[Stoves] Advocacy action: ask the GACC to stop promoting the WBT

[Xavier Brandao]

Dear Francesco,

Thank you for sharing the link with all of us.
I feel we must create more bridges between the researchers who have 
worked and work on the protocols, and the people discussing on this 
List. The recent article from Anna University in Chennai is an 
illustration of that.

I feel your paper is a major contribution to the current debate, and a 
major step. You've expressed the issues in a very clear and documented way.

About the WBT, a few quotes:

p 64

"Therefore, the dominant practice of solely relying on WBT results may 
negatively affect both stove dissemination programs and climate impact 
estimates. As this practice has been further encouraged by the 
definition of stoves performance rankings, by the GACC and the ISO-IWA, 
based on the WBT, a deeper analysis of the possible implications is 
critically needed."

p 80-81

"Still, some of WBT critical issues remain unsolved, with a number of 
researchers claiming the protocol would need to be reviewed in terms of 
precision and accuracy [76] [57] [77].
A lot of debate has been made around metrics formulation, primarily on 
thermal efficiency, which is often interpreted as the most immediate and 
distinctive stove performance parameter."

"The scientific meaningfulness of η at Low-Power has been also 
questioned by Zhang et al. [57], claiming that simmering and low power 
operation are not synonyms and that a proper way to evaluate Low-Power 
efficiency would be simply operating the stove at the lower power 
possible to heat water."

  "Criticism about WBT also concerns thermodynamic subjects. The WBT is 
a controlled laboratory test, thus supposed to have little uncertainty 
and to be effective in comparing different stove designs. Nevertheless, 
the choice to approximate a typical cooking task (boiling and simmering) 
is not functional to this purpose; in fact, as documented by L’Orange et 
al. [78], uncertainties related to temperature reading and vaporisation 
in the boiling region lead to high variability between test replicates."

"Of course, a stove which is specifically designed and optimised for 
insulated pots would be performing differently without insulation; yet 
testing all stoves without a lid is not a solution either. To better 
understand this concept, a simple experiment on a common European 
electric heater – which was actually experienced by the author on a 
Severin KP 1092 (1500 Wnom) – may be performed: the appliance, operated 
at its maximum power, might not be able to heat a small pot of water (2 
litres) up to the boiling point, when no lid is placed on it; yet it may 
be perfectly able to perform the task when the pot is insulated (as 
commonly done by the average European user). Therefore, the electric 
heater would fail to perform a WBT (even on a small pot) yet it would be 
perfectly functioning from a user’s point of view. The example 
highlights how stove performances are not inherent to the design, but 
rather depend on several external factors (viz. pot dimensions and 
insulation, as well as fuel type, moisture content and burn cycle in 
case of wood burning stoves). Trying to approximate a fixed “task” 
cannot be representative of the variety of cooking tasks and habits that 
may be experienced in a real context of use [68]."

To conclude, the WBT strengths:

  * Highly detailed and user-friendly document, including Excel Spreadsheet
  * Adaptability to any fuel and stove type

and weaknesses:

  * Confusion on the protocol purpose and usefulness
  * Not suitable to assess average field performances
  * Questions on some metrics meaningfulness
  * Questions on thermodynamic issues
  * High variability between test replicates and uncertainty
  * Misleading statistical considerations
  * High number of replicates needed to obtain statistically significant
    data.


Now, the study points out that no protocol is perfect, and all protocols 
should be improved.

And, about using the WBT and other protocols to design a stove:
"Furthermore, the review analysis seems to suggest that current testing 
protocols may also provide misleading guidance about stove designs;"

There's a lot of work ahead.

Best,

Xavier




On 2/20/17 11:09, Francesco Lombardi wrote:

Dear all,

I am pleased to inform you that we just published a new article that you 
may find extremely relevant to this discussion. The title is: 
"Laboratory protocols for testing of Improved Cooking Stoves (ICSs): A 
review of state-of-the-art and further developments". This is the link 
for the downlkoad: 
http://www.sciencedirect.com/science/article/pii/S096195341730065X

The paper, published in Biomass and Bioenergy, performs an analysis of 
strengths and weaknesses for each protocol based on defined indicators. 
Real-life relevance, repeatability and data evaluation are set as 
indicators for comparison. Based on the analysis, aternative solutions 
for design rating and statistical analysis are proposed and moreover we 
provide an outlook for the definition of a novel standard.

It is very important that the criticalities here identified are properly 
discussed and solved before the publication of any novel 
protocol/standard. Accordingly, we hope that you can contribute to share 
the results of this study as much as possible within the stove community.

Thanks,

Francesco Lombardi


/Francesco Lombardi, Eng.
Researcher at Department of Energy
UNESCO Chair in Energy for Sustainable Development
www.unescochair-e4sd.polimi.it
Politecnico di Milano, via Lambruschini, 4 – 20156 – Milano
Mobile: +39 338 2749066
zOffice: +39 02 2399 3866/
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