Bristol Robotics Laboratoy and Oxfam
Pee-Power is a novel electricity-generating sanitation solution for decentralised areas, still only tested under controlled laboratory conditions.
Pee-Power is a prototype that uses urine as a source of power to produce electricity, so-called “Urine-tricity”. The microbial fuel power has been able to generate enough power to charge a Samsung mobile phone, which enables SMS messaging, web browsing and to make a brief phone call. It has also been able to generate sufficient levels of electricity to power a LED-based lighting system for one toilet cubicle.
Plans are to develop microbial fuel cells to power indoor lighting in refugee camps and disaster areas. The abundant, free supply of urine makes the Pee-Power toilet practical for aid agencies to use in the field. In phase two, the purpose is that microbial fuel cells (MFC) can provide enough power to light a 10m radius around a block of four toilets.
The prototype has been tested on the University campus. The urinal on the campus resembles a toilet used in refugee camps by Oxfam to make the trial as realistic as possible. Video of the how Pee-Power works and video of mobile phone runs on urine power.
Prototypes installed in the UK’s largest music festival for field-trial purposes. The prototype needs improvement before any commercial deployment, and plans are to install the technology in refugee camps and deprived countries all over the world.
For June 2016, one microbial fuel cell costs about 1.30 USD to make and the complete unit that has been mocked up in the university would cost a total of 800-850 USD to set up in a refugee camp.
No commercialized products yet. Other prototypes include a miniature fuel cell to power mobile phones at the University of Bath, or a urine-powered generator in Nigeria.
Goal 7: Ensure access to affordable, reliable, sustainable and modern energy for all.
Communities in refugee camps and disaster areas, which are often dark and dangerous places particularly for women. By lighting bits of the camp, the Pee-Power toilet can create a safe environment so that women can go out, use the toilets at night, do things at night in a safer environment.
The Microbial Fuel Cell (MFC) is an energy converter, which turns organic matter directly into electricity, via the metabolism of live microorganisms. The bacteria break down organic molecules and generate electricity – that could run on the organic molecules found in urine, such as uric acid, creatinine and small peptides. The electricity output from MFCs is relatively small and these low levels of energy are stored and accumulated into capacitors or super-capacitors, for short charge/discharge cycles.
Smaller cells have higher energy densities and are more efficient, so the technology relies on miniaturisation and multiplication, building stacks of cells. The latest models of MFC use ceramic cylinders.
There is a continuous stream of urine passing through a series of fuel cells, that keeps up the electricity production by constantly ‘feeding’ the bacteria. The electricity collected by an energy harvesting board.
Ceramic cylinders were purchased from International Biological Laboratories (Haryana, India) and were made from porous ceramic (earthenware) material. The average dimensions were 10.2 cm (length), 3.5 cm (outer diameter), 2.5 cm (inner diameter), with an approximate volume of 49 mL. The closed ends of the cylinders were removed so that the 3D printed lids (air-gap adaptors – see below) could be introduced at both ends (see Fig. 1). The anode electrodes were made from 337.5 cm2 of 20 g cm2 carbon fibre veil (PRF Composites, Dorset, UK) with two 10 cm long strips of 0.25 mm diameter stainless steel wire (SWC, UK) folded so as to form a spiral brush. The cathode was prepared by painting two coats of a microporous layer (MPL) on the outer surface of the ceramic cylinder. More details to be found here.
Diagrammatic representation of the MFC system: the urinal feed the MFC stack (stage 1), from which the energy is harvested (stage 2), at a constant voltage by 4 power harvesters connected in parallel, and stored in 8 parallel Lithium Iron Phosphate cylindrical cells (stage 3), connected to a voltage regulator (stage 4) connected to 6LED strips lighting the urinal ≈9h30 per day (stage 5).
Manufacturer performance targets with the second field-trial (2016, UK) was to study the feasibility of SSM-MFC to be deployed as an electricity-generating sanitation solution in decentralised areas for periodic usage.
Field results of the system (2016, UK’s music festival) under uncontrolled usage indicate an optimal retention time for power production between 2h30 and ≈9 h. When measured (HRT of ≈11h40), the COD decreased by 48% and the total nitrogen content by 13%. Compared to the previous Pee-Power field-trial (2015, laboratory) the present system achieved a 37% higher COD removal with half the HRT. The 2016 set-up produced ≈30% more energy in a third of the total volumetric footprint (max 600 mW). This performance corresponds to ≈7-fold technological improvement.
More details about vetted performance to be found here.
Tested (in the lab) and trialled (out of the lab) by the Bristol Robotics Laboratory.
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