[Digestion] AD for cow manure

Theo Bijman thecogasbv at gmail.com
Sun Jun 5 04:59:32 CDT 2011


Hello Rex,

We are a dutch company who are using ecobag digesters; a combined digester and biogasstorage. Quick to install; works well. We have installed it in Indonesia and Tanzania, and Kenia and Senegal is underway. We combine it with either a diesel generator set or a biogas generator set. The partner we are working with in Tanzania is a dutch entrepreneur based in Arusha. We try to fill the gap between the expensive concrete digesters in Europe and the small family sized digesters. Ecobag digesters have electrical mixers installed and heating tubes. Because we rely on hot climate to keep the digester working, we work with a retention time of the manure which is 2 times longer than in concrete digesters. With a premix tank (30 m3) and a chopper pump also fruit waste and other feedstock can be used. Our plant in Indonesia uses the biogas to generate electricity and dry tea. A perfect combination. The ecobag as a digester can be 400 m3 up to 5000 m3 in size. Just have a look to see some pictures on our website thecogas.nl or .com  

Met vriendelijke groet, Theo Bijman


Op 4 jun. 2011 om 11:40 heeft "Rex Zietsman" <rex at whitfieldfarm.co.za> het volgende geschreven:

> 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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>> 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/
> 




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