Bristol Robotics Laboratoy and Oxfam
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 an 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.
Protoypes installed in the UK. Plans to install the technology in refugee camps and deprived countries all over the world.
One microbial fuel cell costs about USD 1.30 (£1 in June 2016) to make. The complete unit that has been mocked up in the university would cost a total of USD 800-850 to set up in a refugee camp (£600 in June 2016).
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.
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.
Manufactured at the Bristol Robotics Laboratory.
The technology which powers the Pee Power urinal is protected by patents.^(interview with representative)
Directly from designer. Currently only available as a prototype.
2 prototypes have been tested outside the lab:
The first is a urinal based on a superstructure, which has been installed on the University campus. It produces enough electricity to power four LED light bulbs in the cubicle. It was tested from February–May 2015 and demonstrated the feasibility of modular MFCs for lighting, with University staff and students as the users; the next phase of this trial is ongoing.
The second is a larger urinal that has been tested during the Glastonbury Music Festival at Worthy Farm, Pilton in June 2015. It demonstrated the capability of the MFCs to reliably generate power for internal lighting, from a large festival audience (∼1000 users per day).
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 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 length strips of 0.25 mm diameter stainless steel wire (SWC, UK) folded so as to form a spiral brush.9 The cathode was prepared by painting two coats of a micro-porous layer (MPL) on the outer surface of the ceramic cylinder. More details to be found here.
The MFC chassis and membrane is the ceramic material. So the outside is the bacterial anode, or the negative terminal of the fuel cell; and the inside is the positive cathode. The bacteria form a robust biofilm on the anode surface of the fuel cell, and pass electrons to the electrode as they respire and metabolise the fuel molecules in the urine. The ceramic is there to allow to exist as a microbial fuel cell, but also to allow ions to flow through from the anode to the cathode.
An individual MFC can produce a current of 0.25mA for 3 days from 25ml of urine. The power output recorded for individual MFCs is 1–2 mW.
Yet these performances are out of date, since new data show better performance levels.^(interview with manufacturer)
The campus urinal consisted of 288 MFCs, generating 75 mW (mean), 160 mW (max) with 400 mW when the lights were connected directly (no supercapacitors); the Glastonbury urinal consisted of 432 MFCs, generating 300 mW (mean), 400 mW (max) with 800 mW when the lights were connected directly (no super capacitors). Source
Tested (in the lab) and trialled (out of the lab) by the Bristol Robotics Laboratory.
I Ieropoulos, J Greenmanab, C Melhuisha, Pee-powered fuel cell turns urine to energy, Urine utilisation by microbial fuel cells; energy fuel for the future Phys. Chem. Chem. Phys., 2011, DOI: 10.1039/c1cp23213d
I Ieropoulos, P Ledezma, A Stinchcombe, G Papaharalabos, C Melhuisha, J Greenmanb, Waste to real energy: the first MFC powered mobile phone. Phys. Chem. Chem. Phys., 2013, 15, 15312
I Ieropoulos, A Stinchcombe, I Gajda, S Forbes, I Merino-Jimenez, G Pasternak, D Sanchez-Herranza, J Greenmanab, Pee power urinal – microbial fuel cell technology field trials in the context of sanitation. Environ. Sci.: Water Res. Technol., 2016,2, 336-343, DOI: 10.1039/C5EW00270B
Lab testing and research; short term real-life situations.
The project has been funded by the Engineering and Physical Sciences Research Council (EPSRC), the Gates Foundation and the Technology Strategy Board.
Expert advisors have stated that the protoype models seem to be effective. Further testing should give people confidence in the value of this technology. They have expressed concerns about possible problems that have not yet been faced. For example, other microbes could displace the ones that are generating electricity, thus causing it to fail. Only long term use in practical applications can prove whether this might happen.
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