Local Grid Research Articles

Chemistry, Microstructure, and Interphases of Magnesium Metal Anodes Captured Via Cryogenic Electron Microscopy

Lithium-ion batteries are an important component in mobile electronics; however, their modest energy density makes them less than ideal for use in all-electric vehicles or localized grid residential/commercial energy storage. Multivalent-ion batteries (MIBs), including Mg2+, are promising high-energy density technologies that are cheaper and more abundant than lithium. Realizing the high theoretical energy density of MIBs requires the native multivalent-ion metal to be used as the anodic electrode, where densely controlled metal plating and stripping has yet to be achieved. The mechanisms governing plating/stripping of MIBs and the resulting microstructural impact on the battery performance must be understood before MIBs can be employed commercially. Understanding the role that the solid electrolyte interface has on multivalent-ion metal plating/stripping may lead to solutions for controlling reversible anodic cycling.Recent advances in cryogenic electron microscopy(cryo-EM) preparation have allowed for scanning transmission electron microscopy (STEM) investigation of intact solid/liquid interfaces and electron-beam-sensitive materials. Here we present results of our chemical and microstructural investigation of plated and stripped Mg2+ anodes, collected with cryo-FIB preparation, cryo-transfer, and cryo-STEM. Details will be presented on the anode porosity, grain orientation maps, chemical maps from the electrode/electrolyte interfaces, and high-resolution structural imaging of the electrode interfaces.This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE’s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government.

Technical performance analysis of a 40 kW photovoltaic installation

To reduce the consumption of classically produced electric energy, which is an important green gas pollution factor, various renewable energy sources are now implemented on larger and larger scale. Both industrial and household consumers make use of such renewable energy sources. This work presents the characteristics and performance of a 40 kW photovoltaic installation mounted on the roof of an industrial production hall. The design and the implementation of the photovoltaic installation allows it to function while connected to the local power grid. On-site measurements have shown that the installation ensures symmetric voltages and currents, functioning at the planned parameters

An efficient embedded discrete fracture model based on the unstructured quadrangular grid

It is important yet challenging to effectively and accurately predict the recovery of fractured reservoirs. Among numerous fractured reservoir simulation models, the embedded discrete fracture model (EDFM) is the most outstanding one for it incorporates the discrete fractures into structured grids of the matrix, which precisely describes the arbitrarily distributed fractures while not increasing the gridding and calculation complexity. However, the current EDFM still possesses drawbacks for its structured grid shows poor adaptivity to irregularly shaped reservoirs, and also causes a sharp pressure gradient between the matrix and fractures and weakens the simulation accuracy. To conquer the drawbacks of the current EDFM, an unstructured quadrangular grid-based EDFM (UnQ-EDFM) is proposed in this paper. In this model, a frontal Delaunay quadrangular grid is adopted that could perfectly adapt to irregular reservoir boundaries without increasing the grid number and gridding complexity; besides, local grid refinement could be achieved flexibly in anywhere of the reservoir, which effectively alleviates the simulation error while not adding too much calculation. Based on the UnQ-EDFM, the production of a multi-stage hydraulic fractured well in irregular shaped naturally fractured shale gas reservoir is simulated, the simulation results under different types of grids are compared. Furthermore, an optimization framework that applies WOA as the optimization algorithm and NPV as the objective function is constructed, the hydraulic fractured well in the above-mentioned reservoir is optimized and the reliability of the UnQ-EDFM is testified through thousands of times of simulation. The results of simulation and optimization demonstrate the reliability and superiority of the UnQ-EDFM over the traditional structured grid-based EDFM, for it adapts to complex-shaped reservoirs, maintains high simulation accuracy, and reduces simulation time, simultaneously. The UnQ-EDFM proposed in this paper severs as an efficient tool and contributes to the precise and efficient simulation for the fractured reservoirs’ development.

Onsite Non-potable Reuse for Large Buildings: Environmental and Economic Suitability as a Function of Building Characteristics and Location

Onsite non-potable reuse (NPR) is a way for buildings to conserve water using onsite sources for uses like toilet flushing, laundry and irrigation. Although early case study results are promising, aspects like system suitability, cost and environmental performance remain difficult to quantify and compare across broad geographic contexts and variable system configurations. In this study, we evaluate four NPR system types – rainwater harvesting (RWH), air-conditioning condensate harvesting (ACH), and source-separated graywater and mixed wastewater membrane bioreactors (GWMBR, WWMBR) – in terms of their ability to satisfy onsite non-potable demand, their environmental impacts and their economic cost. As part of the analysis, we developed the Non-potable Environmental and Economic Water Reuse Calculator (NEWR), a publicly available U.S. EPA web application that allows users to generate planning-level estimates of system cost and environmental performance using location and basic building characteristics as inputs. By running NEWR for a range of scenarios, we find that, across the U.S., rainfall and air-conditioner condensate are only able to satisfy a fraction of the non-potable demand typical of large buildings even under favorable climate conditions. Environmental impacts of RWH and ACH systems depend on local climate and were comparable to the ones of MBR systems where annual rainfall exceeds approximately 10 in/yr or annual condensate potential exceeds approximately 3 gal/cfm. MBR systems can meet all non-potable demands but their environmental impacts depend more on the composition of the local energy grid, owing to their greater reliance on electricity inputs. Incorporation of thermal recovery to offset building hot water heating requirements amplifies the influence of the local grid mix on environmental impacts, with mixed results depending on grid composition and whether thermal recovery offsets natural gas or electricity consumption. Additional environmental benefits are realized when NPR systems are implemented in water scarce regions with diverse topography and regions relying on groundwater sources, which increases the benefits of reducing reliance on centralized drinking water services. In terms of cost, WWMBRs were found to have the lowest cost under the largest range of building characteristics and locations, achieving cost parity with local drinking water rates when those rates were more than $7 per 1000 gallons, which occurred in 19% of surveyed cities.

PV park site selection for utility-scale solar guides combining GIS and power flow analysis: A case study on a Swedish municipality

Utility-scale solar photovoltaic (PV) parks have dominated the international market for the past few years. However, in some countries, like Sweden, utility-scale PV is on the verge to economic viability. Using existing infrastructure in a resource-efficient manner could be a crucial strategy for a successful implementation at scale. In this study, a new methodology for a utility-scale solar guide is developed by studying the hosting capacity in the local grid and identifying land appropriate for PV parks. The method is applied on a rural municipality in Sweden (512 km2) with a local distribution grid (5,000 customers). The impact on the grid, if connecting a PV park to a substation, was analyzed through power flow simulations and the geographical assessment was done using multi-criteria analysis with a Boolean approach. Three different sizes of PV parks, 1, 3, and 5 MWp, were analyzed. Results showed that 3.7% of the studied area is qualified for locating 1 MWp PV parks. However, if introducing a maximum distance threshold to the nearest substation that can host the PV generation from the park, the potential is further reduced (e.g., to 1% for a 750 m threshold). Furthermore, parts of the grid can host PV parks of 3 and 5 MWp, but only near urban areas, where qualified land is lacking. The results highlight that the proposed methodology can function as a tool in the dialog between utility companies, municipalities, PV companies, land-owners and other stakeholders in order to find resource- and system-efficient locations for PV parks.

Water droplet freezing on cold surfaces with distinct wetabilities

This paper investigates the total freezing time of droplets on surfaces with various wettabilities with horizontal and inclined orientations. A two-dimensional Volume of Fluid (VOF) method was applied to capture the liquid-air interface, and an automatic localized grid treatment technique was applied to increase the accuracy, especially near the impact and spreading areas. The Kistler and Shikhumurzaev dynamic contact angle models were implemented to impose the dynamic contact angles on different surfaces. An enthalpy-porosity technique was used to predict the phase change of droplets after impact with the surface. The results of the nondimensional droplet diameter ratios and total freezing times for both dynamic contact angle models have been presented and verified with experimental data. The effects of both wetting properties and the surface inclination on the freezing time have been analyzed. The results indicate that a lower surface temperature, a decrease in static contact angle and a higher inclination will result in more rapid freezing of droplets.

Hierarchical Path-Planning for Mobile Robots Using a Skeletonization-Informed Rapidly Exploring Random Tree*

An efficient, hierarchical, two-dimensional (2D) path-planning method for large complex environments is presented in this paper. For mobile robots moving in 2D environments, conventional path-planning algorithms employ single-layered maps; the proposed approach engages in hierarchical inter- and intra-regional searches. A navigable graph of an environment is constructed using segmented local grid maps and safe junction nodes. An inter-regional path is obtained using the navigable graph and a graph-search algorithm. A skeletonization-informed rapidly exploring random tree* (SIRRT*) efficiently computes converged intra-regional paths for each map segment. The sampling process of the proposed hierarchical path-planning algorithm is locally conducted only in the start and goal regions, whereas the conventional path-planning should process the sampling over the entire environment. The entire path from the start position to the goal position can be achieved more quickly and more robustly using the hierarchical approach than the conventional single-layered method. The performance of the hierarchical path-planning is analyzed using a publicly available benchmark environment.

Combinatorial Double Auction Based Meta-scheduler for Medical Image Analysis Application in Grid Environment

Background: Medical image analysis application has complex resource requirement. Scheduling Medical image analysis application is the complex task to the grid resources. It is necessary to develop a new model to improve the breast cancer screening process. Proposed novel Meta scheduler algorithm allocate the image analyse applications to the local schedulers and local scheduler submit the job to the grid node which analyses the medical image and generates the result sent back to Meta scheduler. Meta schedulers are distinct from the local scheduler. Meta scheduler and local scheduler have the aim at resource allocation and management. Objective: The main objective of the CDAM meta-scheduler is to maximize the number of jobs accepted. Methods: In the beginning, the user sends jobs with the deadline to the global grid resource broker. Resource providers sent information about the available resources connected in the network at a fixed interval of time to the global grid resource broker, the information such as valuation of the resource and number of an available free resource. CDAM requests the global grid resource broker for available resources details and user jobs. After receiving the information from the global grid resource broker, it matches the job with the resources. CDAM sends jobs to the local scheduler and local scheduler schedule the job to the local grid site. Local grid site executes the jobs and sends the result back to the CDAM. Success full completion of the job status and resource status are updated into the auction history database. CDAM collect the result from all local grid site and return to the grid users. Results: The CDAM was simulated using grid simulator. Number of jobs increases then the percentage of the jobs accepted also decrease due to the scarcity of resources. CDAM is providing 2% to 5% better result than Fair share Meta scheduling algorithm. CDAM algorithm bid density value is generated based on the user requirement and user history and ask value is generated from the resource details. Users who, having the most significant deadline are generated the highest bid value, grid resource which is having the fastest processor are generated lowest ask value. The highest bid is assigned to the lowest Ask it means that the user who is having the most significant deadline is assigned to the grid resource which is having the fastest processor. The deadline represents a time by which the user requires the result. The user can define the deadline by which the results are needed, and the CDAM will try to find the fastest resource available in order to meet the user-defined deadline. If the scheduler detects that the tasks cannot be completed before the deadline, then the scheduler abandons the current resource, tries to select the next fastest resource and tries until the completion of application meets the deadline. CDAM is providing 25% better result than grid way Meta scheduler this is because grid way Meta scheduler allocate jobs to the resource based on the first come first served policy. Conclusion: The proposed CDAM model was validated through simulation and was evaluated based on jobs accepted. The experimental results clearly show that the CDAM model maximizes the number of jobs accepted than conventional Meta scheduler. We conclude that a CDAM is highly effective meta-scheduler systems and can be used for an extraordinary situation where jobs have a combinatorial requirement.

Graph Search-Based Exploration Method Using a Frontier-Graph Structure for Mobile Robots.

This paper describes a graph search-based exploration method. Segmented frontier nodes and their relative transformations constitute a frontier-graph structure. Frontier detection and segmentation are performed using local grid maps of adjacent nodes. The proposed frontier-graph structure can systematically manage local information according to the exploration state and overcome the problem caused by updating a single global grid map. The robot selects the next target using breadth-first search (BFS) exploration of the frontier-graph. The BFS exploration is improved to generate an efficient loop-closing sequence between adjacent nodes. We verify that our BFS-based exploration method can gradually extend the frontier-graph structure and efficiently map the entire environment, regardless of the starting position.

An Analysis on Intelligence Innovation with Spirit of Artisans Under Ubiquitous Network in Grid Enterprises

The paper discusses the relationship of spirit of artisans and intelligence Innovation. The survey shows that Intelligence Innovation has great contribution to organizational performance in an intelligent era. The survey from local state grid corporations shows that the interaction between the Artisan spirit and refinement process innovation under Ubiquitous Network in Grid Enterprises and organizational psychological empowerment acts as a significant moderator. This research provides useful tools for organizational intelligence innovation through the exertion of enterprise’ craftsmen examples.

Economic investigation of a Vanadium Redox BESS for the exploitation of wind power rejections in an isolated Greek Island

Greece has plenty of electrically isolated Islands. Most of them, like Crete, Lesvos, or Chios have a great Aeolian Potential which remains un-exploitable due to Power Grid limitations. The aim of this paper is to investigate the possibility of integrating a Vanadium Redox Battery Energy Storage System in order to minimize the unharnessed wind power owing to the local grid limitations. For this purpose, real time series data of theoretical energy production and wind power rejections of two Wind Parks operated in a Medium Size Greek Island which reached the 17% of their theoretical production capability in 2014 will be used. Additionally, the Island load demand hourly variation coming from the archives of the private company that owns the wind parks are used. Based on these data and the electrical model of the Vanadium Redox Batteries (VRB) several simulations for various VRB power/energy capacity combinations were conducted and their capabilities in wind energy recovery were estimated. Afterwards, the simulated systems were examined from the aspect of economic viability with the use of economic indices such as the Internal Rate of Return (IRR) and the Net Present Value (NPV). Finally, the influence on the feasibility of such an investment caused by factors like the selling price of energy provided to the grid based on the VRB initial capital cost found in recent Lazard’s Levelized Cost of Storage (LCOS) were examined in detail. Among many significant results drawn by this simulation, it was found that the maximum percentage of the rejected energy that can be exploited (stored) by the batteries is 60% while the 47% can be reinjected back to the Grid, a fact that leads to a relatively expensive selling price of the Energy that comes from the batteries in order to keep the investment feasible.

Techno-economic analysis of remote microgrid and high voltage interconnected grid development in isolated area

Seram Island is one of the thousand islands in Indonesia. Due to geographical condition, the power system in Seram Island is currently remain isolated. However, based on Electricity Power Supply Business Plan (RUPTL) 2019-2028, there are power system development plan including 150 kV interconnected grid and several medium-sized power plant in this island. Unfortunately, as demand growth is low, reserve margin in related system tend to be very high, with the average of 182% from year 2019 to 2028. With this circumstance, the development plan based on RUPTL 2019-2028 will not be viable both technically and economically. This study will analyze remote microgrid development as an alternative to high voltage interconnected grid in order to perceive optimum configuration for Seram Island. These two alternatives will be compared both technically and economically. Technical analysis will be conducted using software ETAP 12.6 to investigate power quality and system stability. For economical analysis, several economics parameter will be evaluated as well as Levelized Cost of Electricity (LCOE) to perceive the most economically viable alternative. The result shows that remote microgrid is economically more beneficial to be developed in Seram Island, as well as complying the minimum technical requirement of local grid code.

Finite element error analysis on transmission shaft parts and application of local mesh refinement

In view of the strength problem of the transmission shaft parts in the swinging and punching structure of the forging press, based on the finite element analysis theory and the mesh refinement method, the accuracy of the finite element calculation in the whole mesh refinement process is analyzed by comparing the element strain energy error and the energy percentage error of different node numbers. The results show that the edge length of the discretized element is reduced and the calculation accuracy is improved correspondingly, but the calculation amount of the whole mesh refinement is large.Therefore, local mesh refinement is applied to improve the calculation accuracy. The results show that the error of energy percentage tends to be 10%, and the calculation accuracy is high. The accuracy analysis method and the application of local grid refinement provide the theoretical basis for the structural optimization of mechanical products.

PPMaP: Reproducible and Extensible Open-Source Software for Plant Phenological Phase Duration Prediction and Mapping in Sub-Saharan Africa

Understanding the detailed timing of crop phenology and their variability enhances grain yield and quality by providing precise scheduling of irrigation, fertilization, and crop protection mechanisms. Advances in information and communication technology (ICT) provide a unique opportunity to develop agriculture-related tools that enhance wall-to-wall upscaling of data outputs from point-location data to wide-area spatial scales. Because of the heterogeneity of the worldwide agro-ecological zones where crops are cultivated, it is unproductive to perform plant phenology research without providing means to upscale results to landscape-level while safeguarding field-scale relevance. This paper presents an advanced, reproducible, and open-source software for plant phenology prediction and mapping (PPMaP) that inputs data obtained from multi-location field experiments to derive models for any crop variety. This information can then be applied consecutively at a localized grid within a spatial framework to produce plant phenology predictions at the landscape level. This software runs on the ‘Windows’ platform and supports the development of process-oriented and temperature-driven plant phenology models by intuitively and interactively leading the user through a step-by-step progression to the production of spatial maps for any region of interest in sub-Saharan Africa. Maize (Zea mays L.) was used to demonstrate the robustness, versatility, and high computing efficiency of the resulting modeling outputs of the PPMaP. The framework was implemented in R, providing a flexible and easy-to-use GUI interface. Since this allows for appropriate scaling to the larger spatial domain, the software can effectively be used to determine the spatially explicit length of growing period (LGP) of any variety.

Joint Virtual Energy Storage Modeling with Electric Vehicle Participation in Energy Local Area Smart Grid

In this research, the joint virtual energy storage modeling with electric vehicle participation in energy local area Smart Grid is considered. This article first constructs a virtual energy storage model and a joint virtual energy storage model for air conditioning and electric vehicles. Therefore, for the optimization problem of virtual energy storage power, a continuous rolling optimization algorithm to determine the feasible solution of the high-dimensional complex constraint optimization problem is proposed to solve the optimization problem. Finally, the analysis, for example, illustrates the economics of joint virtual energy storage in the Smart Grid. The results prove that air conditioning and electric vehicles have the ability to jointly participate in virtual energy storage, and the comparison proves that joint virtual energy storage can effectively improve the economics of electricity consumption.

Environmental Overcost of Single Family Houses in Insular Context: A Comparative LCA Study of Reunion Island and France

The building and public works sector is, in France as in Europe, a major consumer of raw materials for both the manufacture of products and the construction of buildings and structures. This sector has a direct impact on the natural and built environment. This effect is even more pronounced in the case of isolated territories, such as islands. The latter have their own constraints (geographical location, production of the local grid mix) and particularities: very small territory, massive importation of goods in all fields, such as food, automobile, building, and others). In this study, we focus on the building branch of the construction industry, which covers housing (single-family houses and apartment blocks). The study is based on the analysis of about twenty single-family houses built in metropolitan France and Reunion Island. The construction standards for these two regions comply with European standards (CE) and French regulations. However, in the case of Reunion Island, a tropical island, it applies in particular to the Thermal, Acoustic, and Ventilation Regulations for New Buildings in Overseas Departments and Regions (RTAA DROM). The approach that is used for the environmental assessment of single-family homes is the Life Cycle Assessment (LCA), from cradle to grave. The results initially showed that there is an additional environmental cost in the construction sector between France and Reunion Island. This is initially due to the choice of origin of materials and products, which can greatly contribute to the impacts of construction. Secondly, to the use of the countries’ electricity mix, which also contributes, in part, to the impact of the construction of these single-family homes during the assembly and transformation of the products. Finally, this additional cost also differs according to the transport used (sea, air, rail, road). For the Global Warming Potential (GWP) indicator, in our study we note that the additional environmental cost is 37% higher in Reunion Island. This figure explains the additional impact of the 218 kg-CO2eq/m2 of built-up area built for Reunion Island. This study is one of the first analyses demonstrating the additional environmental cost that exists between mainland France and overseas France. Thus, the results demonstrate the importance of creating a specialized and regionalized database for the case of remote islands. Thus, this database would allow for professionals to have a precise environmental assessment, not on a national but on a regional scale. This document also provides a framework and guideline for policy decision-making in the overseas islands.

Development of coupled two phase flow and geomechanics model to predict stress evolution in unconventional reservoirs with complex fracture geometry

Understanding stress changes associated with reservoir depletion is very important for developments of unconventional reservoirs such as completion of infill well. Fluid flow in reservoir often contains multiple phases mostly a mix of oil and water phase. Multiphase flow in porous media also involves in many applications including water injection. In this paper, we have upgraded our coupled fluid flow and geomechanics with Embedding Discrete Fracture Model (EDFM) to two phase flow using OpenFOAM, an open-source platform for CFD, in order to expand the model to wider range of applications including characterization of stress evolution associated with depletion of two-phase flow in unconventional reservoirs with complex fracture geometries. Coupled geomechanics and fluid-flow was developed based on well-known fixed-stress split, which is unconditionally stable and computationally efficient to simulate how stress changes during reservoir depletion. EDFM was coupled to the model to gain capability of simulating complex fracture geometries using structured grids. The two phase model is based on Implicit Pressure Explicit Saturation (IMPES) method. Validations of our single phase model and EDFM were conducted in our previous paper. Validation of two phase model was done against analytical solution of Buckley-Leverett and Capillary-gravity equilibrium problems. In addition, validation of EDFM part was conducted against local grid refinement. The model was used to run performance test on water injection-oil production problem with geomechanics and capillary effect. Non-planar fractures under production was also used to test for EDFM part. Finally, we applied our model in simulation of 3D multiple fractures under production in a fully 3D reservoir. The results indicate that created fracture geometries have a significant effect on stress distribution and reorientation induced by depletion. Characterization of stress evolution due to reservoir depletion in two phase flow will provide critical guidelines for optimization of completion designs especially in infill well drilling and further development in unconventional reservoirs.

A Numerical Study of Hypoxia in Chesapeake Bay Using an Unstructured Grid Model: Validation and Sensitivity to Bathymetry Representation

AbstractA three‐dimensional unstructured‐grid hydrodynamic and water quality model (Semi‐implicit Cross‐scale Hydroscience Intergrated System Model‐Integrated Compartment Model) is applied successfully for Chesapeake Bay. The model is validated with observations of salinity, chlorophyll‐a, dissolved oxygen, nutrients, and phytoplankton productions from the year 1991 to 1995 for the mainstem and some major tributaries, based on multiple model skill scores. Model experiments are conducted to test the importance of having (1) an accurate representation of bathymetry to correctly predict hypoxia and other processes and (2) a high‐resolution model grid for tributaries to correctly simulate water quality variables. Comparison with the model experiment results with bathymetry smoothing indicates that bathymetry smoothing, as commonly used for many systems, changes the stratification and lateral circulation pattern, resulting in more salt intrusion into shallow water regions, and an increase in the freshwater age. Consequently, a model with bathymetry smoothing can lead to an unrealistic prediction of the distribution of hypoxia and phytoplankton production. Local grid refinement shows significant improvement of model simulations on local stratification and water quality variables. Overall, the use of high‐resolution unstructured grid model leads to a faithful representation of the complex geometry, and thus a seamless cross‐scale capability for simulating water quality processes in the Bay including tributaries and tidal creeks.

Remuneration of Distribution Grids for Enhanced Regenerative Electricity Deployment—An Analysis and Model for the Analysis of Grid Structures in Southern Germany Using Linear Programming

Ecological concerns on the climatic effects of the emissions from electricity production stipulate the remuneration of electricity grids to accept growing amounts of intermittent regenerative electricity feed-in from wind and solar power. Germany’s eager political target to double regenerative electricity production by 2030 puts pressure on grid operators to adapt and restructure their transmission and distribution grids. The ability of local distribution grids to operate autonomous of transmission grid supply is essential to stabilize electricity supply at the level of German federal states. Although congestion management and collaboration at the distribution system operator (DSO) level are promising approaches, relatively few studies address this issue. This study presents a methodology to assess the electric energy balance for the low-voltage grids in the German federal state of Baden-Württemberg, assuming the typical load curves and the interchange potential among local distribution grids by means of linear programming of the supply function and for typical seasonal electricity demands. The model can make a statement about the performance and development requirements for grid architecture for scenarios in 2035 and 2050 when regenerative energies will—according to present legislation—account for more than half of Germany’s electricity supply. The study details the amendment to Baden-Württemberg’s electricity grid required to fit the system to the requirements of regenerative electricity production. The suggested model for grid analysis can be used in further German regions and internationally to systematically remunerate electricity grids for the acceptance of larger amounts of regenerative electricity inflows. This empirical study closes the research gap of assessing the interchange potential among DSO and considers usual power loads and simultaneously usual electricity inflows.

Grid Integration of Solar and Solar/Wind Hybrid Mini-Grid Projects: A Case of Solar/Wind Hybrid Mini-Grid Project Implemented by AEPC

Alternative Energy Promotion Center (AEPC) has been scaling up renewable energy technologies through Mini-grid power supply in Nepal’s off-grid areas in order to fulfill community electricity demands for both households and electricity-based enterprises. It is likely that, in some of the off-grid renewable energy (RE) mini-grid service areas, Nepal Electricity Authority (NEA) grid line might reach in near future. The objective of this study is to highlight success stories of solar and solar/wind mini-grids implemented by AEPC and for their longer-term sustainable operation grid integration policy of isolated mini-grid systems will require. Till the date AEPC has successfully electrified more than 20 rural communities through solar and solar/wind hybrid mini-grid systems. Some of these isolated mini-grid projects will seek grid interconnections in near future due to NEA distribution system expansion trend. When the isolated mini-grids will be connected to the national grid power network in future, the mini-grid can feed surplus electricity to the local utility grid line and will receive deficit electricity from the local utility grid system to serve the consumers connected to the local grid network. The methodology applied to this study is assessment of existing solar and solar/wind mini-grid projects, technological intervention required for grid integration, reviewing grid-connection policy of distributed renewable generations in the country and recommendation of relevant policy option for grid connection of rural mini-grids. Grid integration of isolated solar and solar/wind mini-grids will have positive impacts to the sustainability of the present isolated mini-grids, will help in retaining existing mini-grids end users, energy produced by mini-grid systems will be optimally utilized, the existing mini-grid power will contribute to stabilize weak national grid electrical parameters. The outcome of the study will recommend need of policy options as well as technological interventions in order to do grid integration of solar and solar/wind hybrid mini-grid systems in Nepal.