- Email: [email protected]
Diesel Generator power system for cruise ship: A case study in Stockholm, Sweden
Case Studies in Thermal Engineering 14 (2019) 100497
Contents lists available at ScienceDirect
Case Studies in Thermal Engineering journal homepage: www.elsevier.com/locate/csite
Hybrid solar PV/PEM fuel Cell/Diesel Generator power system for cruise ship: A case study in Stockholm, Sweden
T
Chaouki Ghenaia,∗, Maamar Bettayebb,c, Boris Brdjanind, Abdul Kadir Hamidb a
Department of Sustainable and Renewable Energy Engineering, College of Engineering, University of Sharjah, Sharjah, United Arab Emirates Department of Electrical and Computer Engineering, College of Engineering, University of Sharjah, Sharjah, United Arab Emirates Center of Excellence Intelligent Engineering Systems (CEIES), King Abdulaziz University, Jeddah, Saudi Arabia d Electrical Engineering Department, Power and Network System, University of Belgrade, Belgrade, Serbia b c
A R T IC LE I N F O
ABS TRA CT
Keywords: Solar PV PEM fuel cell Diesel generator Hybrid power system Marine propulsion system Cruise ship
Optimal design and performance analysis of renewable energy system to serve the cruise ship main and auxiliary power in Stockholm, Sweden is presented in this paper. The goal is to integrate renewable energy systems in small and large ships for greener and sustainable marine transport. The power load for the cruise ship was determined, and modeling and simulation analysis was used to investigate the daily and annual performance of the power system architectures including the efficiency and capacity factors of the energy conversion systems. The total electrical power generated from the solar PV, PEM fuel cell, and Diesel generator; the cost of electricity; and the greenhouse gas and particulate matter PM emissions were determined. The proposed renewable energy system offers a good penetration of renewable energy system (13.83%), and greenhouse gas and particulate emissions reduction (9.84% emissions reduction compared to baseline system using Diesel engines). The integration of renewable and clean power systems such as solar PV and PEM fuel cell (high electrical efficiency) is very attractive solution for onboard ship power generation. They are economically viable (reduce the cost of Diesel fuel), cleaner than the conventional gas turbine and internal combustion engines and reduce the dependency on fossil fuel.
1. Introduction Diesel reciprocating engines are used in large cruise vessels for generating power for the propulsion system and auxiliary power for the ship’s system. The main or primary engines are used for the propulsion system and the secondary engines provide the load needed in the ship for the consumers. The optimization of the loading of Diesel engines/generators is needed for the reduction of both the energy consumption and emissions from the Diesel-electric propulsion system [1]. With the development of optimization methods and strategies, engines can operate with high efficiency at high loads and with a large variation in the power demand. This can be achieved with variable speed drive for the propellers (the rpm can be adjusted for minimum Diesel fuel consumption according to the system load). The Diesel-electric propulsion system used for large ferries and cruise ships provides (1) high reliability with the use of multiple engines redundancy (example – 2 engines for single propeller), (2) reduced life-cycle cost (reducing the operational and maintenance costs), (3) improved maneuverability (design and use of high quality propulsor), and (4) precise control of the electric propulsion motors. The engines for the Diesel-electric propulsion system need to be selected accordingly to the power demand (based
∗
Corresponding author. E-mail address: [email protected] (C. Ghenai).
https://doi.org/10.1016/j.csite.2019.100497 Received 9 June 2019; Received in revised form 7 July 2019; Accepted 8 July 2019 Available online 10 July 2019 2214-157X/ © 2019 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
on the highest expected electric load). The recent developments in Diesel-electric propulsion system helped to achieve huge fuel savings by operating the engines on variable speed but the propulsion marine industry still need to comply with the environmental requirement while meeting the operational demands. The environmental impacts from large ferries and cruise ship include greenhouse gas emissions from Diesel engines, oil pollution and acoustic. The exhaust gases from the combustion of Diesel fuel in the ships are a significant source of air pollution (SOX, NOX, PM, CO, CO2, and HCs). Based on the International Maritime Organization (IMO) study, the equivalent carbon dioxide emissions from shipping industry were estimated to 2.2% of the total emissions [2]. The projected equivalent CO2 gas emissions from large ships are expected to rise by 50%–250% by 2050 if we continue for the business as usual (no action is taken) [2]. It is also noted that contribution of marine Diesel engines is higher near the ports. The risks are higher near the port since the Diesel fuel of oil tankers and container ships has higher sulfur content and is cheaper compared to the Diesel fuel used for land applications. Different emissions control strategies and mechanisms are needed to control the greenhouse gas emissions from the marine industry (ships and ferries). Renewable energy options are being considered at the present for emissions reduction from the marine industry. Clean energy solutions such as alternative and renewable fuels (Biodiesel, Biogas, Hydrogen, Liquefied Natural Gas LNG, Methanol and Ethanol), solar and wind energy, PEM fuel cell, hybrid renewable power systems [3,4]; and [5] can be integrated in the existing and new ships. Biofuels (Biodiesel, Biogas, and Bio-hydrogen) are derived from Biomass feedstocks (contribute to the reduction of GHG emissions). Biofuels can be mixed with conventional fossil fuels to power conventional systems and to reduce the greenhouse gas emissions [6]. For example, cleaner fuel such as Biodiesel can replace Diesel fuel in Diesel-Electric propulsion systems of large ships. Hydrogen is another potential alternative and clean fuel for ship propulsion system. The advantage of using hydrogen in PEM fuel cells is that no CO2, NOX and SOX emissions are produced in the ship. In addition to alternative fuels, renewable energy systems can be developed and integrated in large ships and ferries. Wind is one of the greenest sources of energy in the sea. The wind can be used as a source of power for large ships especially when the ship is sailing to meet some of the power demands and reduce the greenhouse gas emissions. Solar PV can also be used to generate power in ships even the contribution will be small compared to power demand to drive the ship. The power generated using solar PV depends on the solar irradiance for each location, the efficiency of the solar cells, and the available deck area on the ships for the solar PV system. Several studies on the development and use of renewable energy system in ships can be found in the literature. [7]; reported the need for the development and integration of renewable energy systems for marine transport. It was highlighted in this study that solar PV is the best renewable and alternative energy technology to power commercial ships. Fuel cell technology was the second-best clean energy technology that can be applied on the ship for the Taiwanese maritime industry. [8]; integrated fuel cells/battery energy system as a solution for the propulsion system for a boat. This solution was selected based on the high efficiency and low emission of the power system. Different strategies were used for energy management from different power sources. Modeling and simulation were used in this study based on Matlab/Simulink environment to study the dynamic performance to maximize the efficiency of the system. The adequacy of this power system and the energy management system was tested for real ship driving cycles. [9]; investigated the distributed energy production from different resources (hydrogen fuel cell, solar, and batteries) used in small electric ships. The propulsion system was equipped with two electric motors, batteries, fuel cell and solar PV array. The proposed power system satisfies the power requirements and it was autonomous. They also concluded that if the operational of the small electric ship is not very demanding, the vessel may run in summer with only solar PV system. [10]; reviewed the techniques and operational solutions to reduce the emissions from the ships. In this study, they used optimization approach for the identifications of different scenarios for the installation of solar PV, and wind energy system in ships. The optimal design of the solar PV, Diesel generator and battery system in ship power system was investigated by [11]. The capacity of the solar PV panels, the Diesel generator and the energy storage system for the off-grid power system was determined with minimum investment cost, fuel cost and the greenhouse gas emissions. The effect of the temperatures and solar irradiations on the solar PV modules power output was investigated. The results show that the net present cost NPC of hybrid PV/Diesel/Energy Storage power generation system is less than that of PV/Diesel power generation. The cost-benefit of the application of hybrid solar energy system on the marine transportation systems has been investigated by [12]. In this study, they examined the feasibility of installing solar panels into vessels and calculated the payback period from the adopted investment with respect to fuel oil savings. The results show that the investment payback period is affected by the fuel prices (the payback period is between 16 and 27 years with an annual increase of the fuel price by 10–15%). The integration of renewable energy system for cruise ships and ferries are still in the first stage of research and development and the implementation. More research is needed to test the design, optimization and control of these power systems and estimate the cost of these renewable energies systems for marine applications. A new and original solar PV array configuration was proposed to increase the penetration of renewables for ships and a new optimization method was developed for the maximum power point tracking (MPPT) was developed by [13]; and [14]. A meta-heuristic optimization method and control strategy was used to control the MPPT in real-time. Effective performance was obtained with an improvement of the power output under different weather conditions. [15]; investigated the use of solar energy and energy storage to power a ship. The goal was to reduce the annual CO2 and NOX emissions and improve the energy efficiency of ships. In this study, they focused more on the effects of the fluctuation of the power output from the solar PV and the degradations of the energy storage devices. A new energy storage scheme was used in order to reduce the effects of solar PV power fluctuations and the aging of the battery. The results of this study show that the proposed energy storage system can give a reduction of 25–35.0% on the battery replacement. The optimal design of solar energy and storage systems for large ship and taking into account the fluctuations in solar energy was investigated by [16,17]. Optimization methods were developed to determine the optimal size of the energy storage system for the ship power system to reduce both the fuel and energy storage system capital costs, and for the reduction of gaseous emissions. Variations of the ship load and the operation conditions were analyzed using these new methods of design and optimization. [18]; investigated different methods and techniques for the improvement of the energy consumption in the 2
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Fig. 1. Renewable energy system model: solar PV/PEM fuel cell/Diesel generator.
ships to achieve sustainability standards and to reduce the environmental impacts for the ports. New energy management methods using renewable sources, energy storage, power connection to the shore, and different marine fuels were investigated for both the ship and port. The results of this study showed that the selected energy management methods provide a lot of benefits for the ships and ports usage and the development of sustainable cities. [19]; investigated and compared the performance of hybrid renewable energy systems for both land and on ship. The focus of this study was on the evaluation of payback of the proposed renewable energy system. The proposed system for the ships was able to decrease the greenhouse gas emissions and the fuel consumptions. Despite the number of studies found in the literature regarding the use of renewable energy systems, energy storage systems and alternative fuels for marine application, this number is very small compared to the number of studies for land applications (power generation, building, transportation, and industry). More studies are needed to investigate the integration of renewable energy systems, energy storage devices, and alternative fuels in the marine industry and to optimize their performance (daily and annual energy production, GHGs emissions, and the cost). The principal objective of the present study is to simulate and optimize the design of hybrid renewable energy system (solar PV, PEM fuel cell/Diesel Generator) to meet the large cruise ship electric load: main electric power for the two propellers and the electric auxiliary power for the consumers. The goal is to increase the renewable fractions and reduce the equivalent CO2 emissions from large ships used by the marine industry (greener and sustainable marine transport). 2. Modeling approach Fig. 1 shows a schematic of the renewable energy system for the cruise ship: solar PV panels, PEM fuel cell, electrolyzer (H2 production), H2 storage tank, and an inverter. The electricity generated by the system will serve the main and auxiliary AC loads of the cruise ship. The proposed hybrid and renewable energy systems are modeled [20]; and [21] as follows: 2.1. Photovoltaic power output The electrical power generated from the solar PV system is given by
IR ⎞ PPV = PSTC DF ⎛ [1 + aP (Tmod − Tmod,STC)] ⎝ IRSTC ⎠ ⎜
⎟
(1)
where, PSTC is the standard test conditions STC (IRSTC = 1000 W/m2, Tmod,STC = 25 °C, and no wind) solar PV power output, DF is the derating factor (power output reduction due to soiling, aging, and wiring losses), IR is the solar irradiance, aP is the power temperature coefficient, Tmod is the module temperature, and Tmod,STC is the module temperature under STC. 2.2. PEM fuel cell The PEM fuel cell is modeled as a power generator with hydrogen as the main fuel. The power output from the PEM fuel cell is 3
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
given by: (2)
PFC = UStack I = USC N I
Where UStack is the stack voltage, I represent the current, USC is the single cell voltage, and N is the number of cells. The PEM fuel cell electrical efficiency is:
ηFC =
PFC m˙ H2 HHVH2
(3)
Where HHVH2 is the hydrogen higher heating value (120–140 MJ/kg) and m˙ H2 (kg/s) is the H2 mass flow rate. 2.3. Electrolyzer (H2 production) An electrolyzer is used to split the H2O in H2 and O2. Electrical power PEZ is needed for hydrogen production in the electrolyzer:
PEZ =
m˙ H2 HHVH2 ηEZ
(4)
The amount of hydrogen produced in the electrolyzer (kg/s) is m˙ H2 , HHVH2 is the H2 energy density and ηEZ is the electrolyzer efficiency. 2.4. Diesel Generator The power generated from the Diesel backup generator depends on the fuel consumption. A linear equation is used to model the generator fuel consumption: (5)
FDG = α1 PDG + α 0 PDGR
where FDG is the generator fuel consumption (l/hr), α0 is the fuel intercept coefficient (l/hr/kWrated), PDGR is the capacity of the generator (kW), α1 is the fuel curve slope (l/hr/kWOutput) and PDG is the power output (kW). 2.5. Converter Fig. 1 shows the inverter to convert the DC power from the solar PV and PEM fuel cell to AC power. It is noted the efficiency (ηInv) of the inverter is assumed constant:
PInvOut = ηInv PInvIn
(6)
Where PInvOut and PInvIn are the inverter power output and input respectively. 2.6. Renewable fraction The renewable fraction (fren) is given by:
fren = 1 −
ENRE Econs
(7)
Where, ENRE is the energy production using conventional or nonrenewable fuels, and Econs represents the total energy consumed by the load. 2.7. Load The energy demand from the cruise ship is split between the main power for the propulsion system, and the auxiliary power for the other ship systems (consumers and electrolyzer). The distributed energy system is to supply the hourly cruise ship AC load:
PL (k ) = PPV (k ) + PFC (k ) + PDG (k )
(8)
2.8. Greehouse gas and particulate matter emissions The emissions of carbon monoxide (CO), carbon dioxide (CO2), Hydrocarbons (HCs), Nitrogen Oxides (NOX), and Sulfur Oxides (SOX), particulate matter (PM) from the power system (Diesel Generators) is determined using the emissions factors (kg of gaseous and particulate matter species emitted per unit of consumed fuel) for each pollutant. The total annual emissions of each pollutant are determined using the following equation: (9)
Ei = FDG EFi Nhours
Where Ei (kg/year) is the pollutant total annual emission, FDG is the Diesel fuel consumption (L/hr), EFi is the pollutant emission 4
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Table 1 Cruise ship hybrid renewable energy system components. System Component
Description
Solar PV
polycrystalline; panel maximum power = 330 W; operating voltage Vmp = 37.5 V, operating current Imp = 8.80 A, Open Circuit Voltage VOC = 45.9 V, Open circuit Current ISC = 9.31 A, Efficiency = 16.97%, Operating Temperature 45 °C, and Derating factor fPV = 90% PV panels are equipped with two-axis tracking system Capital cost $1200/kW, replacement = $1200/kW, O&M = $3/year/kW and lifetime = 25 yrs. Generic Generator; Fuel: Diesel Capital cost $300/kW, replacement = $300/kW, O&M = $0.01/hour, lifetime = 15,000 h. Type: Proton Exchange Membrane fuel cell (DC power) with electrical efficiency ηFC = 70%, Fuel: H2 Capital cost $400/kW, Replacement = $400/kW, O&M = $0.01/hour, lifetime = 50,000 h. Electrolyzer (DC power) with efficiency ηEZ = 90% Capital cost $100/kW, Replacement = $100/kW, O&M = $8/year/kW, lifetime = 15 yrs. H2 fuel cost = $1/kg, and lifetime = 25 years Leonics MTP-4117H 300 kW, Voltage = 480 VDC, efficiency = 94% Capital cost = $40/kW, Replacement = 40$/kW, O&M = 10$/year/kW, Lifetime = 25 yrs
Diesel Generator PEM Fuel Cell Electrolyzer Hydrogen Tank Converter: Inverter
factor (kg/L of fuel), and Nhours (hr/year) is the total operating hours of the generator. 2.9. Optimization method and dispatch control strategies An optimization method is used in this study to determine the best renewable power system configuration. This optimization depends on the cruise ship energy demand, the power system components capacities and the constraints (low life cost of electricity). A search space was generated using the size of each part of the renewable energy system. The capacity of the power system components and the dispatch strategy (load following or cycle charging) were selected. Different renewable power systems were simulated to determine the best power system based on the desired constraints and the low cost of electricity. The simulation time step was set to 60 min, this represents 8760 simulations per year. The load following and cycle charging dispatch control strategies are selected in this study. In the first dispatch control strategy (load following), the PEM fuel cell and Diesel generator (DG) will generate electricity to serve only the electric load of the cruise ship. In the second dispatch control strategy (cycle charging), the two generators (PEM fuel cell and DG) will start to operate to produce electrical power to serve the electric cruise ship loads and the surplus of electricity will serve the electrolyzer for H2 production. 3. Selection of power system components and their sizes Table 1 shows a summary fo the selected parts of the renewable energy system including solar PV, Diesel generator, PEM fuel cell, electrolyzer, H2 tank, converter, and controller: 4. Results and discussions The ship selected for this study is a cruise ship operating in the Baltic Sea between Stockholm (Sweden) and Mariehamn (the Aland Islands) [22]. The annual average irradiance IR in Stockholm is about 2.87 kWh/m2/day with a peak of 5.86 kWh/m2/day in June. The maximum peak temperature is 17.5 °C in July. This range of temperature in Stockholm will not affect the solar PV power output (power decreases at higher temperature). The ship was designed for a speed of 21 knots and is 176.9 m long and has a beam of 28.6 m [22]. Fig. 2 shows the speed and the main and auxiliary electrical power needed for one daily trip (24 h) [22]. The ship propulsion system has two propulsion lines. Each propulsion line has two main Diesel engines rated 5850 kW each, gearbox and a propeller. Four auxiliary engines rated 2760 kW each is used to provide the auxiliary power (lights in the ship, restaurants, Heating and Ventilations Air Conditioning System, and entertainment for the passengers). The main power for the propulsion system is delivered from the main engines ME (4 Diesel engines) and the auxiliary power for the consumers is provided by the auxiliary engines AE (4 Diesel engines). For the present simulation, only two engines for the main propulsion power and two engines for the auxiliary power are assumed to be running (2 engines for the main engine and 2 engines for the auxiliary power are put in stand-by). It is noted that the power loads shown in Fig. 2 represents the percentage of the total power capacity of the main engine (maximum ME Load for the 2 engines: 2 × 5850 kW) and the auxiliary engines (maximum AE load for the 2 engines: 2 × 2760 kW). The daily average energy consumption (maximum power x percentage x hours/day) for the cruise ship is 28,033 kWh/day for the main power (propulsion) and 22,987 kWh for the auxiliary power. The simulation results from the hybrid renewable energy system are the distributed energy production (solar PV array, Diesel generator, and PEM fuel cell); the cruise ship and electrolyzer energy consumption; the power losses in the inverter (DC/AC power conversion); the excess power produced from the system and unmet electrical power for the ship, the greenhouse emissions, the cost of electricity ($/kWh), and the cost summary of the proposed energy system. The daily and monthly average electrical production, the percentage of renewable energy, the greenhouse gas emissions, and the cost of electricity are presented in this paper. A comparison between the performance of the baseline system architecture (Diesel-electric propulsion system) and the proposed renewable 5
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Fig. 2. Daily cruise ship speed and power loads (%) for the main (ME) and auxiliary (AE) engines [22].
power system (solar PV/PEM fuel cell/Diesel Generator electric propulsion system) is presented. The baseline system architecture is composed of two Diesel generators with capacity of 5850 kW (Main Engines) and 2760 kW (Auxiliary Engines). The renewable power system architecture is composed of 1000 kW PEM fuel cell, 5850 kW Diesel Generator, 1200 kW PV system (3636 solar panels), 1083 kW converter, 2000 kW electrolyzer, and 500 kg Hydrogen tank. The production from the baseline system architecture is 58.9% (10,995,429 kWh/year) from the main engines and 41.1% (7,670,788 kWh/year) from the auxiliary engines. All the energy produced by the Diesel engines (18,666,788 kWh/year) is consumed by the cruise ship main and auxiliary electrical load without power shortage (unmet electricity for the load is zero). The excess electricity generated by the baseline Diesel generators is 0.23% (2894 kWh/year). The results show also that the capacity factors of the main and auxiliary engines are respectively 21.5% and 31.7%. The yearly performance of the hybrid solar PV/PEM fuel cell/Diesel Generator power system is shown in Fig. 3. The energy production from the system is: 9.44% (1,941,871 kWh/year) from the PV system, 4.39% (902,374 kWh/year) from the PEM fuel cell, and 86.17% (17,734,133 kWh/year) from the generator. All the energy produced from the distributed generation is consumed by the cruise ship electrical load (90.5% or 18,621,578 kWh/year) and the Electrolyzer for hydrogen production (8.64% or 1,777,417 kWh/ year). It is also noted that there are about 0.85% energy losses in the inverter (AC/DC and DC/AC power conversion). The excess and unmet electricity for the loads is negligible (0.014% and 0.0035% respectively). The Capacity factors for the Diesel engine, solar PV and PEM fuel cell are respectively 34.6%, 18.5%, and 10.3% as shown in Fig. 3. In addition to the yearly energy performance of the system (kWh/year), the daily energy production of the hybrid power system is presented in Fig. 4. The daily primary loads for both the main power and auxiliary powers are met with the proposed system without shortage as shown in Fig. 4. During the day most the power load of the cruise ship is supported by the generator and solar PV. During the night, the cruise ship energy load is provided by the generator and PEM fuel cell systems. The greenhouse gas and particulate matter emissions from the baseline – Diesel Generators and the proposed hybrid renewable power systems were determined. Fig. 5 shows the carbon dioxide (CO2), carbon monoxide (CO) and nitrogen oxides (NOX) emissions from the two power systems. It is noted that the amount the pollutant is expressed as kg/MWh – ratio between the amount of pollutant produced per year kg/year and the total energy produced per year MWh/year. In addition, the Hydrocarbons HCs, Sulfur oxides SO2 and particulate matter PM (kg/MWh) produced by the baseline and the hybrid solar PV/PEM fuel cell/Diesel generator power systems were also calculated. equation (9) was used to calculate the annual emission of each pollutant. The emissions factors for each pollutant (grams of pollutants/liter of fuel) used for the calculation are: 13.56 (g/L) for CO; 0.72 (g/L) for HCs; 0.116 (g/L) for the PM; 2.60 (g/L) for the NOX, and 2.2 (g/L) for SOX. The Diesel fuel has the following characteristics: lower heating value of LHV = 43.2 MJ/kg, density = 820 kg/m3, carbon content (%) = 88, and Sulfur content (%) = 0.4. These assumptions were used in the calculations: (1) any carbon in the fuel that is not emitted as carbon monoxide or unburned hydrocarbons is emitted as carbon dioxide; and (2) the sulfur in the burned fuel that is not emitted as particulate matter is emitted as sulfur dioxide. The results obtained in the course of this study show a net reduction of 9.84% of the greenhouse gas and particulate matter emissions when part of the 6
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Fig. 3. Yearly performance of the hybrid solar PV/PEM fuel cell/Diesel Generator power system.
Fig. 4. Daily performance of the hybrid solar PV/PEM fuel cell/Diesel generator power system.
7
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Fig. 5. Greenhouse gas (CO2, CO, NOX) Emissions from the Baseline (Diesel Generators) and Hybrid Solar PV/PEM fuel cell/Diesel Generator Power Systems.
total energy produced from Diesel generators is replaced with clean energy (solar PV and PEM fuel cell renewable energy systems). Fig. 6 shows a cost summary of the hybrid renewable energy system. The Diesel generator has the highest cost of $38.8 Million for the fuel used for power generation. The cost associated with the replacements of components over the 25 years (life of the system) is about $12.6 Million ($11.9 Million for the Diesel generator, $84,855 for the electrolyzer and $574,234 for the inverter). The operations and maintenance of the system is $6.94 Million ($46,539 for the solar PV, $6.26 Million for the Diesel generators, $206,840 for the electrolyzer, $221,965 for the fuel cell, $64,638 for hydrogen tank and $140,048 for the inverter). The total capital cost is $4.50 Million ($1.44 Million for the solar PV, $1.76 Million for Diesel generator, $200,000 for the Electrolyzer, $400,000 for the PEM fuel cell, $50,000 Hydrogen Tank, and $650,000 for the inverter). The life cost of electricity of the proposed renewable power system is 260 $/MWh. A comparison of the performance and cost for the baseline system and the proposed hybrid renewable energy system is shown in Table 2. 5. Conclusions Simulation, optimization and control strategies of hybrid renewable power systems for a cruise ship are presented in this study. The hybrid renewable energy system includes solar PV, PEM fuel cell, Diesel generator, electrolyzer for hydrogen production and DC/ AC Inverter. A modeling and simulation method were used in this study to determine the performance and the life cost of electricity of the renewable power system. The results of this analysis show that the proposed power system provide all the electrical power needed for the cruise ship and offers a good penetration of renewable resources for the marine applications: the renewable fraction is 13.83% (9.44% energy production from solar PV and 4.39% from the PEM fuel cell), and the greenhouse gas and particulate
Fig. 6. Cost Summary - Hybrid solar PV/PEM fuel cell/Diesel Generator power system. 8
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Table 2 Cruise ship power system performance comparison.
Cost of Energy ($/MWh) Power production - PV (%) Power production – Diesel Generators (%) Power Production – PEM Fuel Cell (%) Renewable and Clean Energy System (%) CO2 (kg/MWh)
Baseline (Diesel Engines)
Hybrid solar PV/PEM fuel cell/Diesel Generator
223 0 100 0 0 707
260 9.44 86.17 4.39 13.83 638
emissions reductions is 9.84%. The results obtained in the course of this study for the cruise ship located in Stockholm (Sweden) where the solar irradiance is low (2.87 kWh/m2/day). Other renewable energy system such as wind turbines can be combined with Diesel generator for Stockholm cruise ship since the annual average speed in this location is 6 m/s. The integration of renewable energy systems for cruise ships and ferries will produce better results with higher renewable fractions, lower emissions and lower cost in regions where the solar irradiance is higher such as the desert regions (Gulf Cooperation Council countries). For example, the average solar radiation in Sharjah, United Arab Emirates is 8.30 kWh/m2/day (three times the solar irradiance in Stockholm) and the solar resource is available throughout the year. A large amount of electrical power can be produced using solar PV to serve the load of the cruise ships and ferries and to generate enough hydrogen to run the PEM fuel cell. Conflict of Interest The authors confirm that there are no known conflicts of interest associated with this publication “Hybrid Solar PV/PEM Fuel Cell/Diesel Generator Power System for Cruise Ship: A Case Study in Stockholm, Sweden” and there has been no significant financial support for this work that could have influenced its outcome. Acknowledgments The authors gratefully acknowledge the financial support from the University of Sharjah, Sustainable Energy Development Research Group Operational Grant, Grant Ref. V.C.R.G./R. 1329/2017. References [1] Z. Wan, Q. Zhang, Z. Xu, J. Chen, Q. Wang, Impact of emission control areas on atmospheric pollutant emissions from major ocean-going ships entering the Shanghai Port, China, Mar. Pollut. Bull. 142 (2019) 525–532. [2] Third International Martime Organization GHG Study, Published by the international maritime organization 4 Albert Embankment, London SE1 7SR, www.imo. org, (2015). [3] C. Ghenai, I. Janajreh, Design of solar-biomass hybrid microgrid system in Sharjah, Energy Procedia 103 (2016) 357–362. [4] C. Ghenai, T. Salameh, A. Merabet, A.K. Hamid, Modeling and optimization of hybrid solar-diesel-battery power system, 7th International Conference on Modeling, Simulation, and Applied Optimization (ICMSAO), IEEE, 2017. [5] S. Bensmail, D. Rekioua, H. Azzi, Study of hybrid photovoltaic/fuel cell system for stand-alone applications, Int. J. Hydrogen Energy 40 (39) (2015) 13820–13826. [6] R.A. Rabu, I. Janajreh, C. Ghenai, Transesterification of biodiesel: process optimization and combustion performance, Int. J. Therm. Environ. Eng. 4 (Issue 2) (2012) 129–136. [7] J. Hua, Y.H. Wu, P.F. Jin, Prospects for renewable energy for seaborne transportation—taiwan example, Renew. Energy 33 (Issue 5) (2008) 1056–1063. [8] J. Han, J.F. Charpentier, T. Tang, An energy management system of a fuel cell/battery hybrid boat, Energies 7 (2014) 2799–2820. [9] N. Fonseca, T. Farias, F. Duarte, G. Gonçalves, A. Pereira, The Hidrocat Project - an all-electric ship with photovoltaic panels and hydrogen fuel cells, World Electr. J 3 (2009) ISSN 2032-6653. [10] M.D. Margaritou, E. Tzannatos, A multi-criteria optimization approach for solar energy and wind power technologies in shipping, FME Trans. 46 (2018) 374–380. [11] H. Lan, S. Wena, Y.Y. Hong, D.C. Yu, L. Zhang, Optimal sizing of hybrid PV/diesel/battery in ship power system, Appl. Energy 185 (2015) 26–34. [12] A. Glykas, G. Papaioannou, S. Perissakis, Application and cost-benefit analysis of solar hybrid power installation on merchant marine vessels, Ocean Eng. 37 (2010) 592–602. [13] R. Tang, Z. Wu, Y. Fang, Configuration of marine photovoltaic system and its MPPT using model predictive control, Sol. Energy 158 (2017) 995–1005. [14] R. Tang, Large-scale photovoltaic system on green ship and its MPPT controlling, Sol. Energy 157 (2017) 614–628. [15] H. Liu, Q. Zhang, X. Qi, Y. Han, F. Lu, Estimation of PV output power in moving and rocking hybrid energy marine ships, Appl. Energy 204 (2017) 362–372. [16] S. Wen, H. Lan, Y.Y. Hong, D.C. Yu, L. Zhang, P. Cheng, Allocation of ESS by interval optimization method considering impact of ship swinging on hybrid PV/ diesel ship power system, Appl. Energy 175 (2016) 158–167. [17] S. Wen, H. Lan, D.C. Yu, Q. Fu, Y.Y. Hong, L. Yu, R. Yang, Optimal sizing of hybrid energy storage sub-systems in PV/diesel ship power system using frequency analysis, Energy 140 (2017) 198–208. [18] K. Yigita, B. Acarkan, A new electrical energy management approach for ships using mixed energy sources to ensure sustainable port cities, Sustain. Cities Soc. 40 (2018) 126–135. [19] F. Diab, H. Lan, S. Ali, Novel comparison study between the hybrid renewable energy systems on land and on ship, Renew. Sustain. Energy Rev. 63 (2016) 452–463. [20] C. Ghenai, A. Merabet, T. Salameh, E.C. Pigem, Grid-tied and stand-alone hybrid solar power system for desalination plant, Desalination J. 435 (2018) 172–180 2018. [21] C. Ghenai, T. Salameh, A. Merabet, Technico-economic analysis of off grid solar PV/fuel cell energy system for residential community in desert region, Int. J. Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.05.110. [22] F. Baldi, F. Ahlgren, T.V. Nguyen, K.E. Andersson, Energy and Exergy analysis of a cruise ship, 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, At Pau, France, 2015.
9
Contents lists available at ScienceDirect
Case Studies in Thermal Engineering journal homepage: www.elsevier.com/locate/csite
Hybrid solar PV/PEM fuel Cell/Diesel Generator power system for cruise ship: A case study in Stockholm, Sweden
T
Chaouki Ghenaia,∗, Maamar Bettayebb,c, Boris Brdjanind, Abdul Kadir Hamidb a
Department of Sustainable and Renewable Energy Engineering, College of Engineering, University of Sharjah, Sharjah, United Arab Emirates Department of Electrical and Computer Engineering, College of Engineering, University of Sharjah, Sharjah, United Arab Emirates Center of Excellence Intelligent Engineering Systems (CEIES), King Abdulaziz University, Jeddah, Saudi Arabia d Electrical Engineering Department, Power and Network System, University of Belgrade, Belgrade, Serbia b c
A R T IC LE I N F O
ABS TRA CT
Keywords: Solar PV PEM fuel cell Diesel generator Hybrid power system Marine propulsion system Cruise ship
Optimal design and performance analysis of renewable energy system to serve the cruise ship main and auxiliary power in Stockholm, Sweden is presented in this paper. The goal is to integrate renewable energy systems in small and large ships for greener and sustainable marine transport. The power load for the cruise ship was determined, and modeling and simulation analysis was used to investigate the daily and annual performance of the power system architectures including the efficiency and capacity factors of the energy conversion systems. The total electrical power generated from the solar PV, PEM fuel cell, and Diesel generator; the cost of electricity; and the greenhouse gas and particulate matter PM emissions were determined. The proposed renewable energy system offers a good penetration of renewable energy system (13.83%), and greenhouse gas and particulate emissions reduction (9.84% emissions reduction compared to baseline system using Diesel engines). The integration of renewable and clean power systems such as solar PV and PEM fuel cell (high electrical efficiency) is very attractive solution for onboard ship power generation. They are economically viable (reduce the cost of Diesel fuel), cleaner than the conventional gas turbine and internal combustion engines and reduce the dependency on fossil fuel.
1. Introduction Diesel reciprocating engines are used in large cruise vessels for generating power for the propulsion system and auxiliary power for the ship’s system. The main or primary engines are used for the propulsion system and the secondary engines provide the load needed in the ship for the consumers. The optimization of the loading of Diesel engines/generators is needed for the reduction of both the energy consumption and emissions from the Diesel-electric propulsion system [1]. With the development of optimization methods and strategies, engines can operate with high efficiency at high loads and with a large variation in the power demand. This can be achieved with variable speed drive for the propellers (the rpm can be adjusted for minimum Diesel fuel consumption according to the system load). The Diesel-electric propulsion system used for large ferries and cruise ships provides (1) high reliability with the use of multiple engines redundancy (example – 2 engines for single propeller), (2) reduced life-cycle cost (reducing the operational and maintenance costs), (3) improved maneuverability (design and use of high quality propulsor), and (4) precise control of the electric propulsion motors. The engines for the Diesel-electric propulsion system need to be selected accordingly to the power demand (based
∗
Corresponding author. E-mail address: [email protected] (C. Ghenai).
https://doi.org/10.1016/j.csite.2019.100497 Received 9 June 2019; Received in revised form 7 July 2019; Accepted 8 July 2019 Available online 10 July 2019 2214-157X/ © 2019 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
on the highest expected electric load). The recent developments in Diesel-electric propulsion system helped to achieve huge fuel savings by operating the engines on variable speed but the propulsion marine industry still need to comply with the environmental requirement while meeting the operational demands. The environmental impacts from large ferries and cruise ship include greenhouse gas emissions from Diesel engines, oil pollution and acoustic. The exhaust gases from the combustion of Diesel fuel in the ships are a significant source of air pollution (SOX, NOX, PM, CO, CO2, and HCs). Based on the International Maritime Organization (IMO) study, the equivalent carbon dioxide emissions from shipping industry were estimated to 2.2% of the total emissions [2]. The projected equivalent CO2 gas emissions from large ships are expected to rise by 50%–250% by 2050 if we continue for the business as usual (no action is taken) [2]. It is also noted that contribution of marine Diesel engines is higher near the ports. The risks are higher near the port since the Diesel fuel of oil tankers and container ships has higher sulfur content and is cheaper compared to the Diesel fuel used for land applications. Different emissions control strategies and mechanisms are needed to control the greenhouse gas emissions from the marine industry (ships and ferries). Renewable energy options are being considered at the present for emissions reduction from the marine industry. Clean energy solutions such as alternative and renewable fuels (Biodiesel, Biogas, Hydrogen, Liquefied Natural Gas LNG, Methanol and Ethanol), solar and wind energy, PEM fuel cell, hybrid renewable power systems [3,4]; and [5] can be integrated in the existing and new ships. Biofuels (Biodiesel, Biogas, and Bio-hydrogen) are derived from Biomass feedstocks (contribute to the reduction of GHG emissions). Biofuels can be mixed with conventional fossil fuels to power conventional systems and to reduce the greenhouse gas emissions [6]. For example, cleaner fuel such as Biodiesel can replace Diesel fuel in Diesel-Electric propulsion systems of large ships. Hydrogen is another potential alternative and clean fuel for ship propulsion system. The advantage of using hydrogen in PEM fuel cells is that no CO2, NOX and SOX emissions are produced in the ship. In addition to alternative fuels, renewable energy systems can be developed and integrated in large ships and ferries. Wind is one of the greenest sources of energy in the sea. The wind can be used as a source of power for large ships especially when the ship is sailing to meet some of the power demands and reduce the greenhouse gas emissions. Solar PV can also be used to generate power in ships even the contribution will be small compared to power demand to drive the ship. The power generated using solar PV depends on the solar irradiance for each location, the efficiency of the solar cells, and the available deck area on the ships for the solar PV system. Several studies on the development and use of renewable energy system in ships can be found in the literature. [7]; reported the need for the development and integration of renewable energy systems for marine transport. It was highlighted in this study that solar PV is the best renewable and alternative energy technology to power commercial ships. Fuel cell technology was the second-best clean energy technology that can be applied on the ship for the Taiwanese maritime industry. [8]; integrated fuel cells/battery energy system as a solution for the propulsion system for a boat. This solution was selected based on the high efficiency and low emission of the power system. Different strategies were used for energy management from different power sources. Modeling and simulation were used in this study based on Matlab/Simulink environment to study the dynamic performance to maximize the efficiency of the system. The adequacy of this power system and the energy management system was tested for real ship driving cycles. [9]; investigated the distributed energy production from different resources (hydrogen fuel cell, solar, and batteries) used in small electric ships. The propulsion system was equipped with two electric motors, batteries, fuel cell and solar PV array. The proposed power system satisfies the power requirements and it was autonomous. They also concluded that if the operational of the small electric ship is not very demanding, the vessel may run in summer with only solar PV system. [10]; reviewed the techniques and operational solutions to reduce the emissions from the ships. In this study, they used optimization approach for the identifications of different scenarios for the installation of solar PV, and wind energy system in ships. The optimal design of the solar PV, Diesel generator and battery system in ship power system was investigated by [11]. The capacity of the solar PV panels, the Diesel generator and the energy storage system for the off-grid power system was determined with minimum investment cost, fuel cost and the greenhouse gas emissions. The effect of the temperatures and solar irradiations on the solar PV modules power output was investigated. The results show that the net present cost NPC of hybrid PV/Diesel/Energy Storage power generation system is less than that of PV/Diesel power generation. The cost-benefit of the application of hybrid solar energy system on the marine transportation systems has been investigated by [12]. In this study, they examined the feasibility of installing solar panels into vessels and calculated the payback period from the adopted investment with respect to fuel oil savings. The results show that the investment payback period is affected by the fuel prices (the payback period is between 16 and 27 years with an annual increase of the fuel price by 10–15%). The integration of renewable energy system for cruise ships and ferries are still in the first stage of research and development and the implementation. More research is needed to test the design, optimization and control of these power systems and estimate the cost of these renewable energies systems for marine applications. A new and original solar PV array configuration was proposed to increase the penetration of renewables for ships and a new optimization method was developed for the maximum power point tracking (MPPT) was developed by [13]; and [14]. A meta-heuristic optimization method and control strategy was used to control the MPPT in real-time. Effective performance was obtained with an improvement of the power output under different weather conditions. [15]; investigated the use of solar energy and energy storage to power a ship. The goal was to reduce the annual CO2 and NOX emissions and improve the energy efficiency of ships. In this study, they focused more on the effects of the fluctuation of the power output from the solar PV and the degradations of the energy storage devices. A new energy storage scheme was used in order to reduce the effects of solar PV power fluctuations and the aging of the battery. The results of this study show that the proposed energy storage system can give a reduction of 25–35.0% on the battery replacement. The optimal design of solar energy and storage systems for large ship and taking into account the fluctuations in solar energy was investigated by [16,17]. Optimization methods were developed to determine the optimal size of the energy storage system for the ship power system to reduce both the fuel and energy storage system capital costs, and for the reduction of gaseous emissions. Variations of the ship load and the operation conditions were analyzed using these new methods of design and optimization. [18]; investigated different methods and techniques for the improvement of the energy consumption in the 2
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Fig. 1. Renewable energy system model: solar PV/PEM fuel cell/Diesel generator.
ships to achieve sustainability standards and to reduce the environmental impacts for the ports. New energy management methods using renewable sources, energy storage, power connection to the shore, and different marine fuels were investigated for both the ship and port. The results of this study showed that the selected energy management methods provide a lot of benefits for the ships and ports usage and the development of sustainable cities. [19]; investigated and compared the performance of hybrid renewable energy systems for both land and on ship. The focus of this study was on the evaluation of payback of the proposed renewable energy system. The proposed system for the ships was able to decrease the greenhouse gas emissions and the fuel consumptions. Despite the number of studies found in the literature regarding the use of renewable energy systems, energy storage systems and alternative fuels for marine application, this number is very small compared to the number of studies for land applications (power generation, building, transportation, and industry). More studies are needed to investigate the integration of renewable energy systems, energy storage devices, and alternative fuels in the marine industry and to optimize their performance (daily and annual energy production, GHGs emissions, and the cost). The principal objective of the present study is to simulate and optimize the design of hybrid renewable energy system (solar PV, PEM fuel cell/Diesel Generator) to meet the large cruise ship electric load: main electric power for the two propellers and the electric auxiliary power for the consumers. The goal is to increase the renewable fractions and reduce the equivalent CO2 emissions from large ships used by the marine industry (greener and sustainable marine transport). 2. Modeling approach Fig. 1 shows a schematic of the renewable energy system for the cruise ship: solar PV panels, PEM fuel cell, electrolyzer (H2 production), H2 storage tank, and an inverter. The electricity generated by the system will serve the main and auxiliary AC loads of the cruise ship. The proposed hybrid and renewable energy systems are modeled [20]; and [21] as follows: 2.1. Photovoltaic power output The electrical power generated from the solar PV system is given by
IR ⎞ PPV = PSTC DF ⎛ [1 + aP (Tmod − Tmod,STC)] ⎝ IRSTC ⎠ ⎜
⎟
(1)
where, PSTC is the standard test conditions STC (IRSTC = 1000 W/m2, Tmod,STC = 25 °C, and no wind) solar PV power output, DF is the derating factor (power output reduction due to soiling, aging, and wiring losses), IR is the solar irradiance, aP is the power temperature coefficient, Tmod is the module temperature, and Tmod,STC is the module temperature under STC. 2.2. PEM fuel cell The PEM fuel cell is modeled as a power generator with hydrogen as the main fuel. The power output from the PEM fuel cell is 3
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
given by: (2)
PFC = UStack I = USC N I
Where UStack is the stack voltage, I represent the current, USC is the single cell voltage, and N is the number of cells. The PEM fuel cell electrical efficiency is:
ηFC =
PFC m˙ H2 HHVH2
(3)
Where HHVH2 is the hydrogen higher heating value (120–140 MJ/kg) and m˙ H2 (kg/s) is the H2 mass flow rate. 2.3. Electrolyzer (H2 production) An electrolyzer is used to split the H2O in H2 and O2. Electrical power PEZ is needed for hydrogen production in the electrolyzer:
PEZ =
m˙ H2 HHVH2 ηEZ
(4)
The amount of hydrogen produced in the electrolyzer (kg/s) is m˙ H2 , HHVH2 is the H2 energy density and ηEZ is the electrolyzer efficiency. 2.4. Diesel Generator The power generated from the Diesel backup generator depends on the fuel consumption. A linear equation is used to model the generator fuel consumption: (5)
FDG = α1 PDG + α 0 PDGR
where FDG is the generator fuel consumption (l/hr), α0 is the fuel intercept coefficient (l/hr/kWrated), PDGR is the capacity of the generator (kW), α1 is the fuel curve slope (l/hr/kWOutput) and PDG is the power output (kW). 2.5. Converter Fig. 1 shows the inverter to convert the DC power from the solar PV and PEM fuel cell to AC power. It is noted the efficiency (ηInv) of the inverter is assumed constant:
PInvOut = ηInv PInvIn
(6)
Where PInvOut and PInvIn are the inverter power output and input respectively. 2.6. Renewable fraction The renewable fraction (fren) is given by:
fren = 1 −
ENRE Econs
(7)
Where, ENRE is the energy production using conventional or nonrenewable fuels, and Econs represents the total energy consumed by the load. 2.7. Load The energy demand from the cruise ship is split between the main power for the propulsion system, and the auxiliary power for the other ship systems (consumers and electrolyzer). The distributed energy system is to supply the hourly cruise ship AC load:
PL (k ) = PPV (k ) + PFC (k ) + PDG (k )
(8)
2.8. Greehouse gas and particulate matter emissions The emissions of carbon monoxide (CO), carbon dioxide (CO2), Hydrocarbons (HCs), Nitrogen Oxides (NOX), and Sulfur Oxides (SOX), particulate matter (PM) from the power system (Diesel Generators) is determined using the emissions factors (kg of gaseous and particulate matter species emitted per unit of consumed fuel) for each pollutant. The total annual emissions of each pollutant are determined using the following equation: (9)
Ei = FDG EFi Nhours
Where Ei (kg/year) is the pollutant total annual emission, FDG is the Diesel fuel consumption (L/hr), EFi is the pollutant emission 4
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Table 1 Cruise ship hybrid renewable energy system components. System Component
Description
Solar PV
polycrystalline; panel maximum power = 330 W; operating voltage Vmp = 37.5 V, operating current Imp = 8.80 A, Open Circuit Voltage VOC = 45.9 V, Open circuit Current ISC = 9.31 A, Efficiency = 16.97%, Operating Temperature 45 °C, and Derating factor fPV = 90% PV panels are equipped with two-axis tracking system Capital cost $1200/kW, replacement = $1200/kW, O&M = $3/year/kW and lifetime = 25 yrs. Generic Generator; Fuel: Diesel Capital cost $300/kW, replacement = $300/kW, O&M = $0.01/hour, lifetime = 15,000 h. Type: Proton Exchange Membrane fuel cell (DC power) with electrical efficiency ηFC = 70%, Fuel: H2 Capital cost $400/kW, Replacement = $400/kW, O&M = $0.01/hour, lifetime = 50,000 h. Electrolyzer (DC power) with efficiency ηEZ = 90% Capital cost $100/kW, Replacement = $100/kW, O&M = $8/year/kW, lifetime = 15 yrs. H2 fuel cost = $1/kg, and lifetime = 25 years Leonics MTP-4117H 300 kW, Voltage = 480 VDC, efficiency = 94% Capital cost = $40/kW, Replacement = 40$/kW, O&M = 10$/year/kW, Lifetime = 25 yrs
Diesel Generator PEM Fuel Cell Electrolyzer Hydrogen Tank Converter: Inverter
factor (kg/L of fuel), and Nhours (hr/year) is the total operating hours of the generator. 2.9. Optimization method and dispatch control strategies An optimization method is used in this study to determine the best renewable power system configuration. This optimization depends on the cruise ship energy demand, the power system components capacities and the constraints (low life cost of electricity). A search space was generated using the size of each part of the renewable energy system. The capacity of the power system components and the dispatch strategy (load following or cycle charging) were selected. Different renewable power systems were simulated to determine the best power system based on the desired constraints and the low cost of electricity. The simulation time step was set to 60 min, this represents 8760 simulations per year. The load following and cycle charging dispatch control strategies are selected in this study. In the first dispatch control strategy (load following), the PEM fuel cell and Diesel generator (DG) will generate electricity to serve only the electric load of the cruise ship. In the second dispatch control strategy (cycle charging), the two generators (PEM fuel cell and DG) will start to operate to produce electrical power to serve the electric cruise ship loads and the surplus of electricity will serve the electrolyzer for H2 production. 3. Selection of power system components and their sizes Table 1 shows a summary fo the selected parts of the renewable energy system including solar PV, Diesel generator, PEM fuel cell, electrolyzer, H2 tank, converter, and controller: 4. Results and discussions The ship selected for this study is a cruise ship operating in the Baltic Sea between Stockholm (Sweden) and Mariehamn (the Aland Islands) [22]. The annual average irradiance IR in Stockholm is about 2.87 kWh/m2/day with a peak of 5.86 kWh/m2/day in June. The maximum peak temperature is 17.5 °C in July. This range of temperature in Stockholm will not affect the solar PV power output (power decreases at higher temperature). The ship was designed for a speed of 21 knots and is 176.9 m long and has a beam of 28.6 m [22]. Fig. 2 shows the speed and the main and auxiliary electrical power needed for one daily trip (24 h) [22]. The ship propulsion system has two propulsion lines. Each propulsion line has two main Diesel engines rated 5850 kW each, gearbox and a propeller. Four auxiliary engines rated 2760 kW each is used to provide the auxiliary power (lights in the ship, restaurants, Heating and Ventilations Air Conditioning System, and entertainment for the passengers). The main power for the propulsion system is delivered from the main engines ME (4 Diesel engines) and the auxiliary power for the consumers is provided by the auxiliary engines AE (4 Diesel engines). For the present simulation, only two engines for the main propulsion power and two engines for the auxiliary power are assumed to be running (2 engines for the main engine and 2 engines for the auxiliary power are put in stand-by). It is noted that the power loads shown in Fig. 2 represents the percentage of the total power capacity of the main engine (maximum ME Load for the 2 engines: 2 × 5850 kW) and the auxiliary engines (maximum AE load for the 2 engines: 2 × 2760 kW). The daily average energy consumption (maximum power x percentage x hours/day) for the cruise ship is 28,033 kWh/day for the main power (propulsion) and 22,987 kWh for the auxiliary power. The simulation results from the hybrid renewable energy system are the distributed energy production (solar PV array, Diesel generator, and PEM fuel cell); the cruise ship and electrolyzer energy consumption; the power losses in the inverter (DC/AC power conversion); the excess power produced from the system and unmet electrical power for the ship, the greenhouse emissions, the cost of electricity ($/kWh), and the cost summary of the proposed energy system. The daily and monthly average electrical production, the percentage of renewable energy, the greenhouse gas emissions, and the cost of electricity are presented in this paper. A comparison between the performance of the baseline system architecture (Diesel-electric propulsion system) and the proposed renewable 5
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Fig. 2. Daily cruise ship speed and power loads (%) for the main (ME) and auxiliary (AE) engines [22].
power system (solar PV/PEM fuel cell/Diesel Generator electric propulsion system) is presented. The baseline system architecture is composed of two Diesel generators with capacity of 5850 kW (Main Engines) and 2760 kW (Auxiliary Engines). The renewable power system architecture is composed of 1000 kW PEM fuel cell, 5850 kW Diesel Generator, 1200 kW PV system (3636 solar panels), 1083 kW converter, 2000 kW electrolyzer, and 500 kg Hydrogen tank. The production from the baseline system architecture is 58.9% (10,995,429 kWh/year) from the main engines and 41.1% (7,670,788 kWh/year) from the auxiliary engines. All the energy produced by the Diesel engines (18,666,788 kWh/year) is consumed by the cruise ship main and auxiliary electrical load without power shortage (unmet electricity for the load is zero). The excess electricity generated by the baseline Diesel generators is 0.23% (2894 kWh/year). The results show also that the capacity factors of the main and auxiliary engines are respectively 21.5% and 31.7%. The yearly performance of the hybrid solar PV/PEM fuel cell/Diesel Generator power system is shown in Fig. 3. The energy production from the system is: 9.44% (1,941,871 kWh/year) from the PV system, 4.39% (902,374 kWh/year) from the PEM fuel cell, and 86.17% (17,734,133 kWh/year) from the generator. All the energy produced from the distributed generation is consumed by the cruise ship electrical load (90.5% or 18,621,578 kWh/year) and the Electrolyzer for hydrogen production (8.64% or 1,777,417 kWh/ year). It is also noted that there are about 0.85% energy losses in the inverter (AC/DC and DC/AC power conversion). The excess and unmet electricity for the loads is negligible (0.014% and 0.0035% respectively). The Capacity factors for the Diesel engine, solar PV and PEM fuel cell are respectively 34.6%, 18.5%, and 10.3% as shown in Fig. 3. In addition to the yearly energy performance of the system (kWh/year), the daily energy production of the hybrid power system is presented in Fig. 4. The daily primary loads for both the main power and auxiliary powers are met with the proposed system without shortage as shown in Fig. 4. During the day most the power load of the cruise ship is supported by the generator and solar PV. During the night, the cruise ship energy load is provided by the generator and PEM fuel cell systems. The greenhouse gas and particulate matter emissions from the baseline – Diesel Generators and the proposed hybrid renewable power systems were determined. Fig. 5 shows the carbon dioxide (CO2), carbon monoxide (CO) and nitrogen oxides (NOX) emissions from the two power systems. It is noted that the amount the pollutant is expressed as kg/MWh – ratio between the amount of pollutant produced per year kg/year and the total energy produced per year MWh/year. In addition, the Hydrocarbons HCs, Sulfur oxides SO2 and particulate matter PM (kg/MWh) produced by the baseline and the hybrid solar PV/PEM fuel cell/Diesel generator power systems were also calculated. equation (9) was used to calculate the annual emission of each pollutant. The emissions factors for each pollutant (grams of pollutants/liter of fuel) used for the calculation are: 13.56 (g/L) for CO; 0.72 (g/L) for HCs; 0.116 (g/L) for the PM; 2.60 (g/L) for the NOX, and 2.2 (g/L) for SOX. The Diesel fuel has the following characteristics: lower heating value of LHV = 43.2 MJ/kg, density = 820 kg/m3, carbon content (%) = 88, and Sulfur content (%) = 0.4. These assumptions were used in the calculations: (1) any carbon in the fuel that is not emitted as carbon monoxide or unburned hydrocarbons is emitted as carbon dioxide; and (2) the sulfur in the burned fuel that is not emitted as particulate matter is emitted as sulfur dioxide. The results obtained in the course of this study show a net reduction of 9.84% of the greenhouse gas and particulate matter emissions when part of the 6
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Fig. 3. Yearly performance of the hybrid solar PV/PEM fuel cell/Diesel Generator power system.
Fig. 4. Daily performance of the hybrid solar PV/PEM fuel cell/Diesel generator power system.
7
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Fig. 5. Greenhouse gas (CO2, CO, NOX) Emissions from the Baseline (Diesel Generators) and Hybrid Solar PV/PEM fuel cell/Diesel Generator Power Systems.
total energy produced from Diesel generators is replaced with clean energy (solar PV and PEM fuel cell renewable energy systems). Fig. 6 shows a cost summary of the hybrid renewable energy system. The Diesel generator has the highest cost of $38.8 Million for the fuel used for power generation. The cost associated with the replacements of components over the 25 years (life of the system) is about $12.6 Million ($11.9 Million for the Diesel generator, $84,855 for the electrolyzer and $574,234 for the inverter). The operations and maintenance of the system is $6.94 Million ($46,539 for the solar PV, $6.26 Million for the Diesel generators, $206,840 for the electrolyzer, $221,965 for the fuel cell, $64,638 for hydrogen tank and $140,048 for the inverter). The total capital cost is $4.50 Million ($1.44 Million for the solar PV, $1.76 Million for Diesel generator, $200,000 for the Electrolyzer, $400,000 for the PEM fuel cell, $50,000 Hydrogen Tank, and $650,000 for the inverter). The life cost of electricity of the proposed renewable power system is 260 $/MWh. A comparison of the performance and cost for the baseline system and the proposed hybrid renewable energy system is shown in Table 2. 5. Conclusions Simulation, optimization and control strategies of hybrid renewable power systems for a cruise ship are presented in this study. The hybrid renewable energy system includes solar PV, PEM fuel cell, Diesel generator, electrolyzer for hydrogen production and DC/ AC Inverter. A modeling and simulation method were used in this study to determine the performance and the life cost of electricity of the renewable power system. The results of this analysis show that the proposed power system provide all the electrical power needed for the cruise ship and offers a good penetration of renewable resources for the marine applications: the renewable fraction is 13.83% (9.44% energy production from solar PV and 4.39% from the PEM fuel cell), and the greenhouse gas and particulate
Fig. 6. Cost Summary - Hybrid solar PV/PEM fuel cell/Diesel Generator power system. 8
Case Studies in Thermal Engineering 14 (2019) 100497
C. Ghenai, et al.
Table 2 Cruise ship power system performance comparison.
Cost of Energy ($/MWh) Power production - PV (%) Power production – Diesel Generators (%) Power Production – PEM Fuel Cell (%) Renewable and Clean Energy System (%) CO2 (kg/MWh)
Baseline (Diesel Engines)
Hybrid solar PV/PEM fuel cell/Diesel Generator
223 0 100 0 0 707
260 9.44 86.17 4.39 13.83 638
emissions reductions is 9.84%. The results obtained in the course of this study for the cruise ship located in Stockholm (Sweden) where the solar irradiance is low (2.87 kWh/m2/day). Other renewable energy system such as wind turbines can be combined with Diesel generator for Stockholm cruise ship since the annual average speed in this location is 6 m/s. The integration of renewable energy systems for cruise ships and ferries will produce better results with higher renewable fractions, lower emissions and lower cost in regions where the solar irradiance is higher such as the desert regions (Gulf Cooperation Council countries). For example, the average solar radiation in Sharjah, United Arab Emirates is 8.30 kWh/m2/day (three times the solar irradiance in Stockholm) and the solar resource is available throughout the year. A large amount of electrical power can be produced using solar PV to serve the load of the cruise ships and ferries and to generate enough hydrogen to run the PEM fuel cell. Conflict of Interest The authors confirm that there are no known conflicts of interest associated with this publication “Hybrid Solar PV/PEM Fuel Cell/Diesel Generator Power System for Cruise Ship: A Case Study in Stockholm, Sweden” and there has been no significant financial support for this work that could have influenced its outcome. Acknowledgments The authors gratefully acknowledge the financial support from the University of Sharjah, Sustainable Energy Development Research Group Operational Grant, Grant Ref. V.C.R.G./R. 1329/2017. References [1] Z. Wan, Q. Zhang, Z. Xu, J. Chen, Q. Wang, Impact of emission control areas on atmospheric pollutant emissions from major ocean-going ships entering the Shanghai Port, China, Mar. Pollut. Bull. 142 (2019) 525–532. [2] Third International Martime Organization GHG Study, Published by the international maritime organization 4 Albert Embankment, London SE1 7SR, www.imo. org, (2015). [3] C. Ghenai, I. Janajreh, Design of solar-biomass hybrid microgrid system in Sharjah, Energy Procedia 103 (2016) 357–362. [4] C. Ghenai, T. Salameh, A. Merabet, A.K. Hamid, Modeling and optimization of hybrid solar-diesel-battery power system, 7th International Conference on Modeling, Simulation, and Applied Optimization (ICMSAO), IEEE, 2017. [5] S. Bensmail, D. Rekioua, H. Azzi, Study of hybrid photovoltaic/fuel cell system for stand-alone applications, Int. J. Hydrogen Energy 40 (39) (2015) 13820–13826. [6] R.A. Rabu, I. Janajreh, C. Ghenai, Transesterification of biodiesel: process optimization and combustion performance, Int. J. Therm. Environ. Eng. 4 (Issue 2) (2012) 129–136. [7] J. Hua, Y.H. Wu, P.F. Jin, Prospects for renewable energy for seaborne transportation—taiwan example, Renew. Energy 33 (Issue 5) (2008) 1056–1063. [8] J. Han, J.F. Charpentier, T. Tang, An energy management system of a fuel cell/battery hybrid boat, Energies 7 (2014) 2799–2820. [9] N. Fonseca, T. Farias, F. Duarte, G. Gonçalves, A. Pereira, The Hidrocat Project - an all-electric ship with photovoltaic panels and hydrogen fuel cells, World Electr. J 3 (2009) ISSN 2032-6653. [10] M.D. Margaritou, E. Tzannatos, A multi-criteria optimization approach for solar energy and wind power technologies in shipping, FME Trans. 46 (2018) 374–380. [11] H. Lan, S. Wena, Y.Y. Hong, D.C. Yu, L. Zhang, Optimal sizing of hybrid PV/diesel/battery in ship power system, Appl. Energy 185 (2015) 26–34. [12] A. Glykas, G. Papaioannou, S. Perissakis, Application and cost-benefit analysis of solar hybrid power installation on merchant marine vessels, Ocean Eng. 37 (2010) 592–602. [13] R. Tang, Z. Wu, Y. Fang, Configuration of marine photovoltaic system and its MPPT using model predictive control, Sol. Energy 158 (2017) 995–1005. [14] R. Tang, Large-scale photovoltaic system on green ship and its MPPT controlling, Sol. Energy 157 (2017) 614–628. [15] H. Liu, Q. Zhang, X. Qi, Y. Han, F. Lu, Estimation of PV output power in moving and rocking hybrid energy marine ships, Appl. Energy 204 (2017) 362–372. [16] S. Wen, H. Lan, Y.Y. Hong, D.C. Yu, L. Zhang, P. Cheng, Allocation of ESS by interval optimization method considering impact of ship swinging on hybrid PV/ diesel ship power system, Appl. Energy 175 (2016) 158–167. [17] S. Wen, H. Lan, D.C. Yu, Q. Fu, Y.Y. Hong, L. Yu, R. Yang, Optimal sizing of hybrid energy storage sub-systems in PV/diesel ship power system using frequency analysis, Energy 140 (2017) 198–208. [18] K. Yigita, B. Acarkan, A new electrical energy management approach for ships using mixed energy sources to ensure sustainable port cities, Sustain. Cities Soc. 40 (2018) 126–135. [19] F. Diab, H. Lan, S. Ali, Novel comparison study between the hybrid renewable energy systems on land and on ship, Renew. Sustain. Energy Rev. 63 (2016) 452–463. [20] C. Ghenai, A. Merabet, T. Salameh, E.C. Pigem, Grid-tied and stand-alone hybrid solar power system for desalination plant, Desalination J. 435 (2018) 172–180 2018. [21] C. Ghenai, T. Salameh, A. Merabet, Technico-economic analysis of off grid solar PV/fuel cell energy system for residential community in desert region, Int. J. Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.05.110. [22] F. Baldi, F. Ahlgren, T.V. Nguyen, K.E. Andersson, Energy and Exergy analysis of a cruise ship, 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, At Pau, France, 2015.
9