biogas storage

[Ivan]

Starting a new topic for this, as it's a large subject in itself.

If we plan to store summer production for use in winter at atmospheric pressure, we're going to need quite a large volume. Let's assume we're going to use the quoted average gas consumption of 20 500kWh/year, and let's assume this is ALL for space heating over the winter months ie worse case scenario.

Biogas energy density is 6kWh/m3.

So we'll need 20500/6 = 3416m3 of gas storage at atmospheric pressure (that's 33m x 33m x 3m)!!!

Looks like we'll need to compress it after all. If we compress it to 10 atmospheres (150psi), in which case we could use propane tanks for storage, we'd need 341m3. If we used 47kg propane bottles (approx 125litres each), we'd need 2700 of them.

Looks like it's going to be more use as a realtime energy source, with a well-insulated, solar heated digester to allow it to produce gas all year round.

[welshboy]

Been thinking about the solar aspect and the possibility of a concrete trombe wall south side of a ferrocement horizontal digester

[billi]

Hi

Good ideas from Jean Pain

http://en.wikipedia.org/wiki/Jean_Pain

http://www.daenvis.org/technology/Jeanpan.htm

He used the composting heat to heat up the digester and big rubber tubes from traktor tyres as gas storage
(put weight on the tubes to regulate the gaspressure)

For people with space perhaps a good idea to heat the underfloorheating with direct heat from the composting process and just produce the amount of gas for cooking /driving ?  in the inbeded digester

Billi

[KenB]

List,

Jean Pain built large compost heaps of about 100 tonnes of biomass and manure.

The heat generated during the rotting, was extracted by a plastic pipe embedded in the heap.  It was alleged that the heat could be used for space heating for up to 9 months.

Unfortunately you can either have methane or heat, but not both, the methanogenic bugs do not like temperatures above 37 to 40 degrees, whilst the rotting occurs at much higher temperatures that would kill them.


Ken

[billi]

Ken

Good point.... but i thought he cooled the digester   

[Bill H]

Thanks Ivan and all, - so we now know that the gas volumes are fairly impractical for storage in the average suburban shed.   

How about the mass of material required  - anyone got a feel for how many kg of vegetation/manure are required to produce a KWh of bio-energy in one of these 'units' ?

My sense is that it might be possible for the amateur/enthusiast to produce enough gas for cooking, space heating probably would be a stretch.

regards

Bill

[welshboy]

Really interesting - Good spot Billi- I wonder if the small stones are limestone . I wonder if haylage would work

[billi]

two small biogas plants , but not a word of how to keep temp .. I supose its warm in india anyhow 

http://www.arti-india.org/content/view/45/40/#Purchasing%20your%20own%20compact%20biogas%20system:%20Cost%20&%20Payment

http://sustainabledesignupdate.com/?p=628

I wounder  if a diggester could be placed in the housefloor between the underfloorheating ---- or like a heatstore in the house  , perhaps dangerous and smelly  , but to overcome winter temps

billi

[welshboy]

this jean pain method with wood pulp has been bugging me all day- then it came back to me- I am sure I read about willow pulp processing some time ago and a health warning about respiratory problems caused by fungi and mould. Anyone know why he died aged 51 ?

[billi]

not so sure about his death ...

Here is a good film about the erecting of the compost pile  , i couldnot find it in english so its german  (this one i will not translate  )

http://www.biomeiler.at/Filmdokumentation_des_Biomeilers.html

http://www.mail-archive.com/sustainablelorgbiofuel@sustainablelists.org/msg71549.html


Anyhow nice to have all these biogas ideas back into my brain    ----- i wounder how good the compostable nappies of my newborn will perform  so he pais his bills allready 

Billi

[Ivan]

I've got the gas yield figures for different materials somewhere - I'll see if I can dig them out.

Don't worry about overheating your digester. There is another class of thermophillic bacteria that convert to methane at 50-60C.

[mikethebee]

There are some excellent links here, and Ivan's posts are very helpful in putting figures on things. I plan to do some trails along these lines, as solar etc is out of my budget at present. I have some concerns about the compost catching fire as I had a friend who's fence burnt down as a result of his compost heap combusting.

[Eleanor]

Welcome Mike and congrats on your first post. Are you really a bee?  If so could you just pop over to the bee thread and tell us what you like to eat 

[mikethebee]

Thx Eleanor,

The Bee's a nickname but I do make Mead :-)

My first trial was with a solar wall for air heating, but I hadn't thought of compost/digester, it could solve the excessive Calor usage of the gas Rayburn when heating water. I'd been thinking of waste oil. I'm working with cousins in Ireland to test out ideas, as they have the space available.

[Eleanor]

It does seem to be an idea that is increasing in popularity. I suppose if we don't produce enough waste of our own we could always collect it from our neighbours  . Everyone wins especially if they decide to charge more for bigger volumes of refuse. Mead ... very nice