... Thermal Investigations of Ics and Microstructures, Roma, Italy, October 4-6, 1999, pp .76 -81. Sustainable Energy Harvesting Technologies – Past, Present and Future 128 Dziurdzia P., Kos ... development TEGs will have better energy conversion coefficients of performance in the future. However, Sustainable Energy Harvesting Technologies – Past, Present and Future 114 In Fig. 4, a ... pp. 18- 27. Penn A. (1 974 ). Small electrical power sources, Phys. Technol, 5, 114,1 974 . Priya S., Inman D. J. (2009). Energy Harvesting Technologies, Springer, 2009, ISBN 978 -0-3 87- 76 463-4....