Hydroelectric Engineering Design Analysis: Resource Evaluation
Hydroelectric design requires three basic steps: 1) power demand estimation; 2) hydrologic resource determination; and 3) electrical engineering. It may be first advantageous to know or have an idea whether AC-Direct or micro-hydro will be the technology pursued. However, this decision does not have to be made up front and can be a logical outgrowth of the design (and discovery) process. The step by step design analysis process outlined below is certainly not the only way to approach hydroelectric system design but should be sufficiently comprehensive to determine if it is a viable alternative for the application in question.
1) Power Demand Estimation. Just as in all alternative energy evaluations, the first step is to determine how much power will be needed in the residence, commerce, or community for which the hydroelectric installation is being evaluated. For this analysis we need to know the specific appliances to be used, their electrical power demand (in watts), the number of hours per day that the appliances are expected to be used during peak usage periods, and the degree of simultaneity of usage, or how many appliances can be reasonably be expected to be used at the same time. A table summarizing typical power demands of typical household appliances, equipment, and tools is given here. To calculate the power demands of your application, download the power demand estimation excel spreadsheet and enter in information for all of the appliances and equipment for your application according to the instructions at the bottom of the sheet.
2) Hydrologic Field Assessment. In order to do a resource evaluation to determine the hydroelectric potential of the target stream, you will need a mechanism for measuring or estimating flow rate, an altimeter, and a means for measuring distance, for which the ideal tool is a Geographic Positioning System (GPS). First step is to determine the best locations for a water intake and for turbine location. Although river conditions bare on these decisions, commonly you are looking for the highest point on your property with good water flow for an intake and the lowest point on your property for an intake. If you have lots of water and lots of head, then you have more flexibility and may use other factors as criteria, such as transmission distance to the point of usage as a criterion for determine the generation point. Once you have determined key locations, then measure the altitudes at all points, the water flow rate at the prospective intake points and the distances between prospective intakes and prospective generation points.
3) Supply / Demand. Use the hydroelectric potential formula for determining the hydroelectric potential at the possible configurations. For flow rate do not exceed one half of the measured stream flow at the driest time of the year to make sure that sufficient flow is left in the stream for environmental integrity. At this point it is possible to determine whether your application can be satisfied with a mini-hydroelectric configuration or whether it can be satisfied only with micro-hydroelectric. This analysis assumes that there is no grid network to tie into. Where a grid-tie hydroelectric is planned, it is nearly always more economic to install a mini-hydroelectric system. Compare the instantaneous power demand that you calculated using the power demand estimation spreadsheet. This is the calculation done in Cell H68. If this number exceeds the hydroelectric potential calculated by use of the power formula, then your resources are not able to satisfy your demands using AC-Direct technology. To determine if micro-hydroelectric power is able to satisfy the power demand of the application, multiply the hydroelectric potential calculated by 24 hours in a day to determine the kilowatt-hour potential of the stream. Compare this with the kilowatt-hour demand of your applications. If the former exceeds the latter, then micro-hydroelectric power supply is viable for the application in question.
4) Continue the analysis by following the appropriate link according to the application that best suits the resources and power demand specific to your application: mini-hydroelectric (AC-Direct) versus micro-hydroelectric.
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