energies Article Analysis of the Use of Electric and Hybrid Drives on SWATH Ships Andrzej Łebkowski * and Wojciech Koznowski * Department of Ship Automation, Gdynia Maritime University, Poland Morska St. 83, 81-225 Gdynia, Poland * Correspondence: [email protected] (A.Ł.); [email protected] (W.K.) Received: 2 November 2020; Accepted: 7 December 2020; Published: 8 December 2020 Abstract: The article presents issues related to the possibility of using electric and hybrid systems to drive Small Waterplane Area Twin Hull (SWATH) vessels. Ships of this type have significantly less sway and heave compared to monohull crafts and catamarans. Thanks to the synergistic combination of the hydrodynamic properties of SWATH hull and electric drive systems, they can be an interesting proposition for use in transport of passengers and offshore wind farms service crews. The paper presents comparative test results of an electric drive system powered by Hybrid Energy Storage System, which are a combination of systems consisting of batteries (BAT), hydrogen fuel cells (FC) and diesel generators (D). For the presented configurations of propulsion systems, mathematical models taking into account the hydrodynamic resistance of the hull of the vessel have been developed and implemented in the Modelica simulation environment. The tests carried out for various configurations of the drive system have shown reduced energy consumption by the DIESEL-ELECTRIC drive system (by approx. 62%), as well as the reduction of harmful greenhouse gas emissions to the atmosphere (by approx. 62%) compared to the conventional DIESEL drive. Keywords: electric vehicles; electric ships; electric marine propulsion; electric hybrid systems 1. Introduction The restrictions related to the emission of harmful gases to the atmosphere related to transport [1–4] contribute to the development of environmentally friendly technologies. In order to achieve this task, an effort related to the use of ecological drive systems [5], including electric and hybrid [6,7], is undertaken. Thanks to the use of low-emission drive systems, the level of energy consumption is reduced, as well as the amount of poisonous exhaust gases emitted to the natural environment [8,9]. The exhaust gases emitted by the internal combustion engine include those that can be classified as harmless to the health of living organisms (oxygen O2, nitrogen N2, hydrogen H2); poisonous to living organisms (carbon monoxide CO, HC hydrocarbons and their derivatives, nitrous oxides (monoxide and dioxide), sulphur oxides (monoxide, dioxide, trioxide), soot and smoke (PM), ashes, heavy metals, other solid substances and heavy organic compounds) harmful to the environment and favouring the development of the greenhouse phenomenon in the atmosphere (carbon dioxide CO2, methane CH4, ammonia NH3, nitrous oxide N2O) [10,11]. Another factor contributing to the reduction of energy consumption and the amount of poisonous exhaust gases emitted to the atmosphere by ships is the use of hull structures with low hydrodynamic drag [12,13] or optimization of the hull shape in terms of minimizing motion resistance [14,15]. In practice, one can come across innovative structures limiting resistance, such as, a catamaran with an air cushion [16], multihull crafts with various float configurations [17,18], numerous designs of SWATH type vessels [19–21] and various innovative structures employing hydrofoils [22–29]. Anti-collision systems [30–34] and methods of optimal ship steering [35–40] are also used as another way of minimizing the ship energy consumption. Energies 2020, 13, 6486; doi:10.3390/en13246486 www.mdpi.com/journal/energies Energies 2020, 13, 6486 2 of 26 Energies 2020, 13, x FOR PEER REVIEW 2 of 27 BearingBearing in in mind mind the the comfort comfort of of people people working working and and transported transported by by sea, sea, parallel parallel efforts efforts are are made made toto develop develop a a ship ship hull hull structure with the greatest possible stability in wave. The The minimum minimum level level of of accelerationacceleration that shouldshould bebe metmet byby sea sea vessels vessels in in order order to to ensure ensure the the comfort comfort of travelof travel according according to ISO to ISO6954: 6954: 2000 2000 is 0.2 is g0.2 for g thefor crewthe crew and and passengers passengers and and 0.4 g0.4 for g anfor experienced an experienced crew crew [41]. [41]. TheThe above above criteria are certainly metmet byby SmallSmall WaterplaneWaterplane Area Area Twin Twin Hull Hull (SWATH) (SWATH) vessels. vessels. Due Due to tothe the stable stable position position of this of typethis type of ships of inships wave, in theywave, can they be usedcan be in hydrographicused in hydrographic surveys, passenger surveys, passengertransport, transport, public utility public services, utility o ffservshoreices, wind offshore farms wind and farms others. and others. WithWith the the development development of of tools tools for for modeling modeling the the hydrodynamic hydrodynamic drag drag of the of theship’s ship’s hull hull[42], [the42], designthe design of the of SWATH the SWATH type type underwent underwent modifications modifications [21] [from21] from the 1st the generation 1st generation developed developed in the in 1970s,the 1970s, consisting consisting of two of struts two struts and two and torpedo-sh two torpedo-shapedaped floats floats through through the SWATH the SWATH II (four II (fourstruts, struts, two torpedoes)two torpedoes) [43], [SWATH43], SWATH III (four III (four struts, struts, four four torp torpedoes),edoes), up up to tothe the SWASH SWASH (one (one central central strut strut and and largelarge torpedo, torpedo, with with two two small small side side floats) floats) (Figure (Figure 11)) andand finallyfinally toto vesselsvessels usingusing hydrofoilshydrofoils underunder itsits hullhull like like the the HYSWATH HYSWATH [[44].44]. FigureFigure 1. 1. ComparisonComparison of of hull hull shapes shapes of of various various vessel vessel types: types: ( (aa) )MONOHULL, MONOHULL, (b (b) )CATAMARAN, CATAMARAN, ((cc)) SWASH, SWASH, ( d) SWATH I,I, ((ee)) SWATHSWATH II, II, ( f(f)) SWATH SWATH III. III. SWATHSWATH type type vessels vessels are are built built on on the the basis basis of oftw twoo submerged submerged floats floats connected connected by struts by struts to the to platformthe platform above above the waterline. the waterline. Thanks Thanks to this, to they this, have they a havehull with a hull a withsmall awaterline small waterline area, which area, minimizeswhich minimizes the contact the contact area with area the with sea the surface. sea surface. Minimizing Minimizing the area the of area the ofship the having ship having contact contact with thewith water the water surface surface has a hasvery a verybeneficial beneficial effect e ffonect reducing on reducing the wave the wave resistance resistance of the of ship’s the ship’s hull. hull. At theAt thesame same time, time, basing basing the structure the structure on two on twosubmerged submerged torpedoes torpedoes results results in very in veryhigh highstability stability at high at operatinghigh operating speeds speeds and andsignificant significant waves waves on onthe thehigh high seas. seas. Unfortunately, Unfortunately, the the use use of of submerged submerged torpedoestorpedoes increases increases the the total total wetted wetted surface surface area area an andd increases the frictional resistance. Thanks Thanks to to this,this, SWATH SWATH ships ships achieve achieve very very high high stability stability at athigh high operating operating speeds speeds and and significant significant waves waves on the on high seas [12,21,45]. Additionally, they have a large, wide and flat platform that can be used for Energies 2020, 13, 6486 3 of 26 Energies 2020, 13, x FOR PEER REVIEW 3 of 27 the high seas [12,21,45]. Additionally, they have a large, wide and flat platform that can be used for transportation ofof goodsgoods oror to to install install specialized specialized equipment. equipment. Examples Examples of of SWATH SWATH vessel vessel structures structures are areshown shown in Figure in Figure2. 2. (a) (b) (c) (d) Figure 2.2. SampleSample photosphotos of of SWATH SWATH ships: ships: (a) SWATH(a) SWATH GEN. GEN. I [46 ],I ([46],b) SWATH (b) SWATH GEN. II GEN. [47], (cII) SWATH[47], (c) SWATHGEN. III [GEN.48], (d III) SWATH[48], (d) GEN.SWATH IV–SWASH GEN. IV–SWASH [49]. [49]. The article analyzes the possibility of using an electric propulsion system system for for a a SWATH SWATH type vessel powered by HybridHybrid EnergyEnergy StorageStorage System,System, consistingconsisting of:of: a chemical-based energy store (rechargeable batterybattery packs—BAT),packs—BAT), aa hydrogenhydrogen fuelfuel cellcell (FC)(FC) andand aa dieseldiesel engineengine generatorgenerator (D).(D). Based on the operational data from the actual SWATH SWATH ship, simulation models were developed for which the conventional internal combustion en enginegine propulsion system was replaced with an electric one powered by Hybrid Energy Storage SystemSystem (HESS). The advantage of using electric main propulsion ofof the the ship ship is theis possibilitythe possibility of reducing of reducing the energy the consumptionenergy consumption and emission and ofemission poisonous of poisonousgases into thegases atmosphere. into the atmosphere. 2. Operational Operational Properties of SWATH VesselsVessels Increased stabilitystability of of SWATH SWATH