Polymer Solar Cells—Interfacial Processes Related to Performance Issues

Harnessing solar energy with solar cells based on organic materials (in particular polymeric solar cells) is an attractive alternative to silicon-based solar cells due to the advantages of lower weight, flexibility, lower manufacturing costs, easier integration with other products, low environmental impact during manufacturing and operations and short energy payback times. However, even with the latest efficiencies reported up to 17%, the reproducibility of these efficiencies is not up to par, with a significant variation in the efficiencies reported across the literature. Since these devices are based on ultrathin multilayer organic films, interfaces play a major role in their operation and performance. This review gives a concise account of the major interfacial issues that are responsible for influencing the device performance, with emphasis on their physical mechanisms. After an introduction to the basic principles of polymeric solar cells, it briefly discusses charge generation and recombination occurring at the donor-acceptor bulk heterojunction interface. It then discusses interfacial morphology for the active layer and how it affects the performance and stability of these devices. Next, the formation of injection and extraction barriers and their role in the device performance is discussed. Finally, it addresses the most common approaches to change these barriers for improving the solar cell efficiency, including the use of interface dipoles. These issues are interrelated to each other and give a clear and concise understanding of the problem of the underperformance due to interfacial phenomena occurring within the device. This review not only discusses some of the implemented approaches that have been adopted in order to address these problems, but also highlights interfacial issues that are yet to be fully understood in organic solar cells

The impacts of climate change on the winter water cycle of the western Himalaya

Some 180 million people depend on the Indus River as a key water resource, fed largely by precipitation falling over the western Himalaya. However, the projected response of western Himalayan precipitation to climate change is currently not well constrained: CMIP5 GCMs project a reduced frequency and vorticity of synoptic-scale systems impacting the area, but such systems would exist in a considerably moister atmosphere. In this study, a convection-permitting (4 km horizontal resolution) setup of the Weather Research and Forecasting (WRF) model is used to examine 40 cases of these synoptic-scale systems, known as western disturbances (WDs), as they interact with the western Himalaya. In addition to a present-day control run, three experiments are performed by perturbing the boundary and initial conditions to reflect pre-industrial, RCP4.5 and RCP8.5 background climates respectively. It is found that in spite of the weakening intensity of WDs, net precipitation associated with them in future climate scenarios increases significantly; conversely there is no net change in precipitation between the pre-industrial and control experiments despite a significant conversion of snowfall in the pre-industrial experiment to rainfall in the control experiment, consistent with the changes seen in historical observations. This shift from snowfall to rainfall has profound consequences on water resource management in the Indus Valley, where irrigation is dependent on spring meltwater. Flux decomposition shows that the increase in future precipitation follows directly from the projected moistening of the tropical atmosphere (which increases the moisture flux incident on the western Himalaya by 28%) overpowering the weakened dynamics (which decreases it by 20%). Changes to extreme rainfall events are also examined: it is found that such events may increase significantly in frequency in both future scenarios examined. Two-hour maxima rainfall events that currently occur in 1-in-8 WDs are projected to increase tenfold in frequency in the RCP8.5 scenario; more prolonged (one-week maxima) events are projected to increase fiftyfold

Seasonal variation on radon emission from soil and water

Radon is being measured continuously in spring water and soil-gas at Badshahi Thaul Campus, Tehri Garhwal in Himalayan region by using radon Emanometer since December 2002. An effort was made to correlate the variance of radon concentrations in spring water and soil-gas with meteorological parameters at the same location. The main meteorological parameters that affect the radon emanation from host material is surrounding temperature, barometric pressure, wind velocity, rain fall and water level of the spring. The correlation coefficient between radon concentration in spring water and different atmospheric parameters was computed. The correlation coefficient between radon concentration in spring water and the maximum atmospheric temperature was 0.3, while it was 0.4 for minimum atmospheric temperature at the monitoring site. The correlation coefficient for radon concentration in spring water with minimum and maximum relative humidity was 0.4. Spring water radon concentration was found positively correlated (0.6) with water discharge rate of the spring. A weak correlation (0.09) was observed between the radon concentration in spring water and rain fall during the measurement period. As temperature of near surface soil increases, the radon emanation coefficient from the soil surface also increases. The possible effects due to global warming and other climatic changes on environment radiation level were also discussed in detail.Yogesh Prasad1, Ganesh Prasad1, G S Gusain1, V M Choubey2 and R C Ramola1* 1Department of Physics, H N B Garhwal University, Badshahi Thaul Campus, Tehri Garhwal-249 199, Uttarakhand, India 2Wadia Institute of Himalayan Geology, Dehradun-248 001, Uttarakhand, India E-mail : [email protected] of Physics, H N B Garhwal University, Badshahi Thaul Campus, Tehri Garhwal-249 199, Uttarakhand, India Wadia Institute of Himalayan Geology, Dehradun-248 001, Uttarakhand, Indi

Using Cossembler for Rapid Prototyping of Co-simulations for Power System Operations

Improved modeling and simulation of power and energy systems has become increasingly important in the face of energy transition. The main challenge is to capture the complexity that heterogeneity of technologies and uncertainty of renewable resources bring along. One approach to improve simulation modeling capabilities, that relies on reusing existing expertise and legacy tools, is a so-called combined simulation (co-simulation). In this approach, well-established tools are combined together resulting in simulation environments with greater capabilities. In this paper, we introduce a new cosimulationrapid prototyping tool called Cossembler (which stands for Co-simulation assembler), whose main benefits are high usability and a variety of potential application domains that could be addressed by it. The paper further presents two use cases which illustrate Cossembler capabilities

Open Data Based Model of the Dutch High-Voltage Power System

A numerical model of a power system can be used to get accurate insights into the impact of policies and investment decisions regarding the transformation of the energy system, while also helping in identifying bottlenecks in implementing decisions. Spatial aggregation, especially for generation and load, must be carefully approached to obtain such a valid model of a power system. The two main contributions of this paper are introducing a valid model of the Dutch high-voltage power system based on open data and open-source software, and proposing a method for spatially aggregating generation and load capacities to high-voltage nodes of the power system. The representative model will enable interdisciplinary research on policy-making and investment decisions specific to the Netherlands

Variation of radon concentrations in soil and groundwater and its correlation with radon exhalation rate from soil in Budhakedar,Garhwal Himalaya

Radon was measured in soil-gas and groundwater in the Budhakedar area of Tehri Garhwal, India in summer and winter to obtain the seasonal variation and its correlation with radon exhalation rate. The environmental surface gamma dose rate was also measured in the same area. The radon exhalation rate in the soil sample collected from different geological unit of Budhakedar area was measured using plastic track detector (LR-115 type II) technique. The variation in the radon concentration in soil-gas was found to vary from 1098 to 31,776 Bq.m–3 with an average of 7456 Bq.m–3 in summer season and 3501 to 42883 Bq.m–3 with an average of 17148 Bq.m–3 in winter season. In groundwater, it was found to vary from 8 to 3047 Bq.l–1 with an average value 510 Bq.l–1 in summer and 26 to 2311 Bq.l–1 with an average value 433 Bq.L–1 in winter. Surface gamma dose rate in the study area varied from 32.4 to 83.6 .R.h–1 with an overall mean of 58.7 .R.h–1 in summer and 34.6 to 79.3 .R.h–1 with an average value 58.2 .R.h–1 in winter. Radon exhalation rate from collected soil samples was found to vary from 0.1 × 10–5 to 5.7 × 10–5 Bq.kg–1.h–1 with an average of 1.5 × 10–5 Bq.kg–1.h–1 in summer season and 1.7 × 10–5 to 9.6 × 10–5 Bq.kg–1.h–1 with an average of 5.5 × 10–5 Bq.kg–1.h–1. A weak negative correlation was observed between radon exhalation rate from soil and radon concentration in the soil. Radon exhalation rate from the soil was also not found to be correlated with the gamma dose rate, while it shows a positive correlation with radon concentration in water in summer season. Inter-correlations among various parameters are discussed in detail.Variation of radon concentrations in soil and groundwater and its correlation with radon exhalation rate from soil in Budhakedar,Garhwal Himalaya Ganesh Prasad, Yogesh Prasad, G S Gusain, Manjari Badoni, J M S Rana and R C Ramola* Department of Physics, H N B Garhwal University, Badshahi Thaul Campus, Tehri Garhwal-249 199, Uttarakhand, India E-mail : [email protected] of Physics, H N B Garhwal University, Badshahi Thaul Campus, Tehri Garhwal-249 199, Uttarakhand, Indi

Technical Assessment of Large Scale PEM Electrolyzers as Flexibility Service Providers

To counter the inherent intermittent and unpre dictable power generation from large amounts of wind and solar, fast-acting resources are required, one of the options being sector coupling via power to gas devices. Industrial Power to Gas (IPtG) resources, such as an electrolyzer, represent an attractive solution to satisfy the rising energy flexibility needs of renewable-rich power systems. Since these electrolyzers can be asked to respond quickly following steep power ramps of renewables, it is imperative to understand their capabilities and limitations in fulfilling such requirements. The contribution of this paper is twofold. First, we introduce a detailed model of a Proton Exchange Membrane (PEM) electrolyzer suitable for power system flexibility studies. Second, using this model we assess large scale electrolyzer as a flexibility service provider (FSP) to the grid. To evaluate electrolyzer performance, we construct the V-I characteristic curve before and after simulating each test case to derive insights on the influence of time and dynamic operation on the electrolyzer system.</p