Energy from Human Dung

ohanian · Light Sweet Crude Joined: Oct 17, 2004 Posts: 1143

I have a question.

If Cow Dung can be turn into methane gas and then into energy

So why can't we do the same with Human Dung?

http://www.itdg.org/?id=biogas

I hate to see millions of tonnes of human dung go to waste in waste treatment plants around the world.

WisJim · Posted: Sun May 14, 2006 6:34 pm Post subject: Re: Energy from Human Dung

Some sewage treatment plants used to use the methane produce in the plants to run engines to produce power to run the plant and other loads. I don't think that as many treatment plants do this as in years past, but it is entirely possible to do.

Ludi · Posted: Sun May 14, 2006 6:46 pm Post subject: Re: Energy from Human Dung

Yep, all human waste could be used to produce methane to power the waste treatment plants or nearby facilities, and the product at the end of methane digestion could be composted and used to grow plant products for other uses (such as more methane production,or ethanol production, wood products, etc). Most "waste" products have several uses and no "waste" product should just be disposed of without serving a useful purpose. In my opinion.
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oilfreeandhappy · Posted: Sun May 14, 2006 11:12 pm Post subject: Re: Energy from Human Dung

As an Engineer, I had the opportunity to tour a Wastewater Treatment plant. At this facility, they were burning off the methane into the atmosphere. The flame was continuous, and about 2 feet high.

We asked the Engineers about using this gas, and they mentioned that it was more cost effective to burn it off, than to try to sterilize it, and deal with the potential legal ramifications and bureacracy. This was about 10 years ago, but I doubt much has changed.
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pstarr · Posted: Sun May 14, 2006 11:18 pm Post subject: Re: Energy from Human Dung

my local plant that services 15,000 people uses the burnoff to heat the digester. It is not good for much more.

This just goes to show how little energy these natural systems (inlcuding oil crops and other biofuels) have in comparison to petroleum. There will never be another party like this one. whoopee Laughing

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azreal60 · Posted: Sun May 14, 2006 11:26 pm Post subject: Re: Energy from Human Dung

I'm curious about a statement previous. You said it was more cost effective to burn it off rather than sterilize it. I thought we where talking about using it for power generation in which case burning it off is exactly what would be happening. I guess that statement didn't seem to make sense to me. Isn't burning it off exactly what was being proposed?
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pstarr · Posted: Sun May 14, 2006 11:30 pm Post subject: Re: Energy from Human Dung

As i understand it anaerobic digesters produce methane erratically and irregularly. The tanks are periodically emptied and refilled, tempatures and ph change, etc. so the methane is not consistant enought to power systems. It would be like gunnnig you car motor and turning it off. The cost of storage etc. is prohibitive. And I live in a town that is sooooo ecogroovey and they can't justify it.
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MonteQuest · Posted: Sun May 14, 2006 11:39 pm Post subject: Re: Energy from Human Dung

Ludi · Posted: Mon May 15, 2006 6:19 am Post subject: Re: Energy from Human Dung

Do you know how many of those plants are still in service, Monte? I recall someone posted that many are not still in service because the people found them difficult to use, requiring collection of dung. They were not convenient to use because the waste was not in a central location as it is at our sewage plants and animal feedlots here in North America.
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thor · Heavy Crude Joined: Jun 21, 2005 Posts: 453

nocar · Intermediate Crude Joined: Nov 05, 2004 Posts: 685

The vast sewage treatment plant in Stockholm collects sewage from about a million people. It produces biogas to fuel a few buses i central town. At most about a thousand people can travel 5 km daily on that. By bus.

So it is possible. But a lot of people need to produce in order for a few to travel on it. And there is necessary to a huge infrastructure in place.

nocar

thor · Heavy Crude Joined: Jun 21, 2005 Posts: 453

gigacannon · Posted: Mon May 15, 2006 9:09 am Post subject: Re: Energy from Human Dung

Humans aren't ruminants. You can't use human faeces as a fuel source like you can with cow dung for pretty much the same reason you can't smear human faeces over fields to grow crops.

grabby · Light Sweet Crude Joined: Nov 08, 2005 Posts: 1328

Human dung is infectious to humans.
and estimated 4% of people in a city have hepatitis C (and B)
some have aieds, 10% have gastroenteritis and viruses.

in a group of 100 people this would guarantee that all these viruses are present.
These viruses do not dissipate or become destroyed there is also staph and MRSA in the community now

Putting human waste on a garden is a very foolish behaviour.

in n contrast, cow dung has NONE of these things and is safe.
Pig dung is not safe, they carry many of the things we can catch, the people thousands of years ago knew this and classed them as contagious animals.
Cow and ruminants are safe we rarely catch anything from them.

now the energy left in our stoooll is very little, there is more energy in grass clippings.

to make enough grass clippings to supply our power needs we need about 4 billion bushels which would stretch across the world 22 times DAILY forgetaboudit.
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Ludi · Posted: Mon May 15, 2006 10:13 am Post subject: Re: Energy from Human Dung

Human waste makes a perfectly fine fertilizer for some crops, and can be solar pasteurized to kill most pathogens.

See the book "Solviva" (or the website linked below) for discussion of human waste treatment using composting.

The Chinese used human waste as fertilizer for approx 4000 years and had one of the most productive farming methods ever developed, which is one reason why their population was always so enormous.
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