Dear all,
I have been subscribed to the list for only a few days, and am
pleasantly surprised by the relevance of the ongoing discussions,
especially since our NGO is also working on the temperature management /
insulation of household digesters.
Let me introduce our projects. Our NGO, Initiative Développement (ID),
www.id-ong.org/cn , has built in China more than 2500 household
digesters in poorly developed areas. These are of the Chinese fixed dome
model, 10m3, and made of either brick/concrete, or concrete alone. We
are following up these digesters and their users very closely, in
particular since we certify the emission reductions with Gold Standard
and sell the ERs to further self-fund our projects. This close
monitoring allows us to detect and solve ongoing technical problems, and
to provide regular biogas trainings and knowledge recycling for the
households.
We are now looking more closely at how to further improve the management
of our digesters, as well as the use of the slurry for agriculture. For
this purpose, we are designing a series of field tests/experiments:
* measuring the influence of a layer of organic insulating material or
compost, on top of the digester, on the temperature of the content and
the gas production
* measuring the influence of different input mixes on the gas production
(pig/cow manure alone; manure + corn stalks; manure + pine needles;
manure + leftover tobacco leaves; these are the substrates available
locally)
* testing the use of the slurry for soaking seeds: impact on germination
rate, shoot growth and diseases (test plots)
* testing the use of the slurry for fertilising and spraying apple
trees: impact on tree health, action against pests&diseases, tree
nutrient uptake, apple yield (test plots)
* testing the efficiency of an optimised mixed fertilisation plan
(biogas slurry+compost+mineral fertiliser) on corn, potato and tobacco
test plots
We will implement these tests on our project sites in the south-eastern
province of Yunnan in China, with half a dozen selected households. This
represents a lot of work and follow-up in remote areas, so we clearly
won't reach the accuracy of a proper research team. However, our goal is
not to make research as such, but instead:
* to test the efficiency and practicality of methods developed elsewhere
and tune them to the local conditions
* to use the experiments sites as hinges to spread adapted practices
within the communities, in particular by organising village meetings and
community trainings around the test sites
If any of you would have advice or documentation relevant to our
projects/experiments, I would be more than happy to hear from you. I'd
also be glad to share our results with people interested.
Furthermore, we are facing two urgent measurement issues:
1 - how to measure the volume of biogas produced (or rather, consumed by
the user on their stove)? The gas indeed varies in pressure, so that
positive displacement flow meters (such as diaphragm meters), are not
suitable. What kind of system would you advice to measure the gas flow
out of a digester, that would be compensated in pressure, or measure the
actual mass flow of the gas? Our typical daily production is in the 1m3
range.
2 - temperature measurement: we would like to measure the temperature
within the digester with 0.5°C accuracy, and are looking at thermistor
(NTC) or pt100 measuring devices with a 3m long cable. The probe could
be introduced through the compensation chamber for each measurement, or
left in place depending on the cost. We've also been thinking of using
data-loggers. Could you advice cost-efficient solutions? We're also
wondering about the temperature layering inside the digester? Can you
suggest an upper limit on the temperature gradient?
Any advice would be welcome!
Regards,
Nicolas Borchers
--
*Nicolas Borchers *???
Organic Farming Officer ????????
+86 159 2552 3303
Skype: nborchers
*Initiative Développement -- *China *????????*
402, B2, Fubang garden, Shulin st., 650100 Kunming, Yunnan province, China
???????? ?????B?2??402???:650100
+86 (0)871 3181557
www.id-ong.org/cn <http://www.id-ong.org/cn>
Energy Globe Award 2009 and 2011
International Solidarity Award (HCCI) 2007
Offset your carbon emissions with ID -- www.id-ong.org
<http://www.id-ong.org/>
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