The energy resource waste heat or low-grade thermal energy is available in vast quantities. Tapping into this resource and converting it to electrical energy would not only reduce energy waste but also has the potential to eliminate greenhouse gas emissions. One technology developed to utilize this resource is the ORC which uses an organic working fluid that has a low boiling temperature and thus can be vaporized at a low temperature. This work has been focused on evaluating a theoretical ORC system working with a constant net power output of 200 kW and heat source temperature of 80 °C. The assessment was conducted with a model developed within the scope of this work. The model was compared against the literature to ensure more reliable results. Assessment of the system was performed with a parametric investigation to assess how the pinch point temperature difference, Condenser cold fluid inlet temperature, and pressure ratio affect the system performance. For a low-temperature ORC system to achieve good performance the pressure ratio is the most impactful parameter to focus on. However, a low Condenser cold fluid inlet temperature allows for a larger pressure range and increases the system performance for any given pressure ratio. Lowering the cold condenser inlet temperature from 20 to 15 °C provides a large system efficiency gain.

With the increase of global emissions and the development of renewable energy, the application of more clean energy to industrial emission reduction has become an increasingly important topic. In metal production, a large amount of carbon dioxide is generated due to the wide application of carbon. Thus, using hydrogen instead of carbon to achieve industrial decarbonization is a way to reduce emissions. Four modes for supplying hydrogen to Höganäs AB and Boliden AB are analyzed and investigated in this work. The four modes are i) on-site hydrogen production. ii) Blending hydrogen into natural gas pipelines.iii) Hydrogen pipeline delivery. iv) Liquid hydrogen truck. These modes are compared in different aspects,such as cost and CO2 emission. To model different modes, some data are assumed, and some are obtained from external sources. All modes need to meet each company’s hydrogen demand, which is estimated at 2000 kg per day. Furthermore, the costs of modes are operated and calculated in Python. One step further, the emissions of each mode are simulated and compared in Matlab. Finally, the most cost-effective and low emission mode for each company can be devised. The results show that the most cost-effective mode for Höganäs AB and Boliden AB is on-site hydrogenproduction. The full load hour is 10 hours per day to meet the hydrogen demand of companies. The cost is proportional to the full load hour and hydrogen mass flow, but inversely proportional to electricity price. The lowest cost, which is 4.07 €/kg, occurs at maximal full load hours and lowest electricity price. The pipeline delivery options are the lowest-emissions options, but the entire mode has high emissions due to the hydrogen production from the site plant. The liquid hydrogen truck is feasible for long-distance delivery. / Med ökningen av de globala utsläppen och utvecklingen av förnybar energi har tillämpningen av mer ren energi på industriella utsläppsminskningar blivit ett allt viktigare ämne. Under metallproduktionsprocessen genereras en stor mängd koldioxid på grund av den breda användningen av kol. Att använda väte istället för kol för att uppnå industriell avkolning är således ett sätt att minska utsläppen. I detta arbete analyseras och undersöks fyra sätt att leverera väte till Höganäs AB och Boliden AB. De fyra metoderna är: i) Väteproduktion på plats. ii) Blandning av väte i naturgas pipeline. iii) Leverans av väte pipeline. iv) Flytandevätgasbil. Dessa metoder jämförs i olika aspekter såsom kostnad och CO2 utsläpp. För att modellera olika metoder antas en del data och en del erhålls från externa källor. Alla metoder måste tillgodose varje företags vätgasbehov som uppskattas till 2000 kg per dag. Dessutom hanteras och beräknas kostnaderna för metoder i Python. Ett steg längre simuleras och jämförs utsläppen från varje metoder i Matlab. Slutligen kan det mest kostnadseffektiva och lågautsläppsläget för varje företag utformas. Resultaten visar att det mest kostnadseffektiva sättet för Höganäs AB och Boliden AB är produktion av vätgas på plats. Den fullastade timmen är minst 10 timmar per dag för att tillgodose företagens vätebehov. Kostnaden är proportionell mot full belastningstimme och vätemassaflödet, men omvänt proportionell mot elpriset. Den lägsta kostnaden, som är 4,07 € / kg, uppstår vid maximal laddningstid och lägsta elpris. Pipeline leverans alternativen är de lägst utsläppalternativen men hela moden har höga utsläpp på grund av vätgasproduktinen från anläggningar, och flytande vätgasbil är möjlig för långdistansleverans.

The feasibility of a PEM hydrogen storage system in a municipal setting using prosumer excess solar power has been investigated. The feasibility was determined upon key performance indicators payback time, internal rate of return (IRR) and net profit margin. The project was done as a case study on Södertälje municipality, Stockholm, Sweden. Different business models were compared to determine the optimal operation scheme. Potential showstoppers were also explored. Literature study and interviews were combined into a system model in Excel which breaks down costs and profits over a 20-year timeline. A sensitivity analysis was performed to measure the stability of yearly net profits during changes in electricity price and hydrogen market price. The available excess solar power was identified and used to size a system consisting of an electrolyser, storage tanks and fuel cells. A daily system was deemed best, where electricity is accepted during the day and discharged during the night. Hydrogen is also sold as a commodity for vehicular charging, and oxygen is compressed into a refill station for hospitals and manufacturers. The results were simulated in two operational scenarios; a Standard scenario and a Truck scenario, the latter which has no fuel cell and more hydrogen is sold at the expense of electricity. The payback time is 5 years for the Standard scenario and 4 years for the Truck scenario. They have an IRR of 4% and 32% after 5 years and a net profit margin of 63% and 86% respectively. The sensitivity analysis shows <6% change in yearly net profits for the Standard scenario and <12% change in the Truck scenario when electricity price and hydrogen market price fluctuatesby 50%. / Genomförbarheten för en PEM vätelageranläggning på kommunnivå användandes av solcellägares överskottsel har undersökts. Genomförbarhetens grad bedömdes efter konsumentprisindex återbetalningstid, intern avkastning (IRR) och nettovinstmarginal. Projektet utfördes som en fallstudie på Södertälje kommun. Olika affärsmodeller jämfördes och potentiella problem identifierades. Litteraturstudie och intervjuer kombinerades till ett system för kostnader och intäkter över en 20 år livstid som modelleradesi Excel. En känslighetsanalys utfördes för att se effekten på årliga vinster när elpriset och marknadspriset för väte ändrades. Det tillgängliga solcells överskottet identifierades och användes för att välja storlek på systemet innehållandes bränslecell, elektrolyserare och förvaringstank. En daglig drift dömdes passa bäst, där lagret fylls på dagen och urladdas på natten. Vätet säljs också som en råvara till fordon och syret komprimeras till en påfyllningsstation för sjukhus och industriella processer. Resultaten simuleras i två scenarier; ett Standardscenario och ett Truck scenario där inget bränslecell finns och mer väte säljs på bekostnad av elektricitet. Återbetalningstiden är 5 år för Standard scenariot och 4 år för Truck scenariot. De har en IRR på 4% och32% efter 5 år och en nettovinstmarginal på 63% och 86% vardera. Känslighetsanalysen visar en <6% ändring i årliga vinster för Standard scenariot och <12% i Truck scenariot när elpriset eller marknadspriset för väte fluktuerar 50%.

In the United Kingdom, 85% of households rely on natural gas for space/water heating and cooking. On average, the yearly demand for one household for providing heat from natural gas is 13300 kWh. The growing need to suppress the use of such fossil fuels to provide energy brings to consider alternative solutions involving renewable energy sources. This thesis aims to study a solar hydrogen plant that will try to provide the necessary energy in the form of hydrogen, which will be used as storage and the primary source of energy for a typical house. The particularity of this plant is that direct seawater electrolysis is used to produce hydrogen. The scope of this study is a mix between fundamental research and practical application. The method involves analytical work, modelling and simulation. The results will show what the required amount of hydrogen is, what technology needs to be used to obtain better performance and the number of solar panels to use. This study will show that if only hydrogen is used as an energy source, the system will be able to tackle about 20% of the energy requirements. Indeed the average available area of roofs is too tiny compared to what would be needed. Nevertheless, if implemented within different scenarios or combined with other technologies such as heat pumps, the saved energy from natural gas will reach almost 80%. This study also discusses the consequences and the interests of using seawater instead of fresh deionised water. The analytical and simulation study performed on seawater electrolysis enabled to select AWE as a suitable technology for performing seawater electrolysis and showed that 150 kg of hydrogen can be produced when coupled with a PV installation of 8 kW. / I Storbritannien är 85 % av hushållen beroende av naturgas för uppvärmning av rum/vatten och matlagning. Det växande behovet av att minska användningen av fossila bränslen för energiförsörjning gör att man måste överväga alternativa lösningar med förnybaraenergikällor. Syftet med den här avhandlingen är att undersöka den tekniska genomförbarheten av en vätgasanläggning för solenergi som ska försöka tillhandahålla den nödvändiga energin i form av vätgas som sedan ska användas som lagring och huvudkälla för energi i ett typiskt hus. Det speciella med denna anläggning är att direkt elektrolys av havsvatten används för att producera vätgas. Den här studien är en blandning av grundforskning och praktisk tillämpning. Metoden omfattar analys, modellering och simulering. Resultaten kommer att visa vilken mängd vätgas som krävs, vilken teknik som måste användas för att uppnå så hög prestanda som möjligt och hur många solpaneler som bör användas. Undersökningen visar att om endast vätgas används som energikälla kan systemet täcka cirka 20 % av energibehovet. Den genomsnittliga tillgängliga takytan är dock för liten jämfört med vad som skulle behövas. Vid olika scenarier i kombination med annan teknik, t.ex. värmepumpar, kommer den sparade energin från naturgas att uppgå till nästan 80 %. I studien diskuteras också konsekvenserna och intresset av att använda havsvatten i stället för färskt avjoniserat vatten. Den analys- och simuleringsstudie som utfördes på havsvattenelektrolys gjorde det möjligt att välja AWE som en lämplig teknik för havsvattenelektrolys och visade att 150 kg vätgas kan produceras i kombination med en solcellsanläggning på 8 kW.

The utilization of different biomass feedstocks in thermal conversion systems can contribute towards mitigation of global warming. However, the formation of different ash fractions (i.e., bottom ash, and fly ash) during thermal conversionof biomass can cause several ash-related problems such as deposit formation, slagging, and particle emissions, all of which may limit its usage as an energy source. It has been found that phosphorus (P), even in relatively low concentrations, can play a vitalrole in the abovementioned ash-related problems. However, the ash transformation reactions occurring in the thermal conversion of P-bearing biomass assortments are not fully understood and rarely described in the literature. Therefore, an understanding ofthe phenomena associated with ash transformations with a special focus on P is crucial. The overall objective was to determine the ash transformation and release of P duringsingle-pelletthermochemical conversion ofdifferent types of agricultural and forest fuelsin the low to medium temperature range (600-950 °C). Different agricultural biomasses (poplar, wheat straw, grass, and wheat grain residues), as well as forest residues (bark, twigs, and a mixture of bark and twigs) were used. Thebark and poplar fuels represent a fuel rich in K and Ca with minor P contents. The wheat straw, grass, and twigs represent a typical Si- and K-rich fuel with minor and moderate P contents. The wheat grain residues represent a typical K- and P-rich fuel witha considerable amount of Mg. The produced residual materials, i.e. chars and ashes, were characterized by SEM-EDS, XRD, and ICP-OES. The experimental results were interpreted with support from thermodynamic equilibrium calculations (TECs). The overall findings are that the majority of P (>80%) in all the studied fuels remained in the final condensed residues, and that the main fraction of P release occurred during the devolatilization stage. The chemical form of P in the residuesis strongly dependent on the relative concentrations of other major ash-forming elements such as K, Ca, and Si, as well as the type of association of P in the pure fuel. For woody-based fuels rich in Ca and K (poplar, bark, and twigs in this study), P in theash is generally found in the form of crystalline hydroxyapatite. For herbaceous fuels rich in Si and K (wheat straw and grass), P in the ash is generally found in Ca5(PO4)3OH, Ca15(PO4)2(SiO4),KCaPO4, and K-Ca/Mg phosphosilicate melts. For wheat grain residues rich in P, K, and Mg, P in the ash is found in crystalline forms K4Mg4(P2O7)3, K2MgP2O7,K2CaP2O7, and KMgPO4, as well as amorphous K-Mg/Ca phosphates. The obtained new knowledge can be used to find practical measures to mitigate ash-related problems during thermochemical conversion of P-bearing biomass fuels. It can also be used to find optimal pyrolysis process conditions to obtain biocharsuitable as alternative fuels and reducing agents in the metallurgical industry.

Quality aspects of wood pellets and their use have been of utmost importance since the development of the pellet market in the early 1980s. Research and hard-earned knowledge have resulted in advancements in the field, but there are still uncertainties in the pellet industry about how different quality aspects affect combustion performance. The focus of this work has been on pellet quality, with investigations divided into three main topics: 1) the effect of physical properties of pellets on their combustion properties, 2) the effect on particle emissions due to manipulation of the ash chemistry by means of additives and, 3) how radio frequency identification (RFID) technology can be used to achieve traceability of bulk pellets.In the literature it is not clear how physical pellet quality parameters affect the combustion behavior. To gain knowledge regarding the perception of pellet quality in practice, interviews with pellet industry representatives were made initially. This was followed by detailed combustion experiments to investigate how the key quality parameters moisture content, density, and durability affect the ignition behavior and the conversion time. A large number of well-defined pellet samples produced from four different raw material mixes were used. The results showed that during stable combustion conditions, i.e., high temperature and sufficient air supply in a fully functioning combustion system, these parameters have little practical influence on the combustion performance. However, the results from the detailed laboratory experiments indicated that the choice of raw material can have a more profound effect on both ignition behavior and conversion rates, although the full-scale tests indicated that this was of little practical importance. Fuel design, i.e. choosing fuels or making adjustments to the fuel based on ash composition, can be used to lower particle emissions. This concept was demonstrated during combustion tests that were performed in three individual campaigns in medium scale boilers, 0.2 MWth, 2 MWth and 4 MWth respectively. In the campaigns, peat was utilized to alter the ash transformation reactions, reducing the emission of particulate matter less than 1 micron (PM1) during combustion of woody biomass, while keeping the slag formation at a manageable level. This was achieved by designing fuel blends of woody biomass with carefully selected Scandinavian peats rich in Si, Ca, and S. In one of the campaigns, softwood-based stemwood pellets were co-pelletized with different additions of peat (5 and 15 wt %) before combustion. In the other campaigns, peat was added as a separate fuel feed to Salix chips (15 wt % peat) and softwood-based stemwood pellets (10 and 20 wt % peat). The results showed that, no matter how peat was added to the fuel, the fuel design approach provided PM1 reductions of between 30 - 50 % for all fuel blends. The PM1 reduction could be achieved without causing operational problems due to slagging in any of the three commercial boilers used, although an expected increased slagging tendency was observed. RFID systems are used today for the tracking of well-defined entities; i.e. the RFID tag is linked to an object - a container, a person etc. While RFID technology has been used in this way in the energy sector to monitor biofuel transport to and from transshipment sites and energy plants, it is not known to have been used for tracing bulk biofuels, i.e. a fuel that cannot be seen as a stand-alone entity. To demonstrate the potential of using RFID technology to trace bulk fuel transportation, three tests were performed. RFID tags were placed together with biomass pellets before being conveyed through a distribution chain, from pellet producer to combustion plant. The two first tests were large-scale trials to investigate if specific RFID tags could be correlated to a specific fuel when fed into the furnace. The third test was performed to see how RFID tags distributed over time in a logistics chain. The results showed that it is possible to trace a bulk biofuel flow using RFID technology, from production site to furnace, although care must be taken to optimize the method, such as using an appropriate number of tags.

No description available.

A critical process phenomenon in fluidized bed combustion and gasification is the bed particle layer formation which might be problematic in cases where it instigates bed agglomeration and bed material deposition or could improve the process performance in cases where it has a positive effect on tar reduction in biomass gasification. The interactions between ash forming matter for a wide variety of wood-derived fuels with different types of bed materials in fluidized bed combustion and gasification have been profusely studied, and the underlying mechanism of bed particle layer formation has been suggested. Howbeit, the influence of bed material’s surface properties on bed layer characteristics has not been elaborated in the literature. In this thesis, the effect of surface morphology on the formation of bed particle layers and crack layers has been investigated for different bed material types in combustion and gasification of woody biomass. Samples were selected from different full-scale and bench-scale conversion units at different ages from the start-up to investigate the development of the bed layer at different surface morphologies over the bed particle. Natural sand samples (consisting mainly of quartz and K-feldspar) were taken from a 30 MWth bubbling fluidized bed (BFB30) combustion unit and a 90 MWth circulating fluidized bed (CFB90) combustion unit, K-feldspar and olivine bed samples were taken from a dual fluidized bed (DFB) gasification unit (consisting of a 2-4 MWth bubbling fluidized bed gasifier and a 12 MWth circulating fluidized bed combustor), and ilmenite bed samples were taken from a 5 kWth bench scale bubbling fluidized bed (BFB5)combustion unit.  X-ray microtomography analysis (XMT) was utilized to inspect the bed layer distribution and determine surface morphology in 3D, including measurements of the bed particle layer thickness over the particle surface. Distribution of the crack layers inside the bed core was also observed through the XMT images. Moreover, scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) along with transmission electron microscopy (TEM) were employed to investigate the elemental compositional distribution and to support interpretation of XMT results.   The results revealed that for all types of bed materials, regardless of the conversion process, both inner and outer layers could be observed over the convex-shaped regions on the bed particle surfaces after some days, while the concave-shaped regions are mainly covered with a thin inner layer. Consequently, a thicker overall layer could be observed over the convex-shaped regions compared to the concave regions. Results from the combustion processes units show that K-feldspar bed particles retain a thinner overall layer compared to quartz when both are exposed to the same process condition and fuel ash composition. Moreover, almost no tendency for crack layer formation was observed in K-feldspar particles while up to 19% and 32% of the quartz bed particle could be engaged by the crack layers in bed samples taken from the BFB30 and CFB90, respectively. It was also observed that the crack layers are initiated from the concave-shaped regions on the bed surface where gaseous alkali can penetrate into the bed core through the inward cracks in the thin inner layer. In the BFB5 combustor, it was observed for the samples taken 6 and 12 hours after the start-up that a thin Fe-rich layer ascends over the convex areas over the ilmenite surface due to the outward migration of Fe from the bed particle core. Over time, this iron-rich layer is covered with a Ca-rich outer layer that obstructs further migration of the Fe through the convex areas. For the older particles (i.e., 30 and 42 hours from the start-up) high concentration of Fe was observed in the concaves and more porous areas inside the bed particle core.  Measurement of the average overall layer thickness for typical K-feldspar and olivine bed particles from the DFB gasifier showed that the latter exhibits thinner overall bed layer thickness. The elemental composition of the bed layer over the concave and convex regions was observed to be different for both bed materials. A slightly higher Fe concentration was observed over the convex areas on olivine. A similar trend was likewise noticed for Mn on both bed types.

Recently, CO2 electrochemical reduction (CO2R) has gained popularity, to cope with the strict environmental rules on greenhouse gas emissions, and to convert CO2 to value-added chemicals/fuels. Ionic liquids (ILs) have been considered as potential media for CO2R owing to their multi-functions in enhancing CO2R solubility and improving CO2R reaction rate and product selectivity. To date, there have been many studies related to CO2R in IL-based systems, which primarily focused on fundamental research to offer findings about CO2R performance and reaction mechanisms, and one article focused on evaluating the economic potential of the stand-alone CO2R process without considering the upstream process or integrating into other processes. In fact, the integration of CO2R with upstream or other production processes will make the evaluation more practically significant, and thus deeper knowledge about the viability of the integrated CO2R process is needed, but relevant work is still lacking. Meanwhile, how to further improve the performance of CO2R is another concern. The goal of this work is to perform systematic studies on techno-economic assessment of the integrated CO2R process and experimental research for producing methanol (CH3OH) with ILsas electrolytes as the focus, since CH3OH is an important solvent, energy and hydrogen carrier, and feedstock. In the first part, an intensive literature survey was conducted to summarize the research progress, identify the state-of-the-art and provide the research gap for CO2R in the IL-based systems. It shows that the multi-functions as CO2 absorbents, reaction media, and co-catalysts give ILs a distinctive boosting effect on the CO2R performance. But now the research mainly focused on lab-scale experimental studies, while the viability of this technique on a large scale is unclear. In the second part, stand-alone CO2R producing CH3OH with IL as the absorbent and electrolyte was studied and then further integrated with biomass gasification. The economic feasibility and environmental impact were investigated and compared, under current and future conditions. Stand-alone CO2R process shows high total production cost (TPC) due to the high electrolyzer and electricity costs. The TPC could reduce from 1.44 to 1.02 €/kg-CH3OH under the current conditions after integration. Additionally, based on the analysis, electricity for CO2R is the main part of energy usage and dominates the CO2 emission of the integrated process. In the third part, techno-economic analysis of the integrated processes that combined CO2R in IL to produce CO, syngas, and CH3OH with biomass gasification for producing CH3OH was performed and contrasted with stand-alone biomass gasification and CO2R processes. The process that integrated with CO2R to CO was identified as the optimal pathway with the lowest TPC of 0.38 €/kg-CH3OH under the current condition. Sensitivity analysis confirmed that electricity and H2 prices are two key parameters influencing the TPC of the process, which is combined with CO2R to CO followed by hydrogenation to CH3OH; while for the integrated processes with CO2R to syngas and CH3OH, simultaneously reducing stack and electricity prices as well as improving CO2R performance are significant to make these processes viable in the future. In the fourth part, preliminary experimental research on CO2R to CH3OH with various catalysts in IL-based electrolytes was conducted to evaluate the influence of catalysts and ILs on the CO2R performance. It was found that CO2R to CH3OH by using copper-deposited nickel foam (CuNi) showed the optimal performance with current density and Faradic efficiency of CH3OH of 14 mA/cm2 and 46.31% under -1.7 V vs Ag/Ag+, respectively.

No description available.