Entity

Time filter

Source Type


Byravan S.,Center for Study of Science and Technology and Policy
Environmental Justice | Year: 2014

The article explores the effects that India's climate policy will have in the context of the country's existing development problems. India is expected to face severe challenges as a result of climate change and these will disproportionately affect the poor and the most vulnerable. The country's current climate policies nevertheless adopt an approach that seems unlikely to improve conditions for the poor, unless it shifts from a top-down, growth-oriented strategy towards prioritizing access to basic goods and services as a primary policy goal. © Copyright 2014, Mary Ann Liebert, Inc. 2014. Source


Kumar U.,Indian Institute of Technology Kanpur | Metya A.K.,Indian Institute of Technology Kanpur | Ramakrishnan N.,Center for Study of Science and Technology and Policy | Singh J.K.,Indian Institute of Technology Kanpur
Journal of the Electrochemical Society | Year: 2014

Performance of a lithium-ion based rechargeable battery is investigated using coupled battery model including heat and stress models via finite element method simulations. An effort is made to elucidate the importance of using diffusivity equation, in the model, as a function of lithium-ion concentration and temperature. Diffusivity expressions for both anode and cathode material are developed using atomistic simulations. Simulation results show ∼10% drop in the battery potential after 100 charge-discharge cycles. This decline in performance is attributed to the concentration gradient, heat generation and stress accumulation, substantiating the need to address these effects simultaneously. Finally, intercalation stress values due to the modified diffusivity expression are found to differ considerably with that due to the constant diffusion values used in earlier works. The findings validate the assertion that intercalation stress values depend greatly on the lithium-ion concentration based diffusivity expression. © 2014 The Electrochemical Society. All rights reserved. Source


Bhowmik A.,Technical University of Denmark | Malik R.,Indian Institute of Technology Kharagpur | Prakash S.,Indian Defence Research And Development Laboratory | Sarkar T.,Center for Study of Science and Technology and Policy | And 3 more authors.
Journal of Alloys and Compounds | Year: 2016

A high concentration of lithium, corresponding to charge capacity of ∼4200 mAh/g, can be intercalated in silicon. Unfortunately, due to high intercalation strain leading to fracture and consequent poor cyclability, silicon cannot be used as anode in lithium ion batteries. But recently interconnected hollow nano-spheres of amorphous silicon have been found to exhibit high cyclability. The absence of fracture upon lithiation and the high cyclability has been attributed to reduction in intercalation stress due to hollow spherical geometry of the silicon nano-particles. The present work argues that the hollow spherical geometry alone cannot ensure the absence of fracture. Using classical molecular dynamics and density functional theory based simulations; satisfactory explanation to the absence of fracture has been explored at the atomic scale. © 2015 Elsevier B.V. All rights reserved. Source


Kandagal V.S.,Center for Study of Science and Technology and Policy | Bharadwaj M.D.,Center for Study of Science and Technology and Policy | Waghmare U.V.,Jawaharlal Nehru Centre for Advanced Scientific Research
Journal of Materials Chemistry A | Year: 2015

Using first-principles simulations, we predict a high-performance solid electrolyte with composition Na10GeP2S12 for use in sodium-sulfur (Na-S) batteries. The thermodynamic stability of its structure is established through determination of decomposition reaction energies and phonons, while Na-ionic conductivity is obtained using ab initio molecular dynamics at elevated temperatures. Our estimate of the room-temperature (RT) conductivity is 4.7 × 10-3 S cm-1, which is slightly higher than those of other superionic solid electrolytes such as β″-alumina and Na3Zr2Si2PO12, currently used in practical high-temperature Na-S batteries. Activation energy obtained from the Arrhenius plot (in the range 800-1400 K) is 0.2 eV, which is slightly lower than the typical values exhibited by other ceramic conductors (0.25-1 V) (Hueso et al., Energy Environ. Sci., 2013, 6, 734). We show that soft Na-S phonon modes are responsible for its thermodynamic stability and the lower activation barrier for diffusion of Na-ions. Finally, the calculated electronic bandgap of 2.7 eV (a wide electrochemical window) augurs well for its safe use in sodium batteries. Opening up a possibility for realizing RT operation of Na-S batteries, our prediction of a new phase in the Na-Ge-P-S system will stimulate experimental studies of the material. © The Royal Society of Chemistry 2015. Source


Suresh N.S.,Center for Study of Science and Technology and Policy | Thirumalai N.C.,Center for Study of Science and Technology and Policy | Rao B.S.,Center for Study of Science and Technology and Policy | Ramaswamy M.A.,Center for Study of Science and Technology and Policy
Solar Energy | Year: 2014

A detailed methodology to design the size of solar field for a parabolic trough plant is not explicitly available in open literature, particularly if thermal storage and hybridization are also considered, as most of the papers present a gross overview. This paper gives a procedure to determine the annual electricity generated for a parabolic trough based solar plant of a given rated capacity (1-50. MWe), at a chosen location & given hourly annual solar input, specified hours of thermal energy storage using a two-tank molten salt system and specified fraction of hybridization using natural gas. In this methodology losses due to shut down or cloud cover are also covered. The size of the solar field is optimized for the maximum annual solar to electric conversion efficiency using the concept of solar multiple (ratio of actual aperture area to the reference aperture area needed to get rated power output at maximum solar input). This procedure is validated with the existing parabolic trough plants (Solar Energy Generating Systems VI and Solana Generating Station) and it was found that the annual electrical energy generated by the plant matches reasonably well.Jodhpur, in India, was considered as a location for the case study and the results are presented to understand the influence of thermal storage and hybridization for a given capacity of the plant. The results for various combinations of thermal storage hours and fraction of hybridization used with respect to plant capacity, solar multiple, annual plant efficiency etc. have been discussed in detail. It is observed from the results that, under design conditions, the reference aperture area per MW decreases as plant capacity increases and reaches a limiting value asymptotically at a capacity of 50. MW. The optimized size of the solar field, with respect to annual efficiency, is found to be 1.4 and 2.3 times the size under design conditions for zero and six hours thermal storage respectively. The benefit of hybridization is high for lower solar multiples. © 2014 Elsevier Ltd. Source

Discover hidden collaborations