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MtnDon
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# Posted: 26 Feb 2016 04:42pm
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It seems that there may be a danger from CO being off gassed by stored wood pellet fuel under some circumstances....
The info below was copied from this website.
"5. Finally, the storage area should have ventilation and a carbon monoxide (CO) detector near the door, as pellets can release CO when stored. Another option to alleviate CO concerns is to store pellets in a silo (inaccessible to people entering it) outside of the occupied building, with an auger feed system into the pellet appliance hopper and a CO detector near the
hopper.
This last point is important because CO is a clear, odorless, and tasteless gas that prevents red blood cells from carrying oxygen. It is extremely dangerous because people cannot detect it. Typically, CO is associated with burning fuel in a combustion appliance, such as wood, pellet, oil or natural gas furnaces and boilers. CO can enter a home if a combustion appliance backdrafts, releasing combustion gases into a home instead of up the chimney.
Stored pellets can release CO, according to recent studies, though the amount depends on several factors, such as the age, content and exposed area of the pellets. This is especially a concern for enclosed storage areas that contain large quantities of pellets and are accessible to humans, such as for district heating systems or on cargo ships.
Not all pellets release measurable amounts of CO. Preliminary testing at CCHRC found no detectable CO emissions when the pellets were stored in a 30°F storeroom. Although when we sampled a plastic bag filled with pellets, sitting inside an 85°F room, the CO concentration in the bag was 60 parts per million (70ppm would trigger CO alarm if sustained for 1 hour). While the room may not have reached the same level as the bag (as the gas would have more space to diffuse), this shows the pellets have the potential to produce CO.
Be sure to take the proper precautions for a pellet storage area by ensuring the area is vented, installing a CO detector near the storage area, and being aware of the symptoms of CO poisoning. All homes with any kind of combustion appliance should have a CO detector in the living area to ensure combustion gases are not entering the home."
A Google search does come up with several other articles citing the danger...
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Julie2Oregon
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# Posted: 26 Feb 2016 05:49pm
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Wood pellets are made of mostly of sawdust. Unless the wood was treated and that sawdust was used, the sawdust shouldn't be a source of CO.
I'm guessing that some companies use different "binders" in forming the pellets, hence the different results. In looking at different brands, types, and prices in Oregon, I've noticed that some pellet producers advertise their pellets as not using wax or anything.
I'm very interested in this producer. Good price, local product:
http://strawberrymtpellets.com/
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MtnDon
Member
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# Posted: 26 Feb 2016 06:06pm - Edited by: MtnDon
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" The chemical reactions responsible for carbon monoxide production from wood pellets are assumed to be an auto-oxidation process, especially oxidation of the fatty acids to be found in wood"
This phenomenon is seemingly associated with bulk storage facilities. The thought of building / using a bulk hopper or bin with direct access to a habitable space might not be a great idea.
Then again, it's a small enough area maybe it is of no concern. However, any amount of CO is not good.
"Experimentation has shown3 that small quantities of wood pellets can produce life-threatening quantities of carbon monoxide in a confined space and that there are various factors that will affect the amount of carbon monoxide produced:
Age - pellets will produce more carbon monoxide within the first six weeks of being manufactured.
Temperature - more carbon monoxide is produced at higher temperatures.
Wood type - pellets made from pine contain more unsaturated fatty acids than spruce so produce more carbon monoxide.
Other factors - carbon monoxide levels will also increase with the amount of available oxygen present, exposed pellet surface area and amount of mechanical abrasion of the pellets that has taken place."
Source
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Julie2Oregon
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# Posted: 26 Feb 2016 06:52pm
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This sounds like no matter what you do, you're going to be exposed to CO and you're basically screwed.  Oxygen doesn't help, burning quickly and hot doesn't help, nothing helps.
But if fatty acids are naturally occurring in wood, then wouldn't burning large pieces of wood in a wood stove be more dangerous and give off more CO than a pellet stove? And wouldn't a lot of people be dead?
I kind of don't understand. 
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Julie2Oregon
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# Posted: 26 Feb 2016 07:08pm
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OK, read the article more carefully and had to consider the terms in regard to the UK. It's not talking about households but mass quantities of pellets in very, very large storage facilities, boiler rooms for apartments, and the holds of cargo ships because the wood pellets in the UK are shipped there from other countries.
The pregnant housewife who died entered a boiler room that stored and operated a biomass system that supplied heat to 60 apartments. That's huge. All of the people physically walked into very large areas where massive amounts of pellets were stored.
So, we're not talking about one little pellet stove and 50 bags of pellets. These are commercial applications and 3 deaths that raised concern. Phew!
I'm glad to know about the CO but I'm really glad that burning a bag of pellets at a time isn't likely to kill me!
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Jebediah
Member
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# Posted: 26 Feb 2016 08:51pm
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These bags are designed to go in your basement or garage so the off gassing doesn't seem to be an issue...
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Julie2Oregon
Member
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# Posted: 26 Feb 2016 11:16pm
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Jebediah
Those are pretty cool. Do they seem to have a flap so you can release pellets from the bottom?
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mick968
Member
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# Posted: 3 Mar 2016 03:54pm
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Wow who would have thought? we have pellet stove we leave (bag) of pellets near stove in lower level extra bags in storage shed outside
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Julie2Oregon
Member
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# Posted: 3 Mar 2016 06:33pm
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I've since been reading up on this at a hearth forum and also a biomass site. The consensus is that if you simply use common sense, all is fine. And, yeah, they recommend having a CO meter in every home where combustible fuels are used.
But it's important to remember that the 3 people who tragically died in this report entered an enclosed space where huge amounts of pellets were stored. It wasn't one average residential use. We're talking a boiler room that served 60 apartments, a cargo ship that transported pellets, etc. Yeah, it says small amounts of pellets can give off CO but that's where common sense enters.
The Biomass mag article I read stated a researcher in New England studied a couple of dozen homes in New England that used pellet stoves for heat and stored pellets, monitoring CO levels. No levels exceeding safe limits were found, except in a case in which the family stupidly stored the pellets in the garage where a motorcycle was also frequently worked on and run.
Just to be on the safe side, I'm probably NOT going to do a pellet silo outside next to my house. With the size of the carport I'm building, it won't be an issue to keep the pellets in bags and perhaps keep the bags themselves in a vented structure to protect them from moisture so they're at least close at hand. And to keep a bag or two inside.
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