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Renewable energy from polymer

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Renewable energy from polymer

  1. 1. E.P.A.M
  2. 2. Stretched State Contracted state
  3. 3. Dielectric elastomers are particularly promising Conducting Polymers Dielectric elasromers Electrostrictive Polymer Artificial Muscle Gels Thermal and Others Nanotubes
  4. 4. With these assumptions the electrical and mechanical aspects of the system are separately and together lossless in the sense that energy is conserved during changes of state(from stretched to compressed and vice versa).
  5. 5. Principle of operation:- A V2 +++++++++ +++++ Z _______________ Charge=Q V1 = V bias A+dA +++++++++++++++++++++ ____________________ Z-d Z Charge= Q Consider a general case, Let the electrostatic energy “U” stored in the initial stage is U=(Q^2/2C) where C=єA/Z where є is the permittivity of the dielectric. As the dimensions changes there will be change in “U”.
  6. 6. The Second term in the dU comes from the Mechanical Energy of the polymer. Consider the situation when dQ=0(That is there is no external electrical power source during the change of state). Then we have dU= U*(dZ/Z-dA/A). As for an elastomer volume is constant we have volume =K A*Z=K => A*dZ + Z*dA =0 =>dZ/Z = -dA/A substituting this relation in above relation we have dU = U*(2dZ/Z) or dU= -U*(2dA/A). From the above relations we can say that the Electrostatic energy increases if dZ is ‘+’ that is Z increases, in other way Electrostatic energy increases if dA is negative ie A decreases.
  7. 7. Que: From Where Does this Energy come? It takes some positive work for any stretching force to stretch the EAPM , when an EAPM is stretched by that force it stores the work done by that force as mechanical energy in it.(It is analogous to that of stretched spring).Now when the force is removed it will convert this mechanical energy to Electrostatic energy that we can use for power generation.
  8. 8. Practical Approach :The cycle for Power Generation:
  9. 9. Practical approach: EAPM in stretched state connected to battery EAPM in contracted state supplying power to load.
  10. 10. Factors effecting the power generated ‘u’: As shown previously we have dU= U*2dz/Z =>∫dU/U = 2* ∫dZ/Z (integrating under suitable limits) =>ln (U2/U1) = 2*ln (Z2/Z1) =>U2/U1= (Z2/Z1)^2 U2=U1*(Z2/Z1)^2 now we know U2-U1=u; u=U1* ( (Z2/Z1)^2 -1) we know U1 =Q^2/(2*C1) As Q=C1*V (V=V bias) we have U1 = ½ C1(V^2) and we know that (Z2/Z1)^2=C1/C2 because C1/C2 =A1*Z2/A2*Z1,put A1=K/Z1 and A2=K/Z2. Substituting these in the above equation for u we have u=0.5*C1*(V^2)*((Z2/Z1)^2) -1) u=0.5*C1*(V^2)*((C1/C2) -1)
  11. 11. Factors effecting the power generated ‘u’: From the above equations we can see that The Electric energy generated by the EAPM is directly proportional to the square of bias Voltage V bias. u œ V^2. And we can also notice that u œ (Z2/Z1)^2 This ratio depends on the elastic properties of the material like stress , strain relations. If a material is more elastic than Z2/Z1 increases as now it can be compressed more so as Z1 decreases and Z2/Z1 increases and u increases. If a material has more energy storing ability per unit volume then that will give more generated energy ‘u’ We had assumed there are no losses any where in the system but in reality there will be some losses because of finite resistances of electrodes, some leakage current through Dielectric material ,Hysteresis loss in the polymer etc.
  12. 12. ⁺ ⁺ Bias Bias ⁻
  13. 13. Experimental result matching the theoretical expectations: The voltage wave generated for one impact in the case of As expected we can see the exponential decay of voltage. EPAM it is on the order V2 . of 150-200 ms [time]. Discharging This is one of the capacitor through significant drain resistor characteristics of EPAM. The long pulse V=bias voltage duration and the high energy density of EPAM in power generation mode helps in mechanical energy to be be effectively converted to electric energy even at low frequencies
  14. 14. Developments and advances in EAPM technology: Thus we can use EAPM as a medium for power generation from mechanical energy with efficiency as high as(80%). There are many areas where this technology has given V2 fruitful results for power generation. . Some of them include Heel strike generators , Power from ocean waves , wind etc. Research is still on for the commercial use of these technologies. SIR international is working in this field and now they are in the process of developing polymer engine. They had successfully developed generators and actuators.
  15. 15. Defense Advanced Research Projects Agency’s(DARPA) Heel strike generator: DARPA developed a heel-strike + Dielectric Elastomer (EAP) generator to capture free energy + _ + _ _ while walking +Vout + _ Demonstrated up to 0.8 J per heel _ + +Vin strike V2 Base Developed multi-layer polymer Compliant Electrodes fabrication techniques . EXPANDED Demonstrated 15 layer device + + + +Vout + _ _ __ + +Vin _ CONTRACTED Heel-Strike generators are expected to produce 1W of power under normal walking conditions
  16. 16. Other significant contributions from EAPM technology : Potential applications of EAPM’s cover areas like actuators sensors , robotics, in medicine as an alternative for the muscle etc. . actuators sensors Applications in robotics for electrically controlled muscle like movements.
  17. 17. .
  18. 18. References: IEEE journal :Current Status and Future Prospects of Electric Generators Using Electroactive Polymer Artificial Muscle. IEEE journal: Innovative wave power generation systems using Electroactive Polymer Artificial muscles. SPIE journals. . Book : Dielectric Elastomers as Electromechanical transducers. Edited By: Federico Carpi , Danilo De Rossi, Roy Kornbluh ,Ronald Perline and Peter Sommer-Larsen Scientific American article –OCT 2003. Google Search engine.

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