Spectrum-splitting is a multijunction photovoltaic technology that can effectively improve the conversion efficiency and reduce the cost of photovoltaic systems. Microscale PV design integrates a group of microconcentrating photovoltaic (CPV) systems into an array. It retains the benefits of CPV and obtains other benefits such as a compact form, improved heat rejection capacity, and more versatile PV cell interconnect configurations. We describe the design and performance of a two-junction holographic spectrum-splitting micro-CPV system that uses GaAs wide bandgap and silicon narrow bandgap PV cells. The performance of the system is simulated with a nonsequential raytracing model and compared to the performance of the highest efficiency PV cell used in the micro-CPVarray. The results show that the proposed system reaches the conversion efficiency of 31.98% with a quantum concentration ratio of 14.41x on the GaAs cell and 0.75x on the silicon cell when illuminated with the direct AM1.5 spectrum. This system obtains an improvement over the best bandgap PV cell of 20.05%, and has an acceptance angle of +/- 6 deg allowing for tolerant tracking. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

The phytoplankton, or plant plankton, live in the open water throughout their life cycle and obtain the necessary nutrients from the water. They are important contributors to the total plant production of lakes and ponds.

L'axe MCH/MCHR1 a d'abord été étudié pour son rôle dans les comportements alimentaires. Ici, nous étudions son implication dans certains comportements liés à la consommation de drogues d'abus, telles que les psychostimulants, chez des souris génétiquement dépourvues du récepteur de type 1 (MCHR1).

Hybrid solar systems as well as concentrating solar collectors are promising solar technologies. To run them efficiently in northern countries is a task Solarus AB is working on.The objective of this MSc project is to investigate and experimentally evaluate the option of implementing a light diffusing sheet in acompound parabolic concentrator (CPC) solar collector, called the “Scania Model”. This component should improve the non-uniform illumination of the photovoltaic cells in concentrating solar collectors.Therefore, scientific publications on this kind of solar collectors were read up on, e.g.Adsten, M. Brogren, M., Roos, A., Karlsson, B. Nilsson, J. and Leutz, R.After researching and procuring possible diffuser materials, experimental tests were carried out and the different materials were reviewed. Implemented in a solar simulator the IV curves of the collector with the different diffusers were generated. Furthermore, the influence of the materials on light was reviewed using daylight, laser light and an artificial light source. In the following, the light intensity distribution on the absorber of the Scania Model was defined and evaluated.The results of this project show that the main problem regarding diffuser material is to provide sufficient diffusion without much transmission losses.

As part of the SUNRISE project (Semiconductors Using Nanostructures for Record Increases in Solar-cell Efficiency), high efficiency, III-V semiconductor, quantum-dot-enhanced, triple-junction solar cells designed and manufactured by Cyrium Technologies Inc. were integrated into OPEL Solar, MK-I, Fresnel-lens-based, 550x concentrating modules carried on a dual axis tracker. Over its first year of operation 1.8 MWh of AC electrical energy was exported to the grid. Measurements of the direct and indirect components of the insolation, as well as the spectral irradiance of light incident on the demonstrator in Ottawa, Canada are presented. The system efficiency is measured and compared to that predicted by a system model to identify loss mechanisms so that they can be minimized in future deployments.

Aquatic photosynthesis accounts for 50% of the global annual net primary production (NPP), despite frequent low availability and limited diffusion of CO2 in the aquatic milieu, and low affinity for CO2 by the primary carboxylating enzyme, Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Many eukaryotic algae, and a single group of land plants, the hornworts, have an inducible carbon concentrating mechanism (CCM), to overcome these limitations. The efficiency of the CCM is improved when RuBisCO is localised to a subcellular compartment, the pyrenoid, which is hypothesised to act as a diffusion barrier for CO2 . Although the pyrenoid is a major player in global carbon balance (we estimate 10-15% of NPP), it is one of the few remaining prominent cellular features without a precise molecular or physiological definition. Under ambient CO2 , at least 90% of the cellular RuBisCO is packed into a dense matrix, together with the chaperone RuBisCO activase. Thylakoid membranes usually traverse the pyrenoid matrix, and the carboxylating substrate is thought to be delivered to the active sites of the enzyme via a carbonic anhydrase located in the lumen of these thylakoids. The mechanism of aggregation of constituents within the pyrenoid, however, still remains largely unknown. Comprehensive mutant screens have yet to reveal mutants incapable of forming pyrenoids other than those mutants with a defective RuBisCO holoenzyme, whereas DNA microarray studies uncovered little with reference to pyrenoid ultrastructure or aggregation. Taken together, this evidence raises the possibility that the basis of pyrenoid ultrastructure and aggregation lies entirely in sequence variations of RuBisCO itself. This work explored, firstly, the advantages conferred by an active CCM in hornworts and in unicellular algae, compared with the passive CO2 acquisition in most terrestrial plants. A physiological framework to CCM and pyrenoid-based photosynthesis, and isotopic discrimination, was provided by comparing the photosynthetic characteristics of selected bryophytes and algae, differing in chloroplast morphology and degrees of internalisation of gas exchanges. The results showed that on-line, carbon isotope discrimination values were a good indicator of CCM occurrence, as well as liquid-phase diffusion limitation, and biochemical limitations resulting from declining RuBisCO activity and electron transport. The methodology was used to diagnose the presence of an active CCM, and the extent of CO2 leakage. Secondly, the effect of RuBisCO sequence variations on the pyrenoid, and associated CCM, was studied using the model alga Chlamydomonas reinhardtii. The starting premise was the report by Nozaki et al. (2002) that, in some species of the family Chlamydomonaceae, a few amino acid residues within the RuBisCO large subunit (LSU) correlated strongly with pyrenoid formation. The specific roles of seven LSU residues were studied by site-directed mutagenesis. Whilst the mutations reduced the affinity of RuBisCO for CO2 and increased CO2 leakage, compared to wild-type Chlamydomonas, there was no effect on the pyrenoid phenotype. Informed by observations that Chlamydomonas mutants with a hybrid RuBisCO, composed of a native LSU, and higher plant small subunit (SSU), lacked a pyrenoid (Genkov et al., 2010), and that defined SSU alterations were neutral with respect to the pyrenoid (Genkov and Spreitzer, 2006), hitherto unexplored SSU domains were modified. A pyrenoid was successfully restored by replacing jointly the two solvent-exposed α-helices, whereas single α-helix replacements had no effect. However, leakage values indicated that the associated CCM was not fully operative, suggesting important correlates between the RuBisCO SSU and the CCM, besides the conditioning of pyrenoid formation. If the pyrenoid is partly defined by simple sequence variations in the RuBisCO SSU, as suggested by the evidence outlined in this thesis, there is the tantalising possibility that transformation of a biophysical CCM into crop plants could be a tractable approach for the future.

As part of the SUNRISE project (Semiconductors Using Nanostructures for Record Increases in Solar-cell Efficiency), high efficiency, III-V semiconductor, quantum-dot-enhanced, triple-junction solar cells designed and manufactured by Cyrium Technologies Inc. were integrated into OPEL Solar, MK-I, Fresnel-lens-based, 550x concentrating modules carried on a dual axis tracker. Over its first year of operation 1.8 MWh of AC electrical energy was exported to the grid. Measurements of the direct and indirect components of the insolation, as well as the spectral irradiance of light incident on the demonstrator in Ottawa, Canada are presented. The system efficiency is measured and compared to that predicted by a system model to identify loss mechanisms so that they can be minimized in future deployments.

The optical properties of the absorber pipe in a parabolic trough collector isessential for the performance of the solar collector. The desirable propertiesare high absorptance (α) of solar radiation and low emittance (ε) of thermalradiation. A surface with these properties is known as a solar selective surface. There are several techniques used to produce selective surfaces, but one of the most common ones is electroplating. Research done by Vargas, indicates that optical properties of α = 0.98 and ε = 0.03 [1], which is superior to the best commercial alternatives (α = 0.95 and ε = 0.04 [2]), can be achieved by electroplating a Co-Cr coating on a stainless steel substrate. Additionally, Vargas used an electrolyte of trivalent chromium dissolved in a deep eutectic solvent, as opposed to the traditionally used aqueous electrolytes containing hexavalent chromium, which is toxic and carcinogenic. In this project, a coating of Co-Cr was electroplated on a stainless steel substratewith a method similar to that of Vargas in order to obtain a solar selective surface. The electrolyte was composed of ethylene glycol, choline chloride, CrCl3•6H2O and CoCl2•6H2O in a molar ratio of 16:1:0.4:0.2. The plating process was conducted using chronoamperometric electrodeposition with an applied potential of -1.2 V (against an Ag/AgCl reference electrode) for 15 min. The system was investigated using Cyclic Voltammetry (CV). The total absorptance was measured using UV-Vis spectroscopy, while the emittance was measured using an IR-thermometer. The microstructure and chemical composition was investigated using Scanning ElectronMicroscopy (SEM), Focused Ion Beam (FIB), Energy-Dispersive X-ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy. The thermal stability of the coating was investigated by exposingit to 400°C in air for 24 h. The electroplated coating is approximately 2.8 μm thick and exhibits a porousstructure with a surface of fine fiber-like flakes. The coating consists largely of Co hydroxides with low concentrations of Cr compounds, Co oxides and metallic Co. Hence, a satisfactory co-deposition was not accomplished, as the Cr concentration is low. The coating is not thermally stable up to 400°C, exhibiting signs of at least partially melting in the annealing process. The compounds in the coating were largely oxidized in the process. The electroplated surface does however exhibits strong selectivity, with a total solar absorptance of α = 0.952 and total emittance of ε = 0.32 at 160°C.

One approach to enabling a larger penetration of renewable sources of energy is the implementation of hybrid power plants. This work presents a process to determine the preliminary optimal configuration of a concentrating solar power-coal hybrid power plant with low solar augmentation, and is demonstrated on a coal power plant in Castle Dale, UT. A representative model is developed and validated against published data for a coal power plant of a different configuration than Hunter Unit 3. The simplifications within the representative model include combining multiple feedwater heaters, combining turbines that operate across the same boundary states, and the mass-average calculation for extraction properties to the combined feedwater heaters. It is shown that the representative model can accurately and consistently simulate a coal power plant. Comparing net power generation and boiler heating estimates from the representative model to the benchmark power plant, the representative model is accurate to within +/- 1% the accepted value from the benchmark power plant. The methods for quantifying solar resource with data from the National Renewable Energy Laboratory are presented with the derivation of an algorithm to simulate a concentrating solar power field arrangement. The solar contribution to electrical power output is estimated using an exergy balance. A simplified financial model is also developed to estimate the solar marginal levelized cost of electricity and payback time using a cash-flow analysis. Estimates for solar resource, solar contribution, and financial performance are consistent with data published by the National Renewable Energy Laboratory or in archival literature. A multi-objective optimization routine is developed consisting of the representative model, the augmentation of solar energy into the solar integration model by means of feedwater heater bypass, solar contribution, levelized cost of electricity, and payback time. Because this study considered complete FWH bypass, higher solar augmentation (>3% of boiler heating) is required for a hybrid design to be considered feasible. However, for higher solar augmentation, the costs are also considerably higher and the financial benefit is insufficient to make any hybrid designs feasible unless a carbon tax is in place. A carbon tax will amplify the financial benefit of hybridization, so optimization results are provided assuming a carbon tax value equivalent to the value used in California's Emissions Trading System (16 USD sh.tn.^-1). The impact of a green energy premium price paid by consumers is also explored in the context of payback time. The resulting optimal design for the Hunter Unit 3 with a carbon tax and no premium is using parabolic trough collector technology at an augment fraction of k=9% to bypass feedwater heater 6. The resulting marginal solar levelized cost of electricity is 9.5 x 10^-4 USD kWh^-1 with an estimated payback time of 25.2 years. This process can be applied to any coal power plant for which operating data and meteorological data are available to evaluate preliminary hybridization feasibility.

No description available.