[Stoves] Aprovecho's ISO certificates

[Crispin Pemberton-Pigott]

Dear Nikhil

>I understood test method and equipment are different. My concern with both is about PM2.5 claims.

OK.

>Tiers for PM2.5 were changed from the Lima Consensus to IWA without

Word(s) missing.

>LC had two sets of ratings for PM2.5. There were four Tiers in all, from 0 to 3.

And these has no justification – they were placeholders.

>One rating was in PM2.5 emission rate and % reduction - the top Tier being >90% reduction and <50 mg/L.

Correct. An emission rate has meaning, a % reduction does not because there is no universal baseline stove, not 3 stone fire.

>The second was for "IAP rating" with > 95% reduction and [Inline image 1] .

That is meaningless because there is no such thing as a stove that ‘reduces IAP by 95%’. It depends on the kitchen and we are not testing kitchens. If there was a universal baseline, there could be a % reduction, Any IAP calculation has to be based on some model of dispersion which has no meaning outside the context of use. It is speculative and cannot be used for product regulation, trade or procurement.

>IWA by contrast had five Tiers and for PM2.5, Tier 3 cut-off was set at =< 8 mg/min and Tier 4 at =< 2 mg/min.

That is a rate which can be measured, but suffers from the error of thinking that all stoves are one size which obviously they are not. A large domestic stove meeting that Tier 4 emission rate would have to be far cleaner per MJ delivered than a small stove with the same emission rate. Several EPA and state regulations are trapped in the same paradigm. Do they permit a home to emit a certain mass total, a mass per minute in use? And total per kg burned? A total per delivered (useful) MJ of heat? Selecting one rating creates problems. Which type of problem do you want?

>Then again, another rating was in terms of power levels - "High Power PM" Tier 4 was =< 41 mg/MJd and "Low Power PM" Tier 4 was =< 1 mg/min/L.

Calculating from the max emission per MJ delivered and comparing it with the max mass that can be emitted per unit time gives a performance curve. If you fall above that curve, fail, below, pass. This only applies to the high power metric.

The Low power metric is not valid (has no scientific basis) because the emissions are divided by the number of litres ‘simmered’ and there is no causal relationship between that number and the emissions (See Zhang<http://ieeexplore.ieee.org/document/6827753/?reload=true&arnumber=6827753&sortType%3Dasc_p_Sequence%26filter%3DAND(p_IS_Number:6827745)>, Y et al 2014). In effect the emission rate is divided by a random number.

>There is some chicanery going on here - from concentration (in Lima) to per MJd and per min/L. Sure, there is a cooking cycle defined somewhere that can link these three with the use of some kitchen circulation model.

The performance of the stove is rated independently of the kitchen. Again, there is no causal relationship between a stove and a kitchen. You could put any stove in any kitchen. Any claim about IAP and a stove is puffery. There is no universal ‘indoors’ and as any kitchen of a given size could have any ventilation rate, there is nothing real about the result of a model. The emission rate is the only valid number and as any other number is speculative, one is restricted to using the emission rate. The IAP claim is no more than a mechanical change to the emission rate by mathematical means.

>That is, I am not prepared to buy the argument that this was just over-simplification so that emission rate and concentrations can be linked via a model of standardized cooking cycle, standardized fuel, standardized kitchen volume and airflow, mobility. Rather, it is a deceit of environmental health zealots, namely EPA and its contractors.

That is possible. The claim for a health response is the problem. Even if one could prove that in a certain region kitchens have typical ventilation rates, egress points for smoke, volume and weather, that doesn’t fill the gap between a speculative exposure and an equally speculative health impact from that speculative exposure. It has reached the point of being silly.

>While you, Ron and many others on the List were arguing about efficiency, EPA and WHO (who had some money from DfID via its "Evidence Base" contract with GACC) were concocting PM2.5 emission ratings in such a way as to drive solid fuel stoves out of market.

It seems so.

>That is, the whole purpose of TC-285 and WHO grandstanding about Guidelines for Household Fuel Combustion was NOT to galvanize market for BioLite, EnviroFit, or Paul Anderson's TLUD stoves - any biomass stoves at all - but to give Kirk Smith the chance to argue that no biomass stove was "truly health protective".

That also seems so. There is a consistent pattern of making such claims while jerrymandering the targets and test methods to produce results that are always a ‘fail’ for most stoves. Obviously the key ingredient is the ‘single box Berkeley model of dispersion and concentration’ contained in the WHO calculations. The text of that same document says that the model is not realistic. I don’t see how you can conclude that an emissions rate is ‘unsafe’ if the exposure model is unrealistic.

>On the basis of emission rates or concentrations, Prof. Smith has never been explicit.

Those working under him and guided by him have been. The WHO documentation makes explicit claims.

>But if he claims concentrations, then he is moving away from his ideology of "dirty cooking fuels"; there are other pollutants in household and ambient air.

Well, the model is incomplete, eh?

>His and Ajay's HAPIT model runs on concentrations before and during an intervention but adjusts for concentrations other than cooking fuel, even chimneys. But only on some impractically high bar such as =< 2 mg/min the argument that no solid fuel is ever clean enough becomes sustainable.

India lists LPG as having 8 mg/MJ delivered. There are several wood stoves and coal stoves that are below that number. If an LPG stove has a rate of 2 mg/minute, then it is equivalent to delivering 2/8 = 0.25 MJ/minute. 250,000 J/minute is 4,167 Watts delivered. That is a heck of a big stove. At an efficiency of 50%, it is a, 8.3 kW fire. 2 mg/minute is easily achieved by kerosene stoves, a supposedly ‘dirty fuel’ as Kirk and GACC would have it. All it has to be is small enough.

>Your mention of Aprovecho LEMS not being able to score at Tier 3.5 made me connect the dots.

Caution here: I do not know what the current LOQ is for the latest LEMS. Maybe someone does, but I haven’t seen it.

>On the one hand, we have EPA Final Rule<https://www.gpo.gov/fdsys/pkg/FR-2015-03-16/pdf/FR-2015-03-16.pdf)> on residential wood heaters dated 16 March 2015, three  years after IWA - see p. 13672 - with PM2.5 emission limit maximum 2g/hr = 3.3 m/min five years after the rule became effective, i.e., 2020.

This is for a stove with a chimney. If you combine the leakage that Kirk anticipates from the stove (25%) then we have something with which to make comparisons. Note that there is no efficiency in that target. 2000 mg per hr is 33 mg/minute. Multiple wood and pellet stoves can reach that, depending on the test sequence. Let’s leak 25% of that into a room; = 8.33 mg/minute.

Well that is a heck of a lot more than 2 mg/minute. It is higher by a factor of 4. So where do stoves permitted in the US (the new regs from 2021) fit on the list of tiers?

Why would the EPA be punting an emission rate for poor developing countries that is 1/4 the rate permitted in the USA?

>The 3.3 mg/min emission rate for PM is between Tiers 3 and 4 of IWA.

Well, it is 2 g * 1000 = 2000 mg / 60 minutes = 33.33 mg/minute, not 3.3. This is IWA Tier 1.

>Is there any conceivable rationale that US would have a higher permissible PM2.5 emission rates from heating stoves - with air-tight insulation - than poor people's cookstoves out in the open or with doors and windows open except in very cold areas and during heavy monsoons?

Nope.

>In short, what you think is my misunderstanding may have a grain of truth by insight. It is not necessarily the case that "The Tier 4 target for the IWA was supposedly based on work by the WHO."

Well that is why I questioned it. I got a reply that it was all explained in the information supplied for the IWA, but looking closely there is no ‘there’ there.

>WHO did not come up with HFC Guidelines until 2014, more than two years after the IWA.

Yup.

>Besides, where in the world did WHO come up with emission rates -> concentration model but for BAMG/EPA?

Bingo.

>I have known EPA shenanigans over the decades. Scientist bureaucrats are worse than bureaucratic scientists; ideology corrupts.

Dunno. Not in my lab…

>Aprovecho equipment, procedures and "certification" merit independent audit if any stovemaker relies on such and risks reputation or money. On the other hand, businesses ought to be able to take EPA to court for poking its nose where it does not belong. I cannot think of any Congressional appropriation rationalized in terms of international standards for cookstoves. GACC and ANSI have been carrying a secret business on dubious legal grounds; it is not clear if Aprovecho is independent of these moves.

No idea. If you use any equipment, you should find out what it is able to rate and what not. Similarly, taking a test protocol as ‘valid’ without checking it is pretty wonky as a policy for spending money. The WBT is used on the basis of argumentum populum.

>I am also surprised that "From that, equipment can be assembled with an eye on the protocol so the result is within specification. As everyone knows, that is not what people are doing." Please say more or start a new thread if that is irrelevant to Aprovecho.

That is not something ‘about Aprovecho’ which is a research and training institution. If you want a particular quality of result, based on some assessment like putting stoves on tiers, then obviously you need equipment capable of doing it. You can’t just guess what that equipment should be. It has to be selected because it is able to perform the task at hand. Because there are multiple instruments involved in testing a stove, and calculations, there is a need to work backwards what the precision and accuracy have to be so that uncertainties propagated through the calculations provide the quality of answer needed. This is not rocket science. It is how things are procured. If you need a 1 ppm CO2 instrument, getting a 100 ppm device will not do. It happens that the EPA certified equipment has a 10 ppm resolution. 0.01%. Getting a 0.001% instrument means it is well inside the service requirement. 0.02% is not. So you buy what is needed.

Regards
Crispin

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