[Stoves] Sunday at ETHOS meeting

Mon Feb 1 10:47:17 CST 2016

Some stove marketing (“behavior change”) organizations at ETHOS challenged the “time saved collecting firewood” metric saying that they increasingly find people buying, rather than gathering wood fuels, even in rural areas.   

Tom

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Crispin Pemberton-Pigott
Sent: Sunday, January 31, 2016 10:51 PM
To: 'Discussion of biomass cooking stoves' <stoves at lists.bioenergylists.org>
Subject: Re: [Stoves] Sunday at ETHOS meeting

Dear Ron

Thanks again for all the details.

Picking one point only:

“Example might be favoring the 55% efficient stove which could entail less time collecting fire wood.”

That was for the sunken pot water heating function, I understand that.  I really like the idea of people cooking with sunken pots but it can be really inconvenient to use such a device in real life.  When the number is analysed closely, is it 55% thermal efficiency? What is the overall efficiency? 45%? 40%? It is a Rocket stove. They are well known for producing an above-average mass of char at the end. That is lost fuel energy. Does the fan assist reduce the char production (or increase it)? It didn’t change the cooking efficiency, and that is the reported thermal efficiency, not the overall fuel efficiency (if it was a WBT).  The energy efficiency (energy from the forest to energy in the pot) of a Rocket stove is about 22-24%. The difference between 23-28 is the char that is left at the end which the Thermal efficiency calculation counts as unburned fuel.

Could we also refer this principle to the stove mentioned the other day? It is metric time again: if the stove has been rated with a ‘thermal efficiency’ of 52% and is making char, then there may be very little time saved ‘collecting firewood’.

Unless this (to me, obvious) change in reporting the thermal efficiency and then talking about ‘fuel consumption’ is made very publicly, the scandalous mis-reporting of stove performance vis-à-vis fuel consumption will continue. All the CDM and Gold Standard projects are financed on the basis of ‘thermal efficiency’ instead of fuel efficiency while claiming to be ‘saving fuel’ based on a comparison of the thermal efficiencies of the baseline and improved stoves. As the ‘performance tiers’ are also reporting the thermal efficiency it is likely that all GACC supported stoves are being selected on the same basis. Has anyone noticed?

If you collect the same amount of firewood and burn half of it to make charcoal with twice the thermal efficiency value, you are not saving or collecting less fuel. 

Given that 5 of the 8 stoves burning in the afternoon were TLUD’s – no doubt making char, the matter has the utmost urgency. 

Thanks again for your copious contributions.

Crispin

I.   8:30‐9:40am Department of Energy Biomass Stoves Grant update, continued Research Summary:   

            1.   * Colorado State University (Jessica Tryner”: When is a TLUD not a TLU”D?)

            The answer I think is  - after you have added extra fuel on top of the hot char (after the pyrolysis front has reached the bottom).  Then the new pyrolysis front moves upward (BLUD mode now).  The results are not as good - but they may not be that bad.  I say “maybe” because although the emissions are certainly worse than for TLUD mode - they may be better than other ways to finish a cooking task.  This is apt to be somewhat controversial - as occurred after a companion talk yesterday given by fellow CSU student Jim Tillotson in Session IV-A.  This talk more on Computational Fluid Dynamics (CFD) with an unusual optical simulation I have never seen before.  

            I had a chance afterwards to talk to their team leader, CSU Professor Anthony Marchese; am very impressed by this team effort.  Although this DoE contract is finished, they have additional funding to continue this important work with TLUD analysis - which is long overdue.  Look for these slides.

            2.  * Aprovecho Research Center (Dean Still: “Clean Burning Biomass Cookstoves” and SSM to Manufacture Side Feed Forced Air Rocket Stove with Chimney)                    

            Dean discussed results with 5 models (different types).   This is written up in an article in 2015 in EcoHealth.  They have conducted field tests in several countries.   In response to a country request, they recently added a chimney.  With a submerged pot, they got an efficiency of  55%; but users wanted more flexibility with pot size, so the efficiency dropped to 28%.   They have added an automatic smoke diverter for when the pot is removed.  They used a catalyst (which got super hot and helped add radiative heat transfer.

            Their partner in China was a big help so they think this can sell $40 top end retail (but Dean thinks they can sell many more if they can drop price to $30.

            Dean has prepared a new second edition stove book covering many stove topics.  Available from at least Dean at $20.  Already scheduled to be translated into Chinese.

            3.  * Berkeley Air Monitoring Group (Michael Johns: Platform for Integrated Cookstove Assessment)

            Emphasis here on monitors with an integrating design.  These are much improved over early versions.  Data obtained in Guatemala and Peru.  Grant ended in March 2015.  Need to see slides.

Question period  (including Doe contractors from previous day.)  In one comment on potential value of more uniform fuels, Dr. Ashok Gadgil disagreed, saying that stoves should work with the fuels available to users - not likely to be uniform.

            Another discussion on best types - with emphasis that consumers want choice

            Anthony Marchese said all the CSU results would all be available free as CSU will be paying extra $2k (for open source)

            ETHOS chair  Elisa Derby announced upcoming 2-part webinar sponsored by Winrock (her employer), GACC, and others

            Ranyee Chiang announced an upcoming China tour - on pellets.

II   10:00 to 11:20    Three-way breakout  (see agenda at  http://www.ethoscon.com/wp-content/uploads/2016/01/ETHOS-2016-Agenda-revJan28.pdf ) 

             I went to #3 group, but got there late because of discussions with Prof. Marchese.       

            D.   The last speaker Nordica McCarty (Engineering systems modeling and decision‐based design tools and their applications for village energy ) carried previous doctoral work at ISU (Advisor Mark Bryden) by Nate Johnson.  This was more directed at individual village residents - and how to meet different objectives (health, costs, etc).

            I especially liked plots showing how to predict different choices base on opportunity costs (what a person might do if they valued their time at numbers like  $4 to $5 per day).   Example might be favoring the 55% efficient stove which could entail less time collecting fire wood.

III   11:30 - 12:30  Last group of three breakouts -  I went to #2 

A.  Michael Johnson of Berkeley Air  “In‐field black carbon emissions from cookstoves in Asia and Africa”.  Very complete analysis of 15 stove types at 500 sites in several countries, including at least India, Uganda, Kenya,  Viet Nam.   Publication in process. 

B.  Erin Rasmussen "Natural charcoals, so much more than a cooking fuel”  (Erin recent past main computer specialist for this list - now having different responsibilities).  This talk mostly on biochar for water filtration.  Mention of experts like Josh Kearns.

C.  Replacement of scheduled speaker.   Francesco Titoricci (sp?)  on biochar to solve water quality issues in Seattle area harbor.  Showed value of biochar in preventing release of zinc from metal roofs and chain link fencing.  Mentioned support from John Miedema.

IV  2‐3pm   Facilitated Discussion: (what we want from ETHOS going forward?) 

            Filled in a blackboard of ideas.  No major changes seem likely - but might add another day.

V.   3‐3:30pm   ETHOS Board Summary (lecture hall) 

            Re-elected Elisa Derby as chair.  Voted in again John Mitchell, Dean Still,  Nordica McCarty + new member Richard Grinnell - all for two year terms, after serving for year #1.

VI.   3:30‐5pm Lighting of the Stoves

            Paul Anderson said there were 8 operating stoves, five were TLUDs this year.    Most seemed to be performing well.   Also one (non-operating) Kon-Tiki on dsplay.  Hope others can supply some photos of this event.

RWL overall estimate of attendee (and my) reactions:  Highly favorable.  

Will try to report again on next few days at Burn Lab and Aprovecho.

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