[Digestion] AD for cow manure

Mon Jun 6 09:32:02 CDT 2011

Hey Rex,

Please contact Greg Austin (greg.austin at agama.co.za), he has a company based
in South Africa. I hope he will be of help.

All the best

On Sat, Jun 4, 2011 at 2:40 AM, Rex Zietsman <rex at whitfieldfarm.co.za>wrote:

> David,
>
> What I have seen down here which sounds and looks attractive is the use of
> bladders. Effectively the "inventor" scraped hollows with adjacent walls
> and
> put in heavy duty bladders that hold about 30m3. He has 11 of them and
> empties and fills one a week with chicken litter. As the bladders are
> black,
> they absorb heat from the sun which helps keep the temperature up. He then
> uses two bladders as his gas storage system. By packing rocks onto the
> bladder, he can pressurise them to deliver gas using PVC piping to his
> generator. His H2S removal system was two 200 litre drums welded together
> and filled with machining swarf. Catchpots served both as flash back
> arrestors and as condensate drains. Each bag costs about $1500.
>
> The benefit of this simple system is that it is easily tested at the
> one/two
> bag size. If successful ie convinces the farmer that it works, it can
> easily
> be expanded. At the same farm mentioned above, the farmer bought an old
> scuba diving tank filling compressor and bought some old gas cylinders. He
> then rigged his tractors and truck to take compressed biogas into their air
> inlets and save diesel that way. So there are ways of extending the use of
> biogas.
>
> If anyone can add to this type of debate, I believe it would be helpful not
> only to me but the list in general.
>
> Kind regards
> Rex
>
> -----Original Message-----
> From: David Fulford [mailto:davidf at kingdombio.com]
> Sent: 04 June 2011 10:59 AM
> To: Rex Zietsman
> Cc: digestion at lists.bioenergylists.org
> Subject: Re: [Digestion] AD for cow manure
>
> Hello Rex and listers,
>
> It depends if you want a set of small cheap systems or a large-scale
> sophisticated system. Farms with >500 cows probably need the type of
> digester that have been developed by various different German companies.
> They are designed to generate power and use hot water from the engine to
> keep the temperature in the digester at an optimum value (35 deg.C). They
> are designed to be as automated as possible. They use both dung and silage
> as the main feedstocks. The only disadvantage is cost.
>
> In other parts of Africa there are small-scale systems that are much
> cheaper, but rely on labour to run them. The majority of these systems use
> the dung from just a few cattle to generate cooking fuel for a family.
> However, there are much larger systems that can be used to run a generator.
>
> I do know of installers based in Tanzania and Kenya, capable of making the
> larger-scale cheaper units, if you would be interested in this approach.
>
> Regards,
>
> David F
>
> Saturday, June 4, 2011, 7:42:52 AM, you wrote:
>
> > Hi all,
>
> > I am going to do something I swore I would never do. Unfortunately, I
> > just don't have the time and know that the folks on this list know far
> > more than me and can point me in the right direction.
> > I live in a rural area where we are subject to occasional power cuts
> > (power lines down mostly due to weather) but, more importantly, our
> > power bills are rocketing as South Africa races to catch up to the
> > rest of the world in terms of cost of power. Historically we had paid
> > off coal fired power plants that gave us the lowest cost of power in
> > the world. Anyway, now that power costs are rising, own generation is
> becoming an economic necessity.
>
> > In my area we have a large number of dairy farms milking >500 cows.
> > These are sizeable operations and the manure they produce is worth
> pursuing.
> > Typically they all have slurry dams and they spread their manure from
> > time to time (much to our temporary dismay while the odour kills us!).
> > The question is: what is an economical way of producing gas? Bear in
> > mind, efficiency is not an issue in this case. What we are talking
> > about is getting gas that can be cleaned up and fed into motors to
> > produce power. I am looking at using 3 litre petrol engines that will
> > push out about 50kW tops. So, we are not looking for anything fancy. A
> > plugflow system would make most sense as they can pump it into the one
> > end while the processed material leaves the other. Heating
> > suggestions? What about using the engine exhaust to heat water and
> > circulate that around the reactor or use it to preheat the incoming
> > feed? Here I was simply thinking of a double tank with hot water in the
> outer tank... any other suggestions?
>
> > The other thing these farmers use a lot of is sileage (chopped maize
> > that is stored and allowed to ferment). Has anyone had experience
> > adding some of this to the AD?
>
> > Looking forward to hearing from you all!
> > Rex
>
>
>
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>
> > for more information about digestion, see Beginner's Guide to Biogas
> > http://www.adelaide.edu.au/biogas/
> > and the Biogas Wiki http://biogas.wikispaces.com/
>
>
>
>
> --
> Best regards,
>  David
>  mailto:davidf at kingdombio.com
>   ********************************************************************
> Dr David Fulford CEnv MEI, 15, Brandon Ave, Woodley, Reading RG5 4PU
> d.j.fulford at btinternet.com, Tel: +44(0)118 326 9779 Mob: +44(0)7746 806401
> Kingdom Bioenergy Ltd, www.kingdombio.com, davidf at kindombio.com
>
>
>
>
>
>
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>
> for more information about digestion, see
> Beginner's Guide to Biogas
> http://www.adelaide.edu.au/biogas/
> and the Biogas Wiki http://biogas.wikispaces.com/
>
>

-- 
Vianney Tumwesige
Director - Green Heat (U) Ltd  [image: Picture]
P.O. Box 10235
Kampala-Uganda
256 (0) 71 237 9889

"The more people are self sufficient in cooking fuel, the more personal and
financial freedom they have." - Emma Casson

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