Abstract: Solid-state hydrogen storage using catalytically-modified porous silicon can be rapidly charged at moderate pressures (8 bar) without exothermic runaway. Discharge requires temperatures of approximately 110oC, so for larger storage vessels a means is required for thermal energy to penetrate bulk storage media. This can be realized with low-density metal foams, such as Celmetâ„¢. This study explores several material and dimensional choices of the metal foam to produce rapid heating of bulk silicon particulates. Experiments run under vacuum and in a pressurized hydrogen environment bracket conditions of empty and full hydrogen storage vessels, respectively. Curve-fitting of the heating profiles at various distances from an external heat source is used to derive both a time delay and a characteristic time constant. System performance metrics of a hydrogen storage subsystem are derived from the experimental results. A techno-economic analysis of the silicon and metal foam provides comparison with other methods of storing hydrogen for mobile and portable applications.Â
Abstract: With the increasing of the penetration of renewable energy in power system, the whole inertia of the power system is declining, which will endanger the frequency stability of the power system. In order to enhance the inertia, virtual synchronous generator (VSG) has been proposed. In addition, the motor-generator pair (MGP) system is proposed to enhance grid inertia. Both of them need additional equipment to provide instantaneous energy, so the economic problem should be considered. In this paper, the basic working principle of MGP system and VSG are introduced firstly. Then, the technical characteristics and economic investment of MGP/VSG are compared by calculation and simulation. The results show that the MGP system can provide same inertia with less cost than VSG.
Abstract: This paper presents a desktop study of comparing two different wave energy to electricity technologies (WECs) using a techno-economic approach. This techno-economic approach forms basis of a framework for rapid comparison of current and future technologies. The approach also seeks to assist in investment and strategic decision making expediting future deployment of wave energy harvesting in South Africa.
Abstract: This paper presents a curriculum of the subject small power plants and renewable energy sources, dealing with the concept of distributed generation, renewable energy sources, hydropower, wind farms, geothermal power plants, cogeneration plants, biogas plants of agriculture and animal origin, solar power and fuel cells. The course is taught the manner of connecting small power plants to the grid, the impact of small generators on the distribution system, as well as economic, environmental and legal aspects of operation of distributed generators.
Abstract: The biodegradable family of polymers
polyhydroxyalkanoates is an interesting substitute for convectional
fossil-based plastics. However, the manufacturing and environmental
impacts associated with their production via intracellular bacterial
fermentation are strongly dependent on the raw material used and on
energy consumption during the extraction process, limiting their
potential for commercialization. Industrial wastewater is studied in
this paper as a promising alternative feedstock for waste valorization.
Based on results from laboratory and pilot-scale experiments, a
conceptual process design, techno-economic analysis and life cycle
assessment are developed for the large-scale production of the most
common type of polyhydroxyalkanoate, polyhydroxbutyrate.
Intracellular polyhydroxybutyrate is obtained via fermentation of
microbial community present in industrial wastewater and the
downstream processing is based on chemical digestion with
surfactant and hypochlorite. The economic potential and
environmental performance results help identifying bottlenecks and
best opportunities to scale-up the process prior to industrial
implementation. The outcome of this research indicates that the
fermentation of wastewater towards PHB presents advantages
compared to traditional PHAs production from sugars because the
null environmental burdens and financial costs of the raw material in
the bioplastic production process. Nevertheless, process optimization
is still required to compete with the petrochemicals counterparts.
Abstract: In this paper, the energy performance of a selected
UHDE Ammonia plant is optimized by conducting heat integration through waste heat recovery and the synthesis of a heat exchange
network (HEN). Minimum hot and cold utility requirements were estimated through IChemE spreadsheet. Supporting simulation was
carried out using HYSYS software. The results showed that there is
no need for heating utility while the required cold utility was found to
be around 268,714 kW. Hence a threshold pinch case was faced. Then, the hot and cold streams were matched appropriately. Also,
waste heat recovered resulted with savings in HP and LP steams of
approximately 51.0% and 99.6%, respectively. An economic analysis
on proposed HEN showed very attractive overall payback period not
exceeding 3 years. In general, a net saving approaching 35% was
achieved in implementing heat optimization of current studied UHDE Ammonia process.
Abstract: Rural areas of Tanzania are still disadvantaged in terms of diffusion of IP-based services; this is due to lack of Information and Communication Technology (ICT) infrastructures, especially lack of connectivity. One of the limitations for connectivity problems in rural areas of Tanzania is the high cost to establish infrastructures for IP-based services [1-2]. However the cost of connectivity varies from one technology to the other and at the same time, the cost is also different from one operator (service provider) to another within the country. This paper presents development of software system to calculate cost of connectivity to rural areas of Tanzania. The system is developed to make an easy access of connectivity cost from different technologies and different operators. The development of the calculator follows the V-model software development lifecycle. The calculator is used to evaluate the economic viability of different technologies considered as being potential candidates to provide rural connectivity. In this paper, the evaluation is based on the techno-economic analysis approach.