digester biogas

[Shaun Burgess]

hi has any one tryed any thing with anaerobic digester .. its a idea been thinking of . i have plenty of cow slurry . would it pay would like to hear from some one who has tryed it or any help. thanks

[Rob Beckers]

Shaun, as it happens I was talking a dairy farmer here last week: Seems they are putting in large anaerobic digesters to produce methane, for running 500kW generators, at many farms these days. I didn't know a farm could run that large a generator from biogas!

On a smaller scale, this month's issue of Home Power Magazine (http://homepower.com/) has a description of a biogas digester at the home-scale (Oct-Nov issue). It makes methane for cooking. Basically it's an oversized septic tank, though the owners built this one themselves from scratch. Take a look at it, maybe something that could help you.

-RoB-

[Shaun Burgess]

thanks rob .. the digester is the easy part the srubbing and storing is not so easy. but it can be done

[Joe Blake]

You might find this of interest from last night's news.

http://www.abc.net.au/news/2012-10-25/pig-poo-powers-nsw-farm/4334072

Joe

[Rob Beckers]

Probably the way farms will all operate in the future. Making electricity from dung. It makes sense (and carbondioxide is less of a greenhouse gas than methane).

-RoB-

[Dave Turpin]

I like the article from Home Power. Seems simple enough. But I wonder:

1) Would it be possible to convert a standard septic tank into an anaerobic digester?
2) Would the tank benefit from "skylights" to take advantage of solar gain instead of burning gas to keep the slurry warm?
3) If the above is possible, is it advisable to use the same tank for blackwater and compost? Like a standard septic tank, with a skylight or two, and also, as in the article, a chute for adding kitchen scraps and grass clippings?
4) Finally, does anyone have a calculation of how much gas you can expect to get from a certain amount of material? Does it differ between, say, dung, kitchen scraps and gras clippings? The article says "10 to 15 pounds of kitchen scraps will produce [about] 70 cubic feet of biogas [at 0.25 to 0.5 psig]".

I am working on a program to calculate key features in a self-sustaining "Earthship" house.:o