[Digestion] Attachment to previous Article - More scientific based research and questions

Anand Karve adkarve at gmail.com
Thu Oct 7 17:17:42 PDT 2010

Dear David,
although we started out with household biogas plants having digesters of one
thousand litres, we now construct them also for large establishments, where
hundreds of persons are fed. In our own campus we have two such plants,
having digester capacities of 10,000 litres each. We operate a hostel in
which our trainees live, so that we have a lot of food waste at our
disposal.  We are in a rural area, where electricity from the grid is
available only during the night. We need electricity during the daytime for
operating our computers,  projector, ceiling fans, etc. We use a 1.5 kW
petrol driven generator for this purpose. The biogas from one of the
generators suffices to provide electricity for about 3 hours. In the
afternoon, the trainees do field work, for which we do not need electricity.
The other biogas plant is connected to a diesel engine, which drives our
charcoal briquette extruder. We can replace petrol completely with biogas in
the electricity generator, but in the case of the diesel engine, we use 20%
diesel and 80% biogas. We do not purify the biogas to remove carbon dioxide,
moisture or H2S from it, but use it as it comes out of the biogas plant.
Many farmers in our vicinity have started to use a similar technique, which
gives them free fuel to run their internal combustion engines, used mainly
for pumping water.
On Thu, Oct 7, 2010 at 9:56 PM, David Fulford <davidf at kingdombio.com> wrote:

> Hello Alex and Listers,
> The best independent papers on the ARTI system are by EAWAG (
> www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_swm/<http://www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_swm/index_EN#owm>)
> who have also looked at the digestion of food residues from markets in
> Kerala, South India. While food residues have an average TS of 50% or less,
> Dr Karve bases his results on starch residues (e.g. flour dropped on the
> floor from milling). Suich residues have a TS of almost 100%. This means
> that we need to consider his gas production results as per kg total solids,
> rather than per kg of wet material.
> As the assessor from Ashden Awards who visited ARTI in 2006 (see
> www.ashdenawards.org/winners/arti06), I had to evaluate Dr Karve's
> statements.and his technology. The biogas plant uses simple cylindrical
> drums, so there is nothing special about the design. The major difference is
> the use of food residues rather than dung as the feed material. Since an
> animal has used as much of the input energy in the food as it can before it
> evacuates the rest, the gas production from undigested food is likely to be
> much higher than that from dung. Processed food (flour, sugar and cooked
> food) is likely to have a higher gas output than raw food, as much more of
> the material is accessible to the microbes. There are several other biogas
> projects in India using food residues as feed material, that started at
> about the same time as the ARTI one. I have visited the first Biotech Ltd
> project in Kerala (www.ashdenawards.org/winners/biotech) about which the
> EAWAG report was written and another in Mumbai called the Nisargruna system
> developed by BARC (see www.green-ensys.org/site/Biogas_Plant.html), which
> uses a two-stage digestor design.
> Looking at the basic thermodynamics of the process, it seems quite feasible
> to generate 1 kWh of electrical energy from 1 kg of starch, as Dr Karve
> suggests, although it does suggest a very high efficiency for the conversion
> of starch to biogas. However, in practice, a 1 cu.m ARTI biogas plant is too
> small to run an ic engine, as small ic engines are not very efficient.
> Regards,
> David Fulford
> On 07/10/2010 01:39, Alexander Eaton wrote:
> Dr Karve,
> Your innovation and work in the field is quite appreciated, and your system
> really opens doors for us who are also not technically focused in the
> biology of biogas, but rather its application to families and communities.
> That is why it seems your use of food waste and loading rates based on gas
> production for a family really widens the populations we may be able to work
> with globally.  Do you have a paper or document that has this data and other
> user data available?
> Best,
> Alex
> On Wed, Oct 6, 2010 at 5:40 PM, Anand Karve <adkarve at gmail.com> wrote:
>> Dear Alexnder,
>> to be quite frank, I do not call myself an expert in biogas technology. I
>> developed my system as a layman. Being a biologist, I argued that since all
>> industrial fermentation systems used sugar, why not try it in a biogas
>> plant. Because sugar was costly, I used only 1 kg sugar in a biogas plant
>> that consumed daily 40 kg cattle dung. To my surprise I found that I got
>> about 700 to 800 litres of biogas, just 24 hours later. Since sugar was
>> costly, I shifted to using flour of cereal grains, which also gave similar
>> results. Then we tested spoilt milk, oilcakes of various edible and
>> non-edible oilseeds and peels of fruits like banana, mango and papaya, and
>> got similar results. We then constructed biogas plants geared to using food
>> waste as feedstock. It was by trial and error, that we arrived at our
>> present configuration which is just a conventional moving dome biogas plant.
>> The rule of thumb is to use 1 g (dry weight) of food waste per litre of
>> digester capacity.  When I started talking about our system in conferences
>> on biogas, I used to be hooted out by the experts. Once they found out that
>> I had no theoretical knowledge of the biogas plants, they would embarass me
>> by asking questions like C:N ratio, volatile solids % etc. It was only after
>> our system received the Ashden Award in London (2006), that the world
>> started believing in me.
>> Yours
>> A.D.Karve
>>  On Thu, Oct 7, 2010 at 7:00 AM, Alexander Eaton <
>> alex at sistemabiobolsa.com> wrote:
>>> Hi Dr. Karve,
>>> I recently had the pleasure of meeting your associate and representative
>>> for Tanzania at a conference in Sweden.  He explained much of the same thing
>>> about the ARTI system.  When you describe your system as primarily a biogas
>>> generation system (as opposed to waste treatment), do you mean that you
>>> optimize HRT and loading rates for biogas production, rather than balancing
>>> biogas production with the reduction of organic load (TOC or COD?).
>>> Reviewing the plans of your systems, it does not seem as though the vessel
>>> itself holds massive differences with any other AD reactor, so can we assume
>>> that this is a management practice, versus technology comparison?
>>> Best,
>>> Alex
>>> On Wed, Oct 6, 2010 at 4:45 PM, Anand Karve <adkarve at gmail.com> wrote:
>>>> Dear Alexander,
>>>> thanks for the correction. In our system, 1 kg (dry) food waste provides
>>>> 1 kW electricity for 1 hour. I am absolutely sure of these figures, because
>>>> we are daily generating electricity on our own campus by using food waste
>>>> from our own hostel. If your calculations show our system to be 3 times as
>>>> efficient as the one reported in the article, then it must be so. All I can
>>>> claim is that our biogas production system is currently the cheapest and the
>>>> most efficient biogas system in the world. Scientists of a prestigeous
>>>> Institute of the Government of India had come to us to have a look at our
>>>> biogas system, because using the same amount of waste, our system
>>>> produced 10 times as much biogas as the two phase system developed by them.
>>>> The report submitted by them to their bosses explained the difference in the
>>>> performance of the two systems being due to the fact that their system was
>>>> primarily a waste disposal system, whereas ours was primarily a biogas
>>>> generating system. So far, we have installed about 5000 such biogas plants
>>>> all over India and also about 50 on the African continent.
>>>> Yours
>>>> A.D.Karve
>>>> --
> ********************************************************************
> 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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Dr. A.D. Karve
President, Appropriate Rural Technology Institute (ARTI)

*Please change my email address in your records to: adkarve at gmail.com *
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