Volume 17 Issue 4
Jan.  2020
Article Contents

Siti Maherah bt Hussin, Zainal Salam, Norzanah Rosmin, Md Pauzi Abdullah, Dalila Mat Said, Madihah binti Md Rasid. Future Hybrid of Photovoltaic and Fuel Cell for Langkawi SkyCab[J]. Journal of Electronic Science and Technology, 2019, 17(4): 348-356. doi: 10.1016/j.jnlest.2020.100016
Citation: Siti Maherah bt Hussin, Zainal Salam, Norzanah Rosmin, Md Pauzi Abdullah, Dalila Mat Said, Madihah binti Md Rasid. Future Hybrid of Photovoltaic and Fuel Cell for Langkawi SkyCab[J]. Journal of Electronic Science and Technology, 2019, 17(4): 348-356. doi: 10.1016/j.jnlest.2020.100016

Future Hybrid of Photovoltaic and Fuel Cell for Langkawi SkyCab

doi: 10.1016/j.jnlest.2020.100016
Funds:  This work was supported by the Research University Grant (GUP-Tier 1) under Vote No. 19H40
More Information
  • Author Bio:

    Siti Maherah bt Hussin received her B.Eng. degree in electrical engineering in 2009 with the first class honours, the M.E.E. degree in electrical power in 2011, and the Ph.D. degree in coordinated generation and transmission maintenance scheduling using mixed integer linear programming in 2016, all from Universiti Teknologi Malaysia (UTM), Johor. She is a senior lecturer at the Faculty of Engineering, UTM Johor. Her research interests include power system planning and renewable energy

    Zainal Salam obtained his B.Sc. degree in electronics engineering, M.E.E. degree in electrical engineering, and Ph.D. degree in power electronics, from the California State University, Chico; UTM, Kuala Lumpur; University of Birmingham, Birmingham in 1985, 1989, and 1997, respectively. Currently, he is a professor with the Faculty of Engineering, UTM, Johor. Since 2011, he has been the editor of IEEE Trans. on Sustainablde Energy, and a member of editorial board for The Scientific World Journal. His main research interests include the design, instrumentation, and control of power electronics renewable energy systems

    Norzanah Rosmin received the B.Eng. and M.E.E. degrees both in electrical engineering from UTM, Johor in 1999 and 2002, respectively. Then, she received the Ph.D. degree in renewable energy from Loughborough University, Loughborough in 2015. Currently, she is a senior lecturer at the Faculty of Engineering, UTM, Johor. She is also a Certified Energy Manager (C.E.M) in Malaysia. Her research interests include alternative/renewable energy, renewable energy management systems, renewable energy management and integration systems, demand-side management, and power systems

    Md Pauzi Abdullah received the B.Eng. degree in electrical and electronic engineering from Universiti Tenaga Nasional (Uniten), Kajang in 2002, the M.Sc. degree in electrical power engineering in 2003, and the Ph.D. degree in 2008, both from University of Strathclyde, Glasgow. Currently, he is an associate professor with the Faculty of Engineering, UTM, Johor. He is also the Director of the Centre of Electrical Energy Systems (CEES), Institute of Future Energy (IFE), UTM, Johor. His research interests include power systems analysis, systems security, deregulated electricity market, and demand-side management

    Dalila Mat Said obtained her B.Eng. degree in electrical engineering in 2000, her M.Eng. degree in electrical engineering in 2003, and the Ph.D. degree in power quality in 2012, all from UTM, Johor. She is a senior lecturer with the Faculty of Engineering, UTM, Johor. Her research interests include power quality and power system measurement and monitoring

    Madihah binti Md Rasid received her B.Eng. degree in 2009 with the first class honours, her M.E.E. degree in electrical power in 2012, and the Ph.D. degree in optimization of renewable energy based distributed generations using differential evolution algorithm in 2016, all from Kyushu University, Fukuoka. She is a senior lecturer with the Faculty of Engineering, UTM, Johor. Her research interests include the optimization of renewable energy and distributed generation

  • Corresponding author: S. M. Hussin, Z. Salam, N. Rosmin, Md P. Abdullah, D. M. Said, and M. Md Rasid are with the School of Electrical Engineering, Universiti Teknologi Malaysia, Johor 81310 (e-mail: maherah@fke.utm.my; zainals@fke.utm.my; pauzi@fke.utm.my; norzanah@fke.utm.my; dalila@fke.utm.my; madihah@fke.utm.my).
  • Received Date: 2019-07-26
  • Rev Recd Date: 2019-08-19
  • Publish Date: 2019-12-01

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Future Hybrid of Photovoltaic and Fuel Cell for Langkawi SkyCab

doi: 10.1016/j.jnlest.2020.100016
Funds:  This work was supported by the Research University Grant (GUP-Tier 1) under Vote No. 19H40
  • Author Bio:

  • Corresponding author: S. M. Hussin, Z. Salam, N. Rosmin, Md P. Abdullah, D. M. Said, and M. Md Rasid are with the School of Electrical Engineering, Universiti Teknologi Malaysia, Johor 81310 (e-mail: maherah@fke.utm.my; zainals@fke.utm.my; pauzi@fke.utm.my; norzanah@fke.utm.my; dalila@fke.utm.my; madihah@fke.utm.my).

Abstract: Langkawi SkyCab has the highest energy demand in Langkawi Island and the demand keeps increasing year by year. This study proposed alternatives energy of a hybrid photovoltaic (PV) and fuel cell system for the SkyCab’s operation. The best sizing and configurations were chosen based on Homer simulation software. A comparative study was done between a conventional system and other hybrid combinations. The results revealed that the proposed system had reduced the cost as well as CO2 emission almost by 39% and 79%, respectively. The hybrid PV and fuel cell system is aligned with the Malaysian government’s goals of reducing carbon emissions 40% by the year 2030.

Siti Maherah bt Hussin, Zainal Salam, Norzanah Rosmin, Md Pauzi Abdullah, Dalila Mat Said, Madihah binti Md Rasid. Future Hybrid of Photovoltaic and Fuel Cell for Langkawi SkyCab[J]. Journal of Electronic Science and Technology, 2019, 17(4): 348-356. doi: 10.1016/j.jnlest.2020.100016
Citation: Siti Maherah bt Hussin, Zainal Salam, Norzanah Rosmin, Md Pauzi Abdullah, Dalila Mat Said, Madihah binti Md Rasid. Future Hybrid of Photovoltaic and Fuel Cell for Langkawi SkyCab[J]. Journal of Electronic Science and Technology, 2019, 17(4): 348-356. doi: 10.1016/j.jnlest.2020.100016
    • Langkawi Island is the largest one of the 104 islands in the Langkawi Archipelago, located in the Straits of Malacca, which has an area of 478.5 km2. Protected from industrial activities and to boost its ecotourism, Langkawi Island became duty-free in 1987[1]. However, supplying the island with enough electricity is a challenge. In line with the tourism concept adapted by Langkawi, the state government plans to turn Langkawi Island into the low-carbon island by 2030. The demand for electricity has been increasing from 2011 to 2015, according to the Feasibility Study for Development of Low Carbon Model for Langkawi by the Ministry of Energy, Green Technology, and Water (KeTTHA)[2]. Currently, all electricity is supplied by the national grid system, connected via a high-voltage substation in Kuala Perlis through submarine cables (2×100 MVA and 1×150 MVA) to the substation in Telok Apau, Langkawi. Based on the energy demand recorded in 2017, the total energy consumption for the cable cars is about 625466 kWh. The cable cars consume all the energy supply from the grid and have two diesel generators as backup supplies in case of an emergency.

      Current development and research show that green energy sources have great potential as alternatives energy in providing feasible power supply for the islands. Many studies have been managed to analyze the feasibility of implementing photovoltaic (PV) systems as an alternative energy source. However, the power generated by the PV system is intermittent and unpredictable since it is prominently dependent on the availability of solar radiation[3]. As a solution, PV systems are usually hybrid with an energy storage system or diesel standby generators. The application of the hybrid PV/battery/diesel systems for rural and island electrifications has been investigated before[4]-[12]. Also, an economic evaluation of the hybrid PV/wind/battery system has been made for an isolated island in Hong Kong[13]. The results showed that the renewable energy, PV and wind, has successfully replaced the existing diesel generator with the generation contribution of 84% and 16%, respectively. To ensure the continuous supply to the island, the battery is used as an energy storage system.

      There are two conditions where the fuel cell operates as a standby generator: The load exceeds PV generation and the charging level of the battery reaches its minimum level[14]-[16]. The significant advantage of the fuel cell over petrol or diesel generator is its high energy conversion. The fuel cell has about 50% efficiency meanwhile diesel has only 8% to 15% for a similar capacity of 1 kW[17]. Besides, the fuel cell has other good properties, such as a low noise level and clean exhaust gases emission. Although the fuel cell has a high initial investment, it could generate electricity at a lower cost as compared with diesel due to its low maintenance cost.

      Renewable energy that is hybrid with batteries or/and diesel generators has many drawbacks in terms of short lifetimes of batteries and high maintenance costs of diesel generators. Moreover, diesel generators produce loud noises and emit hazardous exhaust gases.

      Currently, there have not been any specific study conducted regarding the renewable energy project on Langkawi Island. Here, a hybrid PV/fuel cell system is evaluated for the Langkawi SkyCab system utilizing the real load profile. Several configurations of hybrid systems are simulated utilizing the Homer software to effectively compare economical and emission factors. These three configurations are PV/fuel cell, PV/battery, and PV/fuel cell/battery systems, all of which are grid-connected. The results are used as a reference to determine an efficient, dependable, and cost-effective system for Langkawi SkyCab.

      The rest of this paper is organized as follows. Section 2 explains the detail components involved in the proposed system. While, Section 3 discusses the effectiveness of the proposed system by performing a comparative study between the proposed hybrid PV/fuel cell, current SkyCab, PV/battery, and PV/battery/fuel cell systems. The economic analysis of the project installation also has been explained in this section. Then, the conclusion is drawn in Section 4.

    • Fig. 1 shows the schematic diagram of the proposed PV/fuel cell hybrid system developed using the Homer program. The system consisted of PV modules, a fuel cell generator with an electrolyzer, a hydrogen tank, a compressor, power conditioning units (converters), a DC/AC busbar, a grid, and load models. The main objective was to determine the present aggregate net cost based on Langkawi Island’s data. The simulation has gone through the optimization process and sensitivity analysis to achieve the best hybrid design. The results have been analyzed based on the cost-benefit and environmental impact, which were then compared with the conventional system.

      Figure 1.  Schematic of the proposed PV/fuel cell hybrid system.

      All the costs calculated by the Homer software is based on the United States (US) currency. Since the proposed system is simulated for the Malaysian system, the costs need to convert to Ringgit Malaysia (RM) where for the trade currency of July 2019, US $1 was equivalent to RM 4.12. To analyze the economic effects of the developed system, three main economical parameters were identified: Levelized cost of energy (LCOE), total net present cost (TNPC), and residual cost. These costs were measured to decide the optimum system.

    • The technical properties of solar panels used in this system are given in Table 1[18]. The size of PV arrays chosen in this study is 500 kW, which can be varied from 100 kW to 500 kW, with an interval of 100 kW. The variation is purposely for economic study analysis to identify the optimum size for the proposed hybrid system. The peak load of the system was set to 414 kW. In the case of surplus PV generation, the energy can be supplied to the electrolyzer which is important for hydrogen production. Each PV module is rated at 200 W with a nominal voltage of 12 V. The total modules for this system are 2500 units that cover the area of 3675.36 m2. The lifetime warranty is about 25 years with the derating factor presumed to be 80%.

      ParametersValues
      Type of cellPolycrystalline silicon
      No. of cell72
      Maximum power300.0 W
      Minimum power181.3 W
      Open circuit voltage33.4 V
      Short circuit current8.12 A
      Module efficiency13.6%
      Normal operating cell temperature47.5 °C

      Table 1.  Electrical characteristics of PV panel

      The performance of PV modules is affected by the temperature as it is less effective when the temperature increases[19],[20]. The temperature coefficient of these modules is 0.5%/°C, stating that every 1 °C of temperature increment will reduce 0.5% of its power. In this case, the PV modules have a nominal operating temperature of about 47.5 °C, while its efficiency under the standard test condition is 13.7%[21]. The initial capital, replacement, and operational and maintenance (O&M) costs are assumed to be $7000, $6000, and 10 $/year, respectively.

    • The function of a fuel cell is to transform chemical energy into electrical energy. The main fuels for the conversion process are hydrogen and oxygen gases. The by-product of this reaction is water which is safe to the environment. To represent a complete set of a fuel cell system, several components are included in the Homer simulation, such as the electrolyzer, compressor, and hydrogen tank.

      To assess the implementation of the hybrid system, three different capacities of fuel cells were considered: 0, 200 kW, and 400 kW. Their lifetime, efficiency, and minimum load ratio were considered as 15000 h, 64%, and 30%, respectively. Meanwhile, the initial capital, replacement, and O&M costs were $450, $450, and 0.15 $/year, respectively, for a 100-kW fuel cell[22]. The detailed specification of the fuel cell can be referred to Table 2.

      ParametersValues
      Rated power (kW)2.4 to 10.5
      Rated current (A)135
      Voltage (V dc)17.5 to 77.6
      Cell efficiency (%)54 to 64
      Fuel consumptionHydrogen

      Table 2.  Fuel cell specification

    • Based on Fig. 1, there are two types of energy conversion involved in the proposed system: Alternating to direct and direct to alternating power. In this case, a 400-kW inverter and a 400-kW rectifier are used. The lifetime of the converters is 15 years. Meanwhile, the efficiency of the inverter and rectifier is 90% and 85%, respectively. There is no O&M cost involved for the converters but their initial capital and replacement costs are considered as $800 and $750, correspondingly.

    • To validate the effectiveness of the proposed system, comparative studies were performed between the proposed hybrid PV/fuel cell and the current system of SkyCab. For further analysis, the proposed system was also compared with other configurations: PV/battery and PV/battery/fuel cell.

      There are three stations for the cable car: The base station, middle station, and top station. In general, the electricity is required to power the machine for the cable car operation, lighting, computers, and control room. Fig. 2 illustrates the average and the deviation of the monthly load profile for Langkawi SkyCab. It can be noticed that the lower load demand occurs in April, June, September, and November because they are not a school holiday season as well as the weather condition. The operation requires the peak demand of 414 kW and it has the base demand of approximately 71.4 kW with a load factor of 0.172.

      Figure 2.  Monthly load profile.

      The solar radiation data are obtained from Malaysia Meteorology Centre. The solar radiation ranges from 4.541 kWh/m2/day to 5.694 kWh/m2/day. The annual average of solar irradiance is estimated to be 4.97 kWh/m2/day. It is noticed that the solar irradiance is higher from February to April, while it is at the lowest in November due to the northeast monsoon. Fig. 3 illustrates the annual solar radiation and clearness index for Langkawi SkyCab.

      Figure 3.  Annual solar radiation and clearness index for Langkawi SkyCab.

    • Figs. 4 and 5 show the electrical diagram for current SkyCab and the proposed hybrid PV/fuel cell system, respectively. In the current system, SkyCab is fully supplied by the grid system and there are two diesel generators for emergency conditions, especially when faults or interruptions occur in the power system. Based on the current market price, 0.55 $/L is considered for diesel. Based on the simulation results, TNPC and LCOE of the system are about $1102129 and 0.138 $/kWh, respectively. In this system, the annual average electricity demand of the AC load is 625463 kWh, where the electricity is fully supplied by the grid. The emissions dissipated by the diesel consist of carbon dioxide (CO2) and nitrogen oxides (NOx) are 96712 kg/year, and 2130 kg/year, respectively. The results indicate that the conventional system had released a lot of hazardous emissions into the atmosphere.

      Figure 4.  Current SkyCab energy system.

      Figure 5.  Proposed hybrid PV/fuel cell.

      Meanwhile, the proposed system had two types of renewable energy which are PV and a fuel cell system. For the operation of the fuel cell system, hydrogen is required for the reaction thus the hydrogen tank is one part of the system. The optimum size of the components is chosen based on the highest given renewable fraction. This value represents the fraction of energy from the renewable power sources supplied to the load. Based on Table 3, the highest renewable fraction value is 0.746 and the two configurations give the same value. The best size considered is 500-kW PV, a 400-kW fuel cell, and a 400-kW power converter which gives the lowest costs of capital, operating, TNPC, and LCOE. The amounts of CO2 and NOx emitted by the system are 20402 kg/year and 43.3 kg/year, respectively. It shows that the proposed system has produced lower emissions compared with the conventional system.

      Grid
      (kW)
      PV
      (kW)
      Fuel cell
      (kW)
      Converter
      (kW)
      Electrolyzer
      (kW)
      Capital cost
      ($)
      Operating cost
      ($)
      TNPC
      ($)
      LCOE
      ($/kWh)
      Renewable fraction
      500500400400400189467373596670430.0830.746
      500500800400400191267377046732550.0840.744
      5005001200400400193067377376754690.0840.744
      500500400800400197467375656776740.0850.746
      5005001600400400194867378046781240.0850.743

      Table 3.  Size of grid-connected PV/fuel cell system proposed by Homer

      The results show that the total power generated by the PV, fuel cell, and grid systems is 728814 kWh/year, 12283 kWh/year, and 251926 kWh/year, respectively. Meanwhile, the total power consumption of the load and that of the electrolyzer are 625463 kWh/year and 294223 kWh/year, correspondingly. In this regard, the surplus power is about 73337 kWh/year and there is no capacity shortage occurred in this system. To get some profit, this surplus power can be traded back to electric utility companies but restricted to the terms and conditions.

      The above findings demonstrate that the proposed hybrid system is more efficient for SkyCab as it reduces both the costs and the environmental impact as summarized in Table 4.

      Cost/pollutantCurrent SkyCab systemProposed hybrid PV/fuel cellPercent of reduction (%)
      TNPC ($)110212966704339.48
      LCOE ($)0.1380.08339.85
      CO2 (kg/year)967122040278.90
      NOx (kg/year)213043397.96

      Table 4.  Comparison of costs and emissions for current and proposed systems

    • Table 5 shows the comparative costs of the three configurations. The results state that the proposed configuration obtained the lowest costs compared with the others. In contrast, the grid-connected PV/fuel cell/battery system and grid-connected PV/battery system required high initial capitals due to the expensive price of the batteries. Meanwhile, Table 6 shows the pollutants emitted by these three systems. The PV/fuel cell produced the lowest CO2 emission while producing the least sulfur dioxide (SO2) and NOx. Thus, it can be highlighted that the proposed PV/fuel cell is the most environmentally friendly option of the three configurations. Although the PV/battery and PV/fuel cell/battery systems are capable of satisfying the load, they are not suggested for the SkyCab, because the costs of these systems are higher than the proposed system as stated in Table 7.

      SystemInitial capital cost ($)Replacement cost ($)O&M cost ($)TNPC ($)
      Grid-connected PV/fuel cell18946760996431161667043
      Grid-connected PV/battery226017133676377685697185
      Grid-connected PV/fuel cell/battery371817183748387911893600

      Table 5.  Costs comparison

      System modelEmission (kg/year)
      CO2SO2NOx
      Grid-connected PV/fuel cell2040288.543.3
      Grid-connected PV/battery55163239.0117
      Grid-connected PV/fuel cell/battery2570811154.5

      Table 6.  Emission reading comparison

      Hybrid systemTNPC ($)LCOE ($/kWh)Renewable fraction
      PV/fuel cell6670430.0830.746
      PV/battery6971850.0870.763
      PV/fuel cell/battery8936000.1120.763

      Table 7.  TNPC, LCOE, and renewable fraction for each system

    • Based on the site investigation, the PV modules are strategic to be installed at the roof of the north and south platforms. The total number of solar panels to be installed at the suggested place is 2500 modules with a total area of 3675.36 m2. From the simulation result, the simple payback of the implemented system is around 3.98 years while the discounted payback is 4.69 years. In this analysis, the discounted payback is taken into account as it reflects the currency fluctuation in the inflation rate which directly affects the real interest rate. The return of investment is about 23.2% per year for around 4 years of the payback excluding the first year, which is the year of initial investment, while the internal rate of return is 24.4% per year. After the 5th year of returning on the investment, the system starts to gain the profit from the power generated. The proposed hybrid system shows good economic performance which can be the attraction point to the investor. Table 8 summarizes the economic performance for changing the current generation system to the hybrid system.

      MetricValue
      Present worth ($)372373
      Annual worth ($/year)29130
      Return on investment (%)23.2
      Internal rate of return (%)24.4
      Simple payback (year)3.98
      Discounted payback (year)4.69

      Table 8.  Economic performance for changing current generation system to the hybrid system

    • This paper demonstrates the effectiveness of the proposed hybrid PV/fuel cell system for SkyCab. By installing this system, the costs of TNPC and LCOE would be reduced by almost 39.48% and 39.85%, respectively. Furthermore, the CO2 emission would decrease by about 78.9% which will contribute to the government’s goals towards building a low-carbon emission model for Langkawi Island.

    • The appreciation goes to the Centre of Electrical Energy Systems (CEES) and Power Department, Faculty of Electrical Engineering, Universiti Teknologi Malaysia.

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