DESIGN ASPECTS IN RUN OF THE RIVER PLANTS

Abstract

Hydropower is a renewable, non-polluting and environmentally benign source of energy. It is perhaps the oldest renewable energy technique for electricity generation. Run-of-the-river plants (RORP) which is one of the types of hydropower plants can be considered the best within the types of hydropower because of its•minimum impact on the environment. In this study aspects involved in the planning, layout and design of the RORP are described in brief. Starting with planning process and highlighting the main investigations required for planning, the issues involved in the design of the components of RORP are reviewed. It highlights the main issues to be taken into consideration during design, bearing in mind that the RORP are site unique projects. Two main components of ROR project, the diversion structure and the power channel, are studied in detail in this study. In the diversion structure some-times the geological, topographical and economical aspects favour building of a small concrete dam. This dam may have a gated spillway to discharge the flood water. As the dimension of the gates will influences in the volume of concrete used for the dam, this obviously will reflect in the overall cost of the structure. A study is carried out by taking eight different river cross sections and assuming four different elevations for the dam for each case to get the optimum ratio of the gate height to the structure height. The second component which is studied in detail is the power channel. The effects of the bed width-water depth (b/d) ratio on the cost of the channel are analyzed. The recommended b/d ratios given in the literature and their limitations are also discussed. Efforts are made to find out an equation for determining the depth of the water from the known parameters like discharge, velocity, and bed slope for a concrete lined channel, since most of the power channels are lined channels. An equation for finding the minimum possible discharge within specific velocity and bed slope, and an equation for finding the maximum possible velocity for a specific discharge and bed slope are also developed. These equations will eliminate the iteration process involved in finding the dimensions of trapezoidal section channel.