As a result of the mining that has taken place over the last century in South Africa, many towns and cities have developed around mining hubs, the most significant of these being the city of Johannesburg. Over the years, residential areas have grown around these mine sites, even well after decommissioning of the mining activities. The mining activities left a lasting legacy of derelict mining infrastructure with negative effects on the surrounding environment and community, such as dormant mine shafts, sterilised land and abandoned Tailings Storage Facilities (TSFs). Due to lack of funds, commitment from mine owners and regulators these facilities are often left unrehabilitated, posing negative environmental impacts, including potential health hazards to the surrounding community. This legacy of problems posed by abandoned mines encountered in South Africa is probably unique in scale compared to any country in the world. A significant problem South Africa currently faces is an electricity shortage, especially during the high demand season from the start of June to end of August, when it is winter in South Africa. This period is occasionally associated with so called controlled “load shedding”, i.e. managed power interruptions to prevent overload and subsequent collapse of the electricity supply and distribution network. South Africa is highly reliant on coal-fired power stations for the majority of electricity consumed, which has detrimental effects on the environment due to high carbon emissions. However, a global shift towards renewable energy, as well as South Africa’s energy shortage, has forced the National Energy Regulator of South Africa to encourage greener alternatives. This study is aimed at finding an opportunity to generate more electricity, which is sustainable and with reduced carbon emissions. This study was conducted to determine the financial and practical feasibility of generating energy from the ERGO TSF, near Brakpan Johannesburg, as a post closure land use option. The following options were investigated: • Solar Photovoltaic electricity generation • Pump storage scheme development • A combinations of the above In addition, rainwater harvesting and wind power generation were also considered, but were abandoned early on in the study. From the study it was concluded that a Solar PV plant on top of the ERGO TSF will achieve the highest possible IRR of 10.70% and a power generation capacity of 471.9 MWp. Developing a pump storage scheme at the ERGO TSF can achieve an IRR of 10.27% and generation capacity of 78.2 MW. Combining the two options independently on the same site will result in an IRR of 10.61% and a combined peak generation capacity of 550 MW. If the combined system is required to be independent of the surplus electricity available in the grid an IRR of 10.32% and a combined generation capacity of 550 MW is achievable. From a financial and technical perspective it is considered to be most beneficial to implement only the solar PV plant on top of the ERGO TSF. Construction of a pump storage scheme on TSF is considered to be a challenging undertaking and seeing that its generation capacity is only 17% of that of the solar PV facility on the same ERGO site, it is probably not the optimal solution for utilisation. Solar panels are light weight structures that can easily be installed in large numbers on TSFs with little engineering challenges. / Dissertation (MEng)--University of Pretoria, 2015. / tm2015 / Civil Engineering / MEng / Unrestricted

MaxiDoor AB konstruerar och tillverkar ståldörrar och stålpartier efter specifika kundorder och är specialist på lösningar där hög säkerhet efterfrågas. Företaget ämnar expandera under kommande år och har sjösatt en investeringsplan för att göra verksamheten anpassad för en högre omsättning.  Detta arbete avser att se över och förbättra dagens materialförsörjning vad gäller stålprofiler med förutsättningar om förväntad omsättning för produktionsenheten ES kommer att öka från 100 mkr till 145 mkr samt att företaget vill bibehålla en enstycksproduktion. Detta ska lösas med hjälp av bland annat en lagerhiss. Parallellt med att tillverkningstakten förväntas öka måste även materialförsörjningen utvecklas för att klara framtida efterfrågan.  Med grund i teori och analys av nuläget konstateras att lagerutformningen snabbt blir komplex med de förutsättningar som existerar. Studiens slutgiltiga rekommendation är att dela upp lagret i tre sektioner; lagerhiss, grovbuffert och finbuffert. Detta får till följd en användarvänlig materialförsörjning som förväntas vara hållbar på sikt.  Lagerhissen avses förvara både ordrar med planerad och dedikerad förbrukning samt övriga profiler och slattar. På så sätt agerar hissen såväl lager som buffert. Grovbuffert och finbuffert brukas enligt en trattprincip där ordrar bryts ned till enstaka profiler som skall kapas. Avslutningsvis diskuteras olika aspekter kring materialförsörjningen och framtida arbete. / MaxiDoor AB designs and manufacture steel doors and steel segments to specific customer order and are specialist on solutions where high security is requested. The company seeks to expand during the coming years and have launched an investment plan to adapt the production for higher turnover.  This work intends to look over and improve todays material supply in terms of steel profiles with the basis that expected turnover for the production unit ES will grow from 100 mkr to 145 mkr and in addition the company wishes to keep a one-piece production. This will be solved with the help of, among other things, a vertical storage lift. In parallel with the expected increase in rate of production, the supply of materials must also be developed to meet future demand. Based on theory and analysis of the current situation, it is found that the storage design quickly becomes complex with the existing conditions. The final recommendation of the study is to divide the storage into three sections; a vertical storage lift, a coarse buffer and a fine buffer. This results in a user-friendly material supply that is expected to be sustainable in the long term. The vertical storage lift is intended to store orders with planned and dedicated consumption as well as other profiles and residual profiles. In this way, the elevator acts as both storage and buffer. The coarse buffer and fine buffer are used according to a funnel principle where orders are broken down into individual profiles to be cut. Finally, various aspects are discussed regarding the supply of materials and future work.

The intermittent nature of several sustainable energy sources such as solar and wind energy has ignited the demand of electrochemical energy storage devices in the form of batteries and electrochemical capacitors. The future generation of electrochemical capacitors will in large part depend on the use of pseudocapacitive materials in one or both electrodes. Developing pseudocapacitors to have both high energy and power density is crucial for future energy storage systems. This dissertation evaluates two different material systems to achieve high energy density pseudocapacitive energy storage. This research presents the successful preparation and application of ternary NiCo2S4, which is based on the surface redox mechanism, in the area of pseudocapacitive energy storage. Attention has been paid to understanding its basic physical properties which can impact its electrochemical behavior. Well-defined single- and double-shell NiCo2S4 hollow spheres were fabricated for pseudocapacitor applications, showing much improved electrochemical storage performance with good energy and power densities, as well as excellent cycling stability. To overcome the complexity of the preparation methods of NiCo2S4 nanostructures, a one-step approach was developed for the first time. Asymmetric pseudocapacitors using NiCo2S4 as cathode and graphene as anode were also fabricated to extend the operation voltage in aqueous electrolyte, and thus enhance the overall capacity of the cells. Furthermore, high-performance on-chip pseudocapacitive energy storage was demonstrated using NiCo2S4 as electrochemically active materials. This dissertation also involves another material system, intercalation pseudocapacitive VO2 (B), that displays a different charge storage mechanism from NiCo2S4. By constructing high-quality, atomically-thin two-dimensional (2D) VO2 (B) sheets using a general monomer-assisted approach, we demonstrate that a rational design of atomically thin, 2D nanostructures of atypically layered systems can greatly lower the interaction energy and Li+ diffusion barrier, and it can completely suppress the crystal transformation during the charge-discharge process. As a result, we have successfully enabled the kinetically sluggish step to proceed at room temperature. We show that even at charge-discharge rates as fast as 100C (36 s), these 2D electrodes still offer a high capacity of 140 mAh g-1 due to the rapid Li+ ion diffusion in these 2D sheets. These results discussed in this part conclusively show that the ultrathin 2D geometry of atypically layered or non-layered materials could lead to significantly enhanced pseudocapacitive performance.

The purpose of this thesis is to design a storage system in a machine engineering company with the expected expansion of production volume. The first part describes the theoretical analysis of the processed issue. This is followed by an analysis of the production system and the current situation in the company. The main part consists of determining the amount of inventory, storage location, storage equipment selection and layout design. The part of proposal is also cutting department. Based on the evaluation of selected criteria, more useful version was chosen. The final part is devoted to the economic evaluation of its realization.

No description available.

No description available.

A physical model for redox flow batteries is developed to estimate performance for any chemistry using parameters such as electrolyte conductivity and kinetic rate constants. The model returns the performance as a function of flow rate, current density, and state of charge. Two different models are developed to estimate the current density distribution throughout the electrode in order to evaluate physical performance of the battery. This is done using electrochemical parameters such as conductivity and kinetic rate constant. The models are analytical in order to produce a computationally cheap algorithm that can be used in optimization routines. This allows for evaluating the economic performance of redox flow batteries, and optimization of cost. The models are validated vs data and found to accurately predict performance in a V-V system for a wide variety of operating conditions.

The main objective of this paper is to show the economic and environmental benefits that can be attained through the coupling of borehole thermal energy storage (BTES) and combined heat and power (CHP). The subject of this investigation is the University of Massachusetts CHP District Heating System. Energy prices are significantly higher during the winter months due to the limited supply of natural gas. This dearth not only increases operating costs but also emissions, due to the need to burn ultra low sulfur diesel (ULSD). The application of a TES system to a CHP plant allows the plant to deviate from the required thermal load in order to operate in a more economically and environmentally optimal manner. TES systems are charged by a heat input when there is excess or inexpensive energy, this heat is then stored and discharged when it is needed. The scope of this paper is to present a TRNSYS model of a BTES system that is designed using actual operational data from the campus CHP plant. The TRNSYS model predicts that a BTES efficiency of 88% is reached after 4 years of operation. It is concluded that the application of BTES to CHP enables greater flexibility in the operation of the CHP plant. Such flexibility can allow the system to produce more energy in low demand periods. This operational attribute leads to significantly reduced operating costs and emissions as it enables the replacement of ULSD or liquefied natural gas (LNG) with natural gas.

Storage of canine packed red blood cells (pRBCs) can increase erythrocyte phosphatidylserine (PS) expression and eicosanoid concentrations. The objective of this study was to determine the effects of leukoreduction on erythrocyte PS expression and eicosanoid concentrations in stored units of canine pRBCs. Units of whole blood were leukoreduced (LR) or non-leukoreduced (non-LR), and stored (10 and 21 days) as pRBCs. Samples were collected at donation, and before and after a simulated transfusion. PS expression was measured by flow cytometry, and concentrations of arachidonic acid (AA), prostaglandin F2α (PGF2α), prostaglandin E2 (PGE2), prostaglandin D2 (PGD2), thromboxane B2 (TXB2), 6-keto-prostaglandin F1α (6-keto-PGF1α) and leukotriene B4 (LTB4) were quantified by liquid chromatography-mass spectrometry. Our study demonstrated that PS expression on the surface of erythrocytes was not affected by leukoreduction or storage duration. Additionally, the passage of blood through a leukoreduction filter causes an immediate and dramatic increase in TXB2 and PGF2α concentrations, but these concentrations then decrease during subsequent storage. Despite leukoreduction, the concentration of 6-keto-PGF1α continued to increase during storage and simulated transfusion. Overall, when compared to non-LR units, the addition of a leukoreduction step prior to storage had a minimal impact on the accumulation of eicosanoids in canine units of pRBCs. While leukoreduction may be beneficial in other aspects of transfusion medicine, based on the results in this study, using leukoreduction to decrease PS expression and eicosanoid concentrations does not appear to be effective.

The cost and fuel economy of hybrid electrical vehicles (HEVs) are significantly dependent on the power-train energy storage system (ESS). A series HEV with a minimal all-electric mode (AEM) permits minimizing the size and cost of the ESS. This manuscript, pursuing the minimal size tactic, introduces a bandwidth based methodology for designing an efficient ESS. First, for a mid-size reference vehicle, a parametric study is carried out over various minimal-size ESSs, both hybrid (HESS) and non-hybrid (ESS), for finding the highest fuel economy. The results show that a specific type of high power battery with 4.5 kWh capacity can be selected as the winning candidate to study for further minimization. In a second study, following the twin goals of maximizing Fuel Economy (FE) and improving consumer acceptance, a sports car class Series-HEV (SHEV) was considered as a potential application which requires even more ESS minimization. The challenge with this vehicle is to reduce the ESS size compared to 4.5 kWh, because the available space allocation is only one fourth of the allowed battery size in the mid-size study by volume. Therefore, an advanced bandwidth-based controller is developed that allows a hybridized Subaru BRZ model to be realized with a light ESS. The result allows a SHEV to be realized with 1.13 kWh ESS capacity. In a third study, the objective is to find optimum SHEV designs with minimal AEM assumption which cover the design space between the fuel economies in the mid-size car study and the sports car study. Maximizing FE while minimizing ESS cost is more aligned with customer acceptance in the current state of market. The techniques applied to manage the power flow between energy sources of the power-train significantly affect the results of this optimization. A Pareto Frontier, including ESS cost and FE, for a SHEV with limited AEM, is introduced using an advanced bandwidth-based control strategy teamed up with duty ratio control. This controller allows the series hybrid’s advantage of tightly managing engine efficiency to be extended to lighter ESS, as compared to the size of the ESS in available products in the market.