Catalytic stoves and health concerns

[JA600L]

I saw this link on Alliance for Green Heat's website. Could there be truth to this and should we be concerned?

http://www.familiesforcleanair.org/catalytic-wood-stoves-shown-to-increase-dioxin-emissions/

http://www.sciencedirect.com/science/article/pii/S0045653512002172

 

[begreen]

Suspect it might be so, but lack access to anything but the abstracts.

 

[Lake Girl]

Should be able to get access if you have a student in the house!

 

[drz1050]

Need to know what the actual values were for both stoves before you can make any conclusions...

At what ppm do they become harmful? What was measured?

 

[branchburner]

The abstract of the sciencedirect article says:
"The influence of emissions from wood combustion to human health and the environment is a sum of effects caused by different compounds formed in the combustion. "

Unfortunately, we are given an impression that the higher releases of dioxin totally outweigh the reduced amounts of fine particulate that result from cat stoves. Yet we have to wonder, what is the basis of that implicit assertion?

Until any sum of effects caused by different compounds is broken down into a cost/benefit analysis I don't see any way to say if using cats is better or worse than non-cats.

I also wonder: if the dioxin level is about 10x higher in cat emission than in non-cats, then should I assume dioxins are normally released in all wood combustion (like forest fires) or just as a by-product of combustion occurring in metal wood-burning devices? If dioxin is a natural component of ALL biomass combustion, then I hardly think cat stoves are a big contributor to the total. They would, in fact, be statistically insignificant.

Also: is that high dioxin level released over the entire life of the cat, or do dioxin levels change over the life of the cat? How do levels vary between different makes of combustors?

 

[williaty]

I downloaded the full text of the article in Chemosphere. Here are my take-aways:

0) The researchers reiterate many times that there needs to be much more study on this issue done because they were the first ones to look at it and they had insufficient funding to test all the things that could be going on.

1) The test stove was a sauna heater. These are somewhat different to our wood stoves in that there's no attempt to release heat in a controlled fashion. They're run flat out pretty much constantly. The researchers say they believe the results can be generalized to other types of wood burning that are not well controlled.

2) Test burns were VERY short, 72-75 minutes total. Supposedly, this represents how the locals actually use their sauna heaters and that was the point of the research. So there's no information about the impact of catalytic burning on the kind of long, low burns people do with the IS or BK stoves. However, given that the highest levels of the increased toxins were during the pyrolysis phase of the burn, it's probably worse for a long slow burn like most people try for.

3) The cat was produced by NVI. I don't know if that makes it a ceramic or metallic substrate design.

4) Several classes of very toxic chemicals were meaningfully reduced by the cat. Several other classes of very toxic chemicals were dramatically increased by the cat. That makes the question of whether the use of a cat is better overall very complex.

5) The researches say the situation is sufficiently complex that there really ought to be a proper wide-scale analysis of all of this if the EU and US are going to push the use of cats in wood burners.

 

[Lake Girl]

So the researchers realize the limitations of their study but it points to the need for further research. Sounds like someone should go looking to see if the EPA or cat manufacturers have picked up on this. Who in the US currently does this kind of research.?

 

[begreen]

willaty, thanks for the summary. From the abstract and article it seemed like the main concern was a dramatic 8-10x increase in dioxin output. The study seems to point out that it is the interaction with platinum and palladium that causes this increase, not the substrate, but that also may warrant further testing.

 

[Woody Stover]

Unfortunately, we are given an impression that the higher releases of dioxin totally outweigh the reduced amounts of fine particulate that result from cat stoves. Yet we have to wonder, what is the basis of that implicit assertion?

Yep. And they fail to mention that PAH was reduced. I'm going to look at some of the familiesforcleanair.org stuff and try to figure out where they are coming from. One of their kids burned their hand on a wood stove, or what?
And where did those folks get their money to be able to afford to pay for heat? Working for some big company that pollutes the hell out of us all? I mean, if you're gonna start pointing fingers, you need to look at yourself first...

Until any sum of effects caused by different compounds is broken down into a cost/benefit analysis I don't see any way to say if using cats is better or worse than non-cats.

If familiesforcleanair were to do a cost/benefit on coal or oil, where will that led them?
As an aside, the elephant in the room is always that we should have free energy by now...bass terds are holding out on us. With that, we could free up massive capital and resources, exit our present broken system, and really start advancing as we were meant to do...either that or some demented freak would use it to create a weapon that would give him world (or universe) domination.

I also wonder: if the dioxin level is about 10x higher in cat emission than in non-cats, then should I assume dioxins are normally released in all wood combustion (like forest fires) or just as a by-product of combustion occurring in metal wood-burning devices? If dioxin is a natural component of ALL biomass combustion, then I hardly think cat stoves are a big contributor to the total. They would, in fact, be statistically insignificant.

I don't know much about it, but aren't there other large-scale biomass-burning projects under way now as well?

I downloaded the full text of the article in Chemosphere.

I haven't searched every angle yet to get the full text...got a link? Did you have credentials to be able to avoid paying?

 

[branchburner]

I don't know much about it, but aren't there other large-scale biomass-burning projects under way now as well?

Well, I think wildfires are the biggest of those projects... a quick search shows a huge decrease of man-made emissions to levels about the same as wildfires. Those EPA man-made estimates are ALL sources combined, of which wood stoves must be a small fraction, and cat stoves only a tiny fraction of a fraction.

http://www.dioxinfacts.org/images/fires3.gif

 

[begreen]

Large scale biomass burners have adsorbents, scrubbers and other methods of preventing dioxins from being released into the atmosphere. Ironically tail-end catalysts are sometimes part of this emissions control process, though I am not sure what the catalyst is. It might not be platinum or palladium.
http://www.seas.columbia.edu/earth/wtert/sofos/nawtec/nawtec08/nawtec08-0010.pdf

 

[Woody Stover]

This is Germany, and maybe US percentage distribution would be different but burning wood for residential heat, while significant, doesn't appear to be that big compared to industrial sources. Maybe we don't have as many metal industries here a Germany does.
Then you would have to subtract the pollution that would have been created by production, transportation etc, if the wood burner had instead been heating the home with oil, gas or electric. To be fair, you would also have to factor in pollution created by getting the firewood cut and ready to burn.

 

[Woody Stover]

a quick search shows a huge decrease of man-made emissions to levels about the same as wildfires.

Wow, the totals from wildfires appears to have gone up substantially of late. I guess we're to blame for that as well, since we are causing climate change....or not.

 

[williaty]

Wow, the totals from wildfires appears to have gone up substantially of late. I guess we're to blame for that as well, since we are causing climate change....or not.

Anthropogenic climate change is the lesser thing we're doing that causes wildfires. Our terrible wilderness management policies are the bigger danger. When you go 50-75 years putting out every small fire that pops up, the result is so much fuel you get massive fires that you can't manage. People won't stand for having their parks and woodlands look crispy on a small scale once every decade or so, sadly.

 

[EatenByLimestone]

Yet, look how it revitalized areas of Yellowstone. Remember the doom and gloom after that? Nature fixed that mess too.

 

[williaty]

Yet, look how it revitalized areas of Yellowstone. Remember the doom and gloom after that? Nature fixed that mess too.

Yeah, that's the problem. By not allowing periodic natural fires that the ecosystem evolved to tolerate and even thrive through, we create massive fires that destroy the very thing people want to protect as well as houses and lives. Try explaining that to the soccer mom from Florida who drove all the way to Yellowstone to see a bear and instead finds ashes and charred trunks. Doesn't matter to her that it'll look amazing come next spring.

People have no sense of perspective.

 

[Lake Girl]

Yellowstone didn't have that much charred wood from what I saw this summer! You did hit the reason for larger uncontrolled forest fires ... management practices that does not lessen the fuel load.

 

[EatenByLimestone]

I believe the fires were back in '88. There was some when I was there in the late 90s, but it was standing dead with a young forest sprouting up.

 

[begreen]

Getting way off track here folks.