Acoustic Energy Harvesting in Nigeria: Prospects, Technical Problems and Socio-Economic Obstacles
Authors: Onuu Michael U. 
Published: May 2020

Aims: To investigate the prospects or potentials of acoustic energy harvesting in Nigeria as well as highlight technical problems and socio-economic obstacles.
Study Design: The study re-examined existing data, noise levels and noise power, from road traffic, aircraft, industrial/occupational, outdoor and indoor noise sources. Noise levels and noise power obtained from recent measurements of such noise sources were also examined and analyzed. The data were compared with values from noise sources used for electricity in other countries of the world. Technical problems and socio-economic obstacles have been highlighted.
Place and Duration of Study: The study was carried out in Abakaliki, Ebonyi State, Nigeria. The duration was one year: April, 2019 and April, 2020.
Methodology: Wide range noise level measurements, analysis and re-examination of existing data on road traffic, aircraft, industrial/occupational, outdoor and indoor noise were conducted, in line with the objectives of the study, in cities, industries as well as homes with different noise features. Measurements were carried out using sound level meter, SLM, (Bruel and Kjaer 2203) with – octave band filter and SLM, EXTECH 407750 with RS232, sound level recorder (B & K 7005), and noise level (statistical) analyzer (B & K 2121) to obtain noise levels and indices. Also, noise power was subsequently obtained for each of the various noise levels and indices.
Results: Maximum noise levels, Lmax.; noise power, Wmax.; octave band pressure levels, BPLs; and other indices for the different noise sources were determined. Lmax. and Wmax for aircraft were as high as 116 dB and 0.4 W, respectively, while those for industry and road traffic ranged from 104.0 dB-131.0 dB and 67.5 dB-85.6 dB corresponding to 0.025 W-12.59 W and 0.0000056 W-0.00036 W, respectively. Spectral power of road traffic noise varied between 5.17 x 10-5 W and 9.69 x 10-3 W. Outdoor and household noise sources had Lmax. of up to 48.5 dB and 88.0 dB, that is, 0.000000071 W and 0.00063 W, for quiet and noisy periods, respectively. It was observed that road traffic noise has the highest potential for acoustic energy harvesting in Nigeria being reasonably steady over time, especially, on intra-city roads. Availability of tricycles/motorcycles in abundance and frequent use of horn by motorists support this assertion. The noise levels and noise power from these sources obtained in this investigation are higher than those that have been used as input to acoustic energy harvesters (AEHs) such as piezoelectric based and triboelectric nanogenerators (TRENGs) to achieve known efficiencies as reported elsewhere.
Conclusion: The noise power is such that it could be used in powering microelectronic components, devices and in lighting light emitting diodes (LEDs). Power supply (PS) audio noise harvesters (ANHs) have been identified as potential noise energy sources since there is wide range use of air-conditioned by the political class, elites and government agencies in Nigeria where maximum temperature of 47.2°C is attainable. These findings show the viability of AEH in Nigeria and their addition to the existing body of knowledge in the emerging area of AEH will open a new window of research in AEH in this part of the world. Other prospects of AEH in Nigeria, technical problems and socio-economic obstacles are highlighted.