Avdelningen Marina System på Kungliga Tekniska Högskolan har designat och konstruerat en autonom undervattensfarkost (AUV). I dagsläget drivs farkosten drivs av ett litiumpolymerbatteri. Ett bränslecellssystem bestående utav PEM-bränslecellsstackar (Polymerelektrolytbränslecell), metallhydrid och trycksatt syrgas har designats för att byta ut det befintliga litiumpolymerbatteriet. För att få ett säkert system är det utrustat med vätgassensor, trycksensor, voltmätare samt temperatursensor. Eftersom både syrgas och vätgas måste medföras i farkosten, jämfört med landgående fordon som kan utnyttja syret från omgivande atmosfär, har olika bränslelagringsmetoder undersökts. För att lagra syrgas har trycksatt gas valts, denna lagras i en tank gjord av kolfiber och ett har ett tryck på 300 bar. Vätgasen väljs att lagras i en FeTi-metallhydrid på grund av dess volymmässiga fördel. Metallhydrid är en volymeffektiv men viktineffektiv lagringsmetod, vilket gör att den är perfekt till en undervattensfarkost. Metallhydriden förvaras i en tank gjord av aluminium. Eftersom bränslecellerna producerar vatten har olika sätt att fånga upp detta undersökts. Regenerad cellulosa (disktrasa) har hög absorptionsförmåga och har därför valts för systemet. De bränslecellesstackar som införskaffades har testats med hjälp av programvaran Labview. De presterade något under vad tillverkaren hävdade, något som antas bero på effektbehov hos kontroller och fläktar. Olika driftbetingelser har undersökts för att kunna använda bränslecellsstackarnas fulla potential. Det slutgiltiga systemet får ej plats i farkosten. En teoretisk studie för när bränsleceller blir mer volymeffektiva än batterier visar att för ett helt optimerat system går gränsen vid 3 liter, vilket motsvarar att 822 normalliter vätgas måste tas med. I framtiden skulle en kemisk lagringsmetod av syrgas vara att föredra, exempelvis väteperoxid. Metallhydrid är ett bra sätt att lagra vätgas men tankmaterialet skulle kunna vara exempelvis rostfritt stål istället för aluminium så att tanken blir mer volymeffektiv på grund av den högre brottgränsen hos stålet. Ett syrgasflöde till bränslecellen istället för ut i farkostens atmosfär skulle kunna öka verkningsgraden och därmed räckvidden.

Material degradation and a decrease of fuel quality are common phenomena when storing biomass. A magnitude of 7.8% has been reported to degrade over five months when storing spruce wood chips in the winter in Central Europe. This thesis presents a theoretical study of biomass storage. It includes investigations of bio-chemical, chemical and physical processes that occur during storage of chipped woody biomass. These processes lead to degradation caused by micro-activity, chemical oxidation reactions and physical transformation of water. Micro-activity was modeled with Monod kinetics which are Michaelis-Menten type of expressions. The rate expressions were complemented with dependency functions describing the impact of oxygen, moisture and temperature. The woody biomass was divided into three fractions. These fractions represent how hard different components of the wood are to degrade by microorganisms. Chemical oxidation was modeled as a first order rate expression with respect to the active components of the wood. Two different cases have been simulated during the project. Firstly, an isolated system with an initial oxygen concentration of air was considered. This case displayed a temperature increase of approximately 2˚C and a material degradation less than 1%. The second case considered an isolated system with an endless depot of oxygen. This case resulted in degradation losses around 0.45-0.95% in the temperature range between 65-80˚C during approximately 300 days of storage. The temperature increased slowly due to chemical oxidation.

Global carbon emissions are higher than ever before and in the last decade of 21st century, focus has shifted on reducing these emissions in various ways possible. Carbon capture, utilization and storage (CCUS) has been identified as one of the important ways to reduce carbon emissions and meet climate targets. For a long time, Sweden has promoted the use of biomass as fuel for heat and power generation which has enabled it to meet its climate targets earlier than projected. Now, major Swedish energy companies are looking into coupling exiting biomass fired heat and power plants with CCUS. This opens up the possibility of attaining negative emissions, also known as Bio Energy Carbon Capture and Storage (BECCS). With the right policy framework in place, BECCS can be a major boon and help Sweden attaining net zero carbon emissions. As a contribution in meeting net zero targets, this thesis is aimed to evaluate the installation of a carbon capture plant to abate flue gas emissions from District heating facility in Jordbro which is a ~70 MW (fuel) CHP plant running on biomass.  Among the available carbon capture technologies, Calcium oxide-based carbon capture has been expected to show great promise due to its lower environmental impacts and possibility to extract high quality energy when installed. Hence a concept system for integration calcium looping at Jordbro has been developed through the use of modeling tools like ASPEN. A techno economic assessment was needed to be performed to give conclusive results on the overall viability of the process. Further, key process indicators like energy penalty, plant footprint and cost of capture per tonne of CO2 were identified for making the final evaluation. Finally, through a strategic collaboration with SaltX, major process improvements were introduced and applied to the modeled process.  It was concluded that with the current average flowrates at Jordbro it was possible to capture 154,000 tonnes of CO2 annually. The required amount of energy input to the calciner is 48MW (7.29 MW/kg-CO2 captured) which is one of the major findings of this study. Even though a significant amount of heat is recovered, the main boiler is not capable of producing heat over 900 οC and additional biomass needs to be combusted, leading to an additional CO2 emission of about 125 000 tonnes annually. Considering an optimal integration, the energy penalties became 6.25 %.  However, the plant footprint increased substantially due to requirement for burning additional biomass in the regeneration reactor and addition of several auxiliary units that come along with calcium-based carbon capture. Further, the total capital investment for this project is 1,219 MSEK with reactor costs being most capital intensive. Assuming a plant life of 25 years, the cost of capture per tonne of CO2 (excluding the costs for carbon transport and storage) was evaluated at 988 SEK, which is 58% higher than the reference Mono-ethanol amine based chemical absorption case. The innovative improvements from SaltX substantially reduced the plant footprint but capture costs did not reduce since material transport costs proved to be the major bottleneck.  Upon comparison of this technology with the amine-based technology it was found that Calcium oxide-based carbon capture would need further research and improvements to be more viable than amine-based carbon capture. Integration of thermal energy storage and process intensification can be the possible paths for further improvement.

Per- och Polyfluorerade alkylsubstanser (PFAS) är syntetiskt framställda organiska föreningar som har använts i stor utsträckning i konsument- och industriprodukter. PFAS-substanser besitter attraktiva egenskaper såsom resistans mot väta, fett, fläckar och är dessutom värmetåliga. De används i bland annat brandskum, smink, vattentäta kläder med ”andas-funktion”, möbler och non- stickstekpannor. Den senaste forskningen har dock visat att PFAS utgör en fara för levande organismer och miljön. Vissa PFAS-substanser har klassats som persistenta, bioackumulativa och toxisk (PBT), samt väldigt persistenta och väldigt bioaccumulativa (vPvB).Existerande forskning har fokuserat på beteendet hos PFAS i olika miljöer. Dock finns det en kunskapslucka när det gäller hur dessa PFAS-substanser beter sig under termiska behandlingsprocesser, samt förbränningsgraden i kommersiella förbränningsanläggningar vid temperaturerna 850–950 °C. I detta projekt undersöks därför nedbrytningsgraden av PFAS genom förbränning samt bildning av potentiellt farliga biprodukter efter förbränning. För att genomföra denna studie skulle förbränning av PFAS-haltigt avloppsslam i en pilotskalig bubblande fluidiserad bädd (BFB) genomföras. På grund av hinder utfördes experimenten i stället i en konventionell och simpel laboratorieugn. Dessutom genomfördes en litteraturstudie för att undersöka bildandet av potentiellt farliga biprodukter efter förbränning av PFAS. Denna studie har visat att termisk behandling genom förbränning är en effektiv metod för att behandla PFAS i avloppsslam med reduktion under kvantifieringsgränserna. Undersökning av potentiellt farliga biprodukter baserat på litteraturstudier har visat att kortkedjiga PFCAs var mest förekommande i aska, vätska och gasformiga rester efter termisk behandling. Några undersökningar tyder på att termisk behandling av PFAS-haltigt material möjligen resulterar i ozonnedbrytande ämnen. Utifrån den genomförde litteraturstudien i detta projekt saknas starka bevis för att kunna påstå att det bildas ozonnedbrytande ämnen under förbränning av PFAS. / Per- and polyfluoroalkyl substances (PFAS) are man-made organic compound widely used in consumer and industrial products. They exhibit attractive properties such as resistance to water, heat, and grease. Therefore, PFAS are used in fire foam, non-stick pans, water-resistant clothes, make-up, and furniture. Recent studies have revealed that PFAS substances can be harmful to humans, animals, and the environment. Some PFAS substances have, therefore, been classified as persistent, bioaccumulative, and toxic (PBT), and very persistent and very bioaccumulative (vPvB). This means that PFAS resists degradation, accumulates in living organisms and biota, and inherits toxic effects. In previous and current research, the focus has been on the behavior of PFAS in different environmental settings. However, there is a gap in research on how these PFAS substances behave during thermal treatment processes in commercial facilities at temperatures of 850-950 °C and how effective the thermal degradation is. This project investigates the effectivity of thermal degradation via combustion and the fate of PFAS post-combustion, focusing on the formation of potentially hazardous by-products. Therefore, the combustion of PFAS-containing sewage sludge in a bench- scale bubbling fluidized bed (BFB) was to be conducted to fulfill the objective of this study. Due to hindrances, the experiments were performed in a conventional furnace furnace instead. Also, a literature study was conducted to investigate the fate of PFAS after combustion. From this study, it was concluded that thermal treatment via combustion at temperatures 850 and 950 °C is an effective method to degrade PFAS in sewage sludge. Also, the literature study investigation revealed that persistent short-chain PFCAs were most abundant in the ash, liquid, and gaseous residues after thermal treatment. A few investigations indicate that thermal treatment of PFAS-containing matter possibly results in ozone-depleting compounds. Based on the conducted literature study, there is a lack of strong evidence that supports the claim of the formation of ozone- depleting compounds during combustion of PFAS.

Without a doubt, there is a consensus around the international community which suggests that our current way of life is unsustainable for a healthy planet, society and economy. One focal point that should be taken deeply into consideration is the steel industry as, globally, it accounts for 8% of global emissions. Thus, there is a dire need to incorporate drastic measures, if one wishes to reach net-zero emissions by 2050, in accordance with the Paris Agreement of 2015. Electric Arc Furnaces are seeing a rapid implementation in the steel industry. However, at 0.5 tonnes of CO2 emitted per tonne of liquid steel produced, this emissions rating is still significant considering the amount of steel being produced annually. Additionally, these furnaces emit off-gases which must be treated from the dust. This leaves operators with a conundrum as the dust content compromises the use of waste heat recovery boilers for energy recovery, due to constant breakdowns. Therefore, this study aims to analyse the feasibility of using bioenergy and carbon capture and utilisation (CCU) concepts to capitalise on the high off-gas energy and emissions content to remedy the dust issue, whilst producing higher value products. The proposed concept evaluates the effectiveness of using the off-gas as the energy carrier and feed-stock for a biogasificaiton unit. Three different cases based on different EAF off-gas compositions have been investigated. Case 1 suggested that the off-gas composition is very CO2-heavy, whichled to investigating the option of adopting a CO2 biogasification concept to directly use the CO2. Case 1 performed the best in terms of CO2 utilisation efficiency; being 0.293. The system energy utilisation also noted that 49.3% of the inlet streams energy was transferred to the desired product. On a broader picture, this means that around 11% of the total energy coming out of the EAF would be utilised in producing a value-added product in the form of syngas. This contrasts with allowing around 33% of the energy in the EAF either being completely dissipated to the environment or converting it into electricity via waste heat recovery. The following two cases, Case 2 and 3, indicate EAF off-gas composition containing 72% and 40% nitrogen respectively. For Cases 2 and 3, a steam biogasification process was integrated which did not yield positive results for CO2 utilisation, since is a more promising gasifying agent. In addition, significant energy from EAF off-gas is used in raising the temperature of steam to the design temperature of the gasifier. However, although the CO2 was not directly used in this part of the process, it allows for other opportunities of process integration, for example the reverse water-gas shift step.

Tillgång till rent dricksvatten är en mänsklig rättighet och en viktig del av ett hållbart samhälle. Därför är det viktigt att säkerställa tillgången till samt kvaliteten av dricksvattnet som produceras i Sveriges vattenverk och i vattenverk världen över. Därför har Livsmedelsverket, och andra internationella organisationer och myndigheter så som Europeiska unionen och Europeiska myndigheten för livsmedelssäkerhet, infört lagstiftning och rekommendationer för att säkerställa produktionen av ett hälsosamt dricksvatten. I samband med Norrvattens utbyggnationer av deras vattenverk Görvälnverket önskas bättre rening av högfluorerade ämnen, även kallade PFAS-ämnen, för att säkerställa uppfyllandet av ny lagstiftning som träder i kraft år 2026. Denna rapport undersöker därför hur olika adsorptionsmaterial reducerar mängden PFAS-ämnen i vattnet genom försök på kolfilter i pilotskala. Utöver rening av PFAS-ämnen undersöks även rening av löst organiskt kol, ultraviolett absorption vid 254 nm samt lukt. Denna studie fann att uppehållstiden i kolfiltret inte hade någon större effekt på reduktionen av PFAS-ämnen och löst organiskt kol för biologiskt aktivt kol. Således, en stor ökning i uppehållstid gav endast en liten ökning av reduktion av dessa ämnen. Däremot visade uppehållstiden ha en större effekt på ultraviolett absorption vid 254 nm. När det gäller reduktion av PFAS-ämnen gav granulerat aktivt kol en större reduktion jämfört med biologiskt aktivt kol. Detsamma gällde reduktion av löst organiskt kol och ultraviolett absorption vid 254 nm. Högre halter av löst organiskt kol i inkommande vatten minskade reduktionen av PFAS. Samma trend kunde ses för ultraviolett absorption vid 254 nm, där högre värden i inkommande vatten gav en minskad reduktion av PFAS. Vad gäller lukt påvisades lukt i endast ett prov från kolfilter-piloten. I framtiden bör beslut tas angående vilket adsorptionsmaterial som ska användas i Norrvattens nya vattenverk. Man bör också dimensionera kolfilter för det nya vattenverket samt bestämma deras uppehållstid, hur ofta backspolning skall genomföras samt hur ofta adsorptionsmaterialet bör bytas ut. / Access to clean drinking water is a human right and essential to a sustainable society. Therefore, it is vital to ensure the access to and quality of the drinking water produced in the Swedish drinking water treatment plants and other drinking water treatment plants around the world. Thus, the Swedish National Food Agency, and other international organizations and authorities such as the European Union and the European Food Safety Authority, have introduced legislation and recommendations to ensure the production of healthy drinking water. As Norrvatten plan on expanding their drinking water treatment plant Görvälnverket, they wish to have better treatment of per- and polyfluoroalkyl substances, also called PFAS substances, to ensure the fulfillment of new legislation that will be implemented by 2026. Therefore, this report investigates how different adsorption materials reduce the concentration of PFAS substances in the water through experimenting with pilot scaled carbon filters. Beyond PFAS substances, this report also examined the treatment of dissolved organic carbon, ultraviolet absorption at 254 nm, and odor. This study found that the carbon filter's empty bed contact time did not significantly affect the reduction of PFAS-substances and dissolved organic carbon when it comes to biological activated carbon. Thus, a significant increase in the empty bed contact time only slightly increased the removal of these substances. However, this study showed that the empty bed contact time significantly affects the ultraviolet adsorption at 254 nm. Regarding the reduction of PFAS substances, granular activated carbon gave a more significant decrease compared to biological activated carbon. This trend was also seen in the reduction of dissolved organic carbon and ultraviolet absorption at 254 nm. Higher concentrations of dissolved organic carbon in the incoming water gave a lower decrease in PFAS reduction. Higher values of ultraviolet absorption at 254 nm in the incoming water also decreased the PFAS reduction. When it comes to odor, there was only one sample from the carbon filter pilot plant where an odor was detected. In the future, there needs to be a decision on what type of adsorption material to use in Norrvatten's future drinking water treatment plant. Dimensioning of the carbon filters for the new drinking water treatment plant should also be made, as well as for deciding the empty bed contact time, how often backwashing should be performed and how often they should change the adsorption material.

Examensarbetets syfte var att undersöka möjligheter till denitrifikation på sandfilter (SF) i industriell skala och hur det jämför sig med konventionella metoder för att uppnå denitrifikation och effekten av förändringen på processen vid Bromma reningsverk. Parametrar som undersöktes var rening av ammonium och nitrat, luftning, temperatur, pH, rening av fosfor, rening av organiskt material, rening av suspenderat material, förbigång av vatten vid SF och aktivslamanläggning (ASA), drifttider för SF:arna och total vattenbelastning på ASA och SF. Mätningarna gjordes med aCurve, ett online internt program vid Bromma reningsverk där onlineanalysatorer och driftsparametrar loggades. Nitrat- och nitritvärdena kontrollerades med standardiserade kyvettmetoder. Reningen av totalkväve uppnådde värden på 0,62-0,94 när denitrifikation på SF implementerades. Ökad igensättning av SF inträffade på grund av dosering av metanol på SF och tillväxt av mikroorganismer som orsakade en ökad risk för förbigång av SF, särskilt under hög vattenbelastning. Reningen av suspenderat material, organiskt material och fosfat påverkades inte av implementeringen av denitrifikation på SF. Resultaten av examensarbetet kan användas för att ytterligare optimera konventionella metoder för kväverening i reningsverk. För ytterligare studier kunde igensättning av SF vid användning av metanoldosering på sandfilter undersökas och metoderna kan jämföras i en kontrollerad miljö. / This thesis work aimed to investigate opportunities of denitrification on sand filters (SFs) at industrial scale and how it relates to conventional methods of achieving denitrification and its effect on the process at Bromma WWTP. Investigated parameters were ammonium and nitrate removal, oxygen and aeration, temperature, pH, phosphorus removal, removal of organic material, removal of suspended solids, water bypass of SF and activated sludge facility (ASF), operational times of the SFs and total water load on ASF and SF. The measurements were made with aCurve, an online internal program at Bromma WWTP where online analyzers and operational parameters were logged. The online values for nitrate and nitrite were controlled using standard cuvettes methods. Tot-N removal achieved values of 0.62-0.94 for denitrification on SF. Increased clogging of SFs occured due to dosage of methanol on SFs and growth of microorganisms causing an increased risk of SF bypass especially during high water load. Removal of TSS (total suspended solids), BOD7 and phosphate were unaffected by the implementation of denitrification on SFs.  The findings of the thesis can be used to further optimize conventional methods of nitrogen removal in WWTPs. For further studies the clogging of SFs when using methanol dosage on sand filters could be investigated as well as comparing the methods in a controlled environment.

The Paris Agreement has ambitious targets to limit the global warming below 1.5 °Cin the 21st century. This goal is reflected in the national climate targets, for example, Sweden aims to achieve net zero greenhouse gas emissions by 2045, and thereafter achieve negative emissions. One of the pivotal ways to achieve these goals is by applying the mature bioenergy with carbon capture and storage (BECCS) technology to large-scale industries that emit CO2. Around 6% of the global emissions arise from the pulp and paper industry making them one of the largest localized emitters of biogenic CO2. This makes them suitable for retrofitting BECCS technologies and post-combustion capture (PCC) is one among them. This study presents a techno-economic assessment of an absorption-based PCC unit in SCA Östrand pulp mill. Chemical absorption using MEA and chilled ammonia process (CAP) using NH3 as the solvent are considered in this study. For both the processes, mass and energy balances using Aspen HYSYS were done and validated against published data in literature. Heat integration by applying excess or waste heat from the mill is also considered in this work. CO2 capture from flue gas originating from various emission sources in the mill (recovery boiler, lime kiln and multi-fuel boiler) are considered in different combinations in the analysis. The main key performance indicator (KPI) evaluated in this work is the cost of CO2capture for all the different cases for both the MEA- and chilled NH3-based absorption processes. The minimum cost of CO2 capture for MEA-based absorption process was found to be in the range 37-41 €/tCO2 and for CAP, it was found to be in the range 73-81 €/tCO2. For MEA-based absorption process, the excess low pressure steam from the mill satisfies the steam demand in all the cases, except the one where CO2 is captured from all the three emission sources. For CAP, sufficient excess low pressure steam is present in the mill for all the capture cases due to a lower reboiler duty compared to MEA-based absorption process. An optimal process configuration and capture scenario for the existing design conditions in the mill are derived and justified. A sensitivity analysis was carried out to find the associated bottlenecks from the breakdown of the cost of CO2 capture for each process. The overall BECCS cost is also sensitive to CO2 transport & storage costs. However, it is also clear that incentives for negative emissions will make BECCS an attractive solution for the pulp and paper industry.

High-temperature Co-electrolysis of H2O and CO2 in a solid-oxide electrolyser (Co-SOE) for syngas production is a high-efficiency renewable electricity conversion and storage method part of the Power-to-X technologies. Syngas, a mixture of H2, CO and CO2, is a critical building block to make several chemical and synthesis fuels. The thesis aimed to model the Co-electrolysis process in a steady-state process modelling tool called Aspen Plus. The model was designed at thermoneutral mode and four cases with electrolysis temperatures of 700 °C, 750 °C, 800 °C and 850°C. The results from the model were used to perform an economic assessment and check the feasibility of Co-SOE. The analysis included calculation of Net Present Value (NPV), Internal Rate of Return (IRR) and the Levelised cost of Syngas (LCOS). The LCOS from Co-SOE was compared to the benchmark technology of syngas production in a Reverse Water Gas Shift (RWGS) reactor. The H2 feed to the RWGS reactor was assumed to be obtained from a Proton Exchange Membrane Electrolyser(PEME). A sensitivity analysis was performed to check the effect of electricity price, electrolyser stack price, electrolyser lifetime, CO2 feed price, by-product O2 revenue and discount rate on the LCOS. The LCOS was calculated to be 0.697, 0.727, 0.752 and 0.783 €/kg at 700 °C, 750 °C, 800 °C and 850 °C, respectively, increased with temperature due to increased electricity consumption at thermoneutral mode. The average LCOS from Co-SOE was 18.5% cheaper than the benchmark technology due to the high investment in the PEME and low conversion efficiency of the RWGS process. There was a trade-off between LCOS and system efficiency due to the effect of internal methanation occurring on the cathode side of the SOE. 750 °C was found to be the optimum design temperature to minimise the LCOS and maximise the efficiency. LCOS was most sensitive to electricity price, followed by O2 revenue and discount rate, while other parameters were less significant. The thesis also discussed key challenges to overcome in the future development of the Co-SOE technology. Co-SOE was found to be a promising technology for green syngas production. However, challenges concerning low stack lifetime, high capital investment and high cost of electricity have yet to be overcome to demonstrate it at a commercial scale.

Medan världen undergår en klimatkris, nya sätt för att mildra den har undersökts till det korta och långa loppet. Koldioxid är ett ämne som uppmärksammats då stora mängder av den släpps ut till atmosfären på grund av förbränningsprocesser. Då detta sker, ett sätt för att mildra klimatomställningen är genom ”Carbon Capture and Storage”, CCS. Det finns redan metoder för att fånga och separera CO2, genom exempelvis roterande packade säng eller vattnade vägg kolumner. Dock har staplade disk centrifug inte undersökts. Denna rapport har undersökt och använt en staplad disk centrifug för just koldioxid separering, genom användning av vatten och NaOH-lösning som absorbenter. Några parametrar har varierats såsom koncentrationen på NaOH-lösningen, luftflödeshastighet och koldioxid koncentration. Resultaten visade att användning av en staplad disk centrifug separerade inte märkvärdiga mängder av CO2. Det hittades däremot förklaringar till detta och det var att den låga halten CO2, de begränsade mätinstrumenten och det experimentella uppställningen som ej gav tid för absorption att ske. / As the world is going through a climate crisis, ways to mitigate it in the short and long term have been investigated. Carbon dioxide is a molecule of importance due to the amounts that are freely emitted into the atmosphere because of combustion processes. Due to this, one way of many, to mitigate climate change is Carbon capture and storage, CCS. There are also consequently several ways to capture and separate CO2 in post combustion processes, such as the use of rotating packed beds or wetted wall columns, however the use of disc stack centrifuges has not been investigated for this application. This paper has investigated and used a disc stack centrifuge for this purpose, by using water and NaOH solution as aerosol absorbents. Some parameters have been varied such as NaOH concentration, air flow speed and carbon dioxide concentration.  Results had shown that the use of a disc stack centrifuge did not yield considerable CO2 separation, however, an explanation for this was found to be due to low CO2 concentration and limited measuring instruments as well as a setup that did not make it possible for absorbent and CO2 to fully react and be efficiently separated.