Modeling of hybrid renewable energy system the case study of Istanbul Turkey

Abstract

Keywords: Stand-alone energy system; Hybrid; Renewable energy; HOMER PRO

Introduction

Many modern countries are experiencing a major rise in energy demands as they begin to work towards raising productivity and improving national living standards. In order to meet these new demands, countries typically start expanding their supply base without paying attention to the energy efficiency of the energies being used [1]. However, the combination of global warming as well as the continued depletion of fossil fuels has led to new alternative technologies being created and depended upon to supply today’s new energy demands. Alternative energy sources, mainly renewable energies, have become the frontrunners in the new renewable energy push, attracting more attention than ever before [2].

Solar and wind energy sources provide new ways to control and diminish fossil fuels. However, they face a few drawbacks when considering their high capital costs and dependence on climate. Wind energy technology in particular, is being developed in many modern countries and can be found both commercially as well as in smaller sized domestic wind turbines. These wind energy technologies can vary from just a few kilowatts to utility interconnected wind farm applications that go up to megawatts [3]. A lot of countries with high average daily solar radiations in the range of 3-6 kWh/m^2 are currently looking to reduce their fossil fuels usage [4-7]. In these countries, the current ability to supply power to residential areas mainly depends on “stand-alone” diesel or hybrid generation systems that are capable of supplying the power demands for the residential sector in a connected or off-grid style. The rural communities, who do not have access to the grid, are the ones that typically settle on a “stand-alone” hybrid system. These rural communities can be found across the globe from Denmark, India, Morocco, Kingdom of Bahrain, and Iran [8]. It is important to note that when investigating the costs, component size, and other economic factors associated with using a hybrid system, environmental conditions must be analyzed [9]. In this paper, Hybrid wind/photovoltaic (PV) systems have been studied extensively and it was found that irregular patterns of wind and solar energy must be considered in regards to the energy storage system for hybrid energy systems [10-13]. In addition, combined “stand-alone” diesel generators are generally expensive to operate and maintain at low load levels [14]. This study proposes a hybrid energy system that can be used for a typical residential house located in Istanbul, Turkey

Techncial Note – JTEN – 2016 – 4 (41° 0' N, 28° 58' E). It also analyses the energy production of a hybrid energy system in terms of energy and economic aspects. In addition, a sensitivity analysis was conducted to compare the systems performance under various conditions including different solar panels slope, variable wind speed, and changing electricity load.

System Description

As shown in Fig.1, the proposed hybrid energy system includes two renewable sources (solar panels and wind turbine), a boiler, a electrical converter, a battery, and a diesel generator to supply the 22kWh/d (3.82kW peak load) electric demand and the

Results And Discussion

As it is shown in Fig.5, it is clear that a diesel generator has the most important role in supplying the energy demand. In this figure it shows that during the months with higher solar radiation and wind speed the generator uses less fuel to supply demand. It also shows that February and October have the most wind power and July and August have the highest solar power. By considering February as the highest load demand,

system production has increased significantly. In addition, the economic term is the most important part of analysis. The aim of reaching the most suitable component is done by reducing the costs and increasing the system efficiency. Fig. 4 shows the present value of the system for each type of costs including capital cost, fuel cost, operating cost, and replacement cost separately. It is logical that fuel cost has a more powerful effect 992

Figure 6. Produced power, wind speed and CO2 emission on the present value because the diesel generator works more than the two renewable energy sources.

in generator working capacity can cause less CO2 emission. So by increasing the wind speed, CO2 emissions will decrease. In addition annual emission data has been illustrated in Table 2. The performance assessment and economic feasibility of the stand-alone hybrid energy system will be discussed in this section. Fig.4 shows the present value of the system for each type of costs including capital cost, fuel cost, operating cost, and replacement costs for each system component separately. It is logical that the fuel cost has a more powerful effect on the present value because a diesel generator uses more fuel than the two renewable energy sources. A power electronic converter is needed to convert electricity between the AC and DC components, AC being the generator, load, and wind turbine and DC being the PV and battery. For the 1kW system the installation and replacement costs are taken as $300 and $300, respectively.

Quantity Hours of operation Number of starts Operational life Fixed generation cost Marginal generation cost Electrical production Mean electrical output Min. electrical output Max. electrical output Fuel consumption Specific fuel consumption Fuel energy input Mean electrical efficiency

Fig.6 illustrates the CO2 emission rate for varying wind speeds from 3.25 m/s to 6.5 m/s. Sensitivity analysis shows that by increasing the wind speed, the diesel generator works less than with low speed wind blowing. This reduction

Pollutant Carbon dioxide Carbon monoxide Unburned hydrocarbons Particulate matter Sulfur dioxide Nitrogen oxides

Conclusions

In more recent times, the stand-alone energy system has become highly demanded due to diminishing oil resources and elevated prices. This study proposes a hybrid energy system consisting of solar panels, a wind turbine, a diesel generator, a battery, a converter, and a boiler capable of supplying 22kWh/d electric load and 11.26kWh/d, thermal load. The results show the proposed system is energetically and economically feasible by considering a 25-year lifespan. Sensitivity analysis and energy analysis have been conducted to find the parameter effects on electricity production and CO2 emission.

[13] Türkay, Belgin Emre, and Ali Yasin Telli. "Economic analysis of standalone and grid connected hybrid energy systems." Renewable energy 36.7 (2011): 1931-1943. [14] Nayar, C. V., et al. "Novel wind/diesel/battery hybrid energy system." Solar Energy 51.1 (1993): 65-78.

Nomenclature

Thermal Load Generator Battery Photovoltaic Operation and Maintenance

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