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Micro-Hydro Power Generation for Unattended Ground Sensors

Micro-Hydro Power Generation for Unattended Ground Sensors. May 5, 2005. Joint Service Power Expo. Richard McCall. 2904 44 th Ave N. St. Petersburg, Fl 33714. Unattended Ground Sensors for Jungle and Coastal Environments.

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Micro-Hydro Power Generation for Unattended Ground Sensors

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  1. Micro-Hydro Power Generation for Unattended Ground Sensors May 5, 2005 Joint Service Power Expo Richard McCall 2904 44th Ave N. St. Petersburg, Fl 33714

  2. Unattended Ground Sensors for Jungle and Coastal Environments • Narco-terrorists, gun smugglers, and other insurgents use jungle, riverine and coastal supply routes without much fear of interdiction • Unattended Ground Sensors (UGS) are being developed for various missions, threats, terrain • Sensor systems for anti-terrorism and riverine drug interdiction in jungle terrain pose unique power challenges

  3. Unattended Ground Sensors for Jungle and Coastal Environments • Even the lowest power unattended sensors don’t last more than 3 to 14 days • In riverine transit routes, it’s difficult to deploy long lasting sensors, and a stealthy, quiet, rechargeable capability is needed • Local submersible power generation capability is needed to recharge batteries and extend sensor lifetime

  4. Why Micro-Hydro Power ? • Need a simple, concealable recharging power source to achieve 30 to 180 days of unattended operation • Conventional gasoline generators are heavy, noisy • Solar power works in daytime only; is affected by weather and seasons, shaded by rain forest; is difficult to deploy • Fuel cells carry limited fuel, and additional fuel is bulky and heavy; impractical or lack maturity for jungle environment today

  5. The Case for Micro-Hydro Power • Wind and other power alternatives are difficult to conceal • Security Issue – submerged Micro-hydro power is essentially invisible • Seawater is 832 times as dense as air, so 5 knot current has as much kinetic energy as wind velocity of 168 mph. So abundant energy is available

  6. Problem Analysis • Assume power requirement: 12 VDC @ 1 to 2 amps 12 to 24 watts for charging batteries • Kinetic energy in a two-knot column of water moving past a 12 inch propeller : ½ m V2 = 41 watts • Betz’ Law: The maximum energy that can be extracted from this volume of water => 59 % or 24.5 watts • A commercial underwater generator with a 12 inch propeller measures 9.6 watts at 2 knots

  7. Commercially Available Generators • Most available, small, waterproof generators are designed for use on sailboats • No generators are available with impellers designed for very slow flow rates • None produce significant power below 2 knots • Conclusion: Must increase river current to 2 knots without use of a dam or falling water • A “Zero Hydrostatic Head” system is required. Try a venturi to increase flow rate

  8. Equipment Fan Generator Concept

  9. Venturi Transformer Analogy High Voltage Low Current Low Voltage High Current I1 V2 I2 V1 RL P = I1V1 P = I2V2

  10. Bernoulli’s Equation

  11. Venturi Generator Concept Diagram

  12. CME’s Design for Man-portable Micro-Hydro Generator • Venturi of lightweight, flexible material that automatically expands when de-packaged • May be low-profile to produce power in shallow river environments – inlet doesn’t have to be round • Flaps staked to the bottom using lightweight extendible poles, and weighted with river rocks • Wire inlet guard to protect generator from debris • Patented shape to improve impeller efficiency

  13. Rectify Alternator Output to DC

  14. Micro-Hydro Generator Prototype

  15. Prototype Field TestingRainbow River

  16. Prototype Field TestingFt. Desoto

  17. Prototype Field TestingFt. Desoto

  18. Prototype Field TestingFt. Desoto

  19. Prototype Micro-Hydro Generator Experimental Results • Continuous power was produced with a current of only 1.4 knots. Generator without venturi stalls below 1.6 knots. Venturi concept works. • Measured 6 VDC at 429 mA, into a 14  load, for a total of 2.57 watts. • Prototype venturi dimensions are too small for river currents less than one knot. • Venturi efficiency is considerably lower than anticipated

  20. Conclusions • Venturi generator concept is promising • Investigate ways to improve efficiency • Smoother surfaces and more streamlined transition • Investigate effect of using an outlet bell • Add flotation to heavy end of venturi until neutrally buoyant. Inlet must be normal to flow • CME is evaluating several custom generator concept designs to better handle low current flow rates

  21. Contact Information Richard E. McCall Custom Manufacturing & Engineering, Inc. 2904 44th Avenue North St. Petersburg, FL 33714 727-548-0522 x1899 RMcCall@Custom-Mfg-Eng.com www.custom-mfg-eng.com/

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