The European Green Deal declared that Europe must decarbonize to become carbon-neutral within 2050. To do so, the European Parliament emphasized hydrogen as a major tool for energy transition. In regard of current environmental challenges, liquid hydrogen has raised interest as energy carrier for energy storage and transport. Due to growing use of renewable energy sources such as solar and wind energy, intermittent sources will increase. Hydrogen production methods will become mostly intermittent with renewable energies. However, due to historical hydrogen production by steam methane reforming, liquefaction was developed at steady nominal charge. In order to feed current liquefaction processes with renewable hydrogen, a buffer system will become required. This thesis studies the effect of buffer and liquefaction combination on performances and cost. In order to carry out this liquefaction from intermittent source, the study is performed based on industrial data from a variable co-product hydrogen profile. This profile acts as a simplified case. The scope of the study is drawn by considering compressed hydrogen as temporary storage for the buffer while liquefaction unit is modelled around Linde Leuna cycle. The technical-economical study covers sensitivity analysis on both buffer and liquefaction unit. For the buffer unit, storage capacity, storage pressure, liquefaction flexibility and recuperation rate impacts are examined. Liquefaction sensitivity analysis includes pressure drop, electricity cost and capacity study.  It is highlighted that 100% gaseous hydrogen recovery is not profitable due to high costs increase for recuperation higher than 95%. Storage pressure and capacity as well as liquefaction flexibility drive buffer cost and recuperation rate of the co-product hydrogen. Considering liquefaction study, results highlight that pressure drops cause first order deviations in energy consumption as well as on cost. Results show that the specific buffer cost is evaluated between 71% and 59% of liquefaction cost. Hence the thesis raises attention on future work on heat exchangers design, pressure drop optimization and liquefaction unit flexibility to allow an optimized renewable liquid hydrogen production.

The purpose of this study is to investigate and analyze stops that occur in the painting process of trucks; specifically related to the buffer system after the top coat process. Based on this investigation, improvements are presented in order to eliminate stops and improve overall assembly time. With this scope in mind, the following issues have been raised:   1.     What are the root causes for stops in the buffer system? 2.     How much can corrective maintenance be reduced? 3.     What potential savings are achieved by reducing or eliminating stops in the buffer system? 4.     How would reducing stops increase the availability for the top coat paint shop?   A case study has been performed where historical data has been analyzed and staff from the production, maintenance and IT departments have been interviewed. The analyzed data along with a theoretical framework are the basis for the suggested actions that will improve flows through the top coat production. The result indicates that a great part of the delays related to the buffer system are caused by soft losses. The stops are the results of: Lack of a distinct set of rules for how data and software may be used Lack of communication between the workshops The implications of these delays are: increased costs and reduced efficiency of the production line. The purposed actions presented in the study gives the company opportunity to achieve full capacity, eliminate delays and increase overall efficiency. The study is limited to the top coat paint shop and does not include the primary paint shop or final assembly. The results, analysis and suggestions presented in the study includes the soft losses that causes stop in the buffer system. / Syftet med följande studie är att undersöka och analysera stopp och dess rotorsaker som uppkommer i buffertsystemet på ett täcklacksmåleri. Utifrån denna utredning presenteras sedan åtgärdsförslag i syfte att eliminera undersökta stopp. För att kunna uppfylla syftet med studien har följande frågeställningar formulerats:   Vad finns det för stopp relaterade till buffertsystemet och vad är rotorsakerna till dessa? Hur mycket kan det akuta underhållet reduceras? Hur stora besparingar skulle företaget kunna göra genom reducering eller eliminering av stoppen? På vilket sätt kan en minskning av stoppen öka tillgängligheten för täcklacksmåleriet?   En fallstudie har genomförts där historisk data har analyserats och personal från avdelningar som produktion, underhåll och IT har intervjuats. Den empiri som samlats in tillsammans med det teoretiska ramverket som presenteras i rapporten ligger till grund för resultatet, analysen och åtgärdsförslagen.   Resultatet från studien visar att en stor andel av de stopp som sker i buffertsystemet orsakas av mjuka förluster. Dessa stopp är en konsekvens av bristfällig hantering av data och mjukvara samt bristfällig kommunikation mellan verkstäderna. Konsekvenserna av dessa stopp resulterar i ökade kostnader samt en nedsatt effektivitet för täcklacksmåleriet. Åtgärdsförslagen som presenteras ger företaget goda möjligheter att uppnå sin fulla kapacitet, eliminera stoppen och därmed öka effektiviteten.   Studien är avgränsad till måleriprocessen och omfattas inte av grundmåleriet eller monteringen. De resultat, analyser och åtgärdsförslag som presenteras är avgränsade till de mjuka förlusterna som orsakar stopp i buffertsystemet.