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Hybrid Microgrids/Mini-grids: Literature Review[edit | edit source]

Background[edit | edit source]

Searches

  • Google for hybrid microgrids/mini-grids
  • Google for off-grid energy systems
  • Google for integrated energy systems
  • Google for off-grid energy systems

Journals

Hybrid microgrids/mini-grids[edit | edit source]

From Jharkhand Renewable Energy Development Agency (JREDA): Microgrid/Mini-grid "A ‘Mini-Grid’ is a system of local electricity supply often renewable energy (RE) based (with a capacity of 10KW and above), supplying electricity to a target set of consumers (residents for household usage, commercial, productive, industrial and institutional setups, etc.) through a local distribution network operating either in an isolated mode or in a grid-interactive mode. A ‘Microgrid’ system is similar to a mini-grid but having a RE based generation capacity of below 10KW."

From the International Renewable Energy Agency (IRENA): Renewable mini-grids "There are four different mini-grid types. These are: autonomous basic (AB mini-grids) for lower tier of service, autonomous full (AF mini-grids) for higher tier of service, interconnected community (IC mini-grids) and interconnected large industrial (ILI mini-grids)."

Fig 1: Types of mini-grids

What is a hybrid microgrid/mini-grid?[edit | edit source]

Subhes C. Bhattacharyya, (2018)Mini-Grids for the Base of the Pyramid Market: A Critical Review

Hybrid microgrid/mini-grid are those local energy systems whose generation resources employ a combination of different resources including fossil fuel-based (e.g., diesel) and RE based resources(e.g., solar PV,micro-hydro, wind, biomass, etc.). Thus, the local distribution network can support direct current or alternating current and varying voltage levels.

System configuration[edit | edit source]

A typical mini-grid system consists of: (1) a generating capacity; (2) a power distribution network; (3) a storage unit in the form of battery banks and (4) balance-of-plant items (tracker, inverter, controller, etc.)

System planning, design, and control[edit | edit source]

This encompasses systematized processes including preliminary modeling, business model development, resource planning, and project engineering. This requires software tools for the design, analysis, optimization, and economic viability of the systems.

Tools for system planning, design, and control[edit | edit source]

These include higher-level techno-economic evaluation tools focused on long-term issues, technical evaluation tools for design details focused on the shorter term and broader energy planning tools.

Fig 2: Mini-grid design tools
Higher-level techno-economic evaluation tools[edit | edit source]
Technical evaluation tools[edit | edit source]
Broader energy planning tools[edit | edit source]

Literature Review of Hybrid microgrid/mini-grid[edit | edit source]

Optimal system design of hybrid microgrid/mini-grid, Reference List[edit | edit source]

Check the references in this list for the the electrification planning and rural electrification planning tracts [1]

Technical and economic evaluation[edit | edit source]

Analyzing of a Photovoltaic/Wind/Biogas/Pumped-Hydro Off-Grid Hybrid System for Rural Electrification in Sub-Saharan Africa—Case Study of Djoundé in Northern Cameroon[edit | edit source]

Analyzing of a Photovoltaic/Wind/Biogas/Pumped-Hydro Off-Grid Hybrid System for Rural Electrification in Sub-Saharan Africa—Case Study of Djoundé in Northern Cameroon Nasser Yimen, Oumarou Hamandjoda, Lucien Meva’a, Benoit Ndzana, Jean Nganhou, Analyzing of a Photovoltaic/Wind/Biogas/Pumped-Hydro Off-Grid Hybrid System for Rural Electrification in Sub-Saharan Africa—Case Study of Djoundé in Northern Cameroon, Energies, 2018, 11(10), 2644, DOI: https://doi.org/10.3390/en11102644[1]

Abstract: Traditional electrification methods, including grid extension and stand-alone diesel generators, have shown limitations to sustainability in the face of rural electrification challenges in sub-Saharan Africa (SSA), where electrification rates remain the lowest in the world. This study aims at performing a techno-economic analysis and optimization of a pumped-hydro energy storage based 100%-renewable off-grid hybrid energy system for the electrification of Djoundé, which is a small village in northern Cameroon. Hybrid Optimization of Multiple Energy Resources (HOMER) software was used as an analysis tool, and the resulting optimal system architecture included an 81.8 kW PV array and a 15 kW biogas generator, with a cost of energy (COE) and total net present cost (NPC) of €0.256/kWh and €370,426, respectively. The system showed promise given the upcoming decrease in installation cost of photovoltaic systems. It will be viable in parts of SSA region but, significant investment subsidies will be needed elsewhere. The originality of this study can be emphasized in three points: (1) the modelling with the recently introduced pumped-hydro component of HOMER; (2) broadening sensitivity analysis applications to address practical issues related to hybrid renewable energy systems (HRES); and, (3) consideration of the agricultural sector and seasonal variation in the assessment of the electricity demand in an area of SSA.

A thorough investigation on hybrid application of biomass gasifier and PV resources to meet energy needs for a northern rural off-grid region of Bangladesh: A potential solution to replicate in rural off-grid areas or not?[edit | edit source]

A thorough investigation on hybrid application of biomass gasifier and PV resources to meet energy needs for a northern rural off-grid region of Bangladesh: A potential solution to replicate in rural off-grid areas or not? Md Shahinur Islam, Ruma Akhter, Mohammad Ashifur Rahman, A thorough investigation on hybrid application of biomass gasifier and PV resources to meet energy needs for a northern rural off-grid region of Bangladesh: A potential solution to replicate in rural off-grid areas or not?, Energy, Volume 145, 15 February 2018, Pages 338-355, DOI: https://doi.org/10.1016/j.energy.2017.12.125[2]

Abstract: Rural electrification is a critical global challenge specifically in developing countries and Bangladesh is no exception. Most of the people live in the rural areas of the country and having no access to grid electricity hindering the development of these areas and the overall progress of the country's economy severely. In this regard, renewable energy based hybrid mini-grid can be a viable solution to ensure access to electricity for all. This paper presents a case study of supplying electricity through hybrid mini-grid to the rural unelectrified areas of the northern region of Bangladesh, and provides an analysis of its business creation, operation and related challenges. The study involves modelling of three alternative configurations for electricity generation with the different combination of solar energy, biomass generator, diesel generator and battery storage resources. Hybrid Optimization Model for Electric Renewable (HOMER) software is used to carry out the techno-economic analysis and identify the optimal off-grid system configuration. The analysis exposed that the per unit cost of electricity from the optimum off-grid supply configuration is much higher than the regulated tariff for grid connected residential consumers and cannot reach grid parity even with the full capital subsidy. However, the cost of off-grid supply is economical than the diesel-only supply option or the cost of owning a solar home system. The analysis further considered different electricity selling tariff to obtain a practical and reasonable payback period to make the proposed hybrid mini-grid system economically worthwhile. From the emission analysis, it is found that the proposed hybrid system would produce 75% lower CO2 than the existing methods of fulfilling energy needs in the study area.

  • A comprehensive analysis of a hybrid mini-grid system has been carried out for a rural off-grid area.
  • The optimized hybrid mini-grid system is economical compared to diesel-only system.
  • The optimal system reduces 75% CO2 emission than the existing method of fulfilling energy needs.
  • A self-sustainable business model is introduced targeting to electrify rural areas.
  • To reach the grid parity, certain operating subsidy besides the capital subsidy is required.

Techno-economic design and performance analysis of nanogrid systems for households in energy-poor villages[edit | edit source]

Techno-economic design and performance analysis of nanogrid systems for households in energy-poor villages Daniel Akinyele, Techno-economic design and performance analysis of nanogrid systems for households in energy-poor villages, Sustainable Cities and Society, Volume 34, October 2017, Pages 335-357, DOI: https://doi.org/10.1016/j.scs.2017.07.004.[3]

Abstract: This paper presents the techno-economic design and analysis of a nanogrid system for five neighboring houses, using an energy-poor village in Gwagwalada-Abuja, Nigeria as a case study. It explores the possibility of different energy configurations – solar nanogrid (SNg), solar/wind nanogrid (SWNg), solar/diesel nanogrid (SDNg), solar/wind/diesel nanogrid (SWDNg) and diesel nanogrid (DNg) systems. The study uses the demand patterns obtained during a field survey to determine the aggregate load profile and the energy generation systems. It presents detailed capacities, annual energy, losses, battery state of charge (SoC), unmet demand, loss of load probability (LOLP), availability and the demand growth analyses. Results reveal that 5–14.5 kW SNg can meet the users’ demand of ∼ 12.5–36.5 kWh/d achieving an availability of 99.2–99.6%. However, an availability of 100% was obtained for the hybrid options, including the DNg. These are 2.5–7 kW PV and a 1.8–3.6 kW wind generator; 5 kW PV and 5 kW diesel systems; 2.5 PV, 1.8 kW wind and 5 kW diesel system; 2.5–5 kW diesel generator systems. The results also demonstrate that the hybrid nanogrids achieves better battery profiles compared to the single-source option because of their complementary characteristics; thus, satisfying the battery constraint of SoC ≥ 30% during the year. The initial cost of the DNg option is ∼6–22% of those of the renewable energy-based nanogrids. The study further reveals that nanogrids with diesel generators have relatively higher life cycle costs because of the fuel costs. Though renewable energy-based nanogrids have relatively higher initial capital costs, their life cycle costs are lower than those of the DNg. The research can be used for planning new electrification systems for rural communities around the globe.

  • A 5–14.5 kW solar nanogrid has been modeled for demand of 12.5–36.5 kWh/d.
  • The yield and losses of the solar nanogrid are 4.22 and 1.23 h/d, respectively.
  • The yearly availability of 100% is achieved by hybrid nanogrid systems.
  • The hybrid nanogrid systems provide better battery energy profiles than the solar nanogrid system.
  • The lifecycle costs of the diesel nanogrid is 1.62–2.15 times the values obtained for renewable energy nanogrids.

Renewable energy management in a remote area using Modified Gravitational Search Algorithm[edit | edit source]

Renewable energy management in a remote area using Modified Gravitational Search Algorithm Sahand Ghavidel, Jamshid Aghaei, Kashem M. Muttaqi, Alireza Heidari, Renewable energy management in a remote area using Modified Gravitational Search Algorithm, Energy, Volume 97, 15 February 2016, Pages 391-399, DOI: https://doi.org/10.1016/j.energy.2015.12.132[4]

Abstract: In this paper, a small remote area which is located in Nigeria has been considered as a model to be tested by a managing scheme for providing both electricity and water. In this strategy, the groundwater is pumped into a water tank which can be later used for supplying required irrigation and drinking water. A PAT (Pump as Turbine) is used as a hybrid system for supplying electricity and water as well as storing water in the water tank. Also, a PV (photovoltaic plant), a package of batteries (BAT) in addition to a diesel ICE (internal combustion engine) are used and optimized along with the best size of devices and managing system, with the purpose of obtaining the maximum economical operating strategy. In this paper, two cases are considered to assess the effectiveness of the system under study. Firstly, all of the mentioned devices are used to show how internal combustion engine system dominates all the other components due to the low cost of fuel. In the second case, all renewable resources have been exploited and optimized in order to make a 100% renewable system with least possible cost. Having about 53 variables makes this problem very complicated which requires to be solved by an algorithm with more accuracy. Therefore, a MGSA (Modified Gravitational Search Algorithm) with an adapted mutation tactic is used to find the best cost and management strategy. In the first case, although the cost of diesel oil is very low, by using the PAT, about 5% of diesel oil consumption is reduced. In the second case, in order to make a 100% renewable system, the size of PV is enlarged approximately 16 times in comparison with the first case. The hybrid PV-PAT storing structure is capable to deliver the water for irrigation and domestic requirements as well as 9% of the electricity needed for the rural community.

  • Management strategy for providing both electricity and water in remote area.
  • A pump, PV, batteries and a diesel engine are used and optimized.
  • A Modified Gravitational Search Algorithm has been proposed to solve problem.

Multi-criteria assessment of hybrid renewable energy systems for Nigeria’s coastline communities[edit | edit source]

Multi-criteria assessment of hybrid renewable energy systems for Nigeria’s coastline communities E. O. Diemuodeke, S. Hamilton, A. Addo, Multi-criteria assessment of hybrid renewable energy systems for Nigeria’s coastline communities, Energy, Sustainability and Society volume 6, Article number: 26 (2016), DOI: https://doi.org/10.1186/s13705-016-0092-x[5]

Abstract: Background Nigeria’s rural coastline communities have long suffered from the consequences of both poor rural electrification and environmental degradation. Therefore, there is an urgent need to provide an optimal sustainable and environment-friendly energy system for the coastline communities in Nigeria, which has the potential of ameliorating the climate change in this country.

Methods The HOMER hybrid optimisation software and multi-criteria decision-making, based on the TOPSIS algorithm, were used to determine the best hybrid energy system. The decision is based on four alternatives as well as 15 different economic, social and environmental criteria. The NASA SEE data base with monthly averaged values for global horizontal radiation over a 22-year period (July 1983–June 2005) was considered in the current analysis.

Results The results show that the most promising hybrid energy system, based on a multi-criteria decision analysis and prevailing economic data, is the diesel-PV-wind energy system, which has a relative closeness of 0.489226. The suggested best hybrid energy system has a cost of electricity of 0.787 $/kWh and potential to reduce gas emission by 48.5 %/year. The best energy system gives the best components with an appropriate operating strategy to provide an efficient, reliable, cost-effective and environment-friendly system. It is shown that both positive energy policies of the Federal Government of Nigeria towards renewable energy penetration and the support from the oil producing companies towards their operational areas would see the cost of electricity being significantly reduced.

Conclusions It is envisaged that the implementation of the suggested energy system with other environmentally responsible interventions would support the Niger Delta coastline communities, whose livelihoods have been impaired by gas and oil exploration, to attain their full environmental, social and economic potentials. The suggested energy system could be useful in other coastline communities globally once there are available renewable energy sources.

Hybrid renewable power supply for rural health clinics (RHC) in six geo-political zones of Nigeria[edit | edit source]

Hybrid renewable power supply for rural health clinics (RHC) in six geo-political zones of Nigeria Lanre Olatomiwa, Saad Mekhilef, Olayinka S. Ohunakin, Hybrid renewable power supply for rural health clinics (RHC) in six geo-political zones of Nigeria, Sustainable Energy Technologies and Assessments, Volume 13, February 2016, Pages 1-12, DOI: https://doi.org/10.1016/j.seta.2015.11.001[6]

Abstract: The potentials of major renewable energy sources (wind and solar) in selected locations across the six geo-political regions of Nigeria, based on long-term daily meteorological data spanning between 18 and 39 years were reviewed in this study. In addition, the techno-economic feasibility of utilizing hybrid photovoltaic/wind/diesel with battery storage systems to meet the load of a typical rural healthcare facility at the selected sites were assessed. The optimum dimensions of the system are defined for the locations. Hybrid Optimization Model for Electric Renewable (HOMER) software developed by National Renewable Energy Laboratory’s (NREL) was employed to conduct the study. Findings from the study showed that Sokoto and Jos exist in the high wind potential regions, while the remain sites are only suitable for small wind applications. Values obtained for global, beam and diffuse radiation as well as clearness index, show that all the sites enjoy considerable solar energy potential suitable for varying degree of solar energy applications. Monthly optimum tilt angle for Iseyin, Sokoto, Maiduguri, Jos, Enugu and Port-Harcourt lies in the range of 0–39.8°, 0–44.5°, 0–44.1°, 0–43.2°, 0–38.5° and 0–36.3° respectively thereby having the optimum angle to be equal to 0° in all sites in April, May, June, July and August. The simulation results from HOMER indicate that the hybrid system is the best option for all the sites considered in this study. The PV/wind/diesel/battery hybrid system configuration is considered optimum for RHC applications at Sokoto, Maiduguri, Jos and Enugu, while hybrid systems involving PV/diesel/battery is considered ideal for RHC at remote locations within Iseyin and Port-Harcourt, due to the quality of renewable energy potential. The diesel-only system provides the highest COE ($0.911/kWh), and emits 9211 kg of CO2 per year in all the site considered.

Feasibility Analysis[edit | edit source]

Energy Management and Optimization of a PV/Diesel/Battery Hybrid Energy System Using a Combined Dispatch Strategy[edit | edit source]

Energy Management and Optimization of a PV/Diesel/Battery Hybrid Energy System Using a Combined Dispatch Strategy Ali Saleh Aziz, Mohammad Faridun Naim Tajuddin, Mohd Rafi Adzman, Makbul A. M. Ramli, Saad Mekhilef, Energy Management and Optimization of a PV/Diesel/Battery Hybrid Energy System Using a Combined Dispatch Strategy, Sustainability 2019, 11(3), 683, DOI: https://doi.org/10.3390/su11030683[7]

Abstract: In recent years, the concept of hybrid energy systems (HESs) is drawing more attention for electrification of isolated or energy-deficient areas. When optimally designed, HESs prove to be more reliable and economical than single energy source systems. This study examines the feasibility of a combined dispatch (CD) control strategy for a photovoltaic (PV)/diesel/battery HES by combining the load following (LF) strategy and cycle charging (CC) strategy. HOMER software is used as a tool for optimization analysis by investigating the techno-economic and environmental performance of the proposed system under the LF strategy, CC strategy, and combined dispatch CD strategy. The simulation results reveal that the CD strategy has a net present cost (NPC) and cost of energy (COE) values of $110,191 and $0.21/kWh, which are 20.6% and 4.8% lower than those of systems utilizing the LF and CC strategies, respectively. From an environmental point of view, the CD strategy also offers the best performance, with CO2 emissions of 27,678 kg/year. Moreover, the results show that variations in critical parameters, such as battery minimum state of charge, time step, solar radiation, diesel price, and load growth, exert considerable effects on the performance of the proposed system.

Optimal design and implementation of solar PV-wind-biogas-VRFB storage integrated smart hybrid microgrid for ensuring zero loss of power supply probability[edit | edit source]

Optimal design and implementation of solar PV-wind-biogas-VRFB storage integrated smart hybrid microgrid for ensuring zero loss of power supply probability Tathagata Sarkar, Ankur Bhattacharjee, Hiranmay Samanta, Konika Bhattacharya, Hiranmay Saha, Optimal design and implementation of solar PV-wind-biogas-VRFB storage integrated smart hybrid microgrid for ensuring zero loss of power supply probability, Energy Conversion and Management, Volume 191, 1 July 2019, Pages 102-118, DOI: https://doi.org/10.1016/j.enconman.2019.04.025[8]

Abstract: Uninterrupted access to electric power has become the basic need of today’s world. Rural parts of many countries still do not have access to electricity or have electric power access to weak distribution grids with inadequate transmission and distribution system infrastructure. However, the countries where there is an abundance of solar radiation, a good potential of bio-degradable waste and average availability of wind source, access to electricity for those remote areas can be managed by distributed power generation. Considering the fact that the renewable energy sources (Solar, Wind etc.) are intermittent in nature, battery energy storage systems (BESS) and other reservoirs like biogas energy sources are the potential candidates to be integrated with the renewable sources to ensure continuous access to electricity and energy security. In this paper, a unique combination of Solar PV, Wind, Biomass and Vanadium Redox Flow Battery (VRFB) storage integrated hybrid Microgrid has been modeled and implemented practically for the first time. The capacity selection of different renewable sources for satisfying daily energy demand and their techno-commercial optimization has been performed through HOMER simulation. Further, the peak load shaving that is a limitation of HOMER model, has been established through PSCAD simulation by providing the real life data of different renewable sources, VRFB storage and the load profile as input to the model. The simulation model performances have been validated by a practical 10 kWP solar PV, 1 kW wind and 15 kVA Biogas generator integrated with 1 kW 6 h VRFB storage based Microgrid installed at India Institute of Engineering Science and Technology campus, India. In addition to these, zero loss of power supply probability (LPSP) has been ensured by implementing smart scheduling and controller considering the intermittency of the renewable sources. As a part of the financial analysis, project Investment on Return (IRR) and pay back has been calculated considering initial investment, operation and maintenance cost and revenue of generation.

  • First time the solar-wind-biogas-VRFB integrated micrgrid is modeled and validated.
  • The capacity optimization and energy management with lowest LCOE is done by HOMER.
  • Peak load shaving with optimal sources and grid is shown by PSCAD using real data.
  • Optimal schedule of renewable sources and VRFB ensures zero LPSP at consumer end.
  • Financial study of hybrid microgrid demonstrates project viability and up scaling.

Feasibility of KUDURA hybrid generation system in Mozambique: Sensitivity study of the small-scale PV-biomass and PV-diesel power generation hybrid system[edit | edit source]

Feasibility of KUDURA hybrid generation system in Mozambique: Sensitivity study of the small-scale PV-biomass and PV-diesel power generation hybrid system Henrique Garrido, Vivian Vendeirinho, M.C.Brito, Feasibility of KUDURA hybrid generation system in Mozambique: Sensitivity study of the small-scale PV-biomass and PV-diesel power generation hybrid system, Renewable Energy, Volume 92, July 2016, Pages 47-57, DOI: https://doi.org/10.1016/j.renene.2016.01.085[9]

Abstract: The use of agricultural and food processing waste is an important source of biomass fuel for energy generation in rural and remote locations. In particular, gasification of cashew nut shell has a high potential for clean electricity generation due to its relative high energy content. In this study, the techno-economic assessment of a solar photovoltaic-biomass gasification hybrid system is carried out for a case study in Nampula, Mozambique. Model results and sensitivity analysis show that this system is able to achieve competitive levelised cost of electricity when compared with diesel generators.

  • Cashew nut shell is an interesting fuel source for electricity generation.
  • Technical and economic assessment of a solar photovoltaic-biomass gasification hybrid system.
  • Case study in Nampula, Mozambique.
  • Model results system is able to achieve competitive LCOE when compared with diesel generators.

Experimental verification of hybrid renewable systems as feasible energy sources[edit | edit source]

Experimental verification of hybrid renewable systems as feasible energy sources A.Pérez-Navarro, D.Alfonso, H.E.Ariza, J.Cárcel, A.Correcher, G.Escrivá-Escrivá, E.Hurtado, F.Ibáñez, E.Peñalvo, R.Roig, C.Roldán, C.Sánchez, I.Segura, C.Vargas, Experimental verification of hybrid renewable systems as feasible energy sources, Renewable Energy, Volume 86, February 2016, Pages 384-391, DOI: https://doi.org/10.1016/j.renene.2015.08.030[10]

Abstract: Renewable energies are a central element in the search for energy sustainability, so they are becoming a substantial component of the energy scenario of every country, both as systems connected to the grid or in stand-alone applications. Feasibility of these renewable energy systems could be necessary not only in their application in isolated areas, but also in systems connected to the grid, in this last case when their contribution reaches a substantial fraction of the total electricity demand. To overcome this reliability problem, hybrid renewable systems could become essential and activities to optimize their design should be addressed, both in the simulation and in the experimental areas. In this paper, a laboratory to simulate and verify the reliability of hybrid renewable systems is presented and its application to the feasibility analysis of multicomponent systems including photovoltaic panels, wind generator and biomass gasification plant, plus energy storage in a battery bank, are described.

  • A laboratory to check hybrid renewable systems has been designed and built.
  • Laboratory includes PV, wind, biomass and hydrogen energy sources.
  • Energy storage in this laboratory is made in a battery bank and a hydrogen tank.
  • Feasibility of two different hybrid systems for residential sector demand has been measured.
  • Work is in progress for application to other demand curves and analysis of transients.

Feasibility study of using a biogas engine as backup in a decentralized hybrid (PV/wind/battery) power generation system – Case study Kenya[edit | edit source]

Feasibility study of using a biogas engine as backup in a decentralized hybrid (PV/wind/battery) power generation system – Case study Kenya Sara Ghaem Sigarchian, Rita Paleta, Anders Malmquist, André Pina, Feasibility study of using a biogas engine as backup in a decentralized hybrid (PV/wind/battery) power generation system – Case study Kenya, Energy, Volume 90, Part 2, October 2015, Pages 1830-1841, DOI: https://doi.org/10.1016/j.energy.2015.07.008[11]

Abstract: In this study, a hybrid power system consisting of PV (Photovoltaics) panels, a wind turbine and a biogas engine is proposed to supply the electricity demand of a village in Kenya. The average and the peak load of the village are around 8 kW and 16.5 kW respectively. The feasibility of using locally produced biogas to drive a backup engine in comparison to using a diesel engine as backup has been explored through a techno-economic analysis using HOMER (Hybrid Optimization Model for Electric Renewables). This hybrid system has also been compared with a single diesel based power system. The results show that the hybrid system integrated with the biogas engine as backup can be a better solution than using a diesel engine as backup. The share of power generation by PV, wind and biogas are 49%, 19% and 32%, respectively. The LCOE (Levelized Cost of Electricity) of generated electricity by this hybrid system ($0.25/kWh) is about 20% cheaper than that with a diesel engine as backup ($0.31/kWh), while the capital cost and the total NPC (Net Present Cost) are about 30% and 18% lower, respectively. Regarding CO2 emissions, using a biogas engine as backup saves 17 tons of CO2 per year compared to using the diesel engine as backup.

  • We did a feasibility study on a hybrid energy system with biogas engine as backup.
  • We compared using biogas and diesel engine as backup in the hybrid energy system.
  • Using locally-produced biogas in the hybrid system decreases the CO2 emissions.
  • Using the biogas engine as backup decreases the LCOE of the hybrid system.
  • Locally-produced biogas can be a good substitute for diesel in the hybrid system.

Incorporating demand-side management via demand response[edit | edit source]

MPC for optimal dispatch of an AC-linked hybrid PV/wind/biomass/H2 system incorporating demand response[edit | edit source]

MPC for optimal dispatch of an AC-linked hybrid PV/wind/biomass/H2 system incorporating demand response César Y. Acevedo-Arenas, Antonio Correcher, Carlos Sánchez-Díaz, Eduardo Ariza, David Alfonso-Solar, Carlos Vargas-Salgado, Johann F. Petit Suáreze MPC for optimal dispatch of an AC-linked hybrid PV/wind/biomass/H2 system incorporating demand response, Energy Conversion and Management, Volume 186, 15 April 2019, Pages 241-257, DOI: https://doi.org/10.1016/j.enconman.2019.02.044[12]

Abstract: A Model Predictive Control (MPC) strategy based on the Evolutionary Algorithms (EA) is proposed for the optimal dispatch of renewable generation units and demand response in a grid-tied hybrid system. The generating system is based on the experimental setup installed in a Distributed Energy Resources Laboratory (LabDER), which includes an AC micro-grid with small scale PV/Wind/Biomass systems. Energy storage is by lead-acid batteries and an H2 system (electrolyzer, H2 cylinders and Fuel Cell). The energy demand is residential in nature, consisting of a base load plus others that can be disconnected or moved to other times of the day within a demand response program. Based on the experimental data from each of the LabDER renewable generation and storage systems, a micro-grid operating model was developed in MATLAB© to simulate energy flows and their interaction with the grid. The proposed optimization algorithm seeks the minimum hourly cost of the energy consumed by the demand and the maximum use of renewable resources, using the minimum computational resources. The simulation results of the experimental micro-grid are given with seasonal data and the benefits of using the algorithm are pointed out.

  • A PV-wind-biomass-battery-hydrogen hybrid micro-grid was modeled from LabDER.
  • A model predictive control based on the evolutionary algorithms is proposed to manage it.
  • The MPC searches for a stable and smooth control strategy that improves the total cost of the system.
  • Results show a 14.790% mean improvement in total micro-grid costs and 16.211% in LCOE.

Integration of renewable energy in microgrids coordinated with demand response resources: Economic evaluation of a biomass gasification plant by Homer Simulator[edit | edit source]

Integration of renewable energy in microgrids coordinated with demand response resources: Economic evaluation of a biomass gasification plant by Homer Simulator Lina Montuori, Manuel Alcázar-Ortega, Carlos Álvarez-Bel, Alex Domijan, Integration of renewable energy in microgrids coordinated with demand response resources: Economic evaluation of a biomass gasification plant by Homer Simulator, Applied Energy, Volume 132, 1 November 2014, Pages 15-22, DOI: https://doi.org/10.1016/j.apenergy.2014.06.075[13]

Abstract: This paper deals with how demand response can contribute to the better integration of renewable energy resources such as wind power, solar, small hydro, biomass and CHP. In particular, an economic evaluation performed by means of the micro-power optimization model HOMER Energy has been done, considering a micro-grid supplied by a biomass gasification power plant, operating isolated to the grid and in comparison with other generation technologies. Different scenarios have been simulated considering variations in the power production of the gasified biomass generator and different solutions to guarantee the balance generation/consumption are analyzed, demonstrating as using demand response resources is much more profitable than producing this energy by other conventional technologies by using fossil fuels.

  • Renewable generation integration with demand response in isolated microgrids is discussed.
  • Power production with gasified biomass and conventional generation resources is considered.
  • A method based on Homer Energy Simulator is developed for economic evaluation.
  • The economic impact of different resources for balancing purposes in a microgrid is done.
  • High profitability is demonstrated when using demand side to supply renewable variability.

Buisness models[edit | edit source]

Hybrid renewable mini-grids on non-interconnected small islands: Review of case studies[edit | edit source]

Hybrid renewable mini-grids on non-interconnected small islands: Review of case studies A.A. Eras-Almeida, M.A.Egido-Aguilera, Hybrid renewable mini-grids on non-interconnected small islands: Review of case studies, Renewable and Sustainable Energy Reviews, Volume 116, December 2019, 109417, DOI: https://doi.org/10.1016/j.rser.2019.109417[14]

Abstract: Most small islands, with populations of between 1000 and 100,000 inhabitants, have non-interconnected power generation systems consisting of thermal power plants. This affects their ecological balance and implies a financial dependency on the price of fossil fuels and high electricity generation costs. However, small islands can accelerate their energy transition to become lower-carbon economies thanks to their enormous renewable energy potential. This research presents the current state of the art of hybrid renewable mini-grids (HRMGs) on non-interconnected small islands. To do so, a comparative analysis was applied among islands located in the Atlantic and Arctic, Pacific and Indian Oceans, and the Caribbean and Mediterranean Seas based on an extensive review of the literature. This study identifies business models applied to support the introduction of renewable energy and the key factors for the implementation of HRMGs on small islands. This review highlights how developed islands are successful in achieving their ambitious renewable energy targets. On the other hand, it is demonstrated that the least developed islands from the Pacific and Indian Oceans need to strengthen their weak regulatory frameworks and define suitable business models to promote renewable energy projects, involving private entities. Furthermore, these islands should find alternative funding sources apart from foreign aid. Developing islands should guide international cooperation in favor of effective policies and fostering local capacities. In those regions, thanks to the low prices of renewable technologies, the most attractive mechanisms for the implementation of HRMGs are the Renewable Energy Service Company model, competitive auctions and tax incentives.

  • Only islands from developed countries have achieved high shares of renewable energy.
  • The least developing islands need to install reliable control and storage systems.
  • Suitable business models support the successful penetration of renewable energy.
  • Pacific and Indian islands should apply public-private business models.
  • Foreign aid should focus on strengthening local capacities and effective policies.

Mini-Grids for the Base of the Pyramid Market: A Critical Review[edit | edit source]

Mini-Grids for the Base of the Pyramid Market: A Critical Review Subhes C. Bhattacharyya, Mini-Grids for the Base of the Pyramid Market: A Critical Review, Energies 2018, 11(4), 813, DOI: https://doi.org/10.3390/en11040813[15]

Abstract: The lack of access to electricity of more than 1.1 billion people around the world remains a major developmental challenge and Goal 7 of the Sustainable Development Goals (SDG) as well as Sustainable Energy for All (SE4ALL) have set a target of universal electrification by 2030. Various studies have identified mini-grid-based electrification as a possible solution. There is a growing body of literature available now that has explored the feasibility, practical application and policy interventions required to support mini-grids. Through a review of available literature, this paper explores whether mini-grids can be a solution for the base of the pyramid (BoP) market and the challenges faced in deploying mini-grids in such markets. Interventions to support the mini-grid deployment are also discussed. The paper finds that the mini-grids are targeting the BoP market but the business is not attractive in profitability terms and requires financial support. Lack of regulatory clarity and non-coordinated policies affect the financial viability of projects, which requires careful support. Mini-grid electrification has hardly been embedded in rural development agenda and hence they have not contributed significantly to livelihood generation. Careful realignment of policies, regulatory frameworks and support systems can better support mini-grid deployment in developing countries.

Evaluating business models for microgrids: Interactions of technology and policy[edit | edit source]

Evaluating business models for microgrids: Interactions of technology and policy Ryan Hanna, Mohamed Ghonima, Jan Kleissl, George Tynan, David G. Victor, Evaluating business models for microgrids: Interactions of technology and policy, Energy Policy, Volume 103, April 2017, Pages 47-61, DOI: https://doi.org/10.1016/j.enpol.2017.01.010[16]

Abstract: Policy makers are increasingly focused on strategies to decentralize the electricity grid. We analyze the business model for one mode of decentralization—microgrids—and quantify the economics for self-supply of electricity and thermal energy and explicitly resolve technological as well as policy variables. We offer a tool, based on the Distributed Energy Resources Customer Adoption Model (DER-CAM) modeling framework, that determines the cost-minimal capacity and operation of distributed energy resources in a microgrid, and apply it in southern California to three “iconic” microgrid types which represent typical commercial adopters: a large commercial building, critical infrastructure, and campus. We find that optimal investment leads to some deployment of renewables but that natural gas technologies underpin the most robust business cases—due in part to relatively cheap gas and high electricity rates. This finding contrasts sharply with most policy advocacy, which has focused on the potentials for decentralization of the grid to encourage deployment of renewables. Decentralization could radically reduce customer energy costs, but without the right policy framework it could create large numbers of small decentralized sources of gas-based carbon emissions that will be difficult to control if policy makers want to achieve deep cuts in greenhouse gas emissions.

  • We offer a modeling tool to study technology and policy variables for microgrids.
  • We construct comprehensive load profiles for three likely adopters of microgrids.
  • Investment in natural gas generators is key to enabling business models.
  • Solar PV and storage are optimal but as supplements to gas generation.
  • Business models are highly robust to sensitivity in technology and policy variables.

Citation List[edit | edit source]

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  6. Lanre Olatomiwa, Saad Mekhilef, Olayinka S. Ohunakin, Hybrid renewable power supply for rural health clinics (RHC) in six geo-political zones of Nigeria, Sustainable Energy Technologies and Assessments, Volume 13, February 2016, Pages 1-12, DOI: https://doi.org/10.1016/j.seta.2015.11.001
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  11. Sara Ghaem Sigarchian, Rita Paleta, Anders Malmquist, André Pina, Feasibility study of using a biogas engine as backup in a decentralized hybrid (PV/wind/battery) power generation system – Case study Kenya, Energy, Volume 90, Part 2, October 2015, Pages 1830-1841, DOI: https://doi.org/10.1016/j.energy.2015.07.008
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  14. A.A. Eras-Almeida, M.A.Egido-Aguilera, Hybrid renewable mini-grids on non-interconnected small islands: Review of case studies, Renewable and Sustainable Energy Reviews, Volume 116, December 2019, 109417, DOI: https://doi.org/10.1016/j.rser.2019.109417
  15. Subhes C. Bhattacharyya, Mini-Grids for the Base of the Pyramid Market: A Critical Review, Energies 2018, 11(4), 813, DOI: https://doi.org/10.3390/en11040813
  16. Ryan Hanna, Mohamed Ghonima, Jan Kleissl, George Tynan, David G. Victor, Evaluating business models for microgrids: Interactions of technology and policy, Energy Policy, Volume 103, April 2017, Pages 47-61, DOI: https://doi.org/10.1016/j.enpol.2017.01.010

See also[edit | edit source]