[Stoves] Understanding what TLUD means.... was Re: stoves and credits again

[Crispin Pemberton-Pigott]

Dear Gordon

>A basic question: What is the intended purpose in mixing char in with dry biomass for cooking?

Gordon

It improves the fuel efficiency. Not all stoves can do this, and there is a question on the application specifically looking at this question. Can the partially burned remnant fuel be included in the next replication?

If so, the first test run is used to generate the char for the first official test. In such cases there are 4 tests instead of three. I can tell the how the question was answered by looking at the number of tests in the set. If there are 4, the fuel forwarding was included in the replications. If only three, which is a common case with TLUD’s, then there is no remnant fuel recovered and saved for the next run.

Because stoves that consume less fuel get a higher subsidy (paid to the marketer for getting the stoves sold) it is important to correctly operate the stove on the limits of its capabilities – that is, according to the most beneficial operating method available.  If the users do not achieve the fuel economy potential, there is a failure to communicate or train users. This is detected in the follow-up field investigations. Generally speaking, comparing ideal contextual lab tests and in-field performance, users get at least 80% of the potential savings that we identified.

Before saying that there is a gap, one must ascertain whether or not the shortfall in savings is in fact due to increased cooking time made possible by the fuel efficiency. This is a very common outcome of field investigations. For example in Kyrgyzstan the fuel saving is about 60-66% in terms of the stove, but 20-25% is ‘spent’ keeping the house warmer or cooking longer. Similarly we found in Maputo that when people had a really improved stove, they cooked much longer at low power to keep food warm, using (spending) about half the fuel saved. This behaviour does not impact the performance rating of the stove alone on the contextual test result.

Regards
Crispin

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