In today’s world there are 2.6 billion people that lack basic sanitation (37% ofworld inhabitants). In August of 2012, Cranfield University was awarded by theBill & Melinda Gates Foundation with $810,000 to produce a prototype of theCranfield’s innovative Nano-membrane Toilet (NMT). Finally, the prototype isgoing to be exhibited at the “Reinvent the Toilet Fair” during 21st and 22nd ofMarch 2014 in the Taj Palace Hotel, New Delhi (India).Cranfield’s NMT demands electricity for its daily performance. Nevertheless, it istargeted to off-grid communities. Consequently, a human-powered generator(HPG) was selected as a backup solution. The current MSc by Research aimedto design and test of a prototype of the aforesaid HPG. Moreover, to promote itsusage, a portable power supply unit is designed to store energy and powersmall-loads like charging mobile phones and electric lighting.To select the most suitable design for our case study, a methodology using theTechnique for Order of Preference by Similarity to the Ideal Solution has beendeveloped. As a result the plugged-in bike HPG alternative was selected. Next,prototypes of this generator and the portable power supply unit were developed,tested and shipped for display.While testing of the plugged-in generator and portable power supply unit, 26Watt-hours (Wh) were harvested over 15 minutes, with its correspondingaverage charging power of 105 Watts. Nevertheless, the present studyconcludes 96 Wh as a more accurate energy level to be harvested during onehour of pedalling.Considering 96 Wh of energy, a round-trip battery efficiency of 70% (lead-acid),and a NMT’s demand of 283 Wh; a 10 people household needs to pedal theHPG over 4 hours and 20 minutes. Nevertheless, if considering an 85% inverterefficiency, 57.12 Wh are available to fully charge one mobile phone (5.6 Wh)and provide 4.5 hours of room and desk lighting (11 Watts bulb).
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