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Post in 'The Boiler Room - Wood Boilers and Furnaces' started by BrownianHeatingTech, Feb 7, 2008.
Sounds like Solar would be the only solution, or nuclear.
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That's a nice summary and conclusion, Jim.
I think that in the future, as energy supplies of all kinds become depleted and expensive, we're going to be using them all, for better or worse. Unless we modify our behavior dramatically, I don't think we'll have the luxury, like we do now, of picking and choosing our poison. One of my main motivations in the direction of alternative energy is something my dad said several decades ago: "Oil is such a valuable substance that someday we're going to look at each other and say, 'I can't believe they burned this stuff back in the 20th Century.'"
My current, modified take on that is that you won't find a better fuel than oil, so we should be conserving it for the things for which there is no replacement, and using viable alternatives for everything else. That's not a solution to our many problems, but a step in the right direction, I think. It's the best I can do on an individual level, in any event.
To put it another way, why should I, as an able-bodied person with access to wood fuel, burn gas or oil if I don't have to? The gas/oil I don't burn should be available to the little old lady across the street at a reasonable price and through a reliable supply line. To me, that's a sensible, socially-responsible way to approach the problem. On a purely selfish level, I stay in shape and save money.
Are there other Traeger (Pinnacle) boiler users here?
Another dimension for me is the idea of self-sufficiency. I had enough time and money to put in my wood-based heating system. If really bad things happen to me or the world around me, I know that I can at least stay warm without depending on anyone else and without spending any more money - my fixed future costs for heat are pretty near zero.
I'm not being apocalyptic here, but my livelihood could easily disappear, for instance. I'd rather have the insurance of personal control over my heating destiny than the same amount of money in the bank.
And you mock my 43 cords in the backyard?
Of course. I prefer to store my wood standing up, except for the next two year's worth.
I have to say that I'd love to see a practical automatic chip feed system for residential boilers. In my mind that's more attractive than pellets, since I could make my own chips. There are days when I really like the idea of a system where the primary interaction point is the thermostat.
I wonder how small / cheap a wood pellet mill could be?
Storing it in a standing (and growing) state makes sense in your case. My wood source is 60 miles away, however, so I feel more secure having it cut and stacked within reach of the boiler.
My impression is that making pellets isn't all that hard if you have dry, processed wood for feedstock. But I don't think anybody has figured out a good way to turn roundwood or green chips into pellets on a small scale.
I'm surprised that nobody markets a residential chip burner anymore (that I'm aware of). A guy in Vermont had one about 30 years ago that seemed to work really well. You need a special chipper (Valby) to make the kind of uniform chips that a burner like that required, but they're not expensive or hard to come by. I agree that would be the way to go.
We have chatted to great length re home pellet making at another page - one user built a home press soybeans for the oil and the cake to burn or feed. Large pellet mills have issues with product consistency - how could a small operation be better? Two tried and never got it, but thats not a testimonial.
Chips - again consistency due to variable sources of free or inexpensive stock will have issues that Stacked supplies do not. Cutting and stacking allows you to pick first the base stock - then the daily or semi daily choice of load to fire. Chips of pellets in bulk - well your sort of limited to what falls out the auger or is shoveled off the top. But the chips could be conditioned to a consistent quality with a hammer mill and a dryer similar to how grain is dried and cleaned for safe storage.
Maybe not in a residential setting but as Eric is 60 miles from his source maybe this could be done off site also - here is an example of one dryer http://www.sarcornfurnace.com/Videopage.html as they use corn here to dry corn - wood chips could be used in the off season to dry fuel and fuel could be stored in silo as the family farm used to - heck Ill bet we could even adapt a silo unloader to feed bulk daily to the running applinace.
but its that feed system that needs to com back to the market - some cross between the Traeger feed cup delivery and the old brute force Iron Fireman Cole stokers
to shove a consistent sized chip on consistent moisture in to a stirred burn pot.
How do we do that?
then storage - now instead of a nice pile covered we need a farm silo and a tractor to blow the conditioned chips into the silo and some way to access it all year
oh the more I write this the more I like skids of pellets
There are several chip burners sold over seas. The one that is talked about in that artical I posted sounds very interesting but I don't know anything else about it. Chip burners would be the ideal bio-mass boiler as it is avilable every where locally in many forms. That would help keep the cost down because it would eliminate alot of the transportation costs.
I'm not hyping this product, but it is very interesting. Made by Woodmizer, to handle sawdust and all forms of biodust.
That's interesting, Jim. I've heard rumors, but that link is the first time I've seen anything official. Rest assured, next they'll be selling a hog.
A bit more is something of an understatement. I heard it went over the 300/ton mark before falling back some but not all that much. Of course it won't stay there forever, it can't. Once switchgrass catches on like it already is starting to then it will change. Till then its still a good idea to have something capable of burning all of it in a pellet appliance. Go multifuel and cover your bases!
One of the key things that I think needs more consideration in deciding about the desirability of different fuels, and their costs is how much processing is needed to turn the raw material into fuel - The more processing, the less efficient the fuel is overall, regardless of how good it might be in your own stack...
As an example on one extreme, the big wood OWB's that take four foot logs w/ minimal splitting is probably about the lowest fuel processing requirement there is. Cordwood takes a little more cutting, and needs to be split, but still there is not a lot of processing or expensive equipment needed between the tree and the fire.
OTOH, Pellets seem like they are automatically going to be much less efficient on an overall basis, and have much higher costs because there is so much processing and handling involved - the raw material has to be very finely ground (and the finer you grind the more energy it takes...) dried, compressed, etc. usually with some pretty extensive transport requirements along the way - cordwood tends to be very local... The processing equipment is complex and expensive, adding to the costs as you need to amortize it....
The wood-mizer product just mentioned seems to split the difference in that it appears to not require as much processing since the grind may be coarser, and there is no pelletizing required. However a fairly fine grind is still needed.
If I were trying to invent something these days, I'd look for something that could burn coarse chips, grass clippings, leaves, and other such coarse biomass with minimal processing - I think that would be the "sweet spot" of maximum local supply, and minimal processing requirements...
Random thought on drying - what about using a thermal storage tank as a drying heat source? Build a fairly tall skinny tank (1 kGal LP tank on end?) with a second shell around it, say 6-12" away, with the insulation on the outside of this second shell - rig up some way to dump damp chips or other "not ready for prime time" material in the top of that space, and a way to remove material from the bottom and shovel it into the burner... Would cost some efficiency in storage tank losses, but should be able to dry the chips very effectively with minimal handling, no fancy equipment, etc.
Those are some good observations, Goose, as usual.
I can assure you that processing and drying are costs that pellet manufacturers are acutely aware of, for the reasons you mentioned. They would much rather get dried sawdust than roundwood, and the percentage of each (and all the gradations in between) is what determines their profit margin.
The Wood Mizer sawdust burner is designed, as I understand it, to burn sawdust produced by portable sawmills. So in that case, it's a byproduct with essentially no production costs. However, in an attempt to broaden the market for the boiler, they talk a lot about processing bigger stuff soley for use as fuel. As you noted, that adds considerable expense to the fuel, and you don't really have the option of burning unprocessed chunks. So it's a perfect appliance in the right application, but could be a millstone (so to speak) to somebody who can't get cheap or free sawdust.
The woodchip gasifiers I've seen all have big hoppers and rely to some extent upon the heat from the fire knocking down the moisture content of the fuel before it gets to the burner. With the right size hopper and fuel with the right starting mc, it works pretty well. In a sense, gasification boilers do something similar--you fill the firebox and by the time the wood on the top gets down to the nozzles, it's dried out to some extent. I've noticed that my boiler seems to be much more efficient when filled to the brim on very cold days, compared to warmer weather when I tend to make much smaller fires during the day. I guess that's another reason for me to get my tank going.
I know that we're all waiting to see what happens with your tank adventure, but hopefully you'll get it done soon so we don't have to wait until next winter to find out how it works...
My thought on the "storage tank" type dryer setup I was mentioning is that what I see of chips, and what I've experienced with my "splitter trash" that I use for fire starting is that it gets a lot of dampness on the surface from rain and ground moisture, getting rid of that moisture so that what is going into the burner has about the same dryness (or better wouldn't hurt) as what comes out of the chipper seems a lot of the battle.
I figure that working with that grade of material is also good because there seems to be a LOT of it - everything from municipalities and tree services to lawncare places generate large amounts of it as yard waste, and it's a sizeable disposal problem - it would benefit the taxpayers to get it out of the waste stream, and I suspect most of the generators would appreciate having a way to get rid of it that either didn't cost them anything or even made them a bit.