[Stoves] Key differences of performance test protocols for household biomass cookstoves

Tue Jul 1 13:31:41 CDT 2014

Crispin, 
I would not dismiss the ag.r residue biomass IF properly processed and if especially infilled with more dense and energy dense combustibles . I will be talking about / displaying samples of Eric Theiss's  source fibers blended with residual, powdered charcoal off our own ashland house wood stove. 
I hope to submit these samples for testing at Approvecho and would bet that particulates will be far lower that previously measured in less infilled samples. 
But to date this  supposition is based on simple observation of combustion. So lets see the real numbers eh…

Richard 

On Jul 1, 2014, at 8:27 AM, Crispin Pemberton-Pigott wrote:

I am sitting on the floor at the Beijing airport delayed by thunderstorms. 

The figures cited look like nonsense. An electric stove is about 60 percent efficient and an induction electric stove is between 88 and 92. A rocket stove is about 27. They must be measuring something besides the appliance itself. That sort of thing happens a lot. 

The system efficiency of an electric cooker powered by a coal-fired power station in South Africa is about 25-30 percent. When considering the rocket stove and it's system efficiency (which is only fair too) it is well below the number 27. I will be interested to see the article when I get to Singapore tomorrow. 

Thanks for sending it. 

The system efficiency approach is widely eschewed by the greens on certain pet technologies and included on ones that fall from grace. 

How's this: ‎in South Africa where the delivered energy efficiency of the grid is perhaps 35 per cent of the input energy, the total emissions of PM10 and CO per MegaJoule are lower from a domestic space heating stove than a $1bn power station. Heh heh. 

Stove combustion technology is so advanced when it comes to coal that even with particle accumulators and precipitators the humble stove is now cleaner. I was just at the lab in Ulaanbaatar where the only fuel available is lignite. Something like 1/2 the stoves submitted this year to a WB funded project are going to be cleaner than the required 90% reduction (minimum). It's a lot of progress in 7 years, believe me. 

I will be looking at the total system efficiency possibilities of biomass systems with the China Agricultural University in Beijing later this year. I am thinking about how to create fuels from waste biomass in two or three stages with a view to reducing system emissions not just cooking emissions. Which biomass can be burned as cleanly as coal it usually is not. Part of that is the variability and lack of processing of raw materials.  

So, onward and upward. 

Regards 
Crispin

BBM 2B567CC3
From: Cookswell Jikos
Sent: Tuesday, July 1, 2014 22:40
To: Discussion of biomass cooking stoves
Reply To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Key differences of performance test protocols for household biomass cookstoves

Dear Crispin - thank you for sharing this, 

Have you (or anyone else) by any chance read this article http://www.lowtechmagazine.com/2014/06/thermal-efficiency-cooking-stoves.html 

It a real mind turner to say the least.... I would be very interested to hear some of your thoughts on this matter. To quote one of the opening paragraphs - 

''In fact, an electric cooking stove is only half as efficient as a well-tended open fire, while a gas hob is only half as effective as a biomass rocket stove. And even though indoor air pollution is less of an issue with modern cooking stoves, research indicates that pollution levels in western kitchens can be surprisingly high.'' 

The author then follows that article up with this one - http://www.lowtechmagazine.com/2014/07/cooking-pot-insulation-key-to-sustainable-cooking.html

What do you think? I think I need to double my forestry efforts. 

Kind Regards, 

Teddy 

Cookswell Jikos
www.cookswell.co.ke
www.facebook.com/CookswellJikos
www.kenyacharcoal.blogspot.com
Mobile: +254 700 380 009 
Mobile: +254 700 905 913
P.O. Box 1433, Nairobi 00606, Kenya

Save trees - think twice before printing.

On Mon, Jun 30, 2014 at 12:27 PM, Crispin Pemberton-Pigott <crispinpigott at outlook.com> wrote:
Dear Testers

Please see the paper “Key differences of performance test protocols for household biomass cookstoves” by Zhang, Y et al at

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=6827753&queryText%3DKey+differences

Abstract

“In this study, different ways of testing household biomass cooking stoves are compared and analyzed. The differences between test methods relate to the stove operation and data analysis methods, the fueling procedure, the end point selection, the choice of metrics and others factors. The influences of these differences were analyzed by using an induction heater. The results show the use of a pot lid or not, and the selection of the end point of the test have the greatest influence on the rated performance. Consequently test results provided by laboratories using different test methods will place the same stove-plus-fuel combination on significantly different performance ‘tiers’. Also the results show some metrics in popular tests should be reviewed. Some recommendations are provided for improving the accuracy and repeatability of test procedures and select metrics are defined for greater clarity.”

The comment “some metrics in popular tests should be reviewed” is a polite way of saying they are not valid. This is a major issue when making performance comparisons. If the metric itself is not valid then the comparisons of it between products is not meaningful. One cannot trade money or products on the result.

From the conclusions:

b)       Some metrics still need to be revisited, even if they are generally agreed within the “stove enthusiast” community. National or international compulsory regulation of stove products as envisaged by ISO TC 285 must be based on credible science. The point of testing is to provide useful information. Selected indicators that meet specific needs must first be agreed and validated, and then a test method or methods developed to collect the information necessary to deliver product ratings that can be widely compared and accepted by the public.

The paper is accessible free through academic services.

Regards

Crispin

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