Renewable Fraction Research Articles

Optimal Configuration with Capacity Analysis of PV-Plus-BESS for Behind-the-Meter Application

As the cost of photovoltaic (PV) systems and battery energy storage systems (BESS) decreases, PV-plus-BESS applied to behind-the-meter (BTM) market has grown rapidly in recent years. With user time of use rates (TOU) for charging and discharging schedule, it can effectively reduce the electricity expense of users. This research uses the contract capacity of an actual industrial user of 7.5 MW as a research case, and simulates a PV/BESS techno-economic scheme through the HOMER Grid software. Under the condition that the electricity demand is met and the PV power generation is fully used, the aim is to find the most economical PV/BESS capacity allocation and optimal contract capacity scheme. According to the load demand and the electricity price, the analysis shows that the PV system capacity is 8.25 MWp, the BESS capacity is 1.25 MW/3.195 MWh, and the contract capacity can be reduced to 6 MW. The benefits for the economical solution are compared as follows: 20-year project benefit, levelized cost of energy (LCOE), the net present cost (NPC), the internal rate of return (IRR), the return on investment (ROI), discounted payback, total electricity savings, renewable fraction (RF), and the excess electricity fraction. Finally, the sensitivity analysis of the global horizontal irradiation, electricity price, key component cost, and real interest rate will be carried out with the most economical solution by analyzing the impacts and evaluating the economic evaluation indicators. The analysis method of this research can be applied to other utility users to program the economic benefit evaluation of PV/BESS, especially an example for Taiwan’s electricity prices at low levels in the world.

Development of a Hybrid Renewable Energy System with Co-Firing Option

ABSTRACT In this study, a hybrid renewable energy systems (HRES) composed of solar photovoltaic and biogas co-firing is designed for a hazelnut cracking plant in Ordu province of Turkey. Technical and economic analysis are carried out based on the change in government incentives on renewable sources before (Option A) and after 2021 (Option B) based on net present cost (NPC) and cost of energy (COE). In addition, four different HRES configurations namely Scenarios 1, 2, 3, and 4 are analyzed to compare energy generation with/without co-firing of hazelnut shell and natural gas alongside with/without solar photovoltaic (PV). Sensitivity analysis is also made by considering grid sale capacity, inflation rate, discount rate, biomass price, and sellback rate. It is found that Option A has the lowest NPC and COE values, which are estimated as $3.000 M and $0.098/kW, respectively. In the sensitivity analysis of HRES configuration, total NPC and COE values between nominal discount rate and biomass price generally increase, while the values between expected inflation rate and sellback rate are on a downward trend. Consequently, Scenario-4 has the lowest NPC and COE values, and the highest renewable fraction at around 73.6%, whereas CO2 and NOx emissions are lowest in Scenario-2.

Use of a Hybrid Wind—Solar—Diesel—Battery Energy System to Power Buildings in Remote Areas: A Case Study

The emerging environmental consequences of overdependence on fossil fuels have pushed many countries to invest in clean and renewable sources of power. Countries like Iran where these sources can be found in abundance can take advantage of this potential to reduce their dependence on fossil fuels. This study investigated the feasibility of the standalone use of a hybrid renewable energy system (HRES) to power buildings in the Bostegan village in the Hormozgan province of Iran. Technical, economic, and environmental assessments were performed with the help of the Hybrid Optimization of Multiple Energy Resources (HOMER) software, and the optimal configuration for the system components was determined accordingly. The results showed that the simultaneous use of wind and solar systems with a converter and a backup system comprised of a diesel generator and batteries will be the most economic option, offering electricity at a cost of 1.058 USD/kWh and with a renewable fraction of 64%. After selecting the most optimal system using the step-wise weight assessment ratio analysis (SWARA) and weighted aggregated sum product assessment (WASPAS) techniques, a sensitivity analysis with 27 parameter settings was performed to determine the effect of fuel price fluctuations and the uncertainty in the renewable energy potentials on the results. This analysis showed that in the worst-case scenario, the price of electricity will reach as high as 1.343 $/kWh. In the end, the study investigated an alternative scenario where the generated power is used for hydrogen production, which showed that the system output can be used to produce 643.63 ton-H2/year.

Small scale standalone solar and tidal hybrid power system in isolated area

The source of electricity supply in isolated areas is commonly from diesel or other fossil fuel-based generation systems. However, the increasing cost and harmful emissions of these fuels have led researchers to seek alternative solutions in providing electricity. Hence, harnessing renewable resources can be a favourable solution in lowering the dependency on fossil fuels. The Strait of Malacca is blessed with tidal current energy, a research was conducted to design a hybrid renewable energy system (HRES) that consists of tidal current and solar energy as its sources along with backup power such as generators to support the electrical demand of a lighthouse. A simulation method is used to determine and compare the optimal configuration of the HRES with the diesel generator-based system. An evaluation of all possible scenarios of standalone systems was carried out by considering the amount of fuel consumption and pollutant emittance, capacity shortage, excess electricity production, unmet energy and renewable fraction parameters of each system scenario. From the findings, the hybrid energy system of Scenario A that consists of tidal turbines, PVs, generator, battery, and converter produces better results where the diesel fuel consumption can be reduced up to 84% in comparison with the standalone generator-based system.

Optimal Sizing and Techno-Economic Analysis of Minigrid Hybrid Renewable Energy System for Tourist Destination Islands of Lake Tana, Ethiopia

Achieving universal electricity access is a challenging goal for the governments of developing countries such as Ethiopia. Extending the national grid to the remotely located, scattered, and island populations demands a huge investment. This paper aims to show the techno-economic feasibility of minigrid renewable energy system to electrify Kibran Gabriel island in Ethiopia, through the execution of simulation, optimization and sensitivity analysis using Hybrid Optimization Models for Energy Resources (HOMER Pro) software. The minigrid systems were compared with both diesel generation (DG) and grid extension systems. The hybrid photovoltaic (PV)/DG/battery system is more economically feasible compared with other minigrid systems, and the best cost-effective option is the one including load flow (LF) strategy with 25 kW of PV, 10 kW of DG, 40 kWh of battery, and 5 kW of bi-directional convertor. The optimal PV/DG/Battery system, having levelized cost of energy (COE) of USD 0.175/kWh, net present cost (NPC) of USD 119,139 and renewable fraction (RF) of 86.4%, reduces the pollutant emissions by 33,102 kg/yr compared with the stand-alone DG system. The optimal minigrid sensitivity to the variations in global horizontal irradiance (GHI), diesel price and load consumption were considered in the sensitivity analysis, and the result shows that the system will operate reasonably well.

Performance Investigation of a Solar Photovoltaic/Diesel Generator Based Hybrid System with Cycle Charging Strategy Using BBO Algorithm

In the current scenario, sustainable power generation received greater attention due to the concerns of global warming and climate change. In the present paper, a Solar Photovoltaic/Diesel Generator/ Battery-based hybrid system has been considered to meet the electrical energy demand of a remote location of India. The cost of the energy of hybrid system is minimized using a Biogeography-based Optimization (BBO) algorithm under the constraints of power reliability, carbon emission and renewable energy fraction. Load following and cycle charging strategies have been considered in order to investigate the performance analysis of the proposed hybrid system. Further, different component combinations of specifications available on the market are presented for detail analysis. The minimum cost of energy of the proposed hybrid system is obtained as 0.225 $/kWh.

Decarbonizing rural residential buildings in cold climates: A techno-economic analysis of heating electrification

Given the need for decarbonization of the heating sector and the acute need of a propane replacement in the U.S. Upper Midwest, this study quantifies the techno-economic characteristics of sustainable heating electrification in isolated rural, residential buildings in cold climates without natural gas supply. Archetypal buildings are modeled under four levels of electrification. At each electrification level, a parametric solar photovoltaic (PV) sizing analysis is performed and the total life cycle cost, renewable fraction and greenhouse gas (GHG) emissions are calculated based on the primary energy supply for each building type. Cost optimal solutions are stress-tested with multi-dimensional sensitivity analyses. The results show that the total life cycle cost favors heating electrification in all cases and combining PV with heat pumps can reduce residential building GHG emissions by up to 50% immediately. This effect will grow over time, with over 90% reduction of building emissions if renewable energy targets are met. In using primary energy and emissions along with the multi-dimensional sensitivities, this study unique demonstrates the complex techno-economic interactions of PV and heat pumps. It is concluded that electrification is an economically viable decarbonization method for cold climates both now and in the future.

Fuel poverty and low carbon emissions: a comparative study of the feasibility of the hybrid renewable energy systems incorporating combined heat and power technology

Fuel poverty is most prevalent in North East England with 14.4% of fuel poor households in Newcastle upon Tyne. The aim of this paper was to identify a grid connected renewable energy system coupled with natural gas reciprocating combined heat and power unit, that is cost-effective and technically feasible with a potential to generate a profit from selling energy excess to the grid to help alleviate fuel poverty. The system was also aimed at low carbon emissions. Fourteen models were designed and optimized with the aid of the HOMER Pro software. Models were compared with respect to their economic, technical, and environmental performance. A solution was proposed where restrictions were placed on the size of renewable energy components. This configuration consists of 150 kW CHP, 300 kW PV cells, and 30 kW wind turbines. The renewable fraction is 5.10% and the system yields a carbon saving of 7.9% in comparison with conventional systems. The initial capital investment is $1.24 million which enables the system to have grid sales of 582689 kWh/a. A conservative calculation determined that 40% of the sales can be used to reduce the energy cost of fuel poor households by $706 per annum. This solution has the potential to eliminate fuel poverty at the site analyzed.

Off-grid solar photovoltaic/hydrogen fuel cell system for renewable energy generation: An investigation based on techno-economic feasibility assessment for the application of end-user load demand in North-East India

In this paper, an optimal off-grid solar photovoltaic (PV)/hydrogen fuel cell (FC) (HFC) based energy system is proposed for renewable energy generation to supply electricity to the end-user load demand in north-east (NE) Indian states. The energy system is modeled and simulated in the HOMER software. The monthly average global horizontal solar radiation (GHSR) and ambient temperature of the NE states are found to be 3.95–4.79 kWh/m2 and 12.9–25.3 °C, respectively. The synthesized typical AC electrical load profile of 10 kWp is assumed to have a scaled daily annual mean value equal to 138 kWh/d and an average base demand value equal to 5.75 kW. With the considered connected load, the available GHSR and ambient temperature, the optimal sizes of renewable energy components for the considered eight geographical locations (latitude: 23° 30′-27° 3′ North, longitude: 88° 37' – 94° 7′ East) are determined based on the minimum levelized cost of energy (COE) and lowest net present cost (NPC). The optimal system architecture range obtained is 110–120 kW PV array, 10–15 kW FC, 30–60 kW electrolyzer, 40–60 kg hydrogen tank capacity and 15 kW converter. Based on optimization results, the levelized COE and NPC range obtained are 0.509–0.689 $/kWh and $ 3,27,557–4,43,004, respectively, which confirm the cost-effectiveness of the proposed optimal energy system. Besides, with a renewable fraction of 100%, the electricity generated by the PV/HFC system satisfied the load demand and produced excess electricity with capacity factor found to be 16.4–31.2% in all the NE Indian states. Moreover, the optimized electrical profile, PV profile, inverter profile, and hydrogen production from an FC are compared and analyzed in terms of monthly average and annualized values for all the NE states. Also, the range of net hydrogen produced by the electrolyzer over the year obtained is 1538–1856 kg/yr.

Techno Economic Evaluation of Hybrid Energy Isolated Micro-Grids for Rural Areas in Four Zones of Egypt

In this paper, Rural electrifications and optimum sizing of isolated hybrid micro-grids improve the quality of the life in rural areas by using the optimization technique. A software homer optimization technique has been used to model isolated micro-grid performance during a time of one year, considering hourly variations in both the availability of renewable resources and variations in load demands. The optimum solution is obtained considering the minimization of the levelized costs of energy (LCOEs) over a project lifetime of 25 years. The simulations concentrated on the net present costs (NPCs), LCOEs, and a renewable fraction (RFs) of the given hybrid isolated micro-grids for all four zones. The gotten analyses show that SPV/wind/diesel/battery storage hybrid isolated micro-grids configuration is found as optimal solutions for 1.3 $/l of diesel fuel consumption. This paper studied the feasibility of different isolated micro-grid configurations comprising SPV, WT, and diesel in different areas of Egypt. Four rural isolated micro-grids have been randomly chosen for the four areas in Egypt with the intention that the obtained results of this study could be replaced in other rural locations of the selected areas with similar terrains. HOMER simulation was used to calculate the economic feasibility of the isolated micro-grids. The simulations focused on the LCOEs and RFs of the given hybrid component for all four regions. The analyses showed that SPV/wind/diesel/battery hybrid isolated micro-grids configuration is found as the best architecture for all rural areas. It also presented a good performance in fuel consumption and CO2 reduction.

Assessing the influence of legal constraints on the integration of renewable energy technologies in polygeneration systems for buildings

Hybrid polygeneration systems offer a great opportunity to meet growing energy demands with cost efficiency and environmental benefits. The identification of the optimal solution (configuration and operational strategy) is strongly affected by the relationship between the system and its surroundings. Previous studies have analyzed the influence of boundary conditions on the synthesis of polygeneration systems for buildings. However, local regulations are often disregarded or oversimplified in those studies. Therefore, this paper aims to evaluate the influence of legal conditions on the integration of renewable energy technologies in polygeneration systems for buildings. A comprehensive synthesis model is developed, including different types of legal conditions, such as power exchange modalities, subsidies/surcharges on energy prices and investment costs, and total ban on fossil fuels. Then, the model is applied to the case study of a Brazilian hospital. The current Brazilian net metering scheme is implemented. Results show that natural gas cogeneration is an attractive solution to cover the hospital's energy demands with or without the possibility of selling/exporting electricity. Also, the Brazilian net metering scheme, by itself, is not enough to ensure renewable energy deployment. An in-depth discussion about the conditions that would promote renewable energy integration is reported and recommendations are made on how current policies can be improved, including the need to explicitly address renewable technologies, the application of minimum renewable fractions, and the role of renewable heat/cooling. While the case study considers the specific circumstances in Brazil, it provides insights that can be extended to other countries or applications.

Case Study of a Hybrid Wind and Tidal Turbines System with a Microgrid for Power Supply to a Remote Off-Grid Community in New Zealand

This paper evaluates the feasibility of using a hybrid system consisting of wind and tidal turbines connected to a microgrid for power supply to coastal communities that are isolated from a main supply grid. The case study is Stewart Island, where the cost of electricity, provided by a central diesel power station, is higher than the grid network in New Zealand. Local residents believe that reducing the consumption of diesel and having a renewable source of electricity generation are two of the island’s highest priorities. Merging a tidal energy source (predictable) with wind (unpredictable) and diesel (back-up), through a microgrid, may be a way to increase reliability and decrease the cost of generation. Several off-grid configurations are simulated using HOMER and WRPLOT software. Using two wind and four tidal turbines, plus one diesel generator for back-up, is the best design in terms of lower greenhouse gas emissions, higher renewable fraction, and reduced net present cost.

Techno-Economic Analysis of Grid-Connected PV System for a Location in Perlis, Malaysia

Hybrid Renewable Energy System (HRES) is a system that comprises of multiple renewable generations with backup generation such as diesel generator or battery system. Currently, most of the remote areas depends on diesel generator for energy. However, diesel releases high amount of CO2. Moreover, diesel prices also are high and fluctuates according to the global market price. Hence, techno-economic analysis of a HRES system of grid-connected photovoltaic (PV) were conducted using Hybrid Optimization of Multiple Energy Resources) software (HOMER. The analyses include inputs such as load demands and renewable resources. The results include Net Present Cost, capital investment, renewable energy fraction, Cost of Energy and CO2 emissions. Multiple configurations will be assessed that suited best for the selected location.

Comparative study and sensitivity analysis of a standalone hybrid energy system for electrification of rural healthcare facility in Nigeria

This paper investigated the techno-economic viability assessment of solar PV/wind/diesel generator (DG)/battery hybrid energy systems (HES) for powering an isolated rural health clinic in northern Nigeria. HOMER–software tool developed by the US National Renewable Energy Laboratory (NREL) has been utilized for the techno-economic assessment of the proposed HES. The results of the simulation reveal that PV/DG/battery HES with 5.43 kW PV, 2 kW DG, 3.06 kW power converter, and 10 units of batteries emerged as the optimum system and most preferable with the minimum Net Present Cost (NPC) of $16,457 and Cost of Energy (COE) of $0.259/kWh compared to other system cases. The outcome also shows that the optimized solution is environmentally friendly as it presented an acceptable carbon dioxide emission of 1304 kg/year, which was about 80% and 82.5% less than that of system case 3 (DG/battery) and system case 5 (DG-Only). To have a good understanding of the operation of various system configurations considered, details of the system’s battery storage status and power flow are discussed via the energy balance of the various system configurations. This analysis shows operating cost, fuel cost, COE, fuel consumption, and renewable fraction are sensitive to the variation in all the considered sensitivity parameters.

Integrated Renewable Energy System for Stand-Alone Operations with Optimal Load Dispatch Strategy

The hybrid system configuration is used for meeting the thermal and electrical load demands of an off-grid network simultaneously with the model proposed in this paper. Li-ion battery, Micro Gas Turbine (MGT), wind turbine and solar photovoltaic configurations are analyzed. Hybrid Optimization of Multiple Electric Renewables (HOMER) software is used for estimating utilization of various strategies for power management, recovered waste heat and excess energy in the model. The heating demand is met and examined by the thermal load controller with and without the options of waste heat recovery. The hybrid system hardware components are sized, compared and analyzed based on cyclic charging (CC) and load following (LF) dispatch strategies. Various electrical to thermal load ratio are considered for examining the system performance. Various uncertainties and their effects are reported on comparison of grid-connected and stand-alone options. The hardware components are reduced in size thereby appreciable cost benefits are observed in the results. In the optimized hybrid system, the renewable energy fraction is increased causing high renewable penetrations and the CO2 emission is reduced by a large value. For all the configurations analyzed, several environmental and cost benefits are offered by the CC strategy.

Adaptiveness of a model predictive controller for a thermal-electrical renewable energy system in four different German single-family house energy standards

Model predictive controller (MPC) until now is required to be custom designed for each particular case. A combined system-level controller and universalization of MPC is yet to be achieved. This article focuses on simulatively investigating the adaptability of a previously developed whitebox-model MPC using a generic objective function for increasing renewable energy fraction and self-consumption in a decentralized integrated renewable energy system. The chosen single-family house energy standards are: high renewable fraction house (Sonnenhaus); modern building (KfW55); low primary energy house (passive house); and old building from 1995 (WSchVO95). From the perspective of universal implementation, it could be identified that a change in weightage factors is only required for the old WSchVO95 building. An astonishing reduction in space heating demand: 15% for Sonnenhaus; −30% for KfW55; −30% for passive house; and −2% for WSchVO95 could be accomplished. In terms of energy supply, ca. 10% increase in solar thermal fraction with the new buildings and a 14% increase in PV supply in all buildings could be achieved. Altogether, decentralized system self-consumption fraction increases by 8–12% via MPC. Whitebox MPC is however still a hindrance with huge optimization time making it not suitable for real-time implementation.

An integrated photovoltaic/wind/biomass and hybrid energy storage systems towards 100% renewable energy microgrids in university campuses

The incorporation of energy storing units into hybrid systems reallocates the excess electricity to meet demand requirements in the deficiency periods. This study seeks to determine the optimal size of a Photovoltaic (PV)/wind/biomass hybrid system with and without energy storage built on the base of boosting the demand–supply fraction (DSF) and the renewable energy fraction (FR) with a net present value larger than or equals to zero. The Generalized Reduced Gradient algorithm has been utilized in this study to evaluate the optimal components’ capacities of the proposed system. Middle East Technical University Northern Cyprus Campus was used as a case study. The proposed system consists of 1.79 MW PV, 2 MW wind and 0.92 MW biomass systems with 24.39 MWh pumped hydro storage system and 148.64 kWh batteries achieving FR of 99.59%, DSF of 98.86%, and a cost of electricity equals to 0.1626 $/kWh. The simulations results proved that the integration of a hybrid energy storage system with the PV/wind/biomass system ensures very high autonomy approaching almost 99%. Finally, considering the significant excess energy produced by the tri-hybrid system, this excess could also be allocated towards meeting the campus’s thermal and domestic hot water demands creating a polygeneration power system.

Optimization of Hybrid Energy Systems for Rural Electrification

This study is an optimization of hybrid energy system in Nigeria, the energy requirement of Ikot Inyang rural community is satisfied after carrying out the design and simulation of different variables, the optimal systems were a system that consisted of 5 wind turbines, solar models and a diesel generator as energy sources. Ikot Inyang is a rural community located in Akwa Ibom state, South-South Nigeria, the community is connected to the national electricity network (grid) but the power supply is rarely consistent. The load estimate analysis showed that Ikot Inyang had peak load 58.62kW and peak energy demand per day as 670.65kWh. Eight (8) different design plans were considered and simulations were carried out using HOMER software. Several factors were used to determine the most optimal system, which includes the Net Present Cost, Levelized Cost of Energy, Renewable Fraction and system emissions. This was carried out for the 25 years project life time. The design plans were made of stand-alone systems as well as combination of many generating sources with battery included in some systems, various simulations were carried out. HOMER Presented the most technical and economical solution to meet the load demand at the least Net Present Cost, least Levelized Cost of Energy and allowable Renewable fraction. The most optimal solution for Ikot Inyang involved a combination of a 50Kw diesel generator, 5 Bergey Excel 10 wind turbine, 134kW solar model, 204 strings of Hoppecke 12 OPzS 1500 battery and 2 Leonics MTP-413F 25kW converter. The dispatch method used for this system was the Load Following dispatch method. This method produced at least Net Present Cost of $1.7M (N349.36M), Levelized Cost of Energy of $0.228 (N74.74), considerably high Renewable Fraction of 84.7%, When this result was compared with a diesel generator only system, it showed 77.2% reduction in the diesel saving fuel cost. Comparison with a design plan consisting of diesel generator only showed that 202,155kg of carbon dioxide is saved per year and 1,262kg of carbon monoxide is saved per year when making use of the most optimal system design.

Exploring the cost implications of increased renewable energy for the U.S. power system

Over the last decade, the fraction of annual U.S. electricity generation for renewable energy has doubled from 10 % to 20 %. This growth has been driven by several factors, including technology cost reductions and policy support. The share of renewable generation is projected to increase over time. Reference case scenarios from four different organizations show least-cost U.S. electricity buildouts with renewable energy generation fractions of 31–36 % by 2030 and 40–65 % by 2050. Using a capacity expansion modeling tool, we investigate how changing the amount of renewable energy from the least-cost solution impacts the cost of building and operating the electricity system. The relationship between system cost and renewable energy generation fraction is non-linear. Small deviations near the least-cost solution have minimal cost impacts (changing the renewable energy penetration by +/- 5% results in system cost changes of less than 1%), while similar deviations that are farther from the least-cost solution can result in large cost changes. Increased levels of RE lead to lower absolute emissions, and we evaluate the trade-offs between emissions savings and system costs for higher and lower levels of RE penetration.

Experimental investigation on a combined solar and ground source heat pump system for a single-family house: Energy flow analysis and performance assessment

This paper presents experimental investigations on a combined solar and ground source heat pump (SGHP) system for a single-family house. The SGHP system was installed at the Lyngby campus of Technical University of Denmark with horizontal ground heat exchanger (HGHE). Detailed experiments were carried out on the system in 2019 under real weather conditions and the heating demand for domestic hot water (DHW) and space heating (SH). The focuses of the investigation are energy flow analysis and performance assessment on the SGHP system. The results showed that the yearly system seasonal performance factor of the SGHP system (SPFSHP) was 2.8, and the maximum monthly SPFSHP was up to 5.7 in April with the highest solar radiation. Directly utilized solar energy for the combi-storage was 500 kWh lower than the annual solar heat for charging the ground, and it accounted for 36.6% of annual heat input of the combi-storage, the rest of the heat was supplied by the heat pump system that consumed 84% of total electricity energy. Different from the large fluctuations of monthly solar fraction due to solar radiation, the monthly renewable heat fraction was within the range from 57% to 83%, and the yearly value was 65%.