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With increasing demands on lowering carbon emissions, fuel cell hybrid electric vehicles (FCHEV) have been seen as an alternative to the fossil-fuel driven trucks of today. These would have less emissions and strive to have the same range as any diesel driven transport vehicle. A lot of effort and resources have been put into fuel cell research for incorporation in new powertrains. There are however many different fuel cell types, so the aim of the thesis was to explore two different fuel cell types for use in a FCHEV model.The thesis sets up a model consisting of various subsystems of a high temperature proton exchange membrane fuel cell (HT-PEMFC). Components for the power electronics and a cooling system are also incorporated. The system was then combined with a vehicle model, where a power split between the fuel cell and battery was investigated. The performance of the HT-PEMFC was compared to a low temperature proton exchange membrane fuel cell (LT-PEMFC) on three levels with increasing complexity. These were on a single cell level, stack level and on a vehicle level.The results showed that the HT-PEMFC had worse performance than the LT-PEMFC on both a cell and vehicle level. The power output of an HT-PEMFC was lower for all current densities, meaning more cells were needed in order for the HT-PEMFC to have the same power output as an LT-PEMFC. It did however have a better cooling ability and was a simpler system, which therefore does warrant further investigation on its future use in transport applications. If heat recuperation was investigated further, the HT-PEMFC performance would have been increased to a higher degree than the LT-PEMFC.

Fuel cells are promising candidates for converting chemical energy into electrical energy. The Molten Carbonate Fuel Cell (MCFC) is a high temperature fuel cell that produces electrical energy from a variety of fuels containing hydrogen, hydrocarbons and carbon monoxide. Since the waste heat has a high temperature it can also be used leading to a high overall efficiency. Material degradation and the cost of the components are the problems for the commercialisation of MCFC. Although there are companies around the world starting to commercialise MCFC some further cost reduction is needed before MCFC can be fully introduced at the market. In this work, alternative materials for three different components of MCFC have been investigated. The alternative materials should have a lower cost compared to the state-of-the-art materials but also meet the life-time goal of MCFC, which is around 5 years. The nickel dissolution of the cathode is a problem and a cathode with lower solubility is needed. The dissolution of nickel for three alternative cathode materials was investigated, where one of the materials had a lower solubility than the state-of-the-art nickel oxide. This material was also tested in a cell and the electrochemical performance was found to be comparable with nickel oxide and is an interesting candidate. An inexpensive anode current collector material is also desired. For the anode current collector, the contact resistance should be low and it should have good corrosion properties. The two alternative materials tested had low contact resistance, but some chromium enrichment was seen at the grain boundaries. This can lead to a decreased mechanical stability of the material. In the wet-seal area, the stainless steel used as bipolar/separator plate should be coated. An alternative process to coat the stainless steel, that is less expensive, was evaluated. This process can be a suitable process, but today, when the coating process is done manually there seems to be a problem with the adherence. This work has been a part of the IRMATECH project, which was financed by the European Commission, where the partners have been universities, research institutes and companies around Europe. / QC 20101123

I samband med den globala uppvärmningen ökar efterfrågan för rena och förnybara bränslen alltmer i dagens samhälle. Eftersom flygindustrin idag är ansvarig för samma mängd växthusgaser som all motortrafik i Sverige, skulle ett byte till en avgasfri energikälla för flygfarkoster vara ett stort framsteg. Därför har projektet genom modellering framtagit ett hybridsystem av ett batteri och en bränslecell och undersökt hur kombinationen av olika storlekar på dem presterar i en driftcykel. Då batterier har hög specifik effekt men är tunga, kompletteras de med fördel av bränsleceller, som är lättviktiga och bidrar med uthållig strömförsörjning. På så sätt blir hybriden optimal för flygfarkoster. Kandidatarbetet är en del av projektet Green Raven, ett tvärvetenskapligt samarbete mellan instutitionerna Tillämpad Elektrokemi, Mekatronik och Teknisk Mekanik på Kungliga Tekniska Högskolan. Driftcykelmodelleringen gjordes i Simulink, och flera antaganden gjordes beträffande effektprofilen, samt bränslecellens mätvärden och effekt. Tre olika energihushållningsscheman skapades, vilka bestämde bränslecellseffekten beroende på vätgasnivån och batteriets laddningstillstånd. Skillnaden på systemen var vilka intervall av laddningstillstånd hos batteriet som genererade olika effekt hos bränslecellen.  Det bästa alternativet visade sig vara 0/100-systemet, eftersom det var det enda som inte orsakede någon degradering av bränslecellens kapacitet. / In today’s society, with several environmental challenges such as global warming, the demand for cleanand renewable fuels is ever increasing. Since the aviation industry in Sweden is responsible for the sameamount of greenhouse gas emissions as the motor traffic, a change to a non-polluting energy source forflying vehicles would be considerable progress. Therefore, this project has designed a hybrid system of abattery and a fuel cell and investigated how different combinations of battery and fuel cell sizes perform ina drive cycle, through computer modelling. As batteries possess a high specific power but are heavy, thefuel cells with high specific energy complement them with a sustained and lightweight power supply,which makes the hybrid perfect for aviation. The bachelor thesis is a part of Project Green Raven, aninterdisciplinary collaboration with the institutions of Applied Electrochemistry, Mechatronics andEngineering Mechanics at KTH Royal Institute of Techology. The drive cycle simulations were done inSimulink, and several assumptions regarding the power profile, fuel cell measurements and power weremade. Three different energy management strategies were set up, determining the fuel cell powerdepending on hydrogen availability and state of charge of the battery. The strategies were called 35/65,20/80 and 0/100, and the difference between them was at which state of charge intervals the fuel cellchanged its power output. The best strategy proved to be 0/100, since it was the only option which causedno degradation of the fuel cell whatsoever.

Den miljöpåverkan förbränning av fossila bränslen ger upphov till måste minskas och med fortsatt ökad e-handel blir behovet att lagerverksamheter, där de interna transporterna oftast utgörs av dieseltruckar, större. Konkurrenskraftiga alternativa bränslen behövs för att tillgodose det ökade behovet. Bränslecellstruckar drivna på vätgas producerad med elektricitet från förnyelsebara energikällor skulle kunna vara ett alternativ då emissionerna enbart består av vatten. För att undersöka om bränslecellstruckar orsakar mindre miljöpåverkan utfördes en jämförande livscykelanalys på en 5 tons diesel- respektive bränslecellstruck. Jämförelsen utfördes både för en bränslecellstruck där framställningen av vätgasen sker lokalt och för en där vätgasen köps in från en gasleverantör. Framställningen i de båda fallen sker genom alkalisk vattenelektrolys. Jämförelsen gjordes på ett fallspecifikt lager för Ramirent i Brunna där det idag finns 21 stycken truckar som drivs på diesel. Resultatet visar på att skillnaden i miljöpåverkan mellan bränslecellstruckarnas två olika fall är minimal, men att dieseltrucken bidrar till mer miljöpåverkan i 14 av 18 miljöpåverkanskategorier utifrån ett livscykelperspektiv. För dieseltrucken är det utvinningen och förbränningen av dieseln som har störst påverkan i de flesta miljöpåverkanskategorier. Vidare visar resultatet att bränslecellen, samt tillverkningen av den, är det som generellt bidrar till mest miljöpåverkan för de flesta påverkanskategorierna för bränslecellstrucken. För att möjliggöra en omställning krävs ofta inte bara att den är bättre ur miljösynpunkt, utan att omställningen dessutom är kostnadseffektiv. Därmed beräknades även kostnaderna för en omställning med hjälp av nuvärdesmetoden för de tre olika fallen. Detta gjordes genom att först låta de befintliga dieseltruckarna, med en antagen livslängd på 20 000 drifttimmar, bytas ut succesivt under en 10 års period mot nya dieseltruckar. För de båda andra fallen säljs dieseltruckarna med restvärden och nya bränslecellstruckar, samt en ny tankstation, köps in. För fallet med egenproducerad vätgas måste även en elektrolysanläggning införskaffas till skillnad från fallet med inköpt vätgas. Resultatet visar på att investeringen med bränslecellstruckar inte är kostnadseffektiv för varken egenproducerad eller inköpt vätgas. Kostnaderna ökar med 3,4% respektive 28,9% över en 10 års period, jämfört med att fortsätta använda dieseltruckar. Vidare visar en känslighetsanalys i studien att ett nystartat lager, i samma storlek som Ramirents i Brunna, är mer lönsamt om bränslecellstruckar köps in och en vätgasproduktion etableras än om dieseltruckar köps in. Kostnadsreduktionen för detta scenario är 1,4% över en 10 års period. Studiens känslighetsanalys visar att lönsamhet för inköpt vätgas uppnås för ett nystartat lager och Ramirents lager när vätgaspriset sjunkit med 59,5% respektive 71,6% från dagens pris 222 kr/kg. Ytterligare resultat från känslighetsanalysen visar att potential finns att öka de årliga intäkterna för fallet med egenproducerad vätgas genom att sälja den extra mängd vätgas som kan produceras med elektrolysanläggningen, men som inte används av truckarna. Avslutningsvis kan det konstateras att bränslecellstruckar har mindre total miljöpåverkan ur ett livscykelperspektiv. Det är i dagsläget inte lönsamt att övergå från diesel- till bränslecellstruckar på Ramirents lager i Brunna. För en 10 års period är dock de extra kostnaderna för fallet med egenproducerad vätgas relativt små. Känslighetsanalysen visar dessutom på potentiellt mindre kostnader för bränslecellstruckar med egenproducerad vätgas för nystartade lager. Priset på vätgas och dess utveckling är en betydande parameter för investeringens lönsamhet för fallet med inköpt vätgas. Rekommendationer för vidare studier är att undersöka möjligheten att sälja överskottsvätgas, samt biprodukten syrgas, från den egna elektrolysanläggningen för att öka de årliga intäkterna. / The environmental impact from fossil fuels must be reduced and with the continued increase in e-commerce, the need for warehouse operations becomes greater, where internal transports usually consists of diesel forklifts. Competitive alternative fuels are necessary to meet the increased need. Fuel cell forklifts powered by hydrogen produced from renewable energy sources could be an option, since the emissions consist solely of water. To investigate whether fuel cell forklifts cause less environmental impact, a comparative life cycle analysis was performed on a 5-tonne diesel and fuel cell forklift, respectively. The comparison was carried out both for a fuel cell forklift where the hydrogen is produced locally and for one where the hydrogen is purchased from a gas supplier. The production method is alkaline water electrolysis for both cases. The comparison was made on a case specific warehouse for Ramirent in Brunna, where there are currently 21 diesel forklifts. The result shows that the difference in environmental impact between the two different cases of fuel cell trucks is minimal, but that the diesel truck contributes to more impact in 14 of 18 environmental impact categories from a life cycle perspective. For the diesel forklift, it is the extraction and incineration of the diesel that has the greatest impact in most environmental impact categories. Furthermore, the result shows that the fuel cell, as well as the production of it, is generally contributing to the most impact categories for the fuel cell truck. To enable a transformation, it is often not only required that it is better from an environmental perspective, but also cost effective. Thus, calculations were carried out for the cost of a transformation, using the net present value method for the three different cases. This was first done by replacing the existing diesel trucks, with an assumed lifetime of 20,000 hours of operation, successively over a 10-year period for new diesel trucks. In the both other cases, the diesel trucks with residual values are sold and new fuel cell trucks, as well as a new hydrogen station, are purchased. For the scenario with locally produced hydrogen, an electrolysis plant must also be purchased as opposed to the scenario with purchased hydrogen. The result shows that the investment in fuel cell trucks is not cost effective for either locally produced or purchased hydrogen. Costs increase by 3.4% and 28.9%, respectively, over a 10- year period, as compared to a continued use of diesel trucks. Furthermore, a sensitivity analysis in the study shows that a new warehouse, with the same size as Ramirents in Brunna, is more profitable if fuel cell trucks are purchased, and a hydrogen production is established, than if diesel trucks are purchased. The cost reduction for this scenario is 1.4% for a 10-year period. The sensitivity analysis of the study shows that profitability for purchased hydrogen is reached for a new warehouse and Ramirent's warehouse when the hydrogen price has been reduced by 59.5% and 71.6%, respectively, from today's price of 222 SEK/kg. Further results from the sensitivity analysis show that there is a potential to increase the annual revenues, for the scenario with hydrogen production, by selling excess hydrogen from the electrolysis plant. In conclusion, fuel cell trucks have less overall environmental impact from a life cycle perspective. At present, it is not profitable to switch from diesel to fuel cell trucks at Ramirent's warehouse in Brunna. However, for a 10-year period, the extra costs for the scenario with locally produced hydrogen are relatively small. In addition, the sensitivity analysis shows potentially lower costs for fuel cell trucks with local hydrogen production for newly started warehouses. The price of hydrogen and its development is a significant parameter for the investment's profitability for the scenario with purchased hydrogen. Recommendations for further studies are to examine the possibility of selling excess hydrogen, as well as the by-product oxygen, from the electrolysis to increase annual revenues.