Moving water from an available reservoir source to a distant storage location for irrigation distribution, or other use, without incurring high initial system costs, installation expenses and recurring operational costs is a fundamental problem found throughout the world; in particular Ethiopia, Niger and other drought stricken areas. One method of overcoming these problems is outlined in this technical brief.
There have been a variety of developments over the years involving the use of Solar Energy to accomplish water pumping for irrigation and other uses with the use of Solar Stirling Hot Air Engines among these, however it appears no viable low cost, easy to use, portable products are commercially available.
This proposal presents a stand alone, self powered, low maintenance Solar Powered Irrigation water pumping example which is a follow-on application of an earlier NTB entry entitled “The World’s Most Versatile Tracking Solar Collector-Concentrator” and is based upon that presentation’s Tracking Solar Collector-Concentrator (TSCC). Reference:
Benefits and features found in TSCC are leveraged to form an extremely efficient Hot Air Engine configured to drive two single stage centrifugal type water pumps located at each side of the engine.
An example 24 inch diameter primary conic reflector can provide near 380 Watts of solar energy (thermal chamber temperatures > 600ºC) on a clear day. This equates to about ½ horsepower; or with 50% system losses, to around ¼ horsepower running approximately 3000 revolutions per minute (3K RPM). Efficient Stirling engines tend to be bulky however this is not a problem for TSCC configurations as the engine and pumps are located at ground level, or in this case below ground. TSCC height extension sections allow increasing the height of the collector-concentrator while still taking advantage of below ground installations. The entire TSCC unit is enclosed and sealed using bellows, a chamber window and an integrated transparent collector rim cover. An internal flywheel motor/generator supplies battery charge and starter functions.
A diagram showing the general irrigation concept, solar powered pump configuration and technical implementation scheme are provided.
Although not sophisticated, this approach places Solar Pump Stations at rise/run distance intervals, as required, to achieve a usable flow rate, including surplus needs for cloudy periods along the route.
Key to this application is the TSCC efficiency, low initial unit cost, the long trouble free operating cycle of Stirling engines, easy site transport, simplified installation with easy re-configuration options with no long term operating costs.
In summary; this proposal outlines a viable, low cost, reliable irrigation system.