VPV glazing in different meteorological conditions, the results of which could provide guidance for the effective application of VPV glazing.

신뢰도지표를 활용한 신 가치기반신뢰도평가 (VBDRA) 기반의 배전 설비 투자 선택 방안 연구

We select the optimal distribution system investment plan, which has the largest ratio of the financial benefit and investment cost. We measure the financial benefit of investment plan based on the improvement level of reliability index on the target distribution system. However, in the classical value based distribution system reliability assessment (VBDRA), the financial benefit was measured based on the reliability index itself, so our approach is a new VBDRA. The improvement level of reliability index is converted to the financial benefit by multiplying the electricity interruption cost. In this study, we also introduce the reliability index calculation method based on three basic reliability parameters: average failure rate, average power outage time, and average annual power outage time. Then, we calculate the reliability index of six different distribution systems. Finally, we measure reliability index and financial benefits of three virtual distribution systems with different investment plans on distribution components. Based on the ratio of financial benefits to investment costs, we select the optimal distribution system investment plan.

Efficiency Enhancement of Tilted Bifacial Photovoltaic Modules with Horizontal Single-Axis Tracker—The Bifacial Companion Method

Bifacial photovoltaic modules combined with horizontal single-axis tracker are widely used to achieve the lowest levelized cost of energy (LCOE). In this study, to further increase the power production of photovoltaic systems, the bifacial companion method is proposed for light supplementation and the efficiency enhancement of tilted bifacial modules with a horizontal single-axis tracker. Specifically, a solar reflector is added to the rear end of the tilted bifacial photovoltaic module to guide the sunlight and promote power generation on the rear end. The technical feasibility of the proposed method is verified through optimal calculation and prototype experimental test. The theoretical calculation results suggest that the bifacial companion system is particularly suitable for mid-to-high latitude areas. The higher the latitude, the higher the gain ratio of generated power in the system; there is an optimal module tilt angle that maximizes the efficiency at different latitudes. The closer the module tilt angle to the optimal tilt angle, the higher the power generation efficiency of the system. Meanwhile, compared to the fixed solar reflector, the use of tracking solar reflector is more conducive to improving the power generation efficiency of the system. For the 37.5° latitude area, the annual average power generation gain ratio of the bifacial companion system with tracking solar reflector and fixed solar reflector can reach up to 30% and 17%, respectively. Additionally, the test results for the three sets of bifacial companion prototypes (module tilt angles of 10°, 20°, and 30°) with a fixed solar reflector show that the maximum gain ratio of daily power generation in August 2021 are 8.2%, 13%, and 18.1%, and that in September 2021 are 7%, 8.7% and 13.7%, respectively, which are consistent with the theoretical results.

Energy Efficiency and Distributed Generation: A Case Study Applied in Public Institutions of Higher Education

This study focused on developing a sustainability project carried out in 11 Federal Institute of Education, Science, and Technology of Goiás (IFG) campuses wherein energy efficiency and distributed generation actions were developed. Energy consumption was optimized by retrofitting the lighting system, installing a photovoltaic (PV) generation system, quantifying the building efficiency, energy monitoring, training, and qualification, and focusing on the efficient use of electric energy. We first present the Brazilian legislation that regulates the Research and Development Program in the electric energy sector. Then, we describe the case study that was applied to the educational institution. In the lighting system, 18,377 inefficient lamps were replaced by lamps with more efficient technology, with an energy saving of 867.9 MWh/year and a peak demand reduction of 309.6 kW. The proposed generation system aimed to install 3076 PV modules on the roofs of selected campus buildings, totaling 1 MWp of installed power with an average annual power generation of 1736.9 MWh/year. The total project investment was USD 1,348,768.50 and the overall cost–benefit ratio of the project was 0.68, which will result in annual savings of approximately USD 197,321.85. This corresponded to a 58% reduction in energy bills. The project proposed in this work was considered technically and economically viable within the scope of the Brazilian Energy Efficiency Program.

Project Design of a Pulsed D-D Fusion Neutron Source Based on Field Reversed Configuration

The fusion neutron source is of great significance for conducting material testing for future fusion reactors, as it can genuinely reflect the change of material properties under fusion neutron irradiation. The International Fusion Materials Irradiation Facility (IFMIF) is an accelerator-driven neutron source. It still has some differences from the ideal fusion neutron source in terms of fusion neutron energy spectrum, which has led to the reconsideration of the fusion neutron source approach. In this paper, the magnetic field configuration, heating scheme design, and related calculations are carried out regarding the fusion neutron source. The plasma temperature, density evolution process, and the corresponding neutron yield of the field reversed configuration (FRC) plasma after two-stage cascade magnetic compression are analyzed, and the suppression of the magnetic fluid instabilities such as tilted and rotating modes of the FRC plasma after considering the two-fluid effect and the finite Larmor radius effect are studied. The fundamental physical parameters of the fusion neutron source are finally given. The calculation results show that the neutron source is expected to obtain fusion neutrons with an annual average power density higher than 2 MW/m², which can meet the requirements of material testing of the demonstration reactors (DEMO). The power estimation also shows that the scheme has the potential to become an energy source based on the pulsed deuterium-deuterium fusion.

Identifying the functional form of operating rules for hydro–photovoltaic hybrid power systems

The hybrid operation of multiple renewables offers a promising option for enhancing resource use efficiency in power systems. The power system operation is guided by operating rules with specified functional forms, e.g., linear operating rules. However, the functional form of the operating rules is pre-determined instead of theoretically analyzed in previous research. This study aims to identify the functional form of the operating rules for hydro–photovoltaic hybrid power systems using mathematical derivation. First, a two-stage hybrid operation model is formulated with current and future stages. The future stage divides the uncertain inflow into two ranges according to whether the water spill happens. After that, the optimal operating condition is obtained by maximizing the power generation for the hybrid operation model. Finally, the analytical functional form of the operating rules is derived by approximating the stage-storage relationship and probability distribution functions with polynomials. The case study of Ertan hydro–photovoltaic hybrid power system from China shows that the proposed operating rules increase the average annual power generation from 16.71 to 17.37 billion kWh (3.95%) compared with the standard operating policy. Therefore, the derived functional form of the operating rules could offer guidelines for effectively improving the hydro–photovoltaic hybrid operation.

Feasible Distributed Energy Supply Options for Household Energy Use in China from a Carbon Neutral Perspective.

This contribution firstly proposed the concept of annual average power generation hours and analyzed per capita energy consumption, carbon emission, and the human development index from a macro perspective. On this basis, we compared the average household electrical energy consumption of urban and rural residents based on the data from CGSS-2015 from a micro perspective. The results show the positive correlation between carbon emissions per capita and the human development index and China’s regional imbalance characteristics between household electricity consumption and renewable energy distribution. Therefore, the distributed energy supply system is proposed as an effective complement to centralized power generation systems and is the key to synergizing human development and carbon emissions in China. Moreover, we analyzed the characteristics of distributed energy supply systems in the context of existing energy supply systems, pointing out the need to fully use solar energy and natural gas. Finally, two types of typical distributed energy supply systems are proposed for satisfying the household energy requirements in remote or rural areas of western and the eastern or coastal areas of China, respectively. Two typical distributed energy systems integrate high-efficiency energy conversion, storage, and transfer devices such as electric heat pumps, photovoltaic thermal, heat and electricity storage, and fuel cells.

Probabilistic Method for Estimating the Level of Reliability of Solar Photovoltaic Systems for Households in Ghana

Renewable Energy Resources have been identified among the most promising sources of harnessing power for industrial and household consumption but their power generations highly uctuate so building renewable power systems without critical reliability analysis might result in frequent blackouts in the power system. Therefore, in this paper, a robust, effective and ecient design approach is proposed to handle the reliability issues. The study involves a Mathematical modelling strategy of the PV system to estimate the total PV power produced and the Bottom-Up approach for predicting the household load demand. The reliability is defined in terms of Loss of Load Probability. The design methodology was validated with a University Household. The data used for the analysis consists of daily average global solar irradiance and load profiles. The results revealed that throughout the year, November-February is where the system seems to be more reliable. Also, the results indicated that without buck-up systems, the system would experience an average annual power loss of 17.8753% and thus, it is recommended that either solar batteries or the grid are used as backup system to achieve a complete level of reliability.

Study on the performance and free cooling potential of a R32 loop thermosyphon system used in data center

Loop thermosyphon system is an efficient cooling system for energy saving in data center. It is necessary to investigate the performance of the loop thermosyphon system filled with alternative refrigerants to prompt its application. In this paper, a R32 loop thermosyphon system is experimentally investigated in an enthalpy difference laboratory for its performance. R22 and R134a are also used for comparison. The results show that the optimal filling ratio of R22, R134a and R32 is the same (37.3%). At the optimal filling ratio, the flow stability of R32 is obviously better than those of R22 and R134a. When cold water temperatures are 10–22 °C, the cooling capacity of R32 is 5.4–15.6% higher than those of R22 and R134a. After controlling extractor fans, the energy efficiency ratio of R32 is 4.9–206.6% higher than those of R22 and R134a. Moreover, the free cooling potentials of the three refrigerants in five typical climate cities across China are analyzed and compared. Compared with R22 and R134a, R32 has 3.6–11.0% and 18.5–26.7% higher free cooling percentages and annual energy efficiency ratio, respectively; and its annual average partial power usage effectiveness is 0.0012–0.0017 lower than that of other two refrigerants.

A Novel 10 kW Vertical Axis Wind Tree Design: Economic Feasibility Assessment

A novel, small-scale vertical axis wind turbine tree was designed using turbines combining both Darrieus and Savonius blades. We tested for economic viability using wind data collected at a site in Surat Thani, Thailand. The Weibull distribution and Monte Carlo modeling with financial indices (Levelized Cost of Electricity (LCOE), Net Present Value (NPV), Internal Rate of Return (IRR), and Simple Payback Period (SPP)) were used to analyze data. We found that monthly mean wind speeds varied from 2.35 m/s in October to 2.84 m/s in February, corresponding to a wind power of 28.43 W/m2 and 42.68 W/m2. The average annual power output was 1446.1 kWh for May 2019 to April 2021. Results show that for turbine cut-in to cut-out speeds (2 m/s to 15 m/s), the prototype has potential economic feasibility (NPV > 0 for 64.93%), although the small capacity of the wind tree, in combination with the low average wind speed at the Surat Thani test site, showed a lack of economic viability at this specific location (NPV = USD − 20,946.29). A higher-wind-speed location (Chiang Mai) showed viability, especially at a 10 m height (NPV > 0 for 84.83%). We discuss potential conditions that would make broader use of the prototype feasible.

Air quality-related health co-benefits from Pennsylvania’s entry into the Regional Greenhouse Gas Initiative (RGGI)

BACKGROUND AND AIM: Climate policies can provide local health co-benefits by simultaneously reducing local and regional air pollutants co-released with greenhouse gas emissions. The Regional Greenhouse Gas Initiative (RGGI) is a regional cap and trade system that seeks to reduce CO₂ emissions from the electric power sector in eleven northeastern and mid-Atlantic states in the United States. Here we focus on Pennsylvania’s anticipated entry into RGGI in 2022. As a major power producer and carbon-emitter in the PJM interconnection (i.e., the Regional Transmission Organization that manages the wholesale electricity market in Pennsylvania and twelve other states), Pennsylvania’s participation affects both the PJM electricity market and the RGGI carbon market. METHODS: By combining a power system model of PJM with a reduced form model of CO₂ emissions abatement from RGGI states that are not in PJM, we first simulate the effects of Pennsylvania’s participation in RGGI on electricity market outcomes, CO₂ emissions, and other local and regional air pollutants. We then use a range of marginal damage estimates derived from reduced-form air pollution models to monetize air quality-related health impacts. RESULTS:Comparing the scenarios with and without Pennsylvania’s participation in RGGI, we find the annual average power sector CO₂ emissions in Pennsylvania to be 40% lower from 2022 to 2030. During the same time period, the annual emissions are 79%, 68% and 76% lower for SO₂, NOx and PM2.5 emissions, respectively. Such a reduction in co-emitted air pollutants leads to cumulative health co-benefits of $17.7 billion to $40.8 billion. However, the reduced emissions and health damages in Pennsylvania are slightly offset by increases in the other states in PJM that do not participate in RGGI. CONCLUSIONS:Our study highlights the large potential for health co-benefits from Pennsylvania’s entry into RGGI, though the cross-state leakage issue requires careful consideration in the policy design and implementation process. KEYWORDS: Air pollution, climate, health co-benefits, policy

Study on appearance and electrical properties of reused solar modules

A test platform for reused solar modules was established in Wuhan in order to study the appearance changes, aging problems and degradation rate in electrical properties of the reused modules. The photovoltaic modules were mono-Si modules produced by Siemens in 1996. It was found that there was moisture at the edge of the modules. The aging of tin-coated copper strip was obvious, and there was blackening phenomenon. There were many white spots on the solar cells around the tin-coated strip, and the solar cells turned blue locally. The average annual power attenuation rate of different modules varied greatly, but it was mainly related to the increase of series resistance of modules. The integrated average annual power attenuation of PV modules was about 3.59% during 4 years.

Assessment of wind energy resources in the urat area using optimized weibull distribution

Accurate assessment and analysis of wind energy resources are the key to wind farm planning. In this study, we evaluate the wind energy resource potential in the Urat area of Inner Mongolia, China, based on data measured from four 70–100 m/s wind tower. We first model the wind speed by the Weibull distribution where the parameters are estimated by various numerical and intelligent optimization methods. In particular, we introduce the Cross Entropy Method (CEM) and find that it outperforms other methods. Based on the Weibull model, we then evaluate six wind energy metrics for the Urat area. It is shown that the annual average wind speed and wind power density are up to 9.33 m/s and 941 W/m2, respectively, with over 7000 h of annual available time. The wind is relative stable for all seasons except for a mild reduction in speed and a change of direction in summer. The low power production cost and rapid payback period make the Urat area a promising location for deploying wind farms.

Evaluation of Wind Energy Potential in Rayong Province, Thailand by WAsP Program

Over the past decades, Wind energy is one of the alternative energy or renewable sources, which has been harvested to produce electricity. Our research aims to study the wind potential of the areas in the Rayong provinces of Thailand. Data from meteorological stations were collected every 10 minutes for of 3 years (2017-2019), with a measuring tower at 10-meter height above ground level (AGL). The annual average wind speeds were investigated in Rayong (2.02 m/s) with Weibull Probability Distribution Function (PDF). The annual average power density in Rayong regions was 13 W/m2. In all locations, wind direction was detected mainly from Southwest (SSW) and the yearly maximum wind power capacity is 94.376 MWh. The capacity factor of 21.5 % was noticed. With relatively low wind speed was noticed in Rayong provinces of Thailand, a small wind turbine installed at 30 meters would be recommended as a cost-effective way to convert wind power to electricity.

Production flexibility of small run-of-river power plants: KWGO smart-storage case study

In the framework of the new Swiss feed-in-tariff system for Small Hydropower Plants (SHP), the aim of the SmallFLEX project, led by HES-SO Valais and performed in collaboration with EPFL, WSL, EAWAG, PVE and FMV, is to show how SHP can provide winter peak energy and ancillary services, whilst remaining eco-compatible. The pilot and demonstrator site selected is the new SHP of Gletsch-Oberwald (KWGO) owned by FMV and commissioned end of 2017. This run-of-river power plant is equipped with two six-jets Pelton turbine units featuring a maximum power of 7.5 MW each while the average annual power is lower than 5 MW, with a maximum of production during the summer. The capacity of infrastructure, equipment, and other adaptation measures to produce in a flexible way is being assessed while measuring the impact of this new operation on the environment, production and revenues. The paper focuses on the two experimental campaigns and the numerical simulations carried out to assess the flexibility of the power plant by means of smart use of existing infrastructure as additional storage volumes: the settling basin, the forebay and the upper part of the headrace tunnel.