From the American Chemical Society it seems that newer is not always better. Even Yale environment360 bought into this idea. I should add that I’m all for reducing carbon soot, but in the zealous rush for solutions, sometimes too many cooks spoil the soup.
Right: Primitive stoves and open fires pose serious health risks, particularly among women and children. Image: angelic_shrek/flickr. Left: Envirofit says its cook stove will cut smoke and carbon emissions by 80 percent. Image Envirofit
Some ‘improved cookstoves’ may emit more pollution than traditional mud cookstoves
The first real-world, head-to-head comparison of “improved cookstoves” (ICs) and traditional mud stoves has found that some ICs may at times emit more of the worrisome “black carbon,” or soot, particles that are linked to serious health and environmental concerns than traditional mud stoves or open-cook fires. The report, which raises concerns about the leading hope as a clean cooking technology in the developing world, appears in ACS’ journal Environmental Science & Technology.
Abhishek Kar, Hafeez Rehman, Jennifer Burney and colleagues explain that hundreds of millions of people in developing countries in South Asia, Africa and South America are exposed to soot from mud stoves and 3-stone fires used for cooking, heating and light. The particles can be inhaled deeply into the lungs and have been linked to health problems similar to those associated with cigarette smoking. In addition, black soot released into the atmosphere is a major factor in global warming. Aid agencies and governments have been seeking replacements for traditional cookstoves and fires to remedy those problems, with ICs as one of the leading hopes. Until now, however, there have been little real-world data on the actual performance of ICs — which have features like enhanced air flow and a battery-powered fan to burn wood and other fuel more cleanly.
The researchers measured black carbon emissions from five IC models and traditional mud stoves. They did the test in real homes as part of Project Surya, which quantifies the impacts of cleaner cooking technologies in a village in India. Forced draft stoves burned cleaner than any other IC. However, black carbon concentrations from all ICs varied significantly, even for the same stove from one day to the next. Surprisingly, some natural draft stoves occasionally emitted more black carbon than the traditional mud cookstove.
The researchers acknowledge funding from private donors, the National Science Foundation, the Swedish International Development Agency, the United Nations Environment Programme, the Vetlesen Foundation and the Alderson Foundation.
The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 164,000 members, ACS is the world’s largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.
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“Real-time Assessment of Black Carbon Pollution in Indian Households Due to Traditional and Improved Biomass Cookstoves” Environ. Sci. Technol., 2012, 46 (5), pp 2993–3000. DOI: 10.1021/es203388g
Abstract
Use of improved (biomass) cookstoves (ICs) has been widely proposed as a Black Carbon (BC) mitigation measure with significant climate and health benefits. ICs encompass a range of technologies, including natural draft (ND) stoves, which feature structural modifications to enhance air flow, and forced draft (FD) stoves, which additionally employ an external fan to force air into the combustion chamber. We present here, under Project Surya, the first real-time in situ Black Carbon (BC) concentration measurements from five commercial ICs and a traditional (mud) cookstove for comparison.
These experiments reveal four significant findings about the tested stoves. First, FD stoves emerge as the superior IC technology, reducing plume zone BC concentration by a factor of 4 (compared to 1.5 for ND). Indoor cooking-time BC concentrations, which varied from 50 to 1000 μg m–3 for the traditional mud cookstove, were reduced to 5–100 μg m–3 by the top-performing FD stove. Second, BC reductions from IC models in the same technology category vary significantly: for example, some ND models occasionally emit more BC than a traditional cookstove. Within the ND class, only microgasification stoves were effective in reducing BC.
Third, BC concentration varies significantly for repeated cooking cycles with same stove (standard deviation up to 50% of mean concentration) even in a standardized setup, highlighting inherent uncertainties in cookstove performance. Fourth, use of mixed fuel (reflective of local practices) increases plume zone BC concentration (compared to hardwood) by a factor of 2 to 3 across ICs.
Clean burning produces H2O and CO2. Both are GHGs. Therefore, clean burning must be banned!!
The stupid, it burns …
@Peter Kovachev
>I stand corrected, partially, in that I agree that coal-burning technology on an industrial scale has come a long way in reducing emissions of pollutants.
Actually it is the domestic stove with which I have had so much success. There is a set of papers on how it was done and a complete set of drawings for one of the stoves developed – the GTZ 7 series at the website http://www.newdawnengineering.com in the LIBRARY then STOVES.
The PM and CO emissions from the newest stoves are lower than even the most modern power plant with static precipitators. All that I wrote above was about small stoves, not big burners.
>At a consumer level, though, the case for coal appears to be harder to make.
We have finished making it. Extremely clean burning stoves (4 different ones plus the GTZ 7) are available heavily subsidised in UB.
>…a number of advanced home units on the US market,
The US is quote far behind on this I think in part because there is no strong need to worry about them.
>The only info I was able to find on Ulaanbataar and “improved stoves” was a 2005 report whose conclusions are not a glowing recommendation
This started to get onto the right footing in late 2007. The first lesson was to show that the fuel can be burned exceedingly cleanly, against all expectation as it had been defined as ‘dirty’ by so many people who did not know how to burn it. Incidentally the coal they use has high hydrogen and low carbon. Heh heh. So much for being ‘dirty’.
>…but I wonder whether the negative assessment is due to overly high standards set by activist agencies, inferior technology of the “improved stoves” supplied for the study, ones possibly designed to be affordable, the researchers’ concerns and politics over CO2 and greenhouse gases and lack of comparisons with the alternative
The real problem was no one had ever seen or used a really clean burning coal stove. Simple as that. The demonstration of several downdraft stoves with 1/2000th of the emissions was the starting point. It took 2-1/2 years to get people’s heads turned around. Some of them at least. Now MCC is putting massive resources into getting the traditional stoves replaced. The reduction in PM for the main product is 99.94% over the baseline as traditionally operated. We call them ‘Three 9’s stoves’. There are 5 which are in that Three 9’s category. No subsidy for products that are less than an 80% reduction.
>Perhaps you can take a peek at the article
I am familiar with the article. What you need to see is the AMHIB Report produce by the much maligned WB that pulled off this extraordinary improvement. The full name is, “Urban Air Quality Analysis of Ulaanbaatar: Final Report of the Air Monitoring and Health Impact Baseline Study by the World Bank”
It provided a key detail from a times series analysis of smoke which was that the emissions on ignition are nearly all the smoke that will be produced by the stove. By concentrating on ignition emission reduction, we were able to profoundly reduce the PM2.5 production. The coal is a wet lignite and burns very cleanly because of the high H2 content. The combustion trick is to use a long residence time for the cracking of the evolved gases. Basically top lit and cross draft stoves are good at this. I will see what happens with the best downdraft fires. The SeTAR Centre is concentrating on that at the moment.
So Ferd B: young supposedly low quality coals with oil and water and so on are low in Carbon! Ha ha! it’s funny because they have been dismissed on the basis that they do not burn well in a power station designed to burn hard dry coal. Well…..duh! No kidding.
In the stove world, UB is a signal success and was achieved by quite a number of players local and not, coordinated by the local WB staff and the energy office in BJ, China. The Asian Dev Bank supplied crucial funding in 2010 to construct and run a SeTAR Centre testing lab in UB so product developers could get free design advice and testing. It is an approach that can work in China with similar results. One of the fun parts is overthrowing the dominant paradigm and setting a whole industry on a new footing of proper science and engineering. The prospect of repeating that is why I hang out here at WUWT.
Oh, the good stoves save 50% of fuel as well because they burn the smoke and have much better heat exchangers. That will save the city’s poor something like $25 million in fuel purchases per year.
Crispin, thank you for your good work.
Brian H says:
April 9, 2012 at 9:37 pm
Bill;
Not to mention a handy 110V 60Hz socket to plug the transformer into.
True dat, Brian. I run my laptop from a nice, compact converter/transformer with two ganged adapters — smoothes 220/240 at wildly-varying frequencies quite well — and it only cost what the average Somalian makes in a month.
One of our ops guys can’t quite grasp the fact that he isn’t in Kansas anymore — he popped an adapter over the plug of a 110/120 printer and stuck it into a 220/240 socket, with predictable results. His callsign was changed from “Tuffy” to “Sparky” by acclimation…
Nancy Hughes, founder of StoveTeam International
I have just returned from Mexico and Honduras doing Kitchen Performance Testing on the Ecocina rocket stove that is produced in local factories. it is a safe, affordable, portable stove made locally in Central America and Mexico. Testing such as the Kitchen Performance Test, Controlled Cooking Test and Water Boiling Test are being developed to ensure that all “fuel-efficient stoves” really are fuel efficient, safe and affordable. The initiative started by the EPA Partnership for Clean Indoor Air and the Global Alliance for Clean Cookstoves will assist local developers in knowing exactly what they are providing in the way of benefits. Check our website at http://www.stoveteam.org and you can see the results of our development of portable, safe, fuel-efficient rocket stoves.
Crispin,
Thanks for this rather stunning info. The numbers you are rolling off would be unbelievable, except that I took a peek earlier at your impressive background. I’ll be looking more closely at your suggested sources and your site.
This is actually a topic that’s near and dear to me. I grew up with coal as a kid in Prague in the 60s and have a love-hate relationship with it. I hated the chore of lugging buckets of the stuff from the cavernous basement with the single light bulb and the long shadows, three flights up, cleaning out the ashes with down-drafts blowing in my face, getting up at night to load and stoke, waking on a cold morning and waiting for Dad to get the stove going for our breakfast. Some of my classmates lived in the newer projects for Party members and “academicians,” and boasted of central heating (steam from coal-heated boilers) and gas ranges (gas from coke production). But some of my best memories include lounging around our coal stove on bitterly cold nights, heating water for linden tea and slowly crisping orange peels on the stove top for scent.
We had two stoves; one in the kitchen, which included a bake oven and a warming compartment, and one in the living room, with the smoke pipe going through my parents’ bedroom. This was in the ration days when we were stuck with lignite during the shortages, black coal lumps and briquettes most of the time and occasionally coke, which made our stove glow a bright red with the lights off…which happened from time to time due to blackouts. There was always a bit of smoke, a smell I can still “taste” and when both stoves were going at full blast, we felt woozy, from the heat and possibly the CO as well. There was black soot all over the city staining everything and rust-coloured ashes strewn over the sidewalks in lieu of road ice. The bitter-sweet “romance” of the coal stove days.
Here, in Ontario, I have yet to see a single coal stove, although there are plenty of wood ones…something that puzzled me because coal, for all its black dust I hated, is so much more efficient. I’ve dabbled in brick masonry and historical masonry structures, taught the subject at a technical school and built several fireplaces with a colleague, including a Rumford. My friend’s a bit of a math wiz and we modified smoke chambers, played with dampers and constructed angled and spiraling smokestacks which improved efficiency. Recently I co-edited and illustrated the first textbook on Canadian brick and stone masonry, after a hiatus from the trade, and was disappointed to see that not much has changed in masonry fireplaces which are pretty, but as inefficient as ever. Not that anyone is building traditional ones anymore; almost every builder is now specifying metal liners.
The stuff you’re telling me, the efficiency levels, fuel savings, cleanliness and low unit costs are breath-taking, truly revolutionary, if people really thought about it. I have yet to look at the details of your stoves and I’m now wondering whether it’s feasible and practicable to design masonry versions suitable for local installation, combining inexpensive manufactured parts and local masonry skills. Such, I’m thinking, may be useful as more permanent installations in communal kitchens and food service enterprises such as small artisan bakeries, or as upgrades for greater safety and better appearance in houses. The problem I can see is in ensuring quality construction to specs and acquiring good refractory clays and firebrick, as Portland cement mortars and structural clay bricks cannot be used safely.
This is a fascinating and honourable area you’re working in, Crispin. As someone who’s grown up around the struggle for heat and felt the bite of fuel scarcity from time to time, I’m ever-sensitive to this topic. It affronts me, as I now sit in an over-heated house, to know that people all over the world are still scrounging for scraps of fuel and choking on smoke and fumes while trying to stay warm or to prepare a meager dinner. Do remember me if you folks are looking at masonry in any way, as I and my contacts may be able to suggest a thing or two.
Crispin,
I spoke too soon! I just saw your Lion Stove and the masonry work.
I see the guys are using red clay bricks shaped like solid fire bricks and a cement-based mortar, rather than refractory clay, as we’d spec in Canada. They’re keeping the joints tight enough, as required for a fire box, at about 3 mm. For you regular non-mason mortals who are still reading this, tight joints (i.e., the spaces between the units) on a fire box structure reduce heat loss through the joints.
I do fret a tad about the durability of the regular masonry unit (unless your fire clays in SA are red) and have recurring nightmares about structural mortars under high and prolonged heat. Cement mortar has a good bond and is strong enough, but if you are not going to use firebrick and refractory clay, do you require Portland cement in the mortar mix? Portland provides for greater compressive strength, but it is brittle, depending on the type. Going by the pics, and guessing from the colour, it looks like you’re using Type M mortar, the type with the highest cement concentration, possibly from a bag of pre-mix. Not the type I’d use unless I’m building a reinforced c-block foundation. Have you tested lime-sand (Type K) mortar? It’s the weakest in terms of load bearing capacities, but has superior plasticity and some flexibility, and “heals” well. Differential expansion and contraction rates between the brick and the Portland in mortar mix as the stove heats and cools may be of concern and a more flexible mortar…if you can’t use refractory materials…might help. Also, locally available clean sand and slaked lime ,ay be economically more practical.
I’m intrigued by the pumice stones for insulation. With refractory units and mortar we merely parge the back and a clearance between 150 mm to 300 mm is more than sufficient, but heat loss through the walls in a fire place or an oven, in Canada, translates as room warming which is welcome. Are pumice stones widely available and cheap? What about using similarly-sized brick or c-block chips from wasted units? I also note that the inside gets parged, but I don’t know enough about the structure to figure out whether that part is the equivalent of the smoke chamber or the fire box.
And hurray for the superior London trowel I see in the pic! Here masons tend to use the broad Philadephia pattern one, the “glorified shovel,” on everything. The guys need safety boots, though; one of the guys has managed to keep his sneakers a pristine white by some miracle. And a 1200 mm level to help as a straight edge would be nice too.
Very, very, interesting stuff all in all. I’ll be reading up more on it.
Once again I read of various “improved” cooking fire devices that are too fancy, too costly (including because they are attractive to steal – look at that highly-fabricated overly-complex one the second photo). One even requires buying batteries to operate it! (Which isn’t even suitable for hikers here – batteries are heavy. Even thermo-electric junction fans are costly (powered by heat from the stove, won’t work on a clay stove).)
I hope there are principles of creating a “draft” to enhance combustion and propel gases and soot away from users. Those principles might be simple and teachable so poor people could make their own of local materials with minimal tools (like the first photo which appears to be mud, or this efficient one: http://www.stoveteam.org/solution). Perhaps supplemented by something like a galvanized steel chimney pipe as height is harder to make of mud, though is done. Even the Vesto stove is apparently economical to make (though still quite a bit of money for poor people it appears to include a cooking pot at the top and is made of stainless steel for longer life: http://www.newdawnengineering.com/website/stove/singlestove/vesto/). Poor people tend to have time not money (“David in Georgia” fails to actually understand their situation).
The variability of fuel is mentioned – it is a major cost in many poor areas, especially very dry climates. I presume varying the chimney restriction might help (IIRC commonly done with wood heaters here, “David in Georgia” seems to be suggesting that, the Vesto does it by varying air intake at the bottom). A raised stove with pedal-driven fan may we workable, leaves hands free, uses strength of legs, but not as portable as foot-operated bellows.
As for reducing CAGW, well – “I’m from Missouri” on whether or not soot is actually a problem.
Elimination of forests to provide fuel is in major part a result of not owning the resource (owners preserve it, replanting and husbanding the new crop). Hernando de Soto has pointed out the importance of ownership to improving the lot of poor people, and the necessity of law and order to protect property rights.
Poor people often need portability, to move to where food and fuel are, and escape when some tyrannical regime abuses them. “boston12gs” overlooks that – electricity supply cannot happen without a stable society, as there is no incentive to maintain the system, and various combatents will destroy it (if it ever gets built – corrupt officials will build shoddy if at all).
I give credit to an operation called “World Vision”, whose solicitation of funds is for specific things that can be purchased for a poor person, ranging from a breeding animal to a water well. Specific things that would actually work for the recipient, clearly understandable by the prospective donor.
(I know nothing of the outfit otherwise, though the last catalogue I saw was jumbled and I shudder at the cost of the catalogue they put into each newspaper.)
Of course the broader picture is what cooking does – improve digestibility of food. Won’t that reduce the energy cost to each individual of digesting food? That is, the net energy gain from the food is greater due to the use of energy outside the body. Marvelous thing, controlled fire. (But has to be handled well – philosopher Ayn Rand liked Francis Bacon’s point “Nature, to be commanded, must be obeyed.”)
Interesting point; in addition, “digestibility” means extracting maximum energy from the amount of intake, instead of having to hunt/gather a larger quantity — which also costs energy to accomplish. It thus reduces the demands of humans on the environment to supply edible fuel, therefore.