It's been a while since I built my rocket stove out of a water heater... I really loved that project. Ever since then I have had one thought that just keeps popping up in my head... "Instead of burning wood I would like to burn junk mail, used paper goods, etc." I come in contact with so much paper that just gets wasted it is ridiculous.
I recently stopped my trash pickup service... They had been going through my trash. Creepy! So anyways... I currently burn just about anything that will burn outside... Each time I do this I am amazed at the heat it produces.
I've been doing a lot of reading about folks pressing wet paper pulp / saw dust / straw / leaves / corn husks / etc into briquettes. This got me thinking... How cool would it be to engineer a rocket stove to work with briquettes? Maybe some really neat way of gravity feeding the briquettes that would be safe and efficient. Is anyone already doing this?
Re: news paper for fuel.
There are some who have said it is bad to burn newspaper because of some of the chemicals in the ink and paper... but they do use it to start the fire. They have also said not to compost newspaper for the same reason. I have learned that many municipalities even though they collect recycle stuff separate end up putting it in landfill because it is too expensive to actually recycle it. Landfill = compost somewhere. So maybe burning it is the lesser of evils. I get newspapers every week without asking for them, I'm going to burn them.
Because of the feed set up I have, I am rolling them into 4inch by 30inch logs. These seem to weigh about 8lbs. My feed is like this (in the second picture):
And that seems to work just fine. It will be a while before I get things set up again... I have done my outside testing and now will move it inside as I have time... I will test it at that point with the paper logs. While testing outside, I have been somewhat lax with making sure everything is well sealed, so it will take more time setting up next time because I will be making sure everything is air tight.
re: burning manure
just a quick comment. While manure does burn well, I have read that there is much less available energy per lb. It may have to mixed with something that burns faster to keep the riser up to heat. It would certainly take some experimenting. I am not sure I want to bring even dried dung inside my house though but that may be just a "yuck" thing with no reality behind it.... it sure would be for my Yf.
Monte Hines wrote:All good information...
Appears that paper rolled logs would be easiest to use, if you can get them to burn continuously.
Interested in everyone's results.
It may be some time before I get a chance to try. Spare time is in short supply right now, but yes low labour input was my first thought. The tests I have done so far have been good, but the paper has been a small part of the fuel cartridge. I am also not sure about the amount of ash created and how much will blow through the system requiring more frequent clean out.
There is another thread that talks about using bamboo and I am thinking about growing a bamboo "hedge" for fuel. I was thinking to crush the cells to unseal them so they don't pop with heat rather than splitting.
There are also lots of blackberry canes around if I can find a good way of harvesting/bundling.
Anyone have experience using manure in a TLUD? Also whether or not you would need to make briquettes or not as long as its dry since its only off gassing? I know this threads about RS's but I can't find another thread about it ( or even eco logs) and I didn't want to start one just for that question .
I, too, am interested in building a solid fuel burner, with masonry thermal storage capacity. Cooking option is not a priority, though some amount of immediate heat may well prove necessary, as this is for an earth-sheltered greenhouse application. I'm thinking firebox outside, or under the floor of the structure.
Something akin to what Jolly Roger has going in this video:
with a way to capture and utilize the heat, while producing a usable commodity, is quite appealing. Your idea about pyrolizing manure without first turning it into presto logs or bricks is simply brilliant. Cuts out a huge amount of labor.
Now, what sort of firebox/retort configuration would simplify the fuel loading/char unloading process so that one aging individual in reasonably good shape could handle the operation on a daily basis, if necessary?
Karl, it's funny that you linked to the jolly roger set-up, that's what I had intended trying it with (once I build mine, waiting on the drums). I wonder if you would have to layer it so that the top layer of fuel was wood or something easily flammable so that by the time it got to the manure it was already off-gassing. However since I have read that different sources of bio-char have difference characteristics depending on what they were originally, I had planned to mix manure with wood anyway so I don't see that being a problem. My original intention was simply getting the bio-char, but now that you mention it, seems silly not to capture the heat for something useful. Finding a way to store that heat in a thermal mass for a home as you suggested seems like a good use for it. Another possible (although I don't know how practical/potent) an option would perhaps generating electricity with it. I don't have knowledge of the potential from thermocouplers or steam generators (maybe someone else can chime in), but I don't see why it wouldn't be possible. Especially if you planned on making a lot of it, or using it as your soul heating source. It's probably not out of the realm of possibility of using it to both generate electricity (if you were off grid/had a battery bank) AND heat your home.
If you had this unit in your basement, it occurs to me you could in fact have two sets of thermal masses. One in the basement (since the containers get very hot), and then one in the room above (piped through the floor to the second thermal mass, on its way to the outside)
I have a couple ideas buzzing around in my head as I write this for how to make it much easier to load/unload without a great deal of physical effort. Soon as I straighten them out I'll post them! lemme know whatcha think
Oroborus; Just a quick response. I haven't been around gassification much, so I don't know if this is practical, but what if one were to build a masonry firebox, such as is shown in this photo from Fine Homebuilding?
Then, beyond the firebox, you lay out two walls of firebrick, or other suitable high-temp material, say 8-12 feet long, maybe 18 inches wide, or so. Lets say three bricks high, or 7 1/2" high. For the roof of this expansion chamber, instead of refractory slabs, you build a steel box the width of the two walls and, say 24 inches deep, with a hinged lid. This box, you fill with a mixture of dried animal manure and wood pulp. Then you plumb the box so that gasses driven off are returned to the firebox. All this is assumed to be outside the greenhouse, and heat derived from the process is vented through masonry channels or steel duct beneath the greenhouse floor, to the north wall, which might be baffled and masonry doing double duty as a chargeable trombe wall, atop which sits the chimney exit.
For the record Karl my experience with TLUD's and RMH's (which are similar to masonry stoves at least in the concept of storing thermal energy) is purely theoretical since I haven't yet built mine. That and I'm sure there are people on this forum who know more about it. I certainly don't mind speculating about it with you, I just wanted to be upfront so that you wouldn't mistake my conjecture/ideas for experiences and to encourage you to also seek out those with more experience and knowledge than myself. I really don't know anything about the setup of masonry stoves so I'm not sure how that set up would work.
I will answer your question with a question however! Wouldn't a cob type setup for the thermal mass be far cheaper than masonry stone? I am also a little confused as to where the secondary air comes into play in your system, and how easy/difficult it would be to change out the char/fuel. I think a better option might be a setup similar to that of the jolly roger, except the containers are surrounded (not on all sides) by the cob mix (and the appropriate fire retardation), and exhaust pipe is vented through more thermal mass on its way out of the green house. I would use something smaller than the 55 gal drums (as that setup is very large) maybe, and have it inside of the green house. I'm not sure how feasible it is to expect the exhaust gasses to travel through different changes of elevation, but I assume as long as the route isnt too complex and that it ends higher up than the unit (and outside in the colder air) that it should updraft okay? Maybe someone with more experience could chime in.
For the record I'm not bashing your masonry idea, I just have nill experience/knowledge of the units so you'll have ask around about that! I do very much like the idea of thermal mass heaters in green houses though, its one I've considered myself, and with the added bonus of burning manure and creating biochar, it seems win win, assuming it can be made to work
Oroborus; Did you get a chance to open the link to the Fine Homebuilding article? I built that stove under a greenhouse/atrium space attached to a residence in Missoula, Mont. in the 80's. It had approximately 40 ft. of horizontal flue run in five runs with four 180 -degree turns, and it drew like the space shuttle taking off. Draft in these devices is rarely a problem, and it is a problem easily alleviated. Notice the cast iron clean-out door at the chimney base, above the floor, in the left side illustration? That's critical for cold weather operation. If the stove is not kept warm and the inner bricks are allowed to 'get cold', the stove will draft backwards upon firing, with quite unpleasant results. The clean-out door at the chimney base allows you to establish a positive draft in the stove BEFORE lighting a fire in the firebox. Once draft is established in the right direction, the main fire can be lit and will draw properly until the fuel load is consumed.
Cobb is a cheap alternative to high-quality refractory materials. In the primary and secondary combustion zones, I would suggest spending the extra bucks for top notch high temp materials. Downstream, I would be more apt to switch to cheaper materials, as anticipated temperatures should not require expensive refractory to guarantee component longevity.
Secondary combustion air is certainly a design requirement, and has been handled by other designers in a variety of ways. Pre-heated, secondary air, applied strategically to the flue gas stream where it passes from the firebox proper into the secondary combustion chamber is the ideal location. This delivery system might be constructed of stainless pipe exposed to the fire and connected to and pulling its air through a hollow door frame.
One design element missing in most of the talk I've read about rocket stoves is the relationship of excess air control to maximizing combustion. What I found in operating the k'ang in Missoula was that, prior to having an air-tight door in place, the stove would roar away with itself, taking in all the air it wanted and sending a great yellow flame all the way down the first flue run, and presumably, beyond for who knows how far? Yet, there was always some smoke associated with this type burn.
When the door/ air control was installed, turbulence was minimized, the yellow 'thrusters' turned blue and shortened, with the result being much more heat was dumped into the floor over the expansion chamber/first flue run than had been the case previously. Essentially, their is an optimum balance to be achieved through carburetion and an air-tight door, with controls, allows one to experiment with settings until a satisfactory balance is attained.
its not a problem to use pelleted fuels you just need to fiddle things around a bit so the stove can intake air as fast as the combustion material can use it. Richer fuel means more air needed to burn clean.
a friend of mine has used a press to make dung and paper logs about 5 inches round and they work a treat. I have burned presto logs and again they burn well. dung, leaves, paper, nut shells, peat, coal, diesel, corn oil, motor oil, tires, ect. have all been burned in rocket stoves. you have to configure them a bit different to use really rich fuel like tires and motor oil, and you need to figure out a feed for wood chips, pellets, and nut shells.
its not hard to do it just needs to be done and tested over time. (we moved out of portland so i can do some more of this type of testing). I want to get a RMH tuned so i can burn plastic bags an get clean co2 and water.
Why cause i want a stove on my boat and it needs to be able to burn pretty much everything i have as trash and i would rather not pollute the world with plastic smoke.
Need more info?
Ernie and Erica
Wood burning stoves, Rocket Mass Heaters, DIY,
Stove plans, Boat plans, General permiculture information, Arts and crafts, Fire science, Find it at www.ernieanderica.info
I stumbled across this thread via the similar threads function.
The most intriguing thing was thee link to the backwoods article.
I ran down some other links on using the ashes from manure, and its seems that wile one loses the nitrogen, one retains the P and the K.
Still, burning poop seems ...wasteful!
But what if you were stacking functions?
A Humanure compost pile is not in my urban future. A rocket stove is.
Humanure ash seems like it might be useful, but how about humanure biochar? Leaving behind the carbon as well as the P and K might be even better, or it might bind the P and K.
Let us suppose that it will be an awesome product.
The mix of humanure and dry carbonaceous material that comes out of a lovable loo could make for a nice feed-stock for
A stainless steel biochar retort in the flame path could use iron pipe to route the off gasses back into the feed tube or batchbox.
The process kills the pathogens in, and reduces the bulk of, the humanure. The energy produced can warm structures, or drive tasks that run on heat.
I am envisioning stainless steel stockpots rotating from use in the loo to use as a retort.
So, just another crazy idea I wanted to share.