Feb 2019 / by Anders Ahnger, Bent Iversen and Mikael Frejman
Denmark has taken a proactive role in adapting to the changing needs of the energy market. The rest of Europe can learn from this example. Power for a changing world” was a well known marketing slogan used by Wärtsilä Power Plants in the early 90´s. Today the slogan is even more appropriate, especially in Europe, with new renewable power generation, such as wind, solar, etc., becoming a strong part of the energy market.
Feb 2019 / by Ajay Kumar Pandey
In developed countries, most of the hydropower potential has been harnessed. However, India’s hydropower sector has not made the progress it should have made to tap the abundant potential available in the country. In fact, it has miserably lagged behind the other sectors. Most of the hydro potential in the country is remotely located in the young geology of Himalayan Mountains which have their inherent challenges and are difficult to execute. The resistance from natives and land owners, law and order situation, poor logistics, harsh climatic conditions etc. adds to the difficulties of the hydropower developers. The said difficulties clubbed with abnormal delays in various statutory clearances have practically curtailed the growth of the sector. During the last ten years i.e. from financial year 2007-08 to 2017-18, just 8,401 MW has been added. Percentage of hydro as compared to other sources has come down drastically from 45% in 1970 to 13.1% by the end of October, 2018. Although various hydro power projects have been allotted to IPPs, but only few private sector projects have been cleared so far. Today a hydropower developer has to face the uphill task of delays and non-clearances on techno-economic, environment and forest aspects in addition to the opposition of green lobbies and local inhabitants. These factors have made concept to commissioning of the project, i.e. gestation period, too long resulting in a negative perception about the hydro sector as far as its viability and actual investment in the sector is concerned. Reduction in gestation period right from allotment of the project to the stage of revenue realisation is very important. Otherwise, developers and investors will not find enough value in venturing into hydro projects.
This article is a rudimentary effort to fill this gap and make the hydro sector a preferred destination for the development. Relevant existing policies of the government have been touched upon as required while discussing the bottlenecks encountered in accelerating hydropower sector development. Detailed and point wise way forward is also suggested based on the real issues and challenges on the ground. The issues and challenges discussed in this study will make the governing authorities entrusted for accelerated development of hydropower sector in India to understand, make procedures and take decisions to arrest the value erosions in the sector. As a hydropower professional, it is author’s personal reflection, which has emerged out of his day to day experiences in developing hydropower projects in India.
Jan 2019 / by N. Kuppuswamy and P. Sridharan
The most important effects of cavitation are major damages to the solid surfaces, vibration, and reduction in turbine efficiency which have been experienced in this study with a model analysis where a bulb turbine model is tested for cavitation phenomena at various guide vane and runner vane openings. Further plant cavitation factor, critical cavitation factor, critical cavitation factor by solving empirical equation and percentage of reduction in turbine efficiency are calculated for the specific speed of the model turbine. The model test report for critical cavitation factor and turbine efficiency are compared to the analytical results and found a reduction of 1 to 1.53 percentage of turbine efficiency during cavitation region operation. The empirical formula derived for the critical cavitation factor is compared to an actual critical cavitation factor and found both are comparatively same. Hence the empirical formula for cavitation is recommended for arriving the critical cavitation factor for a particular operation of the prototype turbines in the power stations without model studies which is an advantage for selecting the safe operation of bulb turbine installed in the most of the hydropower stations.
Keywords: Bulb turbine model study, critical cavitation factor, specific speed
Jan 2019 / by Dharmveer and Sabyasachi Dasgupta
Selecting Rishiganga Hydroelectric Project as a study area, we studied the effect of flow diversion on soil moisture (%) and diameter increment (cm/year) of Pinus wallichiana A. B. Jacks. Soil moisture was analysed for all three flow conditions (Natural, diverted and altered) for both banks of the river separately at the depth 0-15 cm. To analyse the effect of flow diversion on growth of P. wallichiana the five year diameter increment (cm) were analysed in pre-diversion (2006-2010) and post-diversion (2011-2015) periods. All trees were categorized into two age classes (10-20 and 20-30). Dendrochronological method was used measure the diameter increment per year. The right bank showed relatively higher soil moisture than left bank except in altered conditions. When comparing all three sites in both banks, the moisture content decreased significantly in diverted conditions as compared to other flow conditions. In diverted conditions, the mean diameter increment per year (cm) was more in pre-diversion period in both age classes which decreased significantly in post-diversion period. The decline in diameter increment in altered conditions was not statistically significant. The lowest increment was recorded in the year 2015 in post-diversion period. Trees of lower age class found to be more sensitive to water stress because the roots of young trees are spread in upper layer and use more water from surface layer. As the precipitation in pre- and post-diversion differed non-significantly, it can be suggested that there was no effect of precipitation on diameter increment of trees and declining growth in diverted conditions is due to the water stress on plants as the soil moisture content also decreased in this condition.
Keywords: Hydropower project, dendrochronology, flow conditions, Garhwal Himalaya, diameter increment, water stress, age class, environmental flow