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
<http://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
<http://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
<http://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 <[email protected]
<mailto:[email protected]>> 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
<[email protected] <mailto:[email protected]>> 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 <[email protected]
<mailto:[email protected]>> 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
[email protected] <mailto:[email protected]>, Tel:
+44(0)118 326 9779 Mob: +44(0)7746 806401
Kingdom Bioenergy Ltd, www.kingdombio.com <http://www.kingdombio.com>,
[email protected] <mailto:[email protected]>
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