This thesis describes the design, construction, and evaluation of a series of LED array photolysis systems for high throughput photochemistry. Three generations of array systems of increasing sophistication are evaluated using calorimetric measurements and potassium tris(oxalato)ferrate(III) chemical actinometry. The results are analyzed using descriptive statistics and analysis of variance (ANOVA). The LEDs in the third generation array were shown to be statistically equivalent, with respect to light output, according to physical and chemical actinometry experiments. The third generation LED array was compared with a traditional 1000 W Xe arc lamp source in terms of cost, light intensity, and light stability. Two constant current drivers were evaluated with respect to LED array performance. The optimized third generation LED array was evaluated as the photolysis source for photochemical hydrogen production experiments using the supramolecular catalyst [{(bpy)2Ru(dpp)}2RhCl2](PF6)5. / Master of Science

Orientadores: Carla Kazue Nakao Cavaliero, Ennio Peres da Silva / Tese (doutorado) -Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-12T18:30:16Z (GMT). No. of bitstreams: 1 Varella_FabianaKarladeOliveiraMartins_D.pdf: 2814812 bytes, checksum: 2b3d8b0306df42b90c009281f0150f0d (MD5) Previous issue date: 2009 / Resumo: A Lei nº 10.438/02 estabeleceu o Programa de Incentivo às Fontes Alternativas de Energia Elétrica - PROINFA, único programa nacional a estimular as fontes renováveis alternativas, com o intuito de aumentar a participação da energia elétrica produzida por empreendimentos a partir das fontes eólica, pequenas centrais hidrelétricas - PCHs e biomassa no sistema interligado nacional. Posteriormente, o PROINFA foi revisado pela Lei nº 10.762/03 e alterou em sua regulamentação a obrigatoriedade de um índice mínimo de nacionalização de serviços e equipamentos, que em sua primeira etapa passou a corresponder a 60% do custo total da construção dos projetos contemplados. A energia solar fotovoltaica não foi contemplada pelo Programa, e o objetivo desta tese é estimar o índice de nacionalização para cada um dos três sistemas fotovoltaicos selecionados para estudo (sistema de bombeamento de água, sistema de eletrificação rural e sistema conectado à rede elétrica). Para elaboração desse cálculo foi efetuada uma adaptação da metodologia utilizada pelo PROINFA e considerados somente os custos dos principais equipamentos e não dos serviços. Os resultados obtidos permitiram concluir que os sistemas de bombeamento de água e de eletrificação rural são sistemas que 5% e 35%, respectivamente, dos seus equipamentos já são disponibilizados pela indústria nacional. mesmo não ocorre com os sistemas fotovoltaicos conectados à rede elétrica, que atualmente tem 100% dos seus principais equipamentos importados / Abstract: The Law nº 10.438/02 established the Program of Incentives for Alternative Electric Power Sources - PROINFA, which is the only national program aimed to foster alternative renewable energy sources and to increase the share of electric energy production from enterprises based on wind power, small hydropower plants and biomass in the interconnected national power grid. PROINFA was later modified by the Law nº 10.762/03 which revised the regulation imposing a minimum nationalization index of services and equipment that in its first stage corresponded to 60% of the total cost of the selected projects. Solar photovoltaic power was not included in PROINFA and because of that the objective of this thesis is to estimate the nationalization index of each of the following photovoltaic systems selected for the study: water pumping PV system, rural electrification PV system and grid-connected PV system. In order to carry out the calculations, the methodology used at PROINFA was adapted and only the costs of the key equipment, not the services, were considered. The results led to the conclusion that the water pumping and the rural electrification systems are those in which 5% and 35%, respectively, equipment is already made available by the national industry. The same is not verified for the grid-connected PV systems in which 100% of the key equipment is imported / Doutorado / Doutor em Planejamento de Sistemas Energéticos

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An organic Schottky barrier cell, consisting of a thin layer of the organic semiconductor, GaPc-Cl, in contact with gold on one side and an electrolyte containing a redox couple on the other, was developed as a solar energy conversion device. Schottky barriers were formed at both interfaces. Film morphology, as determined by the sublimation rate, was the major determinant of the photoelectrochemical behavior. An optimum film consisted of a single layer of crystallites about 1.0 micron in thickness, tightly packed together to give a non-porous film. Thinner films did not develop the full theoretical photopotential, and pores acted as recombination sites, decreasing the efficiency. Both negative and positive photopotentials could be developed, depending on the redox couple used. The photopotential, was found to be proportional to the differences between the Fermi level of the Au and the formal potential of the redox couple. Hydrogen evolution was possible with up to 0.1% solar efficiency on a platinized version of the optimum electrode. Results from photocurrent action spectra and pulsed laser photocoulostatics, showed the potential drop across the film was not linear, but formed a potential well about 0.1 eV deep, which captured charge carriers and decreased the efficiency. From scanning electron microscope studies, phthalocyanines, such as AlPc-Cl, GaPc-Cl, and InPc-Cl, with bulky anions were found to form block-like crystal structures favorable for use in Schottky barrier cells. Phthalocyanines with transition metals in the +2 oxidation state, such as FePc and MgPc, were found to form long needles, which were not favorable for use in Schottky barrier cells.

Air-conditioning systems driven by solar energy have can save primary energy and reduce peak power consumption, which is particularly important for utility providers in the summer months. Additionally solar cooling is a promising application of solar thermal technology since the cooling load is well correlated to the overall solar availability. Liquid desiccant air-conditioning, which uses a salt solution to dehumidify air, can be used in a thermally driven air-conditioning system and offers many benefits for solar applications including the ability to store solar energy in the form of concentrated liquid desiccant. The current work focuses on the Queen’s University Solar Liquid Desiccant Cooling Demonstration Project. In previous work, a pre-commercial Liquid Desiccant Air Conditioner (LDAC) was installed and experimentally characterized using a gas-fired boiler to provide heat. As part of the current study a 95m2 solar array was added as a heat source. The Solar LDAC was tested for 20 days in the summer of 2012 to evaluate performance. The solar LDAC was found to provide between 9.2kW and 17.2kW of cooling power with an overall thermal Coefficient of Performance (COP) of 0.40 and electrical COP of 2.43. The collector efficiency was 53%, and 40% of the required thermal energy was provided by the solar array. A model was developed in TRNSYS to predict the performance of the solar LDAC and simulation results were compared to the experimental results with reasonable accuracy. The validated model was then used to simulate the annual performance of the solar LDAC in Toronto, Ontario; Vancouver, British Columbia; and Miami, Florida. The highest performance was achieved in Miami, where an overall thermal COP of 0.48 was predicted. It is proposed that additional improvements be made to the system by replacing inefficient pumps and fans, adding desiccant storage, and improving the control scheme. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2012-10-29 16:34:02.906

PV/Thermal technology is the combination of solar thermal and photovoltaics - two mature and widely understood technologies. Combining the two technologies complicates existing standardized rating procedures and performance modeling methods. Currently a standardized performance test method does not exist for PV/Thermal (PV/T) panels. Existing and developing PV/T panels are commonly tested using separate standardized solar thermal and photovoltaic test procedures. Solar thermal performance is rated in terms of temperature difference whereas photovoltaic performance is dependent on absolute temperature level. The thermal and electrical performance of a PV/T panel is, however, coupled so performance equations derived using traditional test methods may not accurately reflect the performance of a combined PV/T panel over a wide range of conditions. The purpose of this work was to develop an efficiency equation for a PV/T panel which can be derived from a minimal amount of empirical test data and still accurately predict its thermal and electrical performance over a wide range of conditions. To accomplish this, a quasi- 3-dimensional steady-state model of a sheet-and-tube PV/T collector was developed and used to generate a broad data set from which a simplified PV/T performance equation was developed. Using this numerically generated data set, and introducing additional coefficients into the traditional solar thermal performance characteristic, a modified PV/T efficiency equation was derived which expressed the electrical and thermal efficiency in terms of ambient temperature, incident solar irradiation and the temperature difference between the inlet fluid and the ambient. It was also shown, for the case studied, that the efficiency equation can be produced from as few as 6 data points and still accurately predicts the performance at a wide range of operating conditions. A TRNSYS [1] model was developed to demonstrate how the performance equation can be used to simulate the annual performance of a PV/T collector in a domestic hot water system. It was shown that a performance equation, derived from 6 data points, performed as well as a performance map which used over 1000 data points. The annual thermal and electrical production predicted by both models was within 1.5% of each other. The PV/T efficiency equations were also shown to perform well for a range of electrical parameters, thermal properties and substrate thermal conductivity values. Future work is recommended to validate the PV/T performance equation using real empirically derived data for a range of collector designs. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2013-01-22 15:40:03.337

Thesis advisor: Dunwei Wang / Due to the increasing energy demand from human activities, efficient utilization of renewable energy, such as wind, solar and geothermal energies, becomes necessary and urgent. Photoelectrochemical water splitting offers a great example to convert solar energy and storage it in the term of chemical bond. Seeking suitable photoanode materials becomes the research focus of my study, because the development of photoanode materials significantly lags that of robust photocathode (such as Si). The main challenge is to fabricate an efficient and stable photoanode material which can deliver high photocurrent and sufficient photovoltage which can match well with those of photocathode when made into tandem cell configuration. Hematite (α-Fe2O3) represents a promising metal oxide photoanode material, with a suitable band gap (2.1 eV), low cost and toxicity. Applying nanostructures and appropriate surface modification layers help address existing research challenges. As a result, a much lower turn on potential and greater photocurrent density is achieved. Another photoanode material attracts our attention is tantalum nitride (Ta3N5), with a similar band gap to hematite but much better light absorption properties, shows a poor stability in aqueous electrolyte. For both photoanode materials, thermodynamic and kinetic aspects are studied in details when tested in water splitting devices. These works provide new ideas and insights on the future studies. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Solar energy has come to the forefront as a scalable and largely underutilized renewable energy resource. The current cost of solar electricity, namely from photovoltaics, along with other logistics factors, has prevented the widespread adaptation of the technology. A key determinant of efficiency and cost for a solar cell is the current collector grid. This work presents the Collimated Aerosol Beam Direct Write (CAB-DW) system as a non-contact printing method that can achieve current collector grid finger widths of less than 10 μm which are amenable to decreasing both resistive and optical losses. The ability to produce high aspect ratio grid fingers, and deposit optimized grid structures on high efficiency SHJ solar cells using silver nanoparticle inks is also demonstrated. A decrease in shadowing and via profile modification of the grid fingers is presented, along with a study of aging and degradation of electrical properties within silver nanoparticle inks.

This thesis details potential design improvements by exploiting a new general grid model utilizing multiple wind and solar energy plants. A single renewable energy plant which relies on wind speed or solar insolation is unreliable because of the stochastic nature of weather patterns. To allow such a plant to match the requirements of a variable load some form of energy storage must be incorporated. To ensure a low loss of load expectation (LOLE) the size of this energy storage must be large to cope with the strong fluctuations in energy production. It is theorized that by using multiple renewable energy plants in separate areas of a region, the different weather conditions might approach a probabilistically independent relationship. The probability of energy generated from combined plants will then approach a Gaussian distribution by the central limit theorem. While maintaining the same LOLE as a single renewable plant this geographic separation model theoretically stabilizes the energy production and reduces the system variables: energy storage size, energy storage efficiency, and cumulative plant capacity. New generic weather models that incorporate levels of independence are created for wind speeds and solar insolations at different locations to support the geographic separation model. As the number of geographically separated plants increases and the weather approaches independence the system variables are reduced.