DESERT SOLAR POWER INDIA: A SYSTEMATIC STUDY OF POTENTIAL DEVELOPMENT OF SOLAR POWER IN THE INDIAN DESERT

The deserts of Rajasthan have long been known for their spare beauty and their intense sunshine. Now that sun is being turned into a surge of solar power expansion that may one day power not just Rajasthan but a wide swath of India with clean energy. Rajasthan, with its 300 days a year of sunshine and relatively cheap desert land, has set a goal even more ambitious than Indias. In this years state budget, the newly formed state government announced it hoped to install 25,000 megawatts of solar energy in the state within the next five years, and infrastructure to transmit that power to the national grid. Rajasthan is no newcomer to renewable energy. Since the 1990s, the state has been home to a range of wind energy projects, with about 2,800 megawatts of wind capacity now installed, out of an estimated potential capacity of 5,000 megawatts. Altogether wind power in Rajasthan accounts for about 13 percent of Indias wind energy production. But Rajasthans Great Indian Thar Desert, the test site for Indias first underground explosion of a nuclear weapon 15 years ago, may now help make India a solar power as well. The desert set in Rajasthans largest district Jaisalmer, near the border with Pakistan, it is a place of sand dunes and shrub thickets – but also, increasingly, solar installations that could help change the character of Indias energy development. India committed at the U.N. Framework Convention on Climate Change negotiations in Copenhagen in 2009 to reduce its climate-changing emissions, per unit of GDP, by 20 to 25 percent by 2020, compared to 2005 levels. The country is currently the worlds seventh largest emitter of global warming pollution and the fifth biggest producer of emissions from burning fossil fuels. Sixty-eight percent of those emissions from fossil fuel use come from creating energy for the worlds second most populous country, according to Indias energy ministry. Today the country has 2.28 million megawatts of power generating capacity, and about 12.4 percent of that comes from renewable energy. Of the 2,632 megawatts of solar power now installed in India, Rajasthan so far has only 730 megawatts, putting it in second place behind the state of Gujarat, with 916 megawatts, according to Indias Ministry of New and Renewable Energy. But Rajasthan, Indias largest state and 60 percent covered by sunny desert, is now attracting the worlds interest as a solar hotspot. Around 1 lakh (100,000) square kilometers of barren land is available in the northwest arid belt of the state at cheaper rates that could be utilized for large scale solar projects. The government is formulating the policy to harness the enormous solar potential of the region to meet the countrys growing energy requirements. Besides large solar installations, the government is studying the possibility of grid-connected rooftop solar photovoltaic units for households. The Solar Energy Corporation of India estimates that 130 million homes could potentially be equipped with the units, creating 25,000 megawatts of generating capacity. said Alok, Rajasthans Energy Secretary.

Application of Sentinel-1 Radar Remote Sensing Data for Detecting Nuclear Test Location in North Korea on September 3, 2017

Sentinel-1A/B radar remote sensing data were applied for the first time to determine the sixth nuclear test, its underground explosion h-bomb location and affected zone in North Korea, on September 3, 2017. Location of epicenters nuclear test were found according to line-of-sight displacement images via its maximum value. Line-of-sight displacement images were obtained by processing in the GMTSAR package in the VirtualBox virtual machine of the Linux Ubuntu 16.04 operation system. In this research, three scenes Sentinel-B data with descending orbits were considered, one after and two before the event (the nuclear test date) scene were used.

Hypothesis Tests on Rayleigh Wave Radiation Pattern Shapes: A Theoretical Assessment of Idealized Source Screening

Summary Shallow seismic sources excite Rayleigh wave ground motion with azimuthally dependent radiation patterns. We place binary hypothesis tests on theoretical models of such radiation patterns to screen cylindrically symmetric sources (like explosions) from non-symmetric sources (like non-vertical dip-slip, or non-VDS faults). These models for data include sources with several unknown parameters, contaminated by Gaussian noise and embedded in a layered half-space. The generalized maximum likelihood ratio tests that we derive from these data models produce screening statistics and decision rules that depend on measured, noisy ground motion at discrete sensor locations. We explicitly quantify how the screening power of these statistics increase with the size of any dip-slip and strike-slip components of the source, relative to noise (faulting signal strength), and how they vary with network geometry. As applications of our theory, we apply these tests to (1) find optimal sensor locations that maximize the probability of screening non-circular radiation patterns, and (2) invert for the largest non-VDS faulting signal that could be mistakenly attributed to an explosion with damage, at a particular attribution probability. Lastly, we quantify how certain errors that are sourced by opening cracks increase screening rate errors. While such theoretical solutions are ideal and require future validation, they remain important in underground explosion monitoring scenarios because they provide fundamental physical limits on the discrimination power of tests that screen explosive from non-VDS faulting sources.

Seismoacoustic analysis of underground explosions using the Rayleigh integral

SUMMARY A coupled seismoacoustic model is developed for the analysis of acoustic signals produced by underground explosive events with an aim to develop a means of improving estimated depth and yield for explosion monitoring. A ground spall model is used to predict surface motion characteristics produced by an underground explosion and the Rayleigh integral is applied to relate the surface motion to the acoustic signal some distance from surface ground zero. The low-frequency component of the ground motion associated with the prolonged free fall of lofted material during spall is found to dominate the acoustic signal propagating away from surface ground zero at shallow angles. The model is applied to observed ground motion and acoustic signals recorded during the Source Physics Experiment (SPE) with promising results. In addition to accurately predicting characteristics of the observed acoustic signals from several of the SPE events, the model provides a means of explaining the lack of signals observed during several events in the SPE due to the directionality of the higher frequency acoustic signals associated with the uplift and closure components as well as the lack of a spatially localized, longer duration dwell.

Uncertainty Propagation and Stochastic Interpretation of Shear Motion Generation due to Underground Chemical Explosions in Jointed Rock

<p>We have performed 3D simulations of underground chemical explosions conducted recently in granitic outcrop as part of the Source Physics Experiment (SPE) campaign. The main goal of these simulations is to understand the nature of the shear motions recorded in the near field considering uncertainties in a) the geological characterization of the joints, such as density, orientation and persistency and b) the geomechanical material properties, such as, friction angle, bulk sonic speed, poroelasticity etc. The approach is probabilistic; joints are depicted using a Boolean stochastic representation of inclusions conditional to observations and their probability density functions inferred from borehole data. Then, using a novel continuum approach, joints and faults are painted into the continuum host material, granite. To ensure the fidelity of the painted joints we have conducted a sensitivity study of continuum vs. discrete representation of joints. Simulating wave propagation in heterogeneous discontinuous rock mass is a highly non-linear problem and uncertainty propagation via intrusive methods is practically forbidden. Therefore, using a series of nested Monte Carlo simulations, we have explored and propagated both the geological and the geomechanical uncertainty parameters. We have probabilistically shown that significant shear motions can be generated by sliding on the joints caused by spherical wave propagation. Polarity of the shear motion may change during unloading when the stress state may favor joint sliding on a different joint set. Although this study focuses on understanding shear wave generation in the near field, the overall goal of our investigation is to understand the far field seismic signatures associated with shear waves generated in the immediate vicinity of an underground explosion. Therefore, we have abstracted the near field behavior into a probabilistic source-zone model which is used in the far field wave propagation.</p><p>This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344</p>

Infrasound from the North Korea underground explosion and subsequent collapse on 3 September 2017

<p>Strong ground motions induced by North Korea’s declared underground nuclear test in September 2017 and a subsequent subsurface collapse excited substantial and characteristic atmospheric acoustic waves (infrasound) that were detected by multiple stations at regional distances. Back-projection method is applied to the detected long-lasting coherent infrasound wavetrains related to the nuclear test. This allows to reconstruct source locations and reveals ground-to-air coupling in a large area over the northeast Korean Peninsula. To understand the excitation of atmospheric acoustic phases from the underground sources, full 3-D seismo-acoustic simulations are performed with pre-defined seismic moment tensor solutions of the underground sources. The simulations quantitatively predict the excitation of epicentral and diffracted acoustic phases developed by direct vertical ground motion at the immediate epicenter and by seismic surface waves propagating through high mountainous regions, respectively. In the atmosphere, the direct acoustic phases propagate spherically at the speed of sound, but the diffracted phases form inclined wavefronts in the atmosphere as the surface wave moves away from the epicenter. On a broad scale, the simulated acoustic coupling shows good agreement with the infrasound radiation patterns determined from the infrasound observations. Additional simulations for the subsequent subsurface collapse event show that an underground cavity collapse can be a potential mechanism for the production of low-frequency acoustic energy that is also detectable at regional distances. Finally, this study highlights the link between ground motions caused by underground sources and infrasound detection, further enabling infrasound as a depth discriminant for subsurface sources.</p>

Detecting explosion-induced dynamic phenomena using time-lapse seismic surveying

<p>Characterization of seismic events as underground nuclear explosions is a challenging task. Geophysical methods such as seismic monitoring systems are used by CTBTO to link post-explosion phenomena to potential sources. The main challenges in seismic monitoring involve accurately locating of sources and separating underground variations in seismic properties due to the explosion from naturally occurring variations. Underground detonations result in an immense change in pressure and temperature concentrated around the source origin. This results in the formation of characteristic static and dynamic phenomena. This study highlights the potential of using time-lapse seismic to identify ground zero by monitoring post-explosion dynamic phenomena. Time-lapse seismic, also known as 4D seismic, is successfully employed in the oil and gas industry for petroleum production monitoring and management. It involves taking more than one 2D/3D seismic at different calendar times over the same reservoir and studying the difference in seismic attributes.</p><p>Following an underground explosion, dynamic changes in rock and fluid properties are observable for a prolonged period, even up to several decades. This is prominent near to source origin, and it is a result of the redistribution of residual energy, such as pressure, temperature, and saturation. Frequent seismic monitoring surveys (time-lapse seismic) enables one to monitor the changes in rock and fluid properties. This study presents the characteristics of the time-lapse seismic signature observed in a heterogeneous medium (or heterogeneous cavity). We will look into the impact of factors affecting land 4D repeatability on the 4D signature. The significance of identifying the 4D signature related to the explosion in a seismic section, and the feasibility of detecting it during the OSI with resource and time constraints in place will be discussed. We present a fast detection method using a convolutional neural network for the detection of explosion related time-lapse signature, which could be an identifier of the source location or ground zero.</p><p>Acknowledgments: Authors would like to thank EPSRC and AWE for funding this project.</p>