[Stoves] FW: ETHOS 2013: Where is the New Data on Stove Performance in the Field?

Paul Anderson psanders at ilstu.edu
Fri Dec 7 14:56:41 CST 2012


Dear Crispin and all,     (to be posted also at    www.drtlud.com   )

I have been reading the previous messages, and now offer some comments:

1.  The FULL data from the Quad 2 tests were provided to stimulate 
discussions, and I am delighted that Crispin and some others are digging 
into it as an example of the testing procedures.   I do not run the 
rests and do not participate in the definition of the test procedures.   
Maybe other stove manufacturers could release (or point to current 
availability of) full results of tests on their stoves.  I will not 
study their data from the point of view of test procedures, but others 
might.

2.  I accept Crispin's position about the difference between FUEL 
efficiency and ENERGY efficiency, but with this observation: Crispin 
said something like:  "Fuel from the woodpile" or "wood from the fuel 
pile"  should be what is counted.   TLUDs take in fuel and operate best 
if the full batch of fuel is pyrolyzed, leaving behind char that is 
certainly not like the original fuel.   That original fuel is gone!!

Therefore, if "fuel put into the stove, minus that SAME fuel that can be 
saved" is the amount considered in the FUEL efficiency, then a TLUD 
could use more fuel that other stoves.   HOWEVER:

3.  This could imply that the stove was operated until the end of 
pyrolysis even if that was many minutes after the complete WBT was 
conducted.   Unfair disadvantage to batch stoves.    PARTIAL SOLUTION 
that creates havoc is that the SAME stove could be operated identically 
with the amount of fuel carefully calculated to have pyroylsis end 
within a minute after the WBT was completed.   Fill a TLUD with 3 kg of 
fuel for one test run, and then do it with 1 kg for the second test 
run.   In other words, Crispin's correct statement (that the  original 
loading of 1600 grams of wood) is NOT related to the amount of FUEL used 
up until the time of the completion of the WBT.

4.  Because TLUDs can utilize so many different types of dry biomass 
EQUALLY WELL, and because reduction of burning of WOOD is so important, 
then what if the test was done with maize cobs or with stalks or with 
briquettes from true "waste" or with inedible Jatropha seeds?    Then 
the following would be true:
         "No fuel was taken from the woodpile"    and    "No wood was 
taken from the fuel pile."

So the impact of WOODY fuel savings means the TLUDs are the clear 
winners!!!

Remember, the definition that the fuel is to be some uniform type of 
WOOD (to ensure comparability between the stoves) is what has forced the 
TLUDs to be tested with wood.  How well I remember the Stove Camps at 
Aprovecho (I have attended seven thus far) where the kiln-dried Douglas 
fir was the only acceptable fuel for the testing.

5.  About testing of char-making stoves, that include the TLUDs:

Granted that char is not the original fuel.

But the remaining char can have substantially greater value on a weight 
basis (and perhaps in other ways also) than the biomass that was the 
feedstock.   And that char can be for A) burning or for B) biochar (soil 
amendment) or for C) carbon sequestration/climate change/carbon 
credits.   AND B and C can be cumulative!!!!     Or D)  it could be 
thrown away.

Example:  Actual figures:     Chip Energy has a Biomass Furnace (AVUD, 
not TLUD) that can use pellets (and other dry biomass), with a resultant 
yield of much heat plus char.    Pellets purchased retail at under one 
dollar for 10 pounds will yield 2 pounds of char that is quite 
respectable for sale as biochar at one dollar for 2 pounds.    THAT 
Biochar has 5 times the monetary value by weight compared to pellets.   
Meanwhile, all of the heat energy was essentially FREE to heat the Chip 
Energy building during the winter months.

If this example is transformed to be a cookstove (and it is, in the 
TLUDs), the HEAT for cooking could be considered free if the user gives 
reasonable value to the char as biochar.   And do it with maize cobs in 
a rural village where the soil is poor and responds well to the addition 
of biochar.

So, concerning FUEL effeciency, W H O    R E A L L Y    C A R E S    
what the numbers are from the WBT xxx.yy?

Yes, I really do care.   and we all should care.    but "do not crucify 
the TLUDs on a cross of carbon."

Fix (adjust, not "fix" as in illegal horseracing) the tests any way that 
allows for true differences between stoves to be observed.    Just 
please do not have testing that poisons the waterhole for those who are 
working with TLUD and other micro-gasifier stoves.

Professional chemical engineer Hugh McLaughlin and I are examining the 
issues of testing, and output (if any) should be ready before ETHOS in 
late January.    The task is not a pleasant one.

Paul

Paul S. Anderson, PhD  aka "Dr TLUD"
Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
Website:  www.drtlud.com

On 12/6/2012 11:37 PM, Crispin Pemberton-Pigott wrote:
>
> Dear Frank
>
> I am going to discuss the WBT 4.1.2 below, not the UCB-WBT 3.1 which 
> is old now.
>
> What matters is what people who select stoves for their promotion 
> programmes /think/ the fuel consumption number is. If people think 
> that conducting 15 back to back water boiling tests will require a 
> wood pile with a mass of 15 times the WBT fuel consumption number, 
> then we should provide a consumption number that is the actual fuel 
> consumed per replication of the test. We speak of 'dry fuel' because 
> of course the moisture content affects the mass consumed. Correcting 
> for it is reasonable.
>
> Is there any doubt that people think the 'fuel consumption' recorded 
> by the end of the test is the amount of fuel consumed?
>
> Here is the text from the CREEC laboratory at the bottom of the Quad 2 
> TLUD test:
>
> "The Quad 2 stove boils 5L of water in 27 minutes, uses 636 g of wood 
> to boil and simmer (cook) 5L and has an energy use of 11713KJ."
>
> This gives the impression to any careful reader that the fuel consumed 
> per WBT is 636 g. The actual fuel needed each time the stove is 
> operated is about 1600 g.
>
> Most interestingly the energy consumption is 11,713 Joules. It is 
> energy efficient. The dry fuel equivalent of that amount of energy is 
> indeed 636 dry g of fuel (gum tree). So why the large difference? It 
> is because of the charcoal produced, not burned, and unburnable in 
> that stove. This was what Jim Jetter and others have been discussing 
> with me off-list.
>
> The suggested fuel consumption definition attempts to describe, for 
> many different stove types, how to determine the new fuel you would 
> need per replication to keep on repeating an experiment, in this case 
> the WBT 4.1.2.
>
> Because some stoves can use fuel remaining from the previous cooking 
> cycle. In that is the case, the each test should /start/ with that 
> same 'left over fuel' from a previous cycle. If you claim that the 
> remaining char can be used in the same stove next time, prove it by 
> starting the test with the typical amount left from an earlier 
> identical cycle. The advantage of this approach is it corrects for 
> fuel heat determination errors that are almost impossible to correct 
> in a simple lab.
>
> Suppose starting a stove wasted, each time, 250 g of fuel just to get 
> the fire going properly.  That is not unused fuel, it is needed each 
> time because of some characteristics of the stove. We count it even 
> though the energy needed to cook on the established fire starts 
> counting when the pot goes on. The 'energy needed' is the figure used 
> to calculate the thermal efficiency from the fire to the pot. It is a 
> valuable metric for the design who needs to know how the stove 
> structure is performing.
>
> As seen when calculating the CO2, CO and other gas outputs, the 
> difference between fuel consumption and energy production is real.
>
> Simply stated, a stove can be energy efficient but fuel inefficient.
>
> Regards
>
> Crispin
>
> +++++++++++++
>
> Dear Crispin,
>
> "Fuel consumption : The mass quantity of new, raw fuel required to 
> replicate any prescribed performance cycle, per replication, ignoring 
> the results of the first cycle in any series of such replications. 
> Combustible material in any condition remaining from one replication 
> which may be used by the same device as fuel in the next should be so 
> used unless it is common practice in the target community not to do so 
> in which case the test may be conducted with new raw fuel only."
>
> Not sure if this applies here but it seems to me the error is at the 
> start (heating up stove body, getting the fire lite etc) and at the 
> end (measuring flaming fuel left over). To test stoves we can continue 
> the burn for a long time (simmering and boiling) using a --lot- more 
> fuel reduces these two errors at the ends and may give a better 
> indication of stove efficiency.  If we can't get the bias and 
> precision needed when trying to simulate a 'meal' we may need to go to 
> these longer times -- and I think we should.  You say that when you 
> say : The mass quantity of new, raw fuel required to replicate any 
> prescribed performance cycle. It's the amount of fuel (time burning) 
> that is adjusted. To determine efficiencies at start and end is 
> entirely another procedure.  As I see it.
>
> Frank
>
> *From:*Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On 
> Behalf Of *Crispin Pemberton-Pigott
> *Sent:* Thursday, December 06, 2012 4:12 PM
> *To:* Stoves
> *Subject:* Re: [Stoves] FW: ETHOS 2013: Where is the New Data on Stove 
> Performance in the Field?
>
> Dear Jim
>
> I am just getting to your message of Nov 30. I have not been ignoring 
> the conversation. I have just read it and respond as follows:
>
>
Snipped the long but useful message.

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