REASONS FOR HIGH INVESTMENT ON INITIAL SCHEMES BY SEBs
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The SEBs of various states had developed a few pilot schemes at a very high cost and hence there was a doubt within GOI about the viability of such schemes.
1. The study revealed the reasons why mini hydro was thought to be uneconomical by the SEBs. The main reasons were they had conceived, designed and executed the initial pilot schemes as scaled down versions of large conventional hydro installation.
|2. There were a large number of
redundancies in the design of key features for layout such as civil
works, facilities incorporated in the power house structures, the
selection of turbine generator equipment and specification of electrical
switching and protection systems.
Hence these initial projects executed by the SEBs had shown very high implementation cost and escalation. Private sector implementation had proved to be unsuccessful.
|3. Most of the designs by the SEBs did not enumerate alternatives for the electromechanical equipment and civil works. For example the original designs specified use of "S" type full Kaplan units with a scaled down version of a large power house. Use of various alternative types of equipment suitable to project conditions such as upstream elbow, vertical shaft, siphon type, right angle gear drive would have reduced the cost substantially.||4. Minimal use of computer to process daily hydrological data was being made. Instead average monthly flow was being used to compute the flow duration curve with the result that the shape of the curve dictated a non-optimal value of installed capacity and number of units.|
|5. Most of the civil works concentrated on the use of a bypass canal by cutting the existing embankment of dams instead of using existing sluices by extending with a penstock. This dictated large excavation quantity and concreting which raised the estimated cost of the schemes.||6. Synchronous generators with complex excitation, governing and control system were specified in the original designs despite the presence of a strong grid in the vicinity. Use of induction machines will reduce the cost without the need for complicated control equipment.|
|7. The flow pattern in the canals and releases at irrigation dams are almost constant during a month. Hence fixed vane propeller turbines or with manually adjustable blades would have reduced the cost of electro mechanical equipment instead of the full Kaplan units. Also stainless steel was recommended in most specifications whereas cheaper Aluminium Bronze could have been used.||8. Power house was large due to necessity of housing all electrical equipment and the overhead crane. Redesign with simple outdoor equipment eliminates the need for power house. A mobile Crane would have been more economical and able to serve a number of adjacent power houses.|
|9. Due to the above relatively complex layout, the construction period was unacceptably high giving rise to cost escalation and interest during construction.||10. A large number of technical staff were being used to operate and maintain the initial schemes.|
|11. There was a need for application of techno economic concepts to improve the designs, minimize investment requirements, and enhance the economic merits of the schemes.||12. Lack of coordination between key agencies for developing such schemes and no clear accountability within SEBs for mini hydros.|
also addressed the issue of strengthening key agencies responsible for
mini hydro in the country. To achieve effective implementation of the
schemes for which funding would be made available to GOI by the World
Bank, it was suggested that
(a) IREDA's capacity should be strengthened so as to administer the funds to develop mini hydro based on design principles and approach brought out by the study.
(b) Staff of SEBs, professionals from private sector could be trained in planning, design and investigation of mini hydro schemes under DNES/IREDA sponsorship
(c) DNES should promote and support a nationwide effort to improve planning and policy formulation and to accelerate investigation and pre-feasibility studies for prospective schemes in other states assoiciated with irrigation structures
(d) SEBs should be strengthened especially in identification, investigation and preparation of preliminary designs for mini hydro prospects, and on project management involving the application of "cost centers" and project matrix arrangements.
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