Loowatt creates energy and fertilizer from human waste


May 2, 2011

The Loowatt system allows human waste to be extracted from special toilets, and placed in an anaerobic digester to create biogas and fertilizer(All images courtesy Loowatt)

The Loowatt system allows human waste to be extracted from special toilets, and placed in an anaerobic digester to create biogas and fertilizer
(All images courtesy Loowatt)

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Of all the things that people traditionally discard, one that most of us likely think the least about repurposing is human feces and urine. Sure, we recycle our plastic and paper, and compost our fruits and veggies, but ... that stuff? Actually, there are various worldwide projects aimed at using municipal raw sewage for things such as fertilizer or as a power source. While those projects only come into play once the waste has been flushed, however, the UK's Loowatt system gets users involved from the bottom up (sorry), collecting waste directly from the toilet and using it to create biogas and fertilizer.

The Loowatt toilet itself is waterless and chemical-free, and is intended for use at outdoor events, campsites and other remote locations – pretty much the same places that a Porta Potty or outhouse would be used. Feces and urine drop into what is described as an "odorless" sealed cartridge, which incorporates a biodegradable liner. Once or twice a week, that cartridge is removed, and the liner and its contents are dumped into a nearby anaerobic digester.

The digester (which is also part of the system) utilizes microorganisms in an oxygen-free environment, to consume the waste and convert it into methane and carbon dioxide gas. That gas can then be burned for fuel, at which point it reverts back to CO2 and water vapor. Another by-product of the digester is a semi-liquid manure, in which the nutrients have already been homogenized, making them more accessible to plants. This can be separated into liquid plant food, and a more solid manure.

A pilot project is currently operating at a houseboat marina in West London. It consists of five toilets and a small-scale digester, and is apparently working well. "The toilets were successful and we are now in discussions with numerous potential customers," Loowatt's Virginia Gardiner told us. "The digester is producing a steady supply of biogas which we have hooked up for cooking."

The company was recently awarded a US$100,000 Grand Challenges Explorations grant from the The Bill & Melinda Gates Foundation, to develop the technology further. Anyone interested in trying the system out at their location is invited to contact Loowatt.

A similar system is in place at Cambridge, Massachusetts' Park Spark project, in which anaerobically-digested dog feces are used to fuel a gas lamp in an urban dog park.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

Cooking food with Poo gas just doesn\'t sound that appealing to me!

Denis Klanac

@ Denis: Oh c\'mon, the gas we\'re using for cooking food now comes from dead, rotten dinosaurs anyway...

Windmaster Hiroaki

I\'m fine with rotten dino\'s. but human poo is just to much of a mental barrier for me thank you very much Windmaster Hiraoki. you can keep the poo gas brother!

Denis Klanac

Many US water treatment plants capture and sell methane. My garbage disposal came with a flier describing why it was better to put scraps in the disposal than the trash, methane being the key reason.

My major concern would be the possible contamination of the user when changing the cartridge, as well as improper installation.

Since this is designed for non-sewage served areas, the concerns are reduced.


Doesn\'t really make sense for the areas with established waste management systems, but obviously works for lesser developed nations. Seems to be a popular subject lately as I have seen multiple articles from several sources on the subject. Also seems to be named many different things, biogas, gobar gas, etc. The article regarding gobar gas had a major improvement over the people spending countless hours searching for firewood. Since over the years, they deplete their wood sources close by, the search keeps expanding outwards.


The top photo is the pilot plant? Personally I would not like to go the the loo in public like that. They could have made separate cubicles. In my garden I have an aerobic digester, which churns the waste, and digests without smell(no methane is produced) . The solids have to be emptied every 6 months. I have to pay for the disposal. Maybe I should be selling it?


From what I have read these systems work best if the urine and feces are seperated with the urine containing elements needed in fertiliser but wish slow the decompisiton of the feces. Urinals for men divert much of this as would a modified sit down pedestal as has been seen before.

Daniel Humphries
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