Course: REEC 120 Sustainability and Renewable Energy

Unit 9 Overview

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The hydrologic cycle is the movement of liquid in our environment. It rains, rains flow to rivers, rivers to oceans, water evaporates, and the cycle starts again. When talking about hydroelectric systems, one needs to look at a few items.  First the biggest thing to mention is that we take the flow of water in a river and convert its motion to kinetic motion of the turbine.  In order to achieve this we need water head. For every foot in elevation we get .4 PSI of pressure.

Have you ever noticed a water tower in your community?  It is about 200 feet in the air. Why?  Because it is cheaper and easier to take a small pump and move water up to 200 feet, which gives the water system a pressure of nearly 80 psi. Now we let the water flow down the tower and into our homes. The advantage is we use gravity in assisting us to get the water to where we need it to go.

The greater the height difference between the water level and the turbine, the more efficient it becomes. The outlet side of the turbine though can cause great disturbance as it churns up the river.  A problem noted in Belize.