Institute of Operating Systems and Computer Networks A Feasibility Study on Energy Harvesting from Soil Temperature Differences Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf, 2018-11-04
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Smart Farming 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 2 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Smart Farming: Challenges Problem: Solar cells not possible Nodes near surface of soil Lots of dirt, no sun due to crops 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 3 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Idea: Harvest from soil 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 4 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Setup INGA WSN node ID0 (IEEE 802.15.4) WSN node ID1 ID2 Surface ID0 ID3 Temperature sensors ID1 2cm Deployment ID4 ID2 8.5cm ID3 15cm ID5 ID4 21.5cm ID5 28cm ID6 ID6 34.5cm ID7 41cm ID7 ID8 47.5cm ID8 duration: 1 year, sample rate 10s, data are available 1 1 https://www.ibr.cs.tu-bs.de/projects/reap/soil_temp.html 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 5 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Examplary Data 12 11 10 9 8 7 6 5 4 3 2 1 2016-10-25 2016-10-25 2016-10-25 2016-10-26 2016-10-26 2016-10-26 2016-10-26 ID=0 (Surface) ID2 (8.5cm) ID4 (21.5cm) ID1 (2cm) ID3 (15cm) ID5 (28cm) First week 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 6 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Results 12.5 positive T negative T 10.0 7.5 5.0 Average T [°C] 2.5 0.0 2.5 5.0 7.5 6 6 7 7 7 7 7 7 7 7 7 7 7 1 1 1 1 1 1 1 1 1 1 1 1 1 . . . . . . . . . . . . . 1 2 1 2 3 4 5 6 7 8 9 0 1 1 1 0 0 0 0 0 0 0 0 0 1 1 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 0 0 0 0 0 0 0 0 0 0 0 0 0 Gaps due to battery exchange 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 7 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Temperature vs. depth 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 8 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Conclusion 12.5 positive T negative T 10.0 7.5 5.0 Average T [°C] 2.5 0.0 2.5 5.0 7.5 6 6 7 7 7 7 7 7 7 7 7 7 7 1 1 1 1 1 1 1 1 1 1 1 1 1 . . . . . . . . . . . . . 1 2 1 2 3 4 5 6 7 8 9 0 1 1 1 0 0 0 0 0 0 0 0 0 1 1 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 1 . 0 0 0 0 0 0 0 0 0 0 0 0 0 Temperature differences of several degree every day Exception: transition period (spring, autumn) Q: can we actually harvest energy? 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 9 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion General Idea Temperature Data P ( ∆ T )[ W ] Feasability Simulation 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 10 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Setup Chamber left Chamber right Metal Metal TEG Fan Fan Load How much energy can we produce? Electronic load to simulate harvester+microcontroller 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 11 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Setup Chamber left Chamber right Fixed value for load, cycle through temperatures (10-50 ◦ C) Constantly measure temperature Metal Metal TEG Fan Fan In chamber ( T C ) Near element ( T E ) But: | T C − T E | ≫ 0 Result: | T C − T E | → E Load 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 11 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Results 2nd Experiment: Fixed temperature, cycle through resistance (MPPT) 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 12 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Harvesting Model Temperature gradient in chamber differs from the one at TEG ⇒ factor h is introduced P ( ∆ T , h ) = h · ( a · ∆ T 2 + b · ∆ T + c ) [ W ] with TEG specific a,b and c Store harvested energy Estimate the energy collected by a simulated harvester 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 13 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Harvestable energy with different efficiency η Soil temperature experiment → harvested energy per month Best case 1.2 Average case Worst case Positive Polarity 1.0 Negative Polarity Total energy [Wh] 0.8 0.6 0.4 0.2 0.0 Okt 16 Nov 16 Dez 16 Jan 17 Feb 17 Mär 17 Apr 17 Mai 17 Jun 17 Jul 17 Aug 17 Sep 17 Okt 17 Nov 17 Best Case η = 99 % , h = 99 % Average Case η = 60 % , h = 41 % Worst Case η = 20 % , h = 20 % 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 14 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Sample Application Energy Store Observe Simulate a virtual node Slots in simulation, where: Energy is harvested Harvester MCU data is sensed, and (MCU active) transmitted if possible (Radio active) Control Additionally, MCU can sleep (MCU alive) Radio 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 15 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Slot Example Radio active MCU active MCU alive 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 16 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Active states 100 Slots MCU alive Slots MCU active Slots Radio active 80 Usable slots [%] 60 40 20 0 10.04.17 12.04.17 14.04.17 16.04.17 State is entered, if there is enough energy 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 17 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Transmitted frames 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 18 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
Introduction Soil Temperature Experiment Peltier Experiment Simulation Conclusion Conclusion Long-term experiment with soil temperatures from 8 depths Temperature-controlled chambers with TEG to model harvestable energy from ∆ T Simulated WSN Application: 7.5 packets per hour in winter, 40 in summer Next step: deploy an actual system! 2018-11-04 Sven Pullwitt, Ulf Kulau, Robert Hartung, Lars Wolf Page 19 A Feasibility Study on Energy Harvesting from Soil Temperature Differences Institute of Operating Systems and Computer Networks
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