6.Mini-hydro power - Mini-Hydro Power 1 Introduction...

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Mini-Hydro Power 1. Introduction: Hydropower is energy from water sources such as the ocean, rivers and waterfalls. “Mini- hydro” means which can apply to sites ranging from a tiny scheme to electrify a single home, to a few hundred kilowatts for selling into the National Grid. Small-scale hydropower is one of the most cost-effective and reliable energy technologies to be considered for providing clean electricity generation. The key advantages of small hydro are: h High efficiency (70 - 90%), by far the best of all energy technologies. h High capacity factor (typically >50%) h High level of predictability, varying with annual rainfall patterns h Slow rate of change; the output power varies only gradually from day to day (not from minute to minute). h A good correlation with demand i.e. output is maximum in winter h It is a long-lasting and robust technology; systems can readily be engineered to last for 50 years or more. It is also environmentally benign. Small hydro is in most cases “run-of-river”; in other words any dam or barrage is quite small, usually just a weir, and little or no water is stored. Therefore run-of-river installations do not have the same kinds of adverse effect on the local environment as large-scale hydro. 2. Hydro Power Basics: h Head and Flow Hydraulic power can be captured wherever a flow of water falls from a higher level to a lower level. The vertical fall of the water, known as the “head”, is essential for hydropower generation; fast-flowing water on its own does not contain sufficient energy for useful power production except on a very large scale, such as offshore marine currents. Hence two quantities are required: a Flow Rate of water Q , and a Head H . It is generally better to have more head than more flow, since this keeps the equipment smaller. The Gross Head (H) is the maximum available vertical fall in the water, from the upstream level to the downstream level. The actual head seen by a turbine will be slightly less than the gross head due to losses incurred when transferring the water into and away from the machine. This reduced head is known as the Net Head.
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Flow Rate (Q) in the river, is the volume of water passing per second, measured in m 3 /sec. For small schemes, the flow rate may also be expressed in litres/second or 1 m 3 /sec. h Power and Energy Power is the energy converted per second, i.e. the rate of work being done, measured in watts (where 1watt = 1 Joule/sec. and 1 kilowatt = 1000 watts). In a hydro power plant, potential energy of the water is first converted to equivalent amount of kinetic energy. Thus, the height of the water is utilized to calculate its potential energy and this energy is converted to speed up the water at the intake of the turbine and is calculated by balancing these potential and kinetic energy of water. Potential energy of water Ep = m*g*H
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This note was uploaded on 05/05/2011 for the course FC gj, taught by Professor Glokgh during the Spring '97 term at Punjab Engineering College.

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6.Mini-hydro power - Mini-Hydro Power 1 Introduction...

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