[Stoves] Test methods for cook stoves
Frank Shields
franke at cruzio.com
Thu Mar 19 18:00:40 CDT 2015
Dear Philip,
‘reply below'
I agree that developing the improved stove is research, and that once the improvements are proved to the developer’s satisfaction there needs to be one or more independent tests - where we differ is on defining the tests.
I believe we have to start by developing a baseline of what is actually happening in the target community – what do they cook, how do they cook it, what are the primary fuels, how much of those fuels do they actually use when cooking, what utensils do they employ (if any), and what are the emissions when they are cooking.
Then the improved stove is used with the same fuel cooking the same meal in the same way using the same utensils to see how much fuel it uses and what the emissions are. Only then can you be reasonably certain that you have a better cookstove.
FRANK> Let me count the variables: 1) What they cook (should we use five main items? X 2) how do they cook it (are there several ways?) X 3) What are the primary fuels? (are there several available? X 4) How much of the fuels do they use or how much is left? X 5) what utensils do they use (are there several for the same task?) X 6) and what are the emissions? (we take readings of several constituents). = [A LOT of combinations to test!]
FRANK> That’s why I suggest testing the kitchen utensils. I’m guessing there is about two item used for cooking on a small stove: a pot for watery foods and a plancha for frying(?) type foods. Are there others? So we replace water with a formulated common starchy food item they cook. Thanks – I am good with that. We start the clock when the match is struck > start timing when the starchy food reaches a temperature and plot the temperature as we keep it constant for the agreed upon time for the food to cook. Something like that.
FRANK> For the plancha we start time with match. Continue to heat until temperature is reached (water drop spatter, oil smoking, or some other means?) and keep constant for a specified length of time. Do we need to actually cook some food? I don’t think so.
Timing the boiling of water, as you suggest, is not an inherently good test because the users don’t necessarily boil water rapidly. They may bring their starchy food to the boil fairly slowly, to be certain of not burning it, and then hold it at temperature for 20 minutes to complete the cooking. If you then take them what you believe to be a better stove, and it DOES burn the food, then you are lost before you have even started. Or they may heat their plancha to nearly red-heat, and toss the meat onto it with a smear of oil, wait 30 seconds until one side is sealed, turn it over, seal the other side, then move it to a cooler part of the plancha to cook the inner parts of the flesh slowly. What does your water-boiling test tell you about that type of cooking? Absolutely nothing useful.
In a word, one protocol does not fit all. You have to develop the protocol to suit the user, not yourself.
FRANK> We are in complete agreement in understanding the variables. But we can’t test all variables and any test we come up with will not be as good as the actual person using it (like everything in the World that’s sold). Field tests may be the way to go but who gets to have their stove tested? The ones with the money (its real expensive) OR already having an ‘in’? It should be chosen from a ‘most likely to succeed’ based on preliminary tests – like what I have been describing. IMO
FRANK> If we are going to come up with a test method we need to sort through all the complexity and reduce it to a few items that people can afford to have tested and best represent the actual real World. We can’t keep waiting for ‘perfect’ because it will not be perfect.
Thanks
Frank
Frank Shields
franke at cruzio.com
Good question about smoke from the actual food rather than from the fire. Let me think about it!
I hope that helps.
Kind regards
Philip
Frank Shields
franke at cruzio.com
On Mar 19, 2015, at 1:05 PM, Philip Lloyd <plloyd at mweb.co.za> wrote:
> Dear Frank
>
> I agree that developing the improved stove is research, and that once the improvements are proved to the developer’s satisfaction there needs to be one or more independent tests - where we differ is on defining the tests.
>
> I believe we have to start by developing a baseline of what is actually happening in the target community – what do they cook, how do they cook it, what are the primary fuels, how much of those fuels do they actually use when cooking, what utensils do they employ (if any), and what are the emissions when they are cooking.
>
> Then the improved stove is used with the same fuel cooking the same meal in the same way using the same utensils to see how much fuel it uses and what the emissions are. Only then can you be reasonably certain that you have a better cookstove.
>
> Timing the boiling of water, as you suggest, is not an inherently good test because the users don’t necessarily boil water rapidly. They may bring their starchy food to the boil fairly slowly, to be certain of not burning it, and then hold it at temperature for 20 minutes to complete the cooking. If you then take them what you believe to be a better stove, and it DOES burn the food, then you are lost before you have even started. Or they may heat their plancha to nearly red-heat, and toss the meat onto it with a smear of oil, wait 30 seconds until one side is sealed, turn it over, seal the other side, then move it to a cooler part of the plancha to cook the inner parts of the flesh slowly. What does your water-boiling test tell you about that type of cooking? Absolutely nothing useful.
>
> In a word, one protocol does not fit all. You have to develop the protocol to suit the user, not yourself.
>
> Good question about smoke from the actual food rather than from the fire. Let me think about it!
>
> I hope that helps.
>
> Kind regards
>
> Philip
>
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Frank Shields
> Sent: 19 March 2015 08:32
> To: Discussion of biomass cooking stoves
> Subject: Re: [Stoves] Test methods for cook stoves
>
> Dear Philip,
> FRANK> Of the many testing programs I have been involved with like Drinking water, wastewater, potting mixes, soils, compost, asbestos golf course etc. it is never assumed following test protocol and getting the same results is “what labs are good at.” We are inspected for the right equipment, chain of custody protocol, chemicals and knowledge and then we receive samples through the year to test and prove we can get the correct results. My thinking is that this is what was planned for stoves testing and they would be looking for independent labs that could pass the requirements and become Stove Testing facilities. But that has never seemed to be the case. So who are the people testing the stoves and providing the data for comparison? And do they have an unfair advantage over the small start-up backyard stove designer? and is the testing standardize to give fair comparison?
>
> You say “We have (MUST have) control over the biomass and task if we ever want to have a stove test that can be sent to any qualified lab in the World and come back with all the same results.” We want to test stoves, not labs! Labs should be able to be given a protocol and reproduce the same result within reasonable limits. That’s what labs are good at.
>
> I thought we were trying to get a better stove – not a better test - and to find out if one stove performs better than another in a given duty.
> FRANK> Trying to get a better stove is research. All data is kept in-house and not for the public. Once the stove has been made a ‘better stove’ it is sent to the independent Stove Lab for testing and compared to the other stoves. This is the only fair way to do this and until the stoves are tested this way there will always be suspect and bios.
>
> So the first problem is to define the duty, and that is almost entirely set by the user – he/she defines the fuel and what needs to be cooked. The fuel and what needs to be cooked will vary greatly from place to place. Then you need some agreed metrics to measure the stove’s performance in that duty. Finally you can get to decide if one stove is better than another in that duty. Of course, there are a host of duties – different parts of the world really are different.
> FRANK> A question: When you are cooking and measure emissions does the volatiles from the food or oils show up on the emissions analysis? And should we consider these along with the volatiles from just the combustion process?
>
> FRANK> What I am thinking is there are lots of ‘duties’ but few cooking utensils. A pot for boiling water used for many things like rice and soups. A hot plate used for many foods. So we design tests for the different cooking utensils (without food) to be used for comparison. A test might go like this:
>
> Value 1)
> We determine the E450v of a fuel (% by wt) that is used by all labs doing the test and from a fuel available at the marketing location. The weigh of fuel used in the task is determined to give us the energy used. This is a sharp value.
> Value 2)
> One person holds the match in one hand and the striker in the other. Another person has their hand on the stopwatch. When the match is struck the Starting time begins. A sharp value.
> Value 3)
> Once the water starts to boil another start time is in place. We boil for 30 minutes. A fuzzy value. (Someone needs to come up with a better procedure to determined when boiling starts).
> Value 4)
> At the end of exactly 30 minutes boil the stopwatch is pressed to give us the total time to complete the task. A sharp value.
>
> So we have only 4 values and only one is fuzzy and needs improving. That is not a bad test. It gives us the biomass used and the time to complete the task. Simple for a group of labs to show they know how to operate the Champion TLUD. These values can then be used along when doing emission testing to verify the stove was operated correctly (and reproducible) during the emission test.
>
>
> So what metrics do we use to measure whether one stove is better than another? We could use the amount of fuel consumed in the chosen duty, but then we have to ask if the user is really interested in the quantity of fuel.
> FRANK> The stove test (not research that determines improvements) just provides values. The values from testing along with info on the biomass used is published and those interested can pick out the values of interest.
>
> The work that I have done suggests that it doesn’t rank very high – once you get to a reasonable level of fuel use, the user is happy. We could use ease of use, but that is really difficult to measure, because the cooks learn the tricks of the trade as they grow accustomed to a fuel/stove combination.
> FRANK> Agree – the market and customer satisfaction will determine if they like the looks and how it operates. They should be given a choice of approved stoves that pass all the Conditions. You will soon find out the ones they like.
>
> The one metric that the users really seem to value is whether a stove burns the user’s choice of fuel more cleanly than another stove. If it isn’t very “clean” (however that is defined) then it is likely to taint the food being cooked. The cleaner the burn, the less the unwelcome flavour (although sometimes the flavour is welcomed – think smoked salmon).
> FRANK> Customer satisfaction – from a list of independently tested and approved stoves. They are all ‘clean’ because they made the list. Let the dirtier of the clean list be chosen for those liking flavor.
>
>
> And with “clean” as the metric, there IS something on which the international community seems to agree. Emissions from stoves are fingered by organisations like the World Health Organization as having an adverse impact on people’s lives – indeed, on their life expectancy. So cleaner stoves is not merely my target – it underpins the whole rationale for the Global Alliance, for instance. We must not be diverted into things like the Clean Development Mechanism, whose primary target is carbon, a doubtful candidate for a pollutant when you consider how essential the stuff is to life. Indeed, history seems likely to view the US court’s labeling of carbon as a pollutant as one of this generation’s more unlikely aberrations, sort of like the belief in slavery 200 years ago.
> FRANK> My suggestion is to test different stoves (as outlined above) to get a base line of the fuel and time. Then adding emissions to the test package (much like I think it is being done now) and collect the emission data. Form a bell curve of the results and come up with limits on pm, CO etc. Base the limits such that, perhaps, 75 % of the stoves pass. That provides gently pressure to get better stoves and as the stoves get better the limits can be lowered. The limits are different for each fuel group and stove type because places that only have oily type fuels cannot expect to have emissions of those that can burn walnut shells. (?)
> There are a lot of variables to get control of. We need independent labs providing the comparison data so there is an even playing field for all stove designers and the data can be trusted. The train is not even going in the right direction to accomplish this.
>
> Thanks
>
> Frank
> Just retired : )
>
> Frank Shields
> franke at cruzio.com
>
>
> Hope that helps clarify things.
>
> Kind regards
>
> Philip
> Frank Shields
> franke at cruzio.com
>
>
> On Mar 18, 2015, at 12:33 PM, Philip Lloyd <plloyd at mweb.co.za> wrote:
>
>
> Dear Frank
> You say “We have (MUST have) control over the biomass and task if we ever want to have a stove test that can be sent to any qualified lab in the World and come back with all the same results.” We want to test stoves, not labs! Labs should be able to be given a protocol and reproduce the same result within reasonable limits. That’s what labs are good at.
>
> I thought we were trying to get a better stove – not a better test - and to find out if one stove performs better than another in a given duty. So the first problem is to define the duty, and that is almost entirely set by the user – he/she defines the fuel and what needs to be cooked. The fuel and what needs to be cooked will vary greatly from place to place. Then you need some agreed metrics to measure the stove’s performance in that duty. Finally you can get to decide if one stove is better than another in that duty. Of course, there are a host of duties – different parts of the world really are different.
>
> So what metrics do we use to measure whether one stove is better than another? We could use the amount of fuel consumed in the chosen duty, but then we have to ask if the user is really interested in the quantity of fuel. The work that I have done suggests that it doesn’t rank very high – once you get to a reasonable level of fuel use, the user is happy. We could use ease of use, but that is really difficult to measure, because the cooks learn the tricks of the trade as they grow accustomed to a fuel/stove combination. The one metric that the users really seem to value is whether a stove burns the user’s choice of fuel more cleanly than another stove. If it isn’t very “clean” (however that is defined) then it is likely to taint the food being cooked. The cleaner the burn, the less the unwelcome flavour (although sometimes the flavour is welcomed – think smoked salmon).
>
> And with “clean” as the metric, there IS something on which the international community seems to agree. Emissions from stoves are fingered by organisations like the World Health Organization as having an adverse impact on people’s lives – indeed, on their life expectancy. So cleaner stoves is not merely my target – it underpins the whole rationale for the Global Alliance, for instance. We must not be diverted into things like the Clean Development Mechanism, whose primary target is carbon, a doubtful candidate for a pollutant when you consider how essential the stuff is to life. Indeed, history seems likely to view the US court’s labeling of carbon as a pollutant as one of this generation’s more unlikely aberrations, sort of like the belief in slavery 200 years ago.
>
> Hope that helps clarify things.
>
> Kind regards
>
> Philip
>
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Frank Shields
> Sent: 17 March 2015 08:09
> To: Discussion of biomass cooking stoves
> Subject: Re: [Stoves] Test methods for cook stoves
>
> Dear Philip,
>
> see below
>
>
> On Mar 16, 2015, at 11:15 PM, Philip Lloyd <plloyd at mweb.co.za> wrote:
>
>
>
> Dear Frank
>
> You say “There are two we are interested in when picking out a stove. (a) biomass / task and (b) time / task”
>
> I beg to differ. We have little choice of biomass or task – both are almost entirely determined by the user. Then the important variable is NOT the time for a task, but the emissions during the (pre-determined) tasks. Granted, the shorter the time the lower the emissions are likely to be, but that doesn’t necessarily follow.
> We have (MUST have) control over the biomass and task if we ever want to have a stove test that can be sent to any qualified lab in the World and come back with all the same results. We will continue getting nowhere, as we have for the past ten years and continue to do so, until the basics of method development is followed. That is, keep one variable and control all the others so to notice changes in the one we target. We are just piling on variables like there is no tomorrow.
>
>
>
>
>
> Our target is cleaner cookstoves, fully accepted by users. I cannot follow your logic in suggesting that our choice of biomass/fuel and our choice of task can be at all relevant to achieving that target.
>
> YOUR target is cleaner cookstoves. The person designing the legs for the stove has a target of making the stove more stable and the person inspecting the paint job has a target of making the stove look nice.
> Emissions is no more important than the paint job because neither stove will make it to market until those (and all) Conditions have been met.
>
>
>
>
>
> Kind regards
>
> Prof Philip Lloyd
> Energy Institute
> Cape Peninsula University of Technology
> PO Box 652, Cape Town 8000
> Tel:021 460 4216
> Fax:021 460 3828
> Cell: 083 441 5247
>
>
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Frank Shields
> Sent: 17 March 2015 06:52
> To: Discussion of biomass cooking stoves
> Subject: Re: [Stoves] Test methods for cook stoves
>
>
> Greetings Stovers,
> My suggestions:
>
> Test methods for comparing Stoves.
>
> 1) The units of interest: There are two we are interested in when picking out a stove. (a) biomass / task and (b) time / task
>
> 2) Variable = the Stove. We swap out different stoves, run the test and compare the results for biomass per task and time per task.
>
> 3) Controls; there are two: (a) fuel at one end and (b) task at the other.
>
>
> Control (a) Fuel
> We walk up to the stockpile of fuel in town that has been gathered and piled and pull out what we want. If we want to test a Rocket Stove using 2.5cm X 2.5cm X 10 cm long kiln dried sticks we pull out the bigger pieces and have them sawed and dried. The rest of the pile we carry back to the forest and scatter around under the trees. Paul for his TLUD needs uniform pieces to keep an even flame front so he takes out what he wants, chips them to size, and screens out the fines. The fines and overs are carried back to the forest and scattered. Richard collects the material he can turn to mush and sends the rest back. Stoves using pellets and sticks are done the same. Use whatever you want as long as it comes from the pile.
>
> Control (b) Task
> The task chosen must have a clear end point. The start is easy – it’s when the match is struck.
>
> Everything else is NOT part of the test. Our goal is to reduce by elimination variables and get control over the ones left so the test can be conducted at any lab and all will come out with the same results.
>
> We don’t care about the chemistry of the gases, smoke, 2.5 pm, stability of the stove, toxic chemicals, hot surfaces that can burn, or anything else. If Stove A works better than Stove B then check the gases, make some adjustments and have Stove B re-tested. If, for example, Stove A completes a task using less biomass and in a shorter time than Stove B but stove A produces a lot of smoke – then Stove A wins.
>
> Everything else are ‘Conditions’ that must be meet. There are lots of them: paint streaked with runs on new stoves produced is a condition unacceptable, poor welds, toxic galvanized metals, poor quality metal – all conditions unacceptable. Smoke, toxic gases, hot surfaces or unstable are all conditions unacceptable. Too heavy to move or won’t take my favorite pot are more conditions. But these have nothing to do with the Test. We need to keep the Test real simple. All the Conditions in the list must pass or don’t bother doing The Test OR make corrections before testing.
>
>
> Also;
> Control (a) Fuel; we are interested in mass of the biomass used but we can normalize it to energy for convenience and when comparing ‘like fuels’ when the on-site fuels are not available. When measuring energy I fully agree with the method Dean used at Stove Camp. The problem is there are so many unknowns and guesses of the energy content of the different parts of the fuel. Perhaps its possible to get good precision (replicates) but I can’t see how the accuracy (real value) could even be close. Therefore, without knowing of a better replacement, I believe the E450v energy value for the fuel is the best one to use because it is easier to determine. I realize E450v has its own limitations.
>
> Regards
>
> Frank
> (retired)
>
> Frank Shields
> franke at cruzio.com
>
>
>
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