The following diagram depicts DoradoVista’s twelve steps to evaluate a Small or Micro Hydropower site. As mentioned last month we will be covering each of the twelve evaluation steps in more detail as we update our Small & Micro Hydropower posts. Again please add comments or questions to each post so that we can address your needs more adequately.
12 Step Small & Micro Hydropower Evaluation Process
June 11th, 2009 at 6:41 am
#4 PENSTOCK & CHANNELS…How do I determine the diameter of the pipeline(penstock) to carry a given amount of water i.e. 8gps, etc. to my turbine?
How does the ‘head’ affect the pressure and in turn the amount of water a given diameter pipe can deliver?
June 11th, 2009 at 5:55 pm
Penstocks and Channel designs will get a more thorough treatment in a future series of Posts. This is one key to success in any Hydro system design that we want to help you with. It will make or break your hydro ROI.
To start with there are several competing fluid dynamic interactions going on when water flows in a pipe. For optimum design of a hydro system you must consider each of these effects in unison to obtain a truly optimum design. Where an optimum design gives the best power output for a given water flow/head combination for the lowest overall cost.
Bigger pipes are more expensive and yet may pay off if they yield enough extra power. That’s part of why higher head is better in general, smaller penstocks and turbines result.
Head affects pressure as a linear function of water column or height (gravity and density.) In turn the pressure affects the volume flow of water through a jet in a way that increases with pressure.
Since both volume and pressure increase with height of water column (head) the net power output increases slightly faster with head than flow. (Power increases approximately with the head^3/2 power) Again, it’s generally better to increase head to max than to try and increase flow to max.
All that means it’s a tradeoff between power(energy value), efficiency and system cost.
The laws and tables involved can be tricky to use but we’ll try to help. In the mean time drop us a note if you have a specific design problem.
Jess
July 26th, 2009 at 10:15 am
I want to draw water from our creek to the top of the hill (50ft) by syphon then allow gravity to drain it down stream to a lower elevation continuing the syphon technique.. At the lower elevation discharge, I would like to install a power generation system. The syphon pipe and discharge would 6″ diameter. Given the equipment available today, “How much electrical power can be generated per kW hour?
Thank you for your assistance.
Steve