The food industry is increasingly concerned with operational sustainability and food waste reduction. In the United States, the tomato industry was worth $1 billion in 2020, and tomatoes are currently ranked second as the most consumed vegetable after potatoes. Tomato processors have striven to valorize pomace by-products, which contain seeds with valuable compounds such as 45% fiber, 30% oil, and 26% protein. The U.S. peach industry, which was worth $599 million in 2017, is also looking for alternative ways to utilize their seeds, made up of 52% oil. Both tomato and peach seeds are rich in bioactive compounds such as carotenoids and polyphenols, respectively. Meanwhile, global edible oil production is forecasted to reach 632 million tons in 2022, and there is increasing interest to produce specialty oils. Organic solvent extractions are commonly used to extract oils from various commodities in the food industry, but this method comes with some environmental concerns, such as toxicity and flammability. Enzyme-assisted aqueous extractions (EAEP) have been proposed as a green alternative to solvent extractions of oilseeds. However, research on the economic feasibility of this process has been limited. There is a need for a better understanding of the potential of EAEP and performing such analysis on peach and tomato seeds would be valuable based on the importance of these commodities in California and in the U.S. in general. To determine whether applying such a process to tomato and peach seeds would be valuable, data on oil yields from EAEP, quality of the extracted oils, and economics associated with EAEP is needed. The U.S. snack food industry was worth approximately $42 billion as of 2019, and this market continues to grow as an increasing number of people eat snacks as meal replacements. There is also growing consumer demand for natural and functional foods, which offer health benefits beyond basic nutritional value, such as reducing risk of disease. Therefore, this consumer landscape provides excellent opportunities for by-products from vegetable and fruit processing to be transformed into functional ingredients. With these key ideas in mind, the objectives of this research were 1) to determine the impact of various extraction factors on oil yields from EAEP of tomato and peach seeds; 2) to evaluate the effect of aqueous extractions on oil quality; 3) study whether these processing steps are economically feasible for industrial commercialization and 4) identify another potential use for tomato pomace as a functional ingredient in snack food application. Tomato and peach seeds were each isolated and ground into a flour, then analyzed for fiber, fat, protein, moisture, and ash content. The effects of pH (set to 3, 9, and sequential adjustment of 3 followed by 9), time (2–8 h), and addition of cellulase, protease, and 1:1 enzymatic cocktail at a concentration of 4% were evaluated during aqueous extractions of tomato oils. Peach oil extractions were evaluated for the same parameters except for time which was fixed at 2 h. The impact of the pH of aqueous extractions on the oxidative stability and nutritional composition of tomato and peach oils were also determined. Techno-economic analyses were conducted using Superpro software to estimate operational costs and profits from this process. To assess the value of tomato by-product as a functional ingredient, pomace flour was added to crisp snacks at usage levels of 0 and 7% (w/w flour basis). Crisp snacks were stored at ambient room temperature and frozen temperatures (-23 °C) for ten weeks. Proximate analyses on the crisp snacks were conducted. Sensory evaluation was performed over time using hedonic scoring surveys. For tomato seeds, the highest oil yield (41%) was obtained during 2 h extractions at pH 9, which were 68% higher than from 2 h extractions performed at pH 3. Enzyme addition was only beneficial during 8 h extractions of tomato seeds using 4% cellulase at pH 3, which led to 53% higher oil yield compared to the control performed in the same conditions without enzymes. Increasing incubation time from 2 to 8 h improved oil yields by 63% for cellulase extractions at pH 3 and 69% for protease extractions at pH 9. Peach oil yield of the controls at pH 9 (53%) and the yield obtained with protease extractions at pH 9 (45%) were approximately eight times higher than all extractions set to pH 3. Once extracted, some properties of the tomato and peach oils were determined. The pH of the aqueous extractions did not have a significant effect on quality parameters on both tomato and peach oils, except for polyphenol content, DPPH production, peroxide and TBARS values. Overall, both tomato and peach oils had peroxide and free fatty acid values comparable to other specialty oils, such as sunflower and sesame oils. From a techno-economic point of view, tomato oil production at flow rate of 1,752,000 kg pomace/yr garnered $13 million in profit (equivalent to $7.42/kg pomace) after a payback time of 1.6 years, which was more profitable than the industry’s current pomace disposal practice. Peach oil processing became profitable once the production scale reached 65,700,000 kg pits/yr, which led to $15.5 million in profit ($0.24/kg pits). Overall, production of tomato oil was more profitable than peach oil. When tomato pomace was added into crisp snacks at 7% concentration, fiber increased by 35.2% compared to the control. Moisture content and water activity for the control and pomace crisp snacks remained constant during room temperature and frozen storage for ten weeks. However, the addition of tomato pomace led to a bitter aftertaste of the crisp snacks and reduced overall liking scores by panelists compared to scores for the control crisp snacks. Overall, this research took multiple, innovative approaches to valorize tomato and peach seeds, while also studying the economic, environmental, and industrial implications of such approaches. It highlighted alternative, sustainable strategies of how tomato and peach by-products could be repurposed to reduce waste and make value-added food products.

Sewage sludge is a by-product of wastewater treatment that simultaneously gathers contaminants, valuable organic matter, and nutrients. The treatment of the increasing amount of sewage sludge is important from both pollution prevention and resource recovery perspectives as i) large shares of mineral phosphorus, listed as a critical raw material, terminate in the sewage sludge, and ii) energy recovery from sewage sludge can cover the energy-intensive demand of the treatment process. Previous research has identified sewage sludge combustion as a suitable treatment approach as it both addresses contaminant destruction and paves the way for efficient phosphorus recovery from the sewage sludge ash. The commercial development of this practice has, however, been slow. Therefore, this thesis aims to investigate the challenges in sustainable sewage sludge management, and to, in more detail, identify the economic viability of energy and phosphorus recovery from sewage sludge through combustion. The thesis’ aim is divided into two objectives addressed in three papers. First, to investigate how different aspects of sewage sludge management, such as contaminants, economic efficiency, technical aspects, and legislation, evolve and interact. This has been done by a review of sewage sludge management research over fifty years (Paper I). Second, to investigate the economic viability of simultaneous energy and phosphorus recovery from sewage sludge by comparing different technology and market scenarios. This has been done for i) new sewage sludge mono-/co-combustion plants (Paper II), and ii) the integration of treatment technologies, mainly anaerobic digestion, hydrothermal carbonization, and combustion, in an existing wastewater treatment plant (Paper III).  Results from the analysis of sewage sludge management research (Paper I) show a narrow-focused perspective that often excludes inseparable aspects such as combination of economic consideration and advanced extraction technology. The investment viability of a new mono-/co-combustion of sewage sludge (Paper II) is highly conditional on heat, electricity, and fertilizer price, and external financial support is often a crucial requirement. Sewage sludge co-combustion with potassium-rich biomasses improves sewage sludge quality and forms usable ash as fertilizer without further need for phosphorus recovery technology. In this case, the economic feasibility of the process is independent of usable ash revenue, which stimulates a competitive selling price for the ash, thereby improving the marketing of sludge-based fertilizer. Avoided disposal costs of sewage sludge for a retrofitted wastewater treatment plant by introducing hydrothermal carbonization (Paper III) shows good economic feasibility while recovering phosphorus. Integrating anaerobic digestion, hydrothermal carbonization, and combustion may also improve investment incentives by improving energy outputs and phosphorus recovery. The economic feasibility is contingent on product (hydrochar, heat, electricity) prices and sensitive to added equipment costs, and costs for sludge transportation and disposal.

Several CO2 transcritical booster systems in supermarkets use the potential of integrating geothermal storage, enabling subcooling during warm climate conditions as well as being a heat source during cold climate conditions. First of all, field measurements of one of these systems located in Sweden were analysed with particular focus on the heat-recovery performance. The best theoretical operational strategy was compared to the one really implemented and the differences in the annual energy usage were assessed through modelling. The results show that an alternative to the best theoretical operational strategy exists; heat can be extracted from the ground while low-temperature heat is rejected by the gas cooler. Such an alternative strategy has important technical advantages with a negligible increment of the energy usage. In the second part of this work, the benefits of geothermal subcooling were evaluated. Applying the BIN hours method, it was demonstrated that this system is expected to save on average roughly 5% of the total power consumption, in Stockholm’s climate. The models utilized for the winter and summer season were combined to find the relationship between geothermal storage size and annual energy savings. In this way, it was possible to calculate the present value of the operational savings for the study case. Furthermore, a general methodology for assessing the economic feasibility of this system solution is presented. Finally, several scenarios were investigated to produce parametric curves and to perform a sensitivity analysis. Comparing the results with the typical Swedish prices for boreholes, the cases where this system solution is economically justified were identified. These are supermarkets with a Heat Recovery Ratio (HRR) higher than the average. For examples, supermarkets supplying heat to the neighbouring buildings (considering the Stockholm’s climate, systems with an annual average HRR of at least 70%). Relying only on savings from subcooling was found to be not enough to justify a geothermal storage, a not-negligible amount of heat must be extracted in winter. Finally, some interesting concepts and alternatives to a geothermal integration are presented to point out relevant future work.

The objective of this thesis was to assess the market opportunities for two novel Carnot battery system solutions, one supplying power and low temperature heat as well as a system supplying medium temperature heat exclusively. To fulfill the objective, a methodology was developed and implemented to investigate the market potential, further two techno-economic models were developed and utilized to investigate the performance of such Carnot battery solutions. Based on the market review four industrial sectors were identified as most interesting and the geographical scope was confined to Europe. Further, case studies were developed to mimic two different sizes of manufacturing plants, a small and large, for the identified sectors. The cases were then implemented to the techno-economic analysis to compare the performance of a new Carnot battery system against the conventional energy solutions. The identified market offers a vast opportunity for incorporating Carnot battery solutions to meet the industrial sectors requirements, both from a technical and market size perspective. The market review combined with the techno-economic analysis indicates that the heat market is interesting as long as fuel, power grid costs and industrial operations are at the ideal level. For the Carnot battery system supplying both power and heat, it was found that yearly cost savings in the range of 10-15 % could be achieved for the identified market. The added value of incorporating heat generation and surplus power from PV had a strong effect on the business case. Through sensitivity analysis it was approximated that locations in central/south Europe with global horizontal irradiance (GHI) above 1500 kWh/m2 would benefit from the solution. For the Carnot battery system supplying medium temperature heat it was found that solutions would struggle with feasibility for the given market conditions. Through sensitivity it was found that locations with GHI higher than 2100 kWh/m2 would benefit from the solution. For both models it was found that the hybrid solution, Carnot battery combined with on-site PV, yields the most feasible solution for the end user, compared to charging the Carnot storage system from the power grid. Both models were sensitives to changes in energy cost for operating the old conventional system as well as operations times of the industries. The availability of space is a major constraint to implement Carnot battery solutions, as both the Carnot battery as well as PV plant require substantial space. It was found through literature and interviews that industries with close proximity to end customer and which faces pressure to decarbonize, may be most interesting to target, as for e.g. the Food and beverage sector. / Syftet med denna uppsats var att undersöka marknadspotentialen för två stycken Carnot batterisystem, ett system som generar både el och låg tempererad värme och ett som endast generar medel tempererad värme. För att uppnå målet så utvecklades och implementerades en metod för att undersöka marknadspotentialen, vidare så utvecklades och användes två tekno-ekonomiska modeller för att undersöka prestandan för de två Carnot lösningarna. Baserat på marknadsundersökningen så identifierades fyra industriella sektorer som mest intressanta och baserat på dem begränsades omfattningen av studien till Europa. Från marknadsgenomsökningen och de identifierade industriella sektorerna skapades två olika profiler för att representera en liten och stor industri för de identifierade sektorerna. Profilerna användes som utgångspunkt för den tekno-ekonomiska analysen för att jämföra prestandan hos ett nytt Carnot batterisystem mot konventionella energilösningar. Den identifierade marknaden erbjuder en stor möjlighet för att integrera Carnot batterilösningar för att möta industrisektorns krav, både ur ett tekniskt perspektiv och med tanke på marknadensstorleken. Marknadsundersökningen kombinerat med tekno-ekonomiskanalysen indikerar att värmemarknaden för industrier är intressant så länge bränsle- och elkostnader samt drifttiden är i rättnivå. Resultat från analysen tyder på att Carnot batterilösningar, som generar både el och värme, kan skapa energikostnadsbesparingar runt 10–15 % för den identifierade marknaden. Värdet av att addera kassaflöden från överskotts el från solcellerna samt värmegenerering har en stark påverkan på resultaten. Från en känslighetsanalys gick det att identifiera centrala/södra Europa som platser med tillräcklig solinstrålning (runt 1500 kWh/m2) för att dra nytta av ett Carnot batteri. För Carnot batterisystemet som endast producerar medel tempererad värme så skapas inga energikostandsbesparingar för slutanvändaren för den analyserade marknadsförutsättningarna. Genom en känslighetsanalys gick det att fastställa att hög solinstrålning krävs (över 2100 kWh/m2) för att slutanvändaren ska skapa några besparingar med systemet. För båda modellerna generade en hybridsystemlösning med både Carnot batteri samt lokal solcellsanläggning de bästa resultaten, jämfört med om systemet skulle laddas från elnätet. Båda modellerna är känsliga mot förändringar i energikostnader, värme eller el, för det konventionella systemet samt lägre drifttid. Vidare så är tillgänglig yta en annan restriktion som både kan hindra implementeringen av Carnot batteriet samt också solcellsanläggningen. Både litteraturstudien och de genomförda intervjuerna tyder på att industrier som har nära kontakt med slutkonsumenten och som har krav på att reducera sin miljöpåverkan, är en intressant användare av ett Carnot batterilösning, som exempelvis livsmedelsindustrin.

Many countries strengthen their commitments to reduce greenhouse gas emissions to limit climate change and meet the Paris Agreement (Masson-Delmotte et al., 2019). Commitments include achieving net-zero emissions or in some cases even negative emissions (Government offices of Sweden, 2020a; United Nations, 2021a). To achieve these goals, carbon dioxide capture, utilization, and storage (CCUS) is considered as an essential strategy. Carbon capture storage and utilization are recognized methods of reducing or avoiding greenhouse gas emissions (IEA, 2019a, 2020). However, the uncertainty regarding costs, financial incentives, and pricing is impeding adoption. Further information is needed for CCUS concepts both in respect to cost estimates and required market prices for CCUS, this to provide guidance for decision makers and market actors. In this report a study has investigated the economic feasibility of three CCUS concepts for a biogas facility. One CCS concept where CO2 was captured and liquefied on-site to be transported to a terminal for shipping and end storage injection. The CCS concept annual capacity was ~16 500 ton net stored CO2. Two CCU concepts were considered, where synthetic natural gas (SNG) was produced via biologic methanation with on-site produced hydrogen, both with annual production of ~88 GWh SNG. A techno-economic assessment (TEA) was carried out where the key cost-drivers were identified, and the economic feasibility assessed. With performance and cost estimates for each process step in the different considered concepts a model was built where a cash flow was created and a net present value (NPV) could be calculated. The study found transportation to be the most prominent cost driver for CCS where shipping and storage represented 57 % of the total cost of CO2 removal. The cost driver for CCU concepts was found to be hydrogen production, where the electricity for the electrolyser constituted 65 % of the total cost of produced SNG. None of the concepts were found economic feasible when the Swedish market was considered. The break-even price for CO2 removal in the CCS concept was found to be 151 €/ton, just above the assumed base value used in this study. As the voluntary market is still undeveloped it is difficult to know what price that could be expected, however, in discussion with market experts a range between 150-200 €/ton would not be unthinkable for the concept studied. For the CCU concepts to be economically feasible, the estimated minimum price levels for SNG were 184 and 193 €/MWh respectively. Comparing to the benchmark price of diesel of 125 €/MWh, both CCU concepts were concluded to be unfeasible. The sensitivity analysis showed that the CCU concepts were very sensitive to variations in electricity price. When the German fuel market was considered, all studied concepts yielded a positive business case. CCS was the only concept showing economic feasibility, while the CCU concepts remained unfeasible. In the German market a GHG reduction quota credit was accounted for which was valued higher than the carbon removal credits in the voluntary market. / Många länder stärker sina åtaganden att minska utsläppen av växthusgaser för att begränsa klimatförändringen och uppfylla Parisavtalet (Masson-Delmotte et al., 2019). I åtagandena ingår att uppnå nettonollutsläpp eller i vissa fall till och med negativa utsläpp (Regeringskansliet, 2020a; FN, 2021a). För att uppnå dessa mål anses avskiljning, nyttjande och lagring av koldioxid (CCUS) vara en viktig strategi. Avskiljning, lagring och utnyttjande av koldioxid är erkända metoder för att minska eller undvika utsläpp av växthusgaser (IEA, 2019a, 2020). Osäkerheten kring kostnader, ekonomiska incitament och prissättning hindrar dock införandet. Ytterligare information behövs för CCUS-koncept både när det gäller kostnadsberäkningar och nödvändiga marknadspriser för CCUS, detta för att ge vägledning för beslutsfattare och marknadsaktörer. I den här rapporten undersöks den ekonomiska genomförbarheten av tre CCUS-koncept för en biogasanläggning. Ett CCS-koncept där koldioxid avskiljs och kondenseras på plats för att sedan transporteras till en terminal för slutlig sjöfrakt och injektion i geologiskt lager. Den årliga kapaciteten för CCS-konceptet var ~16 500 ton nettolagrad koldioxid. Två CCU-koncept övervägdes, där syntetisk natur gas (SNG) producerades genom biologisk metanisering med vätgas producerad på plats, där båda koncepten hade en årlig produktion av ~88 GWh SNG. En tekno-ekonomisk undersökning genomfördes där de viktigaste kostnadsdrivande faktorerna identifierades och den ekonomiska genomförbarheten bedömdes. Med hjälp av prestanda- och kostnadsberäkningar för varje processteg i de olika tänkta koncepten byggdes en modell där ett kassaflöde skapades och ett netto-nuvärde kunde beräknas. I studien konstaterades att transport var den mest framträdande kostnadsdrivande faktorn för CCS, där sjöfrakt och lagring stod för 57 % av den totala kostnaden för koldioxidavskiljning. Kostnadsdrivande för CCU-konceptet var vätgasproduktionen, där el till elektrolysen utgjorde 65 % av den totala kostnaden för producerad SNG. Inget av koncepten befanns vara ekonomiskt genomförbart när den svenska marknaden beaktades. Nollpunktspriset för koldioxidavskiljning i CCS-konceptet fanns vara 151 euro/ton, vilket är strax över det antagna basvärde som används i denna studie. Eftersom den frivilliga marknaden fortfarande är outvecklad är det svårt att veta vilket pris som kan förväntas, men i diskussioner med marknadsexperter skulle ett prisintervall på 150-200 €/ton inte vara otänkbart för det studerade konceptet. För att CCU-koncepten ska vara ekonomiskt genomförbara var de uppskattade minimipriserna för SNG 184 respektive 193 €/MWh. Jämfört med referenspriset för diesel på 125 €/MWh, ansågs båda CCU-koncepten vara ekonomiskt ogenomförbara. Känslighetsanalysen visade att CCU-koncepten var mycket känsliga för variationer i elpriset. När den tyska bränslemarknaden beaktades gav alla studerade koncept ett positivt netto-nuvärde. CCS konceptet var det enda konceptet som ansågs vara ekonomiskt genomförbart, medan CCU-koncepten förblev ogenomförbara. På den tyska marknaden räknades en kvot för minskning av växthusgasutsläpp in, som värderades högre än de krediter för avskiljning av koldioxid som fanns på den frivilliga marknaden.

Grape pomace (GP) is one of the most abundant and underutilized fruit-derived wastes. GP is generated during winemaking, occupying over 60% of the total solid winery wastes. GP may cause serious environmental problems if it is not properly handled. On the other hand, it is rich in valuable compounds that are worthy of recovery. Although research has been working on GP upgrading, the utilizations are limited to producing a single product (e.g., grape seeds oil or polyphenol powders), which leads to large volumes of secondary wastes left. Therefore, the goal of this study is to develop an integrated process for the comprehensive utilization of GP by the production of multiple value-added products and evaluate its economic feasibility at a commercial scale. First, the chemical composition of different industrial GPs was analyzed to lay the foundation for the process design. Based on the analyzed chemical composition, an integrated process was developed to produce grape oil, polyphenols, and biofuels from GP. In this process, GP was extracted by hexane to produce oil, followed by aqueous ethanol solution extraction to obtain polyphenols. The solid residue rich in structural carbohydrates was then pretreated by alkali to partially remove lignin and enzymatically hydrolyzed to produce monomer sugars. The produced sugars were used as feedstock to produce acetone, butanol and ethanol (ABE) through anaerobic fermentation. Under the optimized conditions, the process was able to produce 71.9 g crude oil, 322.8 g crude polyphenols (equivalent to 72.6 g gallic acid), and 20.7 g ABE from 1 kg dry GP. Besides the valuable products, the process co-generated a large amount (50% of input GP biomass) of secondary waste, which is rich in lignin. Therefore, we further converted the secondary waste to biochars and evaluated their potential application in water purification by removing lead (Pb) from contaminated water. Based on the results, the produced biochar showed a high Pb adsorption ability (134 mg/g), with 66.5% of lead removal achieved within the first 30 min. Experimental and modeling results indicated that both physisorption and chemisorption mechanisms were involved in the Pb adsorption of the biochar. Finally, techno-economic analysis was conducted to evaluate the economic feasibility of the integrated processing of GP into oil, polyphenols, and biochar at an industrial scale. The results showed that compared with generating of single product or dual products, the integrated process aiming to produce multiple products had the best economic performance with the net present value (NPV), internal rate of return (IRR), and payback period of $135.0 million, 47.5%, and 1.8 years, respectively. Sensitivity analysis showed that plant capacity and polyphenol selling price had major impacts on process economics. Therefore, a suggestion for implementing this integrated process is to invest more in the polyphenol production and purification process to generate high-quality polyphenols with a high selling price and running the plant with a large capacity. Overall, we explored a novel integrated process that aims to produce multiple value-added products to increase the economic gain for the wine industry, and at the same time, potentially reduce the environmental burdens caused by GP disposal. / Doctor of Philosophy / During wine making, a large amount of solid waste is generated, and the major one is called grape pomace (GP). GP is mainly consisted of grape skins, seeds, and some stems. Normally, GP is discarded as waste; however, if it is not handled properly, GP may cause serious damages to the environment such as contaminating soil and stream water. On the other hand, GP has valuable compounds that could be recovered for other applications. Previous researchers used GP to produce a single product, which still leads to a large amount of components not used. Therefore, the aim of the current study is to design a process to comprehensively utilize GP to produce multiple value-added products. The developed process can produce grape seed oil, polyphenols, and biofuels from GP. The solid residue generated from the designed process was further converted into biochar, which can be used as an excellent adsorbent to remove lead (Pb) from contaminated water. Based on the economic model results, the developed process to convert GP into grape seed oil, polyphenols, and biochar could be a promising investment at an industrial scale. Generally speaking, various valuable products were obtained from low value GP waste, which could not only reduce the potential environmental problems caused by waste disposal, but also provide different value-added products for food, pharmacy, chemical, and energy industries.

Brewer's spent grain (BSG) is the major byproduct generated by the brewing industry, which contains 14–30% protein and 50–70% of fiber. Currently, BSG is predominantly used as low-value cattle feed or buried in landfills, which is a considerable loss of valuable resources, leading to economic loss and environmental problems. Although research has been done on BSG valorization, the studies are limited to producing a single product (e.g., polyphenols, ethanol, or active carbon) and without further utilization of the produced products. Besides, the economic information available about the production of value-added products from BSG is insufficient. The overall goal of this research is to develop an integrated process to convert BSG into value-added protein-rich feedstuff and cellulose absorbent. The objectives of the research detailed here were to 1) develop a process to simultaneously produce protein-rich (PP) and fiber-rich products (FP) from BSG, 2) assess the replacement of fishmeal with PP in shrimp feed, 3) evaluate the economics of the overall process of PP production at a commercial scale, and 4) explore the potential use of cellulose adsorbent obtained from the FP in removing heavy metals from contaminated water. To attain these objectives, BSG was first subjected to a wet fractionation process to produce PP and FP using different chemical/biological treatments, where the effects of sodium hydroxide, sodium bisulfite, and a protease (Alcalase) at different concentrations were investigated. Under the optimized conditions, the produced PP contained 46% protein and less than 1% fiber. The effectiveness of using PP to replace fishmeal at increasing levels (10–70%) was then evaluated by performing shrimp feeding trials. The results showed that up to 50% of fishmeal in shrimp feed can be replaced by PP without affecting shrimp growth and feed utilization. Moving forward, a techno-economic analysis was conducted to evaluate the economic feasibility of the production of PP. The experimental conditions and results were input into the process simulation model for determining the mass and energy flows. For a processing plant with a capacity of 590 t wet BSG per day, the minimum selling price of PP to achieve a 5% return was determined to be $1044/t, lower than the price of fishmeal, indicating that the use of PP to replace fishmeal in shrimp feed could potentially reduce shrimp farming cost. The utilization of FP will further improve the economic feasibility of the fractionation process. FP was sequentially treated by dilute acid, alkali, and bleach to produce purified cellulose fibers, which were then modified by 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) oxidation to produce a cellulose adsorbent. The feasibility of the adsorbent in removing heavy metals (especially lead and manganese) from contaminated water was then investigated. Based on the results, the produced cellulose adsorbent showed high adsorption capacities for lead (272.5 mg/g) and manganese (52.9 mg/g). Overall, this study demonstrated that BSG can be upcycled into multiple value-added products via an integrated process. The outcomes of this study not only provide a low-cost and sustainable protein source to the aquaculture industry, and provide a novel adsorbent for the water treatment industry, but also offer alternative ways for the brewing industry to manage BSG. / Doctor of Philosophy / Brewer's spent grain (BSG) is the major byproduct generated by the brewing industry. Currently, BSG is predominantly used as low-value cattle feed or buried in landfills due to its high fiber and low protein contents, which is a considerable loss of valuable resources. Besides, raw BSG contains other nutrients and high water content, the inappropriate management of BSG may introduce environmental concerns. Though technologies have been investigated to valorize BSG by extracting protein from it, the process scaled-up is limited by the high drying costs of wet BSG, heavy chemical consumptions, and a large amount of fiber residue. The overall goal of this research is to develop an integrated process to convert BSG into value-added protein-rich feedstuff and cellulose absorbent. In this study, we developed and optimized a process to produce protein and fiber products from wet BSG. The protein content of the produced protein product was doubled and the fiber content was reduced significantly compared with the raw BSG, which lighted the use of the protein product as an alternative to fishmeal. Fishmeal is an expensive aquafeed ingredient, the aquaculture industry is looking for alternatives to replace it. Herein, we investigated the effectiveness of the protein product as an alternative to fishmeal by conducting shrimp trials. A further economic analysis was conducted to evaluate the economic feasibility of the proposed process for protein and fiber production from BSG. In addition, the fiber product was used for producing a cellulose adsorbent to remove heavy metals from contaminated water. Overall, this study demonstrated that BSG can be upcycled into multiple value-added products via an integrated process. The outcomes of this study not only provide a low-cost and sustainable protein source to the aquaculture industry, and provide a novel adsorbent for the water treatment industry, but also provide alternative ways for the brewing industry to manage BSG.

Photovoltaic technology is among the best tools our civilization has to reduce the emissions of greenhouse gas that are currently altering the atmosphere composition of our planet. The idea of using photovoltaic surfaces on the envelope of buildings is called with the acronym of BIPV (building integrated photovoltaics), it offers the advantage of producing energy in the same location of the demand for electricity. Furthermore, BIPV allows to save monetary and environmental costs by substituting building materials with photovoltaic collectors. As every technology,BIPV follows an adoption pattern that is bringing it from a very limited niche product to a pervasive one. Nevertheless, the adoption rate of BIPV appears to be slow, and the industry has offered little opportunities of business for its stakeholders over the last 20 years. There are multiple reasons for this sluggish growth, and a considerable body of scientific literature has offered potential solutions to the problem. The building industry is notoriously slow in picking up innovation, furthermore the BIPV material needs to compete with much more mature, versatile and often cheaper cladding technologies and materials. Numerous research endeavors are focusing on the development of new BIPV claddings to have diversified colors, dimensions, shapes and other properties. The argument is that the technology is not mature and thus cannot be adopted by the bulk of architects and designers. Unfortunately, the premium characteristics of these new materials often come with a higher price and a reduced efficiency, thus reducing their market potential. Other research endeavors, among which this thesis, are focusing on the design of buildings: trying to include the use of photovoltaics into the architectural practice through education and software development. Numerous software has been developed over the last 20 years with the aim of calculating the productivity or the economic outlook of a BIPV system. The main difference between the existing software and the method presented here lies in the following fact: previously, the capacity and positions of a BIPV system are required as input for the calculation of performance, in this method the capacity and positions of the BIPV system are given as the output of an optimization process. A designer whois skeptical or disengaged about the use of BIPV could be induced to avoid its use entirely by the discouraging simulation results given by the lack of a techno-economic optimal configuration. Conversely, a designer who opt for a premium architectural PV material would, thank to the methodology shown, be able to assess the impact its unitary cost has on the optimal BIPV capacity of the building. Ultimately, the method presented provides new knowledge to the designer regarding the use of BIPV on his building, hopefully this can facilitate the spread of BIPV technology. The method described was translated into a software tool to find the best positions and number of PV surfaces over the envelope of the building and the best associated battery capacity. The tool is based on the combined use of ray-tracing (for irradiation calculation) and optimization algorithms, its use led to the following conclusions: • BIPV is profitable under a wide range of assumptions if installedin the correct capacities • 20% of the residential electric demand can easily be covered by PV without the need for electric storage and in a profitable way • Despite an interesting rate of return of the investment, the payback time was generally found to be long (over 10 years) • More research is needed to assess the risk on the investment on BIPV: if found to be low, future financial mechanisms could increase its spread despite the long payback time • The optimal capacity in energy terms (i.e. the energy consumed on-site minus the energy used to produce a BIPV system) tends to be far higher than any techno-economic optimum • The specific equivalent CO2 emissions for an NPV optimal system have been found to be between 70 and 123 [kg CO2 eq/MWh] under the range of assumptions applied • The installation of optimal BIPV capacity could change the overall residential CO2 emission of -12%, +13%, -29% in England, France and Greece respectively • despite the non optimal placement of a BIPV system compared to a ground mounted, south oriented one, and despite the noncontemporaneity of production and consumption, the BIPV still easily outperforms the energy mix of most countries when optimized for maximum NPV. • The part of the building envelope that have the most annual irradiation (i.e. the roof) should not necessarily host the entirety of the system as other facades might have an advantage in terms of matching production and consumption times. • when different scenarios are made in terms of techno-economic input parameters (e.g. degradation of the system, future costs of maintenance, future variation of electricity price etc..) larger capacities are optimal for optimistic outlooks and vice-versa • the optimal capacity for the expected scenario (i.e. the 50 % ile) can be considered robust as it performs close to the optimum in optimistic and pessimistic scenarios alike. • a reduction in price for the electric storage appears to have a positive effect on the optimal capacity of PV installed for the case study considered. • when a group of households is optimized separately V.S. aggregated together, the aggregation have a huge positive effect on all KPIs of the resulting system: in the NPV optimal system of a case study examined the installed capacity ( +118%), the NPV ( +262.2%) and the self-sufficiency( +51%) improved thanks to aggregation.

Brayton cycles are open gas turbine cycles extensively used in aviation and industrial applications because of their advantageous volume and weight characteristics. With the bulk of waste exhaust heat and engine emissions associated, there is need to be mindful of environmentally-friendliness of these engine cycles, not compromising good technical performance, and economic viability. This research considers assessment of power plants in helicopters, and aeroderivative industrial gas turbines combined-heat-and-power (ADIGT-CHP) in the petrochemical industry. Thus, it consists of two parts: part A focuses on performance analysis of helicopter gas turbines, while part B entails technoeconomic and environmental risk assessment of ADIGT-CHP in the petrochemical industry. The investigation encompasses comparative assessment of simple cycle (SC) and advanced gas turbine cycle options including the component behaviours and the environmental and economic analysis of the systems. The advanced cycles considered include: recuperated (RC), intercooled (IC), intercooled-recuperated (ICR), and low pressure compressor zero-staged (LPC-ZS), cycles. The helicopter engines are analysed and subsequently converted to small-scale ADIGT engines. Also, modelling combined-heat-and-power (CHP) performances of small-scale (SS), and large-scale (LS) ADIGT engines is implemented. More importantly, a large part of the research is devoted to developing a techno-economic model for assessing, predicting, and comparing viability of simple and advanced cycle ADIGT-CHP in the petrochemical industry in terms of net present value (NPV), internal rate of return (IRR), and simple payback period (SPBP). The techno-economic performances of the ADIGT-CHP cycles are measured against the conventional case of grid power plus on-site boiler. Besides, risk and sensitivity of NPV with respect to uncertain changes in grid electricity cost, gas fuel cost, emission cost, and electricity export tariff, are investigated. Two case studies underlie the development of the techno-economic model. One case study demonstrates the application of the model for large-scale (LS) ADIGT-CHP, and the other for small-scale (SS) ADIGT-CHP, all in the petrochemical industry. By so doing, techno-economic and environmental risk analysis framework (a multi-disciplinary preliminary design assessment tool comprising performance, emissions, economic, and risk modules) is adapted to ADIGT-CHP in the petrochemical industry, which is the aim of this research. The investigation and results led to the conclusions that advanced cycle helicopter and ADIGT engines exhibit higher thermal efficiencies than simple cycle, and that savings exist in operational costs of ADIGT-CHP above the conventional case. Thus, for both SS ADIGT-CHP, and LS ADIGT-CHP cases, all ADIGT-CHP cycles are profitable than the conventional case. For LS ADIGT- CHP category, the IC ADIGT-CHP is the most profitable, whereas for SS ADIGT-CHP category, the RC ADIGT-CHP is the most profitable. The contribution to knowledge of this research is the development of a technoeconomic model for assessing, predicting, and comparing viability of simple and advanced cycle ADIGT-CHP in the petrochemical industry in terms of NPV, SPBP, and IRR over the conventional case of grid power plus on-site boiler. A second contribution is the derivation of simple and advanced cycle small-scale ADIGT and ADIGT-CHP from helicopter engines. Cont/D.

Student Number : 9202134A - PhD thesis - School of Civil and Environmental Engineering - Faculty of Engineering and the Built Environment / South Africa’s energy economy is dominated by coal, which produces relatively high emissions of greenhouse and noxious gases during combustion. This causes environmental problems that may lead to health risks that are cause for concern. In this thesis, various propositions are tested about whether in the Cape Metropolitan Area natural gas is a lower cost energy source than coal for generating base load power within a specified range of capacity factors under different scenarios. The problem being investigated is the uncertainty about the quantified effect that revenue from monetised carbon dioxide credits and inclusion of damage costs would have on the breakeven selling price of electricity, if natural gas were substituted for coal for generating base load power in the above Area. The research procedure entailed conceptualising and developing technical details of four power generation scenarios and reviewing various tools for cost-benefit analysis. Next, a Te- Con Techno-Economic Simulator model and screening curves were selected from a suite of potential tools. The power generation cost profiles for coal and natural gas were determined, followed by sensitivity analysis. The model was populated and used to compare the lifecycle economic performance of coal and natural gas technologies. Natural gas emerged as a lower cost energy source than coal for generating base load power within a specified range of capacity factors under all the scenarios. This thesis recommends the following: the introduction of tax holidays and favourable capital equipment depreciation regimes to stimulate natural gas exploration; the use of natural gas as an energy source to promote small-scale enterprises in communities contiguous to gas transmission pipelines; in addition, electricity prices should reflect damage costs in order to internalise externalities associated with power generation. The contribution to knowledge is the innovative way of financing the gas-fired power generation project by using the monetised carbon dioxide credits under the novel Clean Development Mechanism to redeem a bank and a shareholders’ loan. This could result in reducing the loan payment by 4.3 years, saving 38 % in interest payments and allow scarce finance available for project funding to be extended to other projects to the advantage of national economic development.