Nice Biodigester System, and Politics of Use

Its been in use for quite some time now. We created one for our school engineering project, for cooking fuel. I live here in San Diego and there is a methane to energy plant in Point Loma and I didn't even know! haha

Glad to hear San Diego was open to it. Love Point Loma!

Should sewage plants their methane to power their plants, and more?

I'm assuming you meant: Should sewage plants recycle their methane to power their plants, and more?

Yes, many do and if not, should.

Not knowing much about these systems, my biggest concern is how to make sure that the methane is concentrated enough for use as a fuel. Any ideas on this?

I meant to put in use. Sorry.

It's OK. How do these things ensure that the CH₄ is concentrated enough for use as a fuel?

The problem with methane from digesters isn't the methane concentration, but the contamination that comes with it, namely sulfur. The corrosive nature of the fuel is the biggest hurdle to make it useful. Concentrations are typically high enough that high cost scrubbers are required to use it in most engines or boilers.

The innovation needed to make this more attractive is to find a cheap way to scrub out the sulfur.

edit: note I'm referring to municipal scale systems for wastewater treatment.

Some 20 years ago National Geographic had on its front page a southern state garbage pile. The top of it was a golf course. It was collecting methane in a controlled fashion for city gas use. Still in application, as it was mentioned, that controlled amount of water influx regulated the gas generation from this dump.

Some 20 years after finishing, you can build on it, or therabout.

That IS recyling, don't you think?

Farms have been using it for years,

http://www.sfgate.com/cgi-bin/article.cgi?

f=/c/a/2004/05/14/BAGJG6LG3R15.DTL&ao=all

http://www.energysavers.gov/your_workplace/farms_ranches/index.cfm/mytopic=30002

http://www.epa.gov/agstar/documents/conf10/Gould_Final.pdf

There are still pros and cons of debates going on of this:

http://nationalhogfarmer.com/environmental-stewardship/manure-management/0310-weighing-methane-digesters

I recall back in the 80's where we would have farm tours to Europe and Europe would have farm tours here in the U.S. Almost like an exchange program.

The European farm tour here in the U.S. toured what we thought was a very progressive and modern methane digester on the farm. unimpressed, the Germany replied, with this plant, your about 20 years behind us. At least our dairy cows were top producers.

And now, if it weren't for government subsidies, farms would not be incorporated this.

Allot of municipalities have this. In my area, the state (Wisconsin) has about 85 communities that use methane digesters.

http://www.mrec.org/pubs/Anaerobic_Report.pdf

I have been pushing these for twenty years. Ever since I heard about India using it in 50 gallon barrels with a rubber top and a valve. Also lots of old Mother Earth News articles.

What I don't know is just how complex the EPA requirements make it. Thanks for your links.

The Germans have always valued their poop. I remember the vineyard workers spreading it out under their grapevines from their " honey pot."

Our local sewage plant gives or sells the processed sewage to local farms. They used to do it at night to avoid attention. I drove the country road at night and thought I was seeing an ET event. Lots of lights and silver trucks grouped together. I never noticed an odor problem but several farm houses near there went up for sale when they started. I wonder how much methane is wasted in their process.

You said it,

Manure is big business............and with big business comes issues, mostly with odor just due to urban crawl unto farms.

As far as methane being wasted, there was a government sponsored study done on the methane production from cows.

The basis of the study was political. It had nothing to do with methane capture, but green house effects the cattle had on the environment.

This kind of plant was first used in Britain in the 1960s, but fell into disuse as electricity and oil was cheap in those days, another such plant has been in use in northern Denmark since the 1980s, it is located near a landfill site, and the methane is used to heat water that is used to heat all the nearby homes, and used as a fuel for a small Stirling engine to produce all the electricity the plant and it's adjoining offices need!

Now in Britain there are several experiments with sewage plants, they are using anaerobic bacteria to produce methane from the sewage, and this methane will be used to power electricity generators!

Spencer.