The steel making industry is highly energy intensive and a great contributor of greenhouse gas (GHG) emissions. It generated between 7% and 9% of direct emissions from the global use of fossil fuels in 2017 [1]. Gas emissions in an integrated steel mill (ISM) arise mainly from three streams: coke oven gas (COG), blast furnace gas (BFG) and basic oxygen furnace gas (BOFG). This study focuses on the short term solutions to become a carbon neutral steelmaker where blast furnaces (BF) and basic oxygen furnaces (BOF) are still a fundamental part of the steel making process. The Rectisol® process is used to capture CO2 from the works arising gases (WAGs) of an ISM and to generate syngas which can be used as a chemical building block to produce liquid fuels among others. The Rectisol® wash is a patented process by Air Liquide and Linde which uses chilled MeOH as a solvent. Both processes were first validated against stream data provided by the patents. PC-SAFT EOS was used to simulate the purification plant because of its strong theoretical foundation and its ability to adapt the parameters to predict component behaviour. Various binary interaction parameters proposed in literature were used to simulate the purification plants. From these simulations, it was found that the standard binary interaction parameters with the adjusted parameter for H2S-CH3OH, as proposed by Sun et al. [2], showed the best results. The configurations of Air Liquide and Linde were used as base configuration to clean the feed stream. From these simulations, it was observed that in both configurations large portions of CO2 are lost in the stripping process of both configurations. Enhanced CCS configurations were investigated to increase the CO2 recovery of both configurations. The desorption of CO2 was altered by introducing multiple intermediate flashes to increase the desorption of CO2. Without optimisation, the downstream constraint for the CO2-rich stream of 95% CO2 content was almost met in the Linde configuration and requires further upgrading in the Air Liquide configuration. The decision was made to use the Linde enhanced CCS configuration as a base configuration since this would solely require a change in operating conditions to meet the downstream CO2 requirement of 95% content in the CO2-rich stream. HCN and H2O require a seperate wash to avoid accumulation in the main wash. To treat these components together with H2S and COS, two pre-wash configurations combined with the Linde enhanced CCS configuration were looked into. A pre-wash configuration with a separate absorber column and dividing wall column (DWC) and a pre-wash configuration with a separate absorber column and rectifier with purge were examined. Both configurations meet the downstream requirements for the purified gas stream and CO2-rich stream. The main difference between the two configurations is the difference in thermal utility consumption and make-up MeOH. The decision was made to move forward with the pre-wash integrated configuration comprising of a rectifier and purge since additional make-up MeOH would be more cost-effective. The energy recovery method proposed by Linnhoff [3] was used to identify any potential energy saving of the purification plant. A heat exchanger network was designed which reduced the cooling duty by 57% to 54,9 MWth and the reboiler duty by 50,6% to 26,8 MWth. Finally, an economic evaluation was made of the final energy integrated configuration. Equivalent annual cost and operating expenditures of the purification plant were estimated at €12.32m and €51.13m respectively per year. This gives a cost per ton captured CO2 of €37,87.

According to International Energy Agency (IEA), the demand for high value chemicals (HVC) will increase by 60% to a total of 400 Mt/year by 2050, leading to an increase of 30% in direct CO2 emissions. However, the Paris agreement forces the sector to reduce its emissions by 90-100% in 2050 compared to 1990. This induces the need for a more sustainable character in the petrochemical industry to produce HVC with net-zero emissions by 2050. Steam cracking is expected to be still the leading production technique for HVC in 2050. Therefore, this research focuses only on petrochemical clusters containing a steam cracker. Accordingly, the research question to be answered was: How can existing petrochemical clusters containing a steam cracker be transformed to produce HVC with net-zero emissions in 2050? This thesis aims to look into the potential of alternative feedstocks and combine them with other decarbonisation options for steam cracking to produce HVC with net-zero emissions by 2050 from a cradle-to-gate perspective. A base model was created of a petrochemical cluster containing a steam cracker capable of serving the global market (3900 kt HVC/year) to answer the research question. The base model was used to develop six models with different decarbonisation options capable of accepting alternative feedstock. Decarbonisation options were based on carbon capture and storage (CCS), both post and pre-combustion, electrification and hydrogen. The alternative feedstock was sourced from the renewable materials: vegetable oils, animal fats, crude tall oil and lignocellulosic biomass. Also, plastic waste (recycled) and synthetic (FT wax and naphtha) feedstock made from captured CO2 and hydrogen were included. The maximum percentage of HVC produced from alternative feedstock was assumed to be 25% due to uncertainties and limitations in the availability of alternative feedstock. The rest of the HVC was yielded from a mixture of fossil feedstock (naphtha, LPG, ethane, gas oil and butene). Different experiments were performed to estimate the emission reduction potential of separate or combined decarbonisation options with HVC yields originating from alternative feedstock ranging from 0% to 25%. The supply chain and associated CO2 emissions of the feedstock were also analysed. Next to determining the emission reduction, the quantitative data from the models were also used to assess the levelized cost of zero emissions HVC and the geographical and infrastructural limitations of decarbonisation options. One problem was the residual fossil fuel gas from the process, possibly leading to unwanted emissions elsewhere if not appropriately handled. In conclusion, the only decarbonisation options capable of dealing with this problem are CCS and auto-thermal reforming combined with CCS. Together with renewable feedstock, from a cradle-to-gate perspective, these options are capable of reaching net-zero emissions or even negative emissions when fossil and renewable feedstock supply chain emissions are drastically reduced. For future research, it is advised to not only focus on producing HVC with steam cracking but also consider other greenfield production method capable of producing HVC with renewable resources. A comparison with the proposed pathways in this research would provide valuable insights.

Regulations and investments in new technologies for biofuel production as an alternative to fossil fuels have boosted in the last years due to concerns about climate change and anthropogenic CO2 emissions. A valuable supply chain of biomass for biofuel production is one the most significant factors, in order to support the market’s demand. A promising feedstock that is widely available and considered a residue can be Namibia’s encroacher bush (EB). Namibia is facing an environmental crisis with bush encroachment, where EB takes over grasslands, reducing biodiversity and groundwater availability. A thermochemical process that can take advantage of EB can be Hydrothermal Liquefaction (HTL). With HTL, biomass feedstocks are liquefied under hot compressed water, producing bio-oil (BO), biochar (BC), an aqueous phase (AP) and gases. Catalytic HTL is a more attractive pathway, due to the increased BO yield and quality. To this day, there has not been a study investigating the potential of catalytic HTL with EB, thus the present MSc Thesis will attempt to close that knowledge gap and provide state-of-theart insight. To achieve that, Acacia Mellifera from Namibia was tested in sub-critical HTL conditions. In particular two campaigns were formulated with two different goals. The first one, focused on the selection of a suitable catalyst among 4 different categories of catalysts (zeolites, alkaline earth metals, lanthanides and transition metals). The catalysts performance was evaluated by comparing the Energy Recovery (ER) under same operational conditions. Then, the catalyst with the highest ER was used in the second experimental campaign using a Desing of Experiments approach. This approach had the goal to optimize HTL reaction conditions -temperature, residence time and catalyst loading- for maximizing BO yield and energy content. Central Composite Design (CCD) of experiments was used, with the parameters ranges being 250-340oC, 5-60mins and 0-10wt%, respectively. Selected BO and BC samples from both campaigns were then characterized using various methods. The HTL experiments with EB revealed that BO from EB could be produced. The highest ER obtained from the catalyst screening campaign was 41.1% . Main organic compounds found in all the BOs were phenolic derivatives, alicyclic ketones and fatty carboxylic acids. Using the best performing catalyst based one ER, the CCD model indicated that the optimum conditions for maximizing BO yield were 340oC, 60 minutes and 5wt%, which yielded 27.0wt% BO. However, the 330oC - 60 minutes - 7.5wt% point gave both the highest yield and highest ER, 28.5wt% and 46.2% respectively. The CCD also reduced the O content in the BO samples by 54%. Finally, BC samples showed fuel characteristics similar to lignite and low concentration of heavy metals, making them legitimate alternatives for solid fuels or soil amendment.

The objective of this study is to generate insights into the application of the reliability of a W2H system and its impact on the techno-economic performance. This involves examining the case of a single system to analyse on a micro-level the underlying conditions affecting performance, as well as exploring W2H farms to observe performance and the effects of changing conditions on a macro-level. To this end, MATLAB models have been utilised and developed to simulate various components of a system, such as wind turbines and electrolysers, focusing on aspects like hydrogen production and the number of breakdowns per year. The model creates insights into technical and economic parameters.

The transport sector remains one of the largest CO2 emitting sectors globally. Decarbonizing the transport sector is an important aspect in the energy transition. The word transition is key, since it will take several decades or more to transition to a fully sustainable world. During this transition mainly heavy-duty vehicles and probably most vehicles in third world countries will rely on liquid transportation fuels. Affordable and competitive biofuels are the way to fill this need in a sustainable way. This study will focus on integrating several sustainable units and feedstocks to produce gasoline and diesel, starting with a pyrolysis oil feedstock. The integrated units consist of a gasifier, whose gasifying agent, oxygen, is produced by a SOEC electrolyser, running on renewable electricity. The syngas produced in the gasifier is produced during a low temperature Fischer Tropsch process over a cobalt catalyst. The aim is to choose operating conditions resulting in a large chain growth probability factor to produce heavier hydrocarbons chains, which can be refined to mainly yield diesel. The hydrogen required to upgrade the syngas formed in the gasifier is supplied by the SOEC electrolyser as well. The final upgrading of the produced crude oil is performed by separating the fractions in distillation columns and using a hydrocracker to raise the yield of the desired products. The end products are diesel and gasoline, meant to be blended in with gasoline and diesel from conventional oil refineries. The gasoline and diesel are sulfur free and especially the diesel is of high quality, due to tuning the process to predominantly produce paraffinic hydrocarbons. The assessment of the process will be a techno-economic analysis based on a model made with Aspen plus. 5000 kg·hr-1 of bio-oil produced by BTG was converted to 990 kg·hr-1 of high-quality diesel and 557 kg·hr-1 of gasoline. The overall carbon conversion of the process to the end products was 57.6 %. By designing a heat exchanger network, optimizing the energy produced and needed by the heat sources and sinks respectively, an overall energy efficiency on LHV base of 57.2 % was reached. The process in the current day and age was found to not be profitable yet, but will definitely be in the future.

Shipping is, and will continue to be, the most important transportation method around the globe. A vital part of the logistic chain, it is also one of the main contributors to the worldwide CO2 emissions. Current propulsion technologies all rely on the same classic diesel driven technology, as diesel is widely available and has a high energy density. The goal of this research is to identify greener solutions to propel a vessel sailing for short distances. During a definition study, several fuels and energy converters were studied and benchmarked based on a use case. The results showed that (a combination of) the dual fuel internal combustion, using bio diesel and hydrogen, and the low temperature proton exchange membrane fuel cell, fuelled with hydrogen, is the most feasible setup for the use case. Such a combination in itself is not a new one, but in the literature only an all-electric setup is described. In the proposed solution an internal combustion engine is driving the propellor shaft directly, assisted by an electric motor powered by the fuel cell. Based on this outcome, the following research question was defined: How can an internal combustion dual fuel engine and/or LTPEM fuel cell be integrated to form a cost effective solution to propel a short sea ship running on hydrogen? First, nine designs were created, ranging from a conventional diesel engine setup as a reference case, to a fully electric design powered by fuel cells. All main components in these designs are analyzed regarding part load efficiencies. With these efficiencies, the fuel consumption at different loads are calculated. Based on a use case scenario the total fuel costs are calculated. The CAPEX and the OPEX of the designs are determined to calculate the total costs. As currently no other fuel can compete with diesel, the designs are compared based on the price per tons of CO2 emissions, as the shipping industry is expected to see a CO2 emission penalty in the near future. For each design, what the height of this penalty has to be to reach the breakeven point at the end of the use case was calculated. Based on the lowest CO2 price, an all-electric, fuel cell powered design was identified as the most promising option. Applying additional operational arguments such as redundancy and end user acceptance, it was decided together with Conoship to choose a combination of an internal combustion engine and a fuel cell. This configuration is worked out in detail to answer the sub questions, covering efficiency improvement and system integration, during which it became apparent that not all information is available to answer all these sub questions. The design needs further research in a multidisciplinary team. A simulation model would be helpful in this further research. A framework and a start to such a model was written together with a list of recommendations.

Following the Paris Agreement of 2015, Indonesia aims to reduce emissions by 29% by 2030, compared to the business as usual scenario. In Indonesia it is expected that between 2015 and 2030 the electricity demand could triple and the total energy demand could increase by 80%. Bioenergy would account for more than half of all renewable energy in 2030 in Indonesia. However, the expansion of energy crops contributes to negative effects like deforestation, loss of biodiversity, and competition with food production. An other problem Indonesia currently deals with is the large amount of degraded land. A solution to these problems would be to cultivate biomass on degraded land. Bamboo can be used as a biomass feedstock, as it meets all selection requirements to be produced on degraded land. This thesis report quantifies the extent and finds the location of degraded land in Indonesia. Also, the technical and economic potential of bamboo cultivation on the degraded land locations is assessed. The research question that will be answered is: how much degraded land would be needed to cover Indonesia’s electricity demand by 2030, when using bamboo as a biomass feedstock, and how likely is this land available? This research question is answered by first doing a geographic information system (GIS) analysis. Through the QGIS software, the degraded land locations in Indonesia which are suitable for bamboo plantations can be found. This is done by layering multiple datasets on top of each other in four steps. Next, the technoeconomic potential analysis is done by calculating how much degraded land would be needed to cover a certain percentage of Indonesia’s electricity demand by 2030, and calculating the levelized cost of electricity (LCOE) of different biomass conversion technologies. The results show that between 0.21% and 49.9% of Indonesia’s total land area can be considered degraded according to different scenarios. The suitable area for bamboo plantations lays between the 0.01% and the 13% of Indonesia’s total land area. Using these areas the potential electricity that can be reached lays between the 0.4732 TWh for gasification, 0.3533 TWh for combustion, 0.3506 TWh for anaerobic digestion, and 0.1266 TWh for pyrolysis. The area needed to cover 25% of Indonesia’s electricity demand by 2030 ranges from 2.05.6% of Indonesia’s total land cover when using different conversion technologies. For 100% electricity demand this area increases to the range of 8.122.4% of Indonesia’s total land cover. The LCOE goes from 13 US$ct./kWh for gasification, to 16 US$ct./kWh for combustion, 22 US$ct./kWh for anaerobic digestion, and finally to 45 US$ct./kWh for pyrolysis. The result show that when using the least strict degraded land scenarios, it would be possible to cover a significant amount of Indonesia’s electricity demand. However, it is not likely that these scenarios will be applied. The definition of degraded land, still is not completely clear, and extensive field research needs to be done to validate the degraded land results. This research shows that bamboo cultivation on degraded land for electricity generation in Indonesia might not be applicable to generate large amounts of electricity. Nevertheless, it can be applied on smaller scales and it is a step in the right direction of Indonesia’s energy transition. Finally, some recommendations for future research can be made. First of all, uncertainty exists about the datasets used to assess the extent of degraded land in Indonesia. It is recommended that the datasets are validated through field research. Furthermore, in this research an assumption for the yield of bamboo is made, which can be tested against the actual yield of a bamboo plantation on degraded land in Indonesia. Also, socioeconomic and environmental effects of bamboo plantations are not considered, which provides the opportunity to address these in further research. Finally, other end uses like biofuel, other conversion technologies like cofiring, and pretreatment technologies to enhance the conversion efficiency can be evaluated in more detail in future research.

Improving circularity and reducing greenhouse gas emissions can be achieved by utilizing secondary streams like Fischer-Tropsch biosludge, which is typically disposed of in landfills. Biochar, which has accumulated increased interest recently, has significant potential for decreasing carbon emissions and can be created from biosludge. This master thesis was set up as an opportunity-based research project to understand the utilization of Fischer-Tropsch biosludge by the hydrothermal carbonisation process and characterise its product phases; biochar, aqueous phase and gaseous phase. A central composite surface response design was used to conduct experiments to analyse the impact of temperature and time on the characteristics of the phases. Three different levels of the factors have been used. The high ash content and low surface area of the biochar made it difficult to determine a specific use case for the biochar. Yet, the aqueous phase has low ash and possible potential for biogas creation by anaerobic digestion. The gas phase is quantitatively not of significance. Stockpiling the biochar could sequestrate carbon credits and more research can be conducted to find a post- or pre-treatment to improve the biochar for a social-economically benefiting application.

As the world population is increasing and cities grow faster than before, food scarcity becomes a bigger issue. To depend less on import and decrease CO2 footprint, food should be produced nearby its consumers. A good solution for food production is a greenhouse which provides a steady high yield throughout the year. Some of the world's fastest growing cities are in Subtropical climates. Subtropical climates are characterized by high temperatures, abundance of sun and high humidity. Due to the high temperatures, cooling in greenhouses in subtropical climates is necessary, but evaporative cooling is not sufficient due to the high humidity. Outside air can be dehumidified by a liquid desiccant to cool the air further with an extra evaporative cooling step. After dehumidifying the air, the absorbed moisture from the air in the desiccant must be removed from the desiccant solution for re-use. This requires a lot of energy, which makes this cooling technique for greenhouses in subtropical climates not economically feasible. The proposed solution is to remove moisture from the desiccant by making use of the hot air that can be collected in the top of the greenhouse. The potential of this solution is assessed in this study. To predict the transfer of mass and heat between air and a calcium chloride solution as desiccant, a mathematical model of the process of mass and heat transfer over a structured cardboard pad is made. An experiment is conducted to validate the mass and heat transfer coefficients of the model. The model is used to evaluate the workings of the proposed system of regeneration. Results show that dehumidification can significantly lower the inlet temperature of the air in the greenhouse, provided that the inlet temperature of the desiccant is low. Regeneration of the desiccant solution with hot air is also possible, provided that the air in the greenhouse is significantly heated by the sun and pre-heating of the desiccant before regeneration is beneficial. The direct coupling of these two systems is not sufficient due to the big difference in temperature of the desiccant that is required at the inlet of the dehumidifier and regenerator. In future work attention should be paid to this temperature difference which is currently limiting the performance of the system. Then it's possible for the concentration of the desiccant to be brought back to the starting conditions for the dehumidifier.

Developments in the field of renewable energy technologies have lead to low energy cost in areas with specific characteristics. In the Middle East solar power plants are built for prices around 3 cent per kilowatt-hour and bids below 3 cent have been placed. In Europe wind energy is the second largest source of renewable energy after biomass. Although, wind farms are being built without subsidy the total cost of a wind farm is much higher in the order of 14 cent per kWh and it can decrease to 10 cent by 2030. In this research an concept study for the transport of electric energy is made to find an answer to the question: “is it possible to ship electric energy which is delivered in a port between areas of generation and consumption over a fixed distance with the use of a ship and deliver it for a levelised cost of electricity (LCoE) which is competitive in the market of unloading.” The cost of a kilowatt-hour of electric energy in the Dutch market is 8.33 if it is produced by a modern gas fired power plant and if the cost for CO2 emissions are included according to the current prices in the European emission trading scheme. If higher carbon cost scenario's are applied the price could increase to prices over 17 cent per kilowatt-hour. The concepts in this study are tested against four different carbon emission cost scenario's ranging from 8 euro/tCO2 to 190 euro/tCO2 Most electrical energy is transported by electric energy power grids. For long distance high volume energy transmission a high voltage direct current energy cable is the most efficient way to transport energy but at larger distances the transmission system gets more expensive. In this research the electric cable is used as a reference case which the concept has to outperform. To test the concepts a non-linear model is made which is solved with Matlab-integrated solvers to find the optimal transport concept. The model works by optimising the main dimensions of the ship. With this optimal ship design concepts are analysed. For this research: a concept based on a hydrogen-carrier (ammonia) and a concept based on thermal energy storage are discussed. . The hydrogen-carrier concept uses ammonia as a carrier. Ammonia has a high energy content and can be produced with the Haber Bosch process or with Solid State Ammonia Synthesis (SSAS). If the energy is produced using the well known Haber-Bosch process in 2018 the levelised cost of energy is 21.2 and 24.2 cent per kilowatt hour depending on the distance. Developments in the field of electrolysers will reduce the capital investment which can reduce the price to 17.8 to 20.8 cent per kilowatt hour by 2025 if the energy is supplied at 2 cent per kilowatt hour to the ammonia production facility. The SSAS method offers higher energy effincies at lower capital investment cost. The LCOE calculated in this research is 11.4 to 16.4 cent per kilowatt-hour. The thermal energy storage concept is based on molten salt. Molten salt is being used in concentrated solar power plants as a storage of energy. In the concept used in this project the molten salt is transported to another part where the heat which is stored in the salt is used to generate electricity. The LCoE is already 28.5 cent per kilowatt-hour at a distance of 1,000 nm. The thermal energy storage concept is more expensive than the ammonia concept. Depending on the distance and the carbon cost scenario's the concept can be competitive to the fixed connection with a cable and fossil fired power plants in the home market. If the low cost carbon scenario's (1 and 2) are applied by law makers the concept of electrical energy by sea is not competitive but if politicians would decide to increase the cost for carbon emissions the transport could become competitive. When the carbon emission cost increase to values over 100 euro/tCO2 the SSAS concept is competitive for distance up to 2,000 nm but it still more expensive than a cable connection. For this distances larger than 4,000 nm and carbon prices according to the 4th scenario (190 euro/tCO2) the SSAS-based concept can be a competitive energy supplier.

Climate change, earthquakes in Groningen and the desire to become more energy independent in the future are all reasons for the Netherlands to strongly reduce the use of natural gas. To realize this ambitious goal the domestic environment will also have to stop using natural gas and start heating, cooking and using warm water sustainably. The distribution system operator Stedin has developed a method/tool that helps munic- ipalities in identifying a viable energy carrier as alternative to natural gas. Stad aan ’t Haringvliet is the first town that approached Stedin about the prospects of hydrogen as an alternative to natural gas. Stedin has made an initial review and concluded that hydrogen could be a promising alternative to natural gas in the case of Stad aan ’t Haringvliet. The objective of this research project is to improve the existing approach for identifying the ideal future energy carrier for different locations within Stedin’s operating area by making a technical assessment of all necessary activities and changes when switching from natural gas to 100% hydrogen in an existing distribu- tion network. All identified relevant aspects of hydrogen are taken into account in the case study of Stad aan ’t Har- ingvliet. The case study shows that the local gas network can be isolated from the larger gas network and function as a hydrogen network. Also, nearly no unfavorable materials (cast iron and asbestos cement) are present in the local network which underscores the suitability. If the town is isolated from the larger network it could be fed from north-west of the town by an alkaline electrolyser. However, a stand-alone system at this scale is not a cost effective scenario in the Netherlands. Therefore, an alternative system comparison was made to verify if hydrogen is indeed a viable option for Stad aan ’t Haringvliet. In the chosen system compar- ison a scenario was sketched in which ’gray’ hydrogen was received from a large industrial hydrogen network to the east of Goeree-Overflakkee. This scenario was compared to an all-electric scenario which utilized the current electricity mix which can also be considered ’gray’, due to that the majority of the generation is from fossil fuels. The system comparison shows that with cost-effective insulation, a hydrogen scenario can be nearly as expensive as an all-electric scenario in Stad aan ’t Haringvliet regarding annual costs. The average initial in- vestment for a home owner in an all-electric scenario is estimated to be e50,000 and the initial investment in the hydrogen scenario is e11,000 on average. The annual costs are e1,540 and e1,460 for hydrogen and all-electric respectively. The carbon footprint of both scenarios is nearly equal at 4000 kg/CO2/year. The costs for adapting the local electric and gas distribution network is also significantly less expensive for a hydrogen scenario compared to the all-electric scenario. This is due to the fact that the natural gas network would have to be removed and the electric network would have to be heavily reinforced in an all-electric scenario in con- trast to light reinforcements to the electric network in the hydrogen scenario to facilitate electric cooking. No ’show stoppers’ were identified in the general part nor in the case study part of this research. Several requirements and favorable characteristics were determined which could help identify other areas in which hydrogen could be a potential energy carrier. The first characteristic of a suitable area is predominantly hous- ing which is very costly to sufficiently insulate for all-electric heating. Large consumers of natural gas in the area are also not favorable due to the fact that they might not be able to switch to hydrogen yet. The following characteristics relate to the network. Areas at the periphery of the local gas network are favorable due to the fact that they can more likely be isolated without creating capacity issues for itself or other areas. Also, areas which have little to no cast iron or asbestos cement are favorable due to increased risk of fractures inherent to these materials. Finally, a credible source of hydrogen is identified as a requirement for a suitable area.

Replacing conventional kerosene has gained interest in an effort to make aviation more sustainable. In 2018 a total of 895 million tonnes of CO2 was emitted, equivalent to 2% of global CO2 emissions. For normal passenger and cargo planes synthetic kerosene is most feasible to replace conventional kerosene, hydrogen powered or electricity driven airplanes face problems and may only be feasible for small airplanes. Increased interest in electrolysis, direct air capture (DAC) and production pathways for synthetic kerosene has encouraged development and reduced the price gap with conventional kerosene. Although small pilot plants are realized last decade, little research has been done on large-scale studies. And most research is focused on one method, while an integrated system can be promising either. This thesis focused on both topics, taking Rotterdam-The Hague Airport as reference airport. Syngas will be obtained from biomass gasification and water electrolysis with a proton exchange membrane (PEM) electrolyzer. CO2 to form CO is retrieved from a DAC plant. The syngas is converted into fuel by Fischer-Tropsch (FT) technology. Several gasification technologies were studied and the direct heated steam/oxygen fluidized bed gasifier was found to be the best option. This gasifier was built and validated according to the Institute of Gas Technology (IGT) gasifier located in Hawaii. In order to accurately estimate the behavior of the process, a steady state model is developed using Aspen Plus. Two scenarios are defined and represent the intermittent behavior of renewable electricity. The first scenario simulates high renewable electricity production, while the second scenario is driven by low supply of electricity. Biomass gasification is integrated to remain a constant syngas flow for the FT reactor and subsequent kerosene production. To reach the intended annual kerosene production of 50.000 ton, it was found that a gasifier with a maximum capacity of 100 ton/h is required. Thermal efficiencies of 35% and 33% are achieved for scenario 1 and 2 respectively, taking gasoline, diesel and waxes into account as useful side-products. Total land-area required to fulfill electricity demand equals 0.9km2 of solar panels together with a wind farm covering 3.6km2 assuming turbines of 10MW. A cost analysis has been conducted to investigate the economical feasibility of the project. The average fuel price obtained in this project reached 1.74-2.87 euro/kg, exceeding conventional fuel prices. But estimated price reductions and technical improvements for wind/solar power, PEM electrolysis and DAC decrease the fuel price to 1.49-2.78 euro/kg by 2050. In addition, carbon taxes are expected to increase hence reducing the gap between conventional and synthetic kerosene even more. Future research and development must focus on extending and improving the model to acquire more precise results. Furthermore, improvements have to be made for electrolysis and DAC plants before they are economically competitive and suitable for large scale. In conclusion, the models in this thesis have shown promising results in terms of future feasibility of large scale synthetic kerosene production in an integrated system. It has proved that when future developments are realised and DAC and PEM electrolysis have become more mature, the price gap between conventional and synthetic kerosene can be overcome and large scale projects become feasible.

Low-carbon hydrogen is expected to have a large role in future energy systems. Recent research shows the short-term financial feasibility of blue hydrogen is often higher than green hydrogen. Ammonia production is particularly carbon-intensive due to its hydrogen production routes. This research focuses on the physics-based modelling of blue hydrogen production for ammonia synthesis, examining the influences of varying input conditions and economic scenarios on process performance and economics. Future energy systems will rely on flexible integrated solutions, emphasizing the importance of understanding how system parameters respond to diverse input conditions. The ammonia plant consists of a desulphurization unit, a pre-reformer, an ATR, two water gas shift reactors, a physical absorption tower for CCS, a PSA for H2 purification and a Haber-Bosch ammonia synthesis reactor. Auxiliary components consist of heat exchangers, compressors and dehydration units. The modelling efforts focus on medium-fidelity models, reflecting the main thermodynamics and kinetics through first-order differentials assuming reactor simplifications. The plant simulations are based on plant operation in the Netherlands in 2030 under the following price assumptions: C_NH3= 0.472 €/kgNH3, C_elec= 41.77 €/MWh, C_NG= 22.64 €/MWh, C_CO2−tax= 0.135 €/kgCO2(eq), C_CCS= 0.05 €/kgCO2. Each reactor model was separately validated through industrial data. Then the operational window was selected based on individual reactor limitations and the overall system chain performance: α=0.6, β=2.0, Tin=873.15K, Pin=2.8MPa. α and Tin are the most influential parameters from an economic and environmental perspective, showing the largest influence on levelized costs and emissions. Overall, under the simulated conditions, blue ammonia results in an 85% direct emission reduction compared to grey ammonia. The levelized costs of blue ammonia amount to 0.417€/kg and the NPV is 104 MEUR, the most influential economic parameters are the natural gas price and the ammonia selling price. Three case studies were conducted in which specific economic and operational conditions were compared. Simulations of three IEA policy scenarios for 2030 show that the overall cost reduction in more sustainable scenarios is mainly driven by the lower natural gas price. Carbon taxes have a limited effect on the price of blue ammonia however do significantly increase the price of grey hydrogen compared to blue (a 0.11-0.17 €/kg difference). This results in a minimum 0.05 €/kgNH3 margin for the capture process costs in the stated scenario (0.09 €/kgCO2(eq) ), the other scenarios give a larger margin. Green ammonia gives a levelized cost of 0.457 €/kg NH3 under the same economic assumptions. The NPV is -480 MEUR, which is most affected by the electricity price and ammonia price. This research yields a 9% LCOA increase for green ammonia when compared to blue. The evolution of electricity prices is paramount in the financial competitiveness of green ammonia, more so than the CAPEX evolution. The indirect emission intensity of green ammonia is lower than blue ammonia in the simulated conditions. However, this depends on the electricity source. Through carbon taxes blue and green ammonia can become cost-competitive to grey however this comes at a cost for the everyday consumer. A simulation with dynamic operation yielded that inputting NG feed following seasonal natural gas pricing is not cost-effective when compared to steady-state production at the same seasonal pricing, even for +/-44% price fluctuations. The additional CAPEX costs for storage and larger process units are not sufficiently compensated by the lower variable OPEX costs. Further research should focus on shorter-term supply and demand matching. Overall, it can be concluded that this model can sufficiently simulate a blue hydrogen chain and be used for further simulation cases, also with alternative economic and operational assumptions. The technical parameters that affect blue ammonia production most are α and Tin. Economically the ammonia and the natural gas price are most influential. In comparison with grey and green ammonia, under the simulated conditions, blue hydrogen is the most cost-effective. Finally, the economic incentives through the seasonality of natural gas prices do not justify a dynamic operation of the process plant.

Embracing the innate human desire to explore and expand our horizons, Mars presents an unparalleled opportunity to secure the future of our species and inspire generations to come. Aiming to facilitate a sustainable human presence on Mars, this master thesis focuses on the design and modeling of an in-situ rocket propellant production plant to fully refuel SpaceX's Starship for the return mission to Earth. The study identifies the best design practices for the in-situ resource utilization (ISRU) rocket propellant production setup and examines its integration with state-of-the-art technologies. The main results include an exergy analysis of the plant to determine its second-law efficiency, and the methodology necessary to conduct an exergy analysis on a different planet with different standard conditions. Furthermore, this work investigates material recycling, sensitivity analyses, exploitation of the Martian environment, and heat recovery opportunities within the plant's modeling. Three essential key performance indicators (KPIs) have been spotlighted to assess the plant’s performance. The first KPI scrutinizes the equipment mass to propellant mass ratio, providing invaluable insights into the economic efficiency of In Situ Propellant Production (ISPP). This ratio reveals that ISPP contributes to an 88.9% reduction in the mass that needs to be transported to Mars, highlighting the economic feasibility of the thesis. The second KPI is the Specific Energy Consumption (SEC) of the plant, standing as a measure of the plant's efficiency. The SEC, calculated by dividing the total power input by the sum of CH4 and O2 mass flows at the outlet, is found to be 6.52 kWh/kg. Furthermore, the plant’s second-law efficiency is examined, revealing how the plant's performance deviates from its theoretical maximum. The second-law efficiency, a significant indicator of the plant's ability to convert high-grade input energy into useful output without substantial degradation, is found to be 62.7%. Lastly, the work addresses the plant's dynamic behavior across Martian seasons, employing data derived from the Curiosity Rover. The focus here is to understand how the plant’s parameters, especially those interacting with the Martian environment, are impacted by diurnal and seasonal cycles. A special operational philosophy is adopted to ensure stable operations amidst these fluctuations. Through these findings, this research offers a thorough understanding of the current best practices and technologies for designing and modeling a propellant production plant on Mars. The output of this work is a model of a full-scale rocket fuel production plant. In conclusion, the insights provided by this work are of great significance for the future exploration and colonization of Mars, as they contribute to the development of a sustainable ISRU rocket propellant production plant, which is a crucial development necessary to guarantee return missions to Earth, thereby making sustained human presence on Mars a closer reality.

At the United Nations Climate Change Conference held in Paris in 2015, ambitious goals for the worldwide CO2 emissions were set. To achieve these goals, a huge reduction in CO2 emissions must be realized. For the energy market, the current aim is to use renewable electricity instead of fossil fuels. However, there are multiple sectors where electricity is not a suitable form of energy, due to storage issues. For example, the chemical industry is heavily based on fossil fuels as a resource to synthesize chemicals. It is therefore useful to investigate the feasibility of renewable synthetic fuels. The goal of this thesis is to design a process that converts the hydrocarbon fuel combustion products CO2 and H2O into a fuel that is a liquid at atmospheric conditions. Methanol is selected as the liquid fuel because of its basic molecule structure. It requires much more energy to obtain methanol from CO2 and H2O than it does from natural gas. The process is determined to be container-sized to become cost competitive through mass production. The technical feasibility of a mass produced, autonomous, renewable and container-sized methanol production plant is studied in this thesis. The whole process is divided into sub processes. H2O is obtained from desalination of seawater. The H2O is split into H2 and O2 using alkaline electrolysis. The CO2 is adsorbed from the air and recovered using pressure and temperature swing. The required energy is obtained using solar PV and solar thermal. The H2 and CO2 are finally converted to methanol in the methanol synthesis sub process. The intermittent character of solar energy yields a dynamically operated process. The methanol synthesis sub process is studied further because of the small scale and dynamic operation that are new concepts for this technology. The other sub processes are considered as black boxes with fixed in- and outputs. The steady state operation of the whole process is modeled using Aspen Plus™ and the distillation process is modelled in MATLAB®. Using the results from Aspen, pinch analysis is performed for optimal use of the available heat. From the results of the model, it is found that an autonomous container-sized methanol production plant is technically feasible. 140 kg of methanol can be produced daily with a purity of at least 96.6 %, using a set-up of three 40 feet sea containers, two of which are dedicated to the capture of CO2. 288 kW of electrical power and 24 kW of heat is required for the operation. This is equal to a solar park with an area of 1663 m2 assuming an average 6 hours of solar irradiance. Using the LHV of methanol in the calculation, the total efficiency of the process is estimated at 45 %. The results from the MATLAB® model of the distillation cannot be validated because the used equation of state of REFPROP underestimates the concentration of methanol in each iteration, yielding an invalid mass balance. Fixing this issue results in an invalid energy balance. It is therefore concluded that REFPROP is not suitable for iterative calculations of distillation columns.

Meeting the ever-increasing energy demands in our planet where conventional sources of energy are finite and fast depleting, controlling adverse phenomena like climate change, soil erosion, greenhouse gas emission, ozone layer thinning and pollution will remain profound challenges until widespread adoption of sustainable sources of energy is achieved. The shift to a sustainable energy system cannot be complete without the contribution of biomass energy. Within the ecosystem of biomass energy, gasification is a thermochemical conversion process undertaken to obtain a high-quality product gas by increasing the low energy density of solid biomass. The product gas can be used in power applications or be converted to liquid fuels for transportation. Gasification is carried out at high temperatures (700-1500°C) by using a gaseous agent under sub stoichiometric conditions (R.A. Kersten & De Jong, 2015). The main non-condensable permanent gases obtained from gasification are CO, H2, CO2 and CH4. Use of allothermal gasifiers, whose working is based on the separation of combustion and gasification chambers within the gasifier, with heat supply for carrying out endothermic reactions, established via heat carrier or heat exchanger, have shown many advantages compared to the conventional gasifiers (Hofbauer & Materazzi, 2019). The mix-up of product gas and flue gas is avoided in this type of gasification. Secondly, while using air for biomass combustion, the nitrogen present in air reduces the quality of the end product by not participating in gasification, thus resulting in a diluted product gas. A high-quality product gas can be obtained from allothermal gasifiers without the need for establishing an expensive air separation unit, as required in case of conventional gasifiers. The 50 kWth Indirectly Heated Bubbling Fluidized Bed Steam Reformer (IHBFBSR) at Delft University of Technology (TU Delft) represents a new concept of allothermal gasification technology where heat required for the endothermic gasification reactions is provided by two radiant tube burners placed vertically inside the reactor, one at the top and one at the bottom. The aim of this research is to optimize and validate the kinetic model developed for the IHBFBSR by a former student, Maarten Kwakkenbos in Aspen Plus®. The optimization is carried out with the help of the several steps, described in the report. The optimized model is then validated by using the results of the gasification tests performed under various operational conditions by PhD Candidates Mara del Grosso and Christos Tsekos. The optimized model predicts the gas composition obtained from the IHBFBSR quite well. In addition to the yield of permanent gases, N2, H2O and tars concentration in the product gas, along with various gas ratios (CO/H2, CH4/H2, CO/CO2) from the model are compared with the experimental values and found to be in reasonable agreement. Moreover, key performance indicators such as carbon conversion (CC), cold gas efficiency (CGE) and overall efficiency (OE) are also evaluated from both model and experiments and compared. The error ranges for most of the parameters lie within the reported deviations observed in various gasifier models in literature. After the validation of the model, the possibility of recycling a fraction of the product gas to feed the burners in order to make the set up more sustainable is evaluated. Sensitivity analyses is performed by varying steam to biomass ratios (SB*), primary and secondary air flowrate to evaluate the best process conditions under which product gas obtained from the gasifier, after subsequent cleaning, can be used for methanol production based on the H2/CO ratio. The results indicate that a higher SB* and a higher secondary air flowrate can result in a H2/CO ratio closer to the desired value required for optimum methanol production. From the heat analysis performed for the model, a possibility of increasing the overall efficiency of the process by adding a bypass line in the gasifier setup is suggested to be explored. The master thesis concludes by answering the research questions and recommendations to improve the detailing and accuracy of the model.

The increasing awareness and urgency of climate change have led to an increase in investments and research into power sources not reliant on fossil fuels. Proton exchange membrane (PEM) fuel cells are a promising technology for automotive, maritime, and auxiliary power applications converting chemical energy into electricity. In order for this upcoming technology to compete with well-established alternatives such as diesel generators and combustion engines, it is of vital importance to improve the power density and durability. PEM fuel cells produce water and heat during operation. The presence of superfluous liquid water in the fuel cell stack gives rise to flooding of the electrodes, which hampers operation and induces degradation processes. On the other hand, it is of great importance to maintain a high membrane humidification to reduce Ohmic losses over the membranes and avoid the formation of cracks. Therefore, water management plays a vital role both in maintaining the power density and guaranteeing durability. This thesis is written under the auspices of both TU Delft and PowerCell Group, a manufacturer of PEM fuel cell systems located in Gothenburg, Sweden. Currently, a substantial amount of water condenses in the anode subsystem of PowerCell’s PEM fuel cells in certain operating ranges which subsequently enters the fuel cell stack. This study identifies the influence of certain system operating parameters on responses as the water crossover through the membranes, the relative humidity at the stack inlet, the temperature at the inlet of the stack, the condensation rate in the mixing chamber of the recirculation loop, and the mass flow rates of liquid water and water vapor in and out of the stack. Multiphysics simulation software provided by Gamma technologies is used to simulate 5600 operating points in which the system operating parameters are varied according to the Latin Hypercube sampling method. These simulations give a clear overview of the influence of the operating parameters on the aforementioned responses over the entire operating range of PowerCell’s PS-100 system. The simulated experiments are subsequently used as a basis to construct metamodels. These metamodels predict the behavior of the system based on the operating parameters varied in the 5600 simulations. The metamodels are constructed both as Krigings and as multilayer perceptrons (MLPs). Kriging is a statistical method which produces an output for a certain response based on known input data where input points which resemble the unknown point are given a greater weight. MLPs are neural networks which recognise patterns in input data and use those to predict an output for a certain response. Finally, the operating parameters are optimized using the metamodels to minimize the liquid water mass flow rate into the stack, to prevent condensation in the mixing chamber of the anode subsystem, and to target a certain inlet relative humidity of the hydrogen feed to the stack. Concluding from these optimizations it would be beneficial to preheat the hydrogen before it reaches the mixing chamber. A number of alternative designs for the anode loop are proposed which require further investigation.

The production of steel is an energy intensive process, using 20GJ/tonne of steel. The energy use needs to be declined by 10% in 2030 in order to be on track of the Sustainable Development Scenario(SDS). About 1GJ/tonne is required today by the annealing process, a heat treatment in which the steel strip is heated to a temperature of about 600-700oC and cooled afterwards. Tata Steel came up with a way of connecting the cooling and heating section in an innovative way, which can potentially reduce the energy requirements of an annealing line by up to 70%. Horizontal rotating heat pipes are proposed to transfer heat efficiently over its axial length from the strip in the cooling section to the strip in the heating section. Dowtherm A has been selected as the working fluid between 150 and 350oC. No research is available on rotating heat pipes with Dowtherm A. The aim of this study is to research the relevant internal heat transfer characteristics of a rotating heat pipe and gain insight into the performance of Dowtherm A as the working fluid in terms of heat transfer efficiency. Furthermore, the aim is to gain knowledge on the effect of non-condensable gas inside a heat pipe and on the way the effects can be modelled in a computationally efficient way. Non-condensable gas is likely to be of influence on heat transfer homogeneity outwards to the relatively cool steel strip. Understanding this influence is another goal of this study. To fulfil the aims of this study, experiments are conducted and a computational model is devised. An experimental setup with working fluid Dowtherm A is used to acquire data at different rotational speeds, operating temperatures and at different thermal inputs and outputs. The rotating heat pipe used is of smaller scale than one in a heat pipe assisted annealing line, but with comparable heat fluxes. Secondly, the devised model is used to both qualitatively and quantitatively study the effect of non-condensable gas for different operating parameters and non-condensable gas amounts, which is done for conditions as in the experimental setup and as in a heat pipe assisted annealing line. The rotating heat pipe worked successfully during conducted experiments and Dowtherm A has shown to be able to transport at least 280W axially through the inner geometry in the non-annular flow regime, which is 192,000W/m2 and corresponds to a vapor flow of 0.001kg/s, at an axial temperature difference of only a few degrees Celsius. Nucleate boiling was considered the dominant heat transfer mechanism through the film in the evaporator, with a typical heat transfer coefficient observed of 4200W/m2K. The condenser has shown a lower film heat transfer coefficient; 1750W/m2K. The effect of rotational speed, power and temperature is minor in the evaporator at conditions tested. The 1D model for determining non-condensable gas distribution showed good agreement with reported experimental data, which show a major axial temperature drop at the condenser end. It was shown that wall conduction influences non-condensable gas distribution for heat pipes with a relatively thick wall, which is modelled by the addition of wall temperature calculations to the 1D model. The effect of non-condensable gas on heat pipe performance showed to be strongly dependent on operating temperature. Axial convective transport showed to be between two and three orders of magnitude more efficient than pure conduction. Homogeneous heat outflow is achieved when non-condensable gas is not present in the condenser, which can be achieved by extending the heat pipe at the condenser end. The devised model is suitable to predict the effect of operating conditions and design adjustments in an efficient way. Results have shown that Dowtherm A is a suitable working fluid for a heat pipe assisted annealing line, due to the low internal resistances to heat and mass transfer.

The Process and Energy department of the Mechanical, Maritime and Materials faculty of TU Delft and the Dutch company Petrogas Gas-Systems B.V. are working together on the commissioning of a small 50 kW (th) Indirectly Heated Bubbling Fluidised Bed Steam Reformer (IHBFBSR) which will be used to gasify the energy crop Miscanthus. However, the new feature is that this fluidised bed will be heated indirectly using radiant tube heaters installed in the reactor. These heaters are made by assembling radiant tubes with self-recuperative burners fired using Dutch Natural Gas. All tubes and burners have been manufactured by the German company WS Warmeprozesstechnik GmbH. This thesis consists of the study of two such distinct burner-tube assemblies, both of different heating capacity. The smaller capacity is of the C80 burner assembled with C100 tube while the larger is of the C100 burner assembled with C150 tube. The heat transfer and fluid dynamics inside both the tubes have been numerically modelled using CFD techniques. The models of the burners have been done using the commercially available software ANSYS Fluent version 18.2. The main objective of this thesis has been to analyse the heat transfer from both the assemblies and calculation of their respective efficiency. To this end, the temperature, velocity, species and turbulence fields have been calculated for inside both the tubes. Also, the total heat output from the radiant tubes has been calculated. However, the mechanism of heat transfer from the radiant tube to the fluidised bed was not known at the time of these calculations. Hence, appropriate boundary conditions have been used to simulate the outer environment. The total heat transfer from the combusting flow to the inner surface of the radiant tube has been calculated. This total heat input has been equated to the heat transfer from the outer surface of the tube to the fluidised bed, assuming steady state condition. The variation of all these parameters has been studied with air factor and preheat temperature. The air factor has been varied from 1.0 to 1.5 for both tubes, by reducing the fuel inlet keeping the air inlet constant. The air preheat temperature has been varied from 300 C to 700 C for C80-C100 assembly and from 300 C to 800 C for C100-C150 assembly. This has been done to calculate an optimum operating condition for both the burner-tube assemblies in terms of maximising heat transfer and radiant tube efficiency and minimising fuel wastage. It has been found that operating at lean condition of 20% excess air by mass at highest air preheat temperature would be the optimum operating condition. The last part of this thesis is the analysis of the robustness of calculations. Three grid sizes have been chosen other than the main grid and all the parameters have been checked for variations, if any. The variation is found to be within scientifically acceptable limits. Hence, it is concluded that the calculations are robust at this level.

In 2015, 30% of the world's energy demand was met through petroleum based sources, whose burning has affected the world's climate. The Paris Climate Agreement, among other policies, has shifted the focus towards usage of renewable energy sources. Currently, the renewable market caters predominantly to meeting the electric demand, which only represents 19% of the world's energy consumption. Zero Emission Fuels (ZEF) aims to create a small-scale chemical plant that uses renewable energy sources to create synthetic methanol. This follows the vision of adapting renewable energy sources for non-electric usage. Methanol is the simplest liquid hydrocarbon at atmospheric condition; it can be used as a fuel or as a base chemical for other products. Presently, the industry reforms syngas obtained from fossil fuels to create methanol, predominantly using large-scale catalytic reactors. For production of methanol from renewable sources, Bos and Brilman developed a small-scale catalytic reactor driven by natural circulation. ZEF adapted the Brilman reactor for their chemical plant, creating a prototype of the modified Brilman reactor (MBR). The present work aims to create a model that describes the steady-state methanol production of the prototype using computational fluid dynamics (CFD) and chemical process models. The MBR is an innovative design based on a closed loop geometry. The gases are driven by buoyant forces from a temperature difference between the high-temperature catalytic reaction zone and the low-temperature condensation zone. Heat recovery elements are used to exchange heat between the hot and cold streams as they travel in the loop. The CFD model developed on Fluent 18.2, uses a RNG k-e turbulent model, with multicomponent species transport, convective heat transfer and momentum loss effects from the catalytic zone. The boundary conditions are based on the operating conditions of the prototype. The model calculates flow-rate, and the effect of heat recovery elements inside the natural circulation loop. A chemical process model developed in COCO 3.2 is used to calculate a mass and energy balance for the two-phase behavior of the gas mixture inside the MBR. A study of the effects of a natural circulation loop with a configuration similar to the reactor is performed, observing potential benefits by tilting the system. The combination of effects due to heat recovery and flow blockage in the reactor is studied, and the results are evaluated with experimental measurements. The chemical process model developed closely resembles the experimental characterization of the reactor. The parameters of flow-rate and internal temperatures can not be validated due to limited data available from experimental procedures.