News Update on Power Generator : May 21

[1] MEMS power generator with transverse mode thin film PZT

A thin film lead zirconate titanate, Pb(Zr,Ti)O3 (PZT), MEMS power generating device is developed. It is designed to resonate at specific frequencies from an external vibrational energy source, thereby creating electrical energy via the piezoelectric effect. Our cantilever device is designed to have a flat structure with a proof mass added to the end. The Pt/Ti top electrode is patterned into an interdigitated shape on top of the sol–gel-spin coated PZT thin film in order to employ the d33 mode of the piezoelectric transducer. This d33 mode design generates 20 times higher voltage than that of the d31 mode design of the same beam dimension. The base-shaking experiments at the first resonant frequency (13.9 kHz) generate charge proportional to the tip displacement of the cantilever with a linearity coefficient of 4.14 pC/μm. A 170 μm × 260 μm PZT beam generates 1 μW of continuous electrical power to a 5.2 MΩ resistive load at 2.4 V dc. The corresponding energy density is 0.74 mW h/cm2, which compares favorably to the values of lithium ion batteries. We expect the next generation design with lower resonant frequencies would harvest sufficient energy from the environmental vibration for wireless miniature sensor networks.

[2] Design and fabrication of a new vibration-based electromechanical power generator

A device is described for generating electrical power from mechanical energy in a vibrating environment. The design utilises an electromagnetic transducer and its operating principle is based on the relative movement of a magnet pole with respect to a coil. The approach is suitable for embedded remote microsystems structures with no physical links to the outside world. Simulation, modelling and test results following fabrication of a first prototype have demonstrated that generation of practical amounts of power within a reasonable space is possible. Power generation of more than 1 mW within a volume of 240 mm3 at a vibration frequency of 320 Hz has been obtained.

[3] Micro electret power generator

We present the first micromachined rotational electret power generator, linearized theoretical model of electret power generation, and novel method to produce uniformly charged electret. We also improved our previously developed (1996, 1999) thin film Teflon AF 1601-S electret technology with respect to dielectric thickness, charge uniformity, and processability. In demonstration, our prototype power generator successfully generated > 25/spl mu/W with electret thickness of 9/spl mu/m, effective charge density of -2.8/spl times/10/sup -4/C/m/sup 2/, and rotational speed of 4170RPM.

[4] Energy Generation Using Thermoelectric Power Generator (TEPG) from the Living Body

In this paper, a general idea about wearable thermoelectric generator from the body heat has been discussed. First, a thermoelectric generator, which is usually used for industrial purposes (Tellurex-G2-40-0329 series), was used for lab experiment to observe the output results at the low-temperature difference (i.e., ΔT=6-18 K). At this temperature range, the power output was approximately 0.0192-0.35 µW which was very low for practical use. Different configurations of TEG (single, double, single TEG with fin, etc.) were used to find out the best one, which could generate maximum power. It is found that a single thermoelectric generator with a fin can harvest a maximum power output of around 2.5 µW. A list of low temperature-based, thermoelectric n-type and p-type materials was presented. n-type 75% Bi2Te3, 25% Bi2Se3 and p-type 25% Bi2Te3 0.75% Sb2Te3 (1.75%Se) were used for numerical and finite element analysis for wearable thermoelectric generator. A maximum of 6.5 µW power can be harvested from body heat when body temperature is 37°C and the ambient temperature is considered as 25°C (ΔT =12 K) for this thermoelectric element. Maple, FlexPDE, and SolidWorks were used for numerical analysis and finite element analysis (FEA).

[5] Effects of Fuel of Electric Power Generators on Soil Properties

Inadequate supply of energy to buildings has informed the use of service items like generators that depend on different types of fuel for its operations which are sources of pollution to various components of the environment. The objective of this study was to assess the impact of fuel of generator on the selected biophysical and chemical properties of soil to which it comes in contact. The study was carried out in Ibadan Metropolis, Oyo State, Nigeria. Five sampling points that were contaminated by the fuel and oil of generators and control points not contaminated and mixed with its fuel were purposively selected in the study area. The soil samples collected were put in labelled polythene bags and taken to the laboratory for the analyses of soil pH, moisture content, porosity, bulk density, particle size distribution and organic matter respectively. Descriptive and inferential statistical techniques such as frequency distribution T-test and Analysis of Variance (ANOVA) were used to analyze the significance of the effect of fuel of generating sets on biophysical and chemical properties of the soil mass. The results of the analyses established that there were significant variations in the mean values of moisture, porosity, particle size distribution-silt content and organic matter content of soil not mixed with fuel/oil of generators (8.2840, 0.4040, 8.00 and 5.0200) and soil mixed with fuel/oil (3.1040, 0.2120,19.60 and 2.4440) respectively. The study concluded that fuel of generating sets disposed of on soil mass would negatively affect its properties necessary for the sustainable growth of flora component of the ecosystem and could cause pollution potential inunder ground water sources to be explored by the building occupants. It was therefore recommended that there is need to use environment-friendly power sources and the associated fuel waste of generators must be properly managed so as not to be a source of threat to the functions and properties of soil resources in the environment.

 

Reference

[1] Jeon, Y.B., Sood, R., Jeong, J.H. and Kim, S.G., 2005. MEMS power generator with transverse mode thin film PZT. Sensors and Actuators A: Physical122(1), pp.16-22.

[2] El-Hami, M., Glynne-Jones, P., White, N.M., Hill, M., Beeby, S., James, E., Brown, A.D. and Ross, J.N., 2001. Design and fabrication of a new vibration-based electromechanical power generator. Sensors and Actuators A: Physical92(1-3), pp.335-342.

[3] Boland, J., Chao, Y.H., Suzuki, Y. and Tai, Y.C., 2003, January. Micro electret power generator. In The Sixteenth Annual International Conference on Micro Electro Mechanical Systems, 2003. MEMS-03 Kyoto. IEEE (pp. 538-541). IEEE.

[4] Siddique, A.R.M. and Majid, S.H., 2016. Energy Generation Using Thermoelectric Power Generator (TEPG) from the Living Body. Physical Science International Journal, pp.1-15.

[5] Wahab, A.B., Adesanya, D.A. and Ata, O., 2018. Effects of Fuel of Electric Power Generators on Soil Properties. Current Journal of Applied Science and Technology, pp.1-10.

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