In Praise of the Pellet

I hate pellet stoves, I always have, but when we went to move into our new Tiny House, the stove we had intended for this place just would not work, so I was given a Pellet Stove.

I kind of like it now. Kind of...

Because it has a consistent fuel source, it has consistent heat output that is settable, and even in temp, which is kind of nice. No freezing if it goes out, and no sweating to death when it is really raging. Coupled with a big bin, it could burn for days with out being tended too. But it has one big drawback; I have hundreds of acres of forest, but making pellets is almost impossible on a home-scale. There are pellet mills that can be bought, but overall it means running the sawdust through a hammer mill, then making pellets, then somehow drying those pellets, all of which happens at only a few hundred pounds per hour. I REALLY looked into this, and it really just is not fesable to do on a home-scale.

But there is actually an alternative. Corn can be burned in a pellet stove with no modifications, so I looked into what it would take to burn corn.

I use 3 ton of pellets to heat this Tiny House a year here in Maine, which would mean I would have to raise a mere 1/2 acre of corn to do it. Drying could be accomplished in the field by not harvesting the corn cobs until after the frost has hit it, and the wind has dried it down. I do not have a corn sheller, but a homemade one looks easy enough to build. In all, it would like it would take me about the same amount of time and expense to produce corn as it would be to produce firewood.

The biggest reason I have an interest in this is: with a pellet furnace, I could leave my home for days, where as with a wood furnace I could not. That would mean I would have to have a back-up heating system which would mean twice the expense as a pellet stove. Normally I would not consider pellets that great of a deal, nor renewable, but if you grow your own annual crop of corn, it seems just fine...if not commendable.

Travis, I like having a pellet stove for all the same reasons.  I heat my house with a woodstove and a pellet stove and it makes wood heating so much easier for folks that need to leave sometimes.  One thing that occasionally goes through my mind is having a log that gravity feeds down to a cutter that grates the log into small chips that are fed down a chute to the burn pot.  Would use more electricity at the home, but it must use less power than they use to make the pellets.  That and then fuel would be nearly free.  Because of the complete burn it wouldn't be a problem to burn softwood.  How hard could it really be to make something like this?

Interesting

Do the pellet stoves require electricity to run a hopper/feed?

We don't have a well yet and run off a water tank so if we had to leave for a few days, I can just drain the system like one would do with an RV as that's the way I set things up. All our plumbing runs uphill from the water tank so all I do is disconnect an RV hose and with the exception of the water heater, the system drains. We'd have a cold house when we came back and depending on how cold, our food in the fridge might be frozen.

Now if we got an ice storm and were stuck here with no electricity for two weeks, would the pellet stove work?

Maybe some have batteries as a backup?

Is field corn what gets used in a pellet stove?

Don't really know much about them.

Just looked at 4 of them that had highest ratings on HomeDepot and they all said wood pellets only, no corn. Doesn't mean you couldn't use corn but technically, it would void the warranty.

There's one multi-fuels stove that will take corn and cherry pits. FYI, User manual says corn should be at 14% moisture level and cherry pits at 4%

This one's an interesting design. They didn't try to make it look like a wood stove.

John Paulding wrote:Do the pellet stoves require electricity to run a hopper/feed?

It depends on what you get for a pellet stove: some do and some do not, but the gravity fed ones are UGLY!

John Paulding wrote:Maybe some have batteries as a backup?

I have a friend who does this to his pellet stove. he has (4) lead based batteries hooked up to it, not even deep cycle ones, and uses an inverter, and he can go for four days on battery power. Typically by then the power is back on. Myself, i have a pretty big back up generator (20 KW) so this is not a concern for me.

John Paulding wrote:Is field corn what gets used in a pellet stove?

Yes it is. My thoughts on harvesting it was, to just have us as a family go gather up the ears right off the stalk since I do not have a corn harvester, then run the ears through a homemade corn sheller, then store the corn for burning later. Even if I only burned a 50/50 split of corn to pellets, I would still reduce my heating costs in my house by half over burning 100% wood pellets. I would have some costs in growing corn, but I cannot imagine it would be $750 for a half acre of corn???

My father has a A Maiz ing Boiler, but they will burn a variety of fuels: wood pellets, corn, soy beans, etc.

Amaing Heaters are different because they are bottom feeders, the biomass comes up from the bottom to feed the fire, as it burns off, the ash "spills" out the sides into the ash pan below. It is kind of a cool design. With the auger controlled by the thermostat, it controls how warm your home is.

My Dad has had his since 2009 and likes it. Its a cheap boiler at $1000, but is simple and works. He was spending $6000 or so heating his big house, but now spends half that.

I even thought about burning sunflower seeds because here sunflowers grow with so little work compared to corn. However the yield would be less per acre, so I would have to grow 3 acres of them instead of 1/2 and acre. Still not a bad deal though. I say that because with either con or sunflowers, I would use the stalk to feed my sheep anyway so there would be no waste.

http://www.sunburst-sales.com/AmaizIngHeat.html

John Paulding wrote:Just looked at 4 of them that had highest ratings on HomeDepot and they all said wood pellets only, no corn. Doesn't mean you couldn't use corn but technically, it would void the warranty.

There's one multi-fuels stove that will take corn and cherry pits. FYI, User manual says corn should be at 14% moisture level and cherry pits at 4%

This one's an interesting design. They didn't try to make it look like a wood stove.

John, do you know what kind of stove that is?  Very interesting design.

Never mind, found it.

Great ideas. I had considered making pellets, and using diverse non-tree-based biomass, but never had I thought about burning seed.

I have looked into the cost of pellet-making machinery, and honestly, unless you're making more than pellets for combustion with the hammer mill and extruder, or unless you can keep them running constantly, with a lot of drying space to cure pellets, it's hard to make the numbers work on the homestead scale. I mean, if you can use the hammer mill for mulching as well, and you have a constant need for that kind of work, it's a different story, but I think this is definitely one of those things where it might only work for you if it helps to stack a number of functions within your systems. Or it might be the kind of purchase more easily justifiable if it's a small intentional community purchase, or one shared by neighbours.

On the face of it, it seems wasteful, I have to admit. I also have to own a little bit of bias here, but it never seemed a good idea to me to turn food into fuel, whether we're talking about biofuels or straight-up combustion for heat.

I suppose, though, that if field corn grows well without inputs or irrigation wherever you are, growing an annual crop, whatever the plant in question, for some of it's biomass trumps growing trees for the same purpose, or at least could be used to take pressure off ecologically sensitive woodlands. In the case of corn or anything where you're only harvesting a part of the biomass, a great deal of the plant remains to put carbon in and on top of the soil, and unless the crop is wholly uprooted, that will always be the case.

I am curious; I know that it's highly situational, but what other kinds of homestead-scale crops could be grown, like field corn, to produce a combustible pellet-sized bit of biomass? To my mind, it would be preferable if it also served multiple functions, in addition to pellet production and the bonus unused biomass, and required either no intervention to thrive, or required active harvesting to contain its spread (within reason; no kudzu of the north, please).

-CK

Travis, what do they grow near you?
What I mean is, what agricultural wastes are available?
Pits of fruit, or the shell of nuts seem to be viable fuels.
Growing corn does seem like a great plan, but burning a waste product seems like a better one, in terms of ROI.

Travis Johnson wrote:I say that because with either corn or sunflowers, I would use the stalk to feed my sheep anyway so there would be no waste.

Chris...it was easy to miss I know, but there would not be any waste. Since I would only be burning the corn kernels or the sun flower seeds, the stalks would be used to feed my sheep (corn silage/sunflower silage). I have done this in the past, and obviously we do it all the time on the dairy farm, mixing a mixture of 60% grass silage to 40% corn or sunflower silage.

William Bronson wrote: Travis, what do they grow near you?
What I mean is, what agricultural wastes are available?
Pits of fruit, or the shell of nuts seem to be viable fuels.
Growing corn does seem like a great plan, but burning a waste product seems like a better one, in terms of ROI.

No, we do not have anything like that here. Everything here is silage for the dairy farms.

Here you can buy "burning corn" for pellet furnaces, but by corn here we mean wheat, barley, rye or oats. It's either old corn or too low quality for even animal feed, I have no experience with it, but might end up with some as our new house has a pellet furnace.

Greg Martin wrote:One thing that occasionally goes through my mind is having a log that gravity feeds down to a cutter that grates the log into small chips that are fed down a chute to the burn pot.  Would use more electricity at the home, but it must use less power than they use to make the pellets.  That and then fuel would be nearly free.  Because of the complete burn it wouldn't be a problem to burn softwood. How hard could it really be to make something like this?

I do not think it would be that hard. We definately have the technology with carbide cutters and electric controllers. Noise might be a problem depending on where the stove was located. i live in a Tiny Home so my pellet stove is upstairs next to the Television, so listening to a machine grind away at a stick of wood might be too much, but maybe with enough sound deadening it could be mitigated. If the stove was in a basment it would not matter at all.

Moisture might be an issue as well, except that it does not matter if softwood is being burned as you said. Here in Maine we can buy softwood, hardwood or a mix of the two types of pellets. They say softwood is better, but the higher price tag did not seem to be worth it to me. But softwood does not have to be "dry" to burn, it will burn right off the stump.

Interestingly enough, our local school; a massive facility, burns wood chips at their heat plant. Compared to the old school and its oil boiler, it costs half as much to heat a much bigger complex, including the sidewalks for snow and ice melting. Unfortunatly it has to use "clean" chips and not "hog fuel" which is a much more expensive chip. Clean chips have a much more uniform size to them, and no bark or leaves. Basically it is a chip used for making paper, but does work.

Right now I am pretty comfortable; it is -10 degrees below zero (f), yet 89 degrees in the basement, and 77 degrees on the first floor. My wood pellet stove on the first floor is running on its lowest setting, but in the basement my pot bellied stove is burning coal. I burn wood up until it gets down to negative temps, then I switch to coal. The only reason I do that is because coal burns for 14 hours between tending so I can sleep through the night without having to add firewood to the burn chamber.

Greg Martin wrote:One thing that occasionally goes through my mind is having a log that gravity feeds down to a cutter that grates the log into small chips that are fed down a chute to the burn pot.  Would use more electricity at the home, but it must use less power than they use to make the pellets.  That and then fuel would be nearly free.  Because of the complete burn it wouldn't be a problem to burn softwood.  How hard could it really be to make something like this?

Another idea I have thought of, and I doodled up some drawings a few weeks ago, is a way to incorporate firewood and solar into an automatic system. I am not a huge fan of outside wood furnaces, but in this case an outside furnace (not an outside wood boiler), would pump its hot into a solar furnace. The solar furnace would be large enough to hold several cord of wood.

When the home called for heat, a blower would come on and draw heat out of the solar furnace and heat the house. IF solar was working, and the solar furnace hot enough, a thermostat would keep the draft fan on the outside wood furnace from coming on. But at night, or on cloudy days, the temperature would drop, and the draft blower would come on and stoke the fire. When the plenum temperature got up to temp, it would then start filling the solar furnace with heat.

The firewood stacked inside the solar furnace, would simply be drying out until it is needed to burn. Until the moisture level got low enough, it would act as a natural humidifier for the home. If the firewood was replaced with green wood as the firewood was depleted, firewood would constantly be drying via kiln action, and also humidifying the home.

All this does NOTHING for automatically filling the firebox, but utilizes every BTU produced!

How hard is it to reduce a 10" chimney pipe to a 3" to accept a pellet stove vent?

Kirk Lundstrom wrote:How hard is it to reduce a 10" chimney pipe to a 3" to accept a pellet stove vent?

I suspect it's not hard at all. Pellet stoves are commonly direct vented through walls, which means they operate at much cooler temperatures than wood stoves.

In theory you could just have a reducer made and mount it in the pipe. In practice, I would be concerned that on a very cold or windy day, the 10" slug of cold/downdraft air could overwhelm the 3" updraft from the stove. Remember that things will go sideways when you need them most. Personally, I think I would pull a 3" flexible chimney pipe all the way to the top of the bigger chimney.

I suggest you keep your insurance people in the loop, and get their approval. Don't give them an excuse: they will use it.

The manufacturer's documentation should provide guidance on this sort of installation as well.

Edit: Some stoves are designed for an outside air supply for combustion. Usually this is built into the direct vent system. It's something to watch out for.