Rocket Stove Burns Steam with High Temp Steam Electrolysis

The Honey Do Carpenter has an aircrete insulated rocket stove that burns at just the right temp to use water vapor as fuel. It is the weirdest thing you've ever seen because you put the wet wood on a mass of coals and the flame is white in the back but you pull the wet piece of wood out of the the stove and it isn't even charred. Anyone else ever heard of this? Almost like it's burning hydrogen? Here are some videos about the stove. Darwin is just about to put the pdf up so people can build them at home. You don't have to know how to weld  and you pour your own refractory mix burn chamber. Also, when attached to a bench the horizontal pipe in the bench doesn't even have to be level to pull the smoke. We dropped our exhaust down 18 inches before going through the bench and we never had any problem with draw. Here are some videos, I am a little giddy about the plans coming out so I apologize if this post is all over the place.

Interesting! That's a very cool (hot) stove you've put together. How long do you think the aircrete will hold up?

I'm not entirely sure about the high temperature steam electrolysis idea. I thought that only started to happen above 2000C unless a catalyst was involved. That's higher than the melting point of steel.

Douglas Alpenstock wrote:Interesting! That's a very cool (hot) stove you've put together. How long do you think the aircrete will hold up?

I'm not entirely sure about the high temperature steam electrolysis idea. I thought that only started to happen above 2000C unless a catalyst was involved. That's higher than the melting point of steel.

The aircrete in the first stove only held up two seasons not because it wasn't good but because the steel that was the first batch box melted. The aircrete then had no hard physical protection and when we put logs in it would dent the aircrete insulation. The Gen. 2 stove is insulated with aircrete but the batch box is a folded brick box with a refractory mix that was mixed for crucibles. Yes, these heats do melt steel.

A quick search finds that high temp steam electrolysis (using electrical input for heat) is more efficient at higher temps because
the heat supplies some of the energy required.
And at 2500C (4532F) no electrical input at all is needed.

The problem becomes one of materials in that steels cannot tolerate elevated temps in this range.

If HDC has discovered anything new to increase wood burning efficiency I would indeed be very surprised.
Moisture in burning firewood is normally heated above 212F and evaporated up the chimney before usable heat is produced.
If HTSE could successfully be done in our woodstove that represents a great efficiency increase since that water is almost always
20% or greater, usually 60% in green wood, and up to 150% according to one source. That's a lot of wasted potential.

The flue gases would be mostly N + CO2 instead of  H2O + N +  CO2...............unless the high temps produced the hazardous  NO pollutant.

Jerry Plush wrote:Moisture in burning firewood is normally heated above 212F and evaporated up the chimney before usable heat is produced.
If HTSE could successfully be done in our woodstove that represents a great efficiency increase since that water is almost always 20% or greater, usually 60% in green wood, and up to 150% according to one source. That's a lot of wasted potential.

HTSE would be a cool side effect, but I'm not sure about the efficiency increase. It strikes me as a zero sum game.

Wouldn't the heat from the combustion of the hydrogen created simply be an offset to the energy input required for HTSE in the first place? And wouldn't the water created by hydrogen combustion ultimately exit the system as water vapour, carrying off some heat energy with it?

Douglas Alpenstock wrote:
Wouldn't the heat from the combustion of the hydrogen created simply be an offset to the energy input required for HTSE in the first place? And wouldn't the water created by hydrogen combustion ultimately exit the system as water vapour, carrying off some heat energy with it?

I believe this is the current understanding of physics (Law of Conservation of Energy). It would require the same amount of energy to dissociate the atoms in water as would be released by their eventual combustion. If it does indeed happen, I believe you are correct that it would be a zero-sum event.

Fascinating claims indeed, I look forward to more info and hopefully more evidence.
To the best of my knowledge the highest temperature recorded in a rocket stove so far is 2446 f or 1340c

Copied from Donkey pro boards …..  Tested the core the other day. Thermocouple was 6 inches up the riser. It displayed 2446 degrees before reading "-----". Happened at least twice that I was watching. At the time it quit reading, it was rising at 2-3 degrees every half second. I have it on video.

Thermocouple survived.

The interior layer of ceramic fiber board seems to have gotten a bit cooked, maybe over cooked.

Riser cracked on the inside.

So, unless somebody has documented something I haven't seen (an obvious possibility) I'm claiming the record.

Fox James wrote:Fascinating claims indeed, I look forward to more info and hopefully more evidence.
To the best of my knowledge the highest temperature recorded in a rocket stove so far is 2446 f or 1340c


So, unless somebody has documented something I haven't seen (an obvious possibility) I'm claiming the record.

Exactly,
    In todays world, one has to see what #1 priority is behind the claims? in this case unless proven by a second person or two (preferably more) I will have to believe "the claims" are to SELL something.  After all the same person, has claimed "his Mass" has held more heat for longer with less weight than anyone else's.  Something we all want, sure, something  that many others have found to be true?  Haven't seen it yet.  But there is always hope! .

Douglas Alpenstock is likely correct here on the zero sum of heat energy expended for steam in HTSE
versus the energy produced by hydrogen then combusted for heat. Concentration of energy is not a
a forgiving principle.

   But if hydrogen production for other usages was the goal and cost could be lower
than for conventional production, that is a definite advantage.  

Any claim of water as "fuel" is suspect in my book. The energy required to break the molecular bonds of water will always be greater than the energy yield from combustion of the hydrogen. Always. There Is No Such Thing As A Free Lunch.

Thermolysis, or molecular breakdown by heat, is possible, but at 2200 degrees C only 3% of the water molecules crack. That's not very good return on investment and it's a wicked high temperature to sustain and contain in something we can build ourselves.

Steam has been well known and exploited in combustion engineering for many years. Lots of high efficiency boilers and gasifiers work best with high moisture content feedstock. They are not "cracking" the water molecules to get more combustion energy, though. They are merely designed to compensate for the extra heat required to turn the water in the fuel to steam (and you can damage them by burning dry fuel unless the air intake is controlled). This is a net loss of combustion energy, but in process heat you can get most of it back by condensing the steam from the exhaust before it leaves the stack. Condensing boilers are good even with perfectly dry wood as feedstock, because water vapour is one of the stack gases anyway, so the boiler design that can cope with higher moisture levels means that the plant does not need the extra machinery and energy to dry the fuel before burning it.

Hey guys and gals, I invented this RMH stove. I use a high temp refractory for the burn box that is typically reserved for foundry use. It is denser than soap stone. when cured at high temperatures above 1500 degrees it's fracturing strength is almost 20000 lbs. per square inch. Its normal operating temperature is between 3-4 thousand degrees. I regularly record temperatures of 2800 degrees in the back of my stove.

I use the insulative properties of aircrete as an energy containment apparatus. It keeps the heat energy where it needs to be and lets it be released into the home when it needs to be released. I also use aircrete in the double wall stove pipe to maintain a hard flue at very low temperature as most of the BTU energy is expelled into the home. It exhausts out of the chimney at just over 100 degrees.

I moved to an off grid property specifically for the purpose of living with this stove. My jaw is on the floor on a regular basis. I had no idea what I had created. Watching this thing burn has been incredible. Winter came early and my cabin is unfinished and uninsulated. This stove really has been a life saver. We are in the rocky mountains of north Idaho and our cabin is 1600 sq. ft. The amount of BTU's that this stove can extract from just a small amount of wood is amazing.

I have read all of the posts on this thread and I must say I am impressed with the knowledge base. nothing was posted that I disagree with.

Here is what I have found. When I burn a fresh cut soft Oregon white pine with its low density (33-35 lbs. cubic ft.) It holds way too much moisture to maintain (HTSE) or hydrogen production. When I burn soft wet wood, I have to add 25-30% dry wood to maintain (HTSE) hydrogen production. However I have multiple Groves of European plum trees on my property which is a much denser fruit wood at (58*60LBS. per cu. ft.) and the higher wood gas compared to moisture retention in harder woods does allow it to sustain (HTSE) hydrogen production independently without adding any dry wood. Hard woods will maintain the burn box temp between 750C and 900C which is the sweet spot where (HTSE) happens.

I will be posting a video on my you tube channel of burning a fresh cut tree for 8 hours. It is incredible to watch a log in a hot box appearing to not be burning with a white greenish blue flame roaring up the back of the stove. it will be posted in the next couple days when the book is finished and up. Pretty cool.

Not going to be electrolysis. If anything, you might get a water-gas shift reaction, (C + H2O = CO + H2, CO + H2O = CO2 + H2) from the hot coals at just the right temperature and oxygen levels. Essentially stumbling on water gas, which is kind of an old school Victorian fuel gas made by blowing air and steam over hot coals.

TANSTAAFL though. Just a curiosity, won't get any extra heat out of it...

Darwin Honeydo wrote:Hey guys and gals, I invented this RMH stove. I use a high temp refractory for the burn box that is typically reserved for foundry use. It is denser than soap stone. when cured at high temperatures above 1500 degrees it's fracturing strength is almost 20000 lbs. per square inch. Its normal operating temperature is between 3-4 thousand degrees. I regularly record temperatures of 2800 degrees in the back of my stove.

I think you've invented something very interesting. It has many possibilities. And because it's lightweight, it could even be integrated into travel trailers and such. Or a portable unit for hunter's tents, emergency shelters, disaster relief, ...the list goes on.

Darwin Honeydo wrote:Hard woods will maintain the burn box temp between 750C and 900C which is the sweet spot where (HTSE) happens.

But respectfully, I suggest that if you promote the HTSE angle, and these temperatures in particular (sans catalyst), what you've achieved will be hacked to death by the howling mob of the wider Internet. The feedback received here has been thoughtful and respectful. That will not apply elsewhere: it paints an easy target for people to shoot at. There is no net energy gain. Why insist on this?

Douglas Alpenstock wrote:

Darwin Honeydo wrote:Hey guys and gals, I invented this RMH stove. I use a high temp refractory for the burn box that is typically reserved for foundry use. It is denser than soap stone. when cured at high temperatures above 1500 degrees it's fracturing strength is almost 20000 lbs. per square inch. Its normal operating temperature is between 3-4 thousand degrees. I regularly record temperatures of 2800 degrees in the back of my stove.

I think you've invented something very interesting. It has many possibilities. And because it's lightweight, it could even be integrated into travel trailers and such. Or a portable unit for hunter's tents, emergency shelters, disaster relief, ...the list goes on.

Darwin Honeydo wrote:Hard woods will maintain the burn box temp between 750C and 900C which is the sweet spot where (HTSE) happens.

But respectfully, I suggest that if you promote the HTSE angle, and these temperatures in particular (sans catalyst), what you've achieved will be hacked to death by the howling mob of the wider Internet. The feedback received here has been thoughtful and respectful. That will not apply elsewhere: it paints an easy target for people to shoot at. There is no net energy gain. Why insist on this?

Hi Douglas,
I can't speak for Darwin but I can speak from my own use of the stove and why this new angle is something we want to share. If by super-insulating the refractory brick batch box you can create these high temps without destroying the stove it makes the stove safer, easier to make and operate, and more useful in less than ideal circumstances. If you HAD to burn wet would because that was all you had without risking creosote problems isn't that pretty useful to the common man? If you can burn less than ideal wood without creating a smoke problem because EVERYTHING is vaporized doesn't that have value. No there is no increase in energy but it does mean less headache and maintenance for the user. Also by trying to understand and hypothesize what is happening in this stove we can get together and brainstorm about uses for such a tool down the road. I have been burning this stove in my off grid cabin for four years and we keep finding new uses for it's tricks. That is all. Juli

Julianne Siddoway wrote:If by super-insulating the refractory brick batch box you can create these high temps without destroying the stove

Julianne Siddoway wrote:If you HAD to burn wet would because that was all you had without risking creosote problems isn't that pretty useful to the common man?

Julianne Siddoway wrote:If you can burn less than ideal wood without creating a smoke problem because EVERYTHING is vaporized doesn't that have value.

These are all qualities of a properly built RMH, they have nothing to do with whether HTSE happening or not.

Julianne Siddoway wrote:Also by trying to understand and hypothesize what is happening in this stove we can get together and brainstorm about uses for such a tool down the road.

It is always wise to understand and great to hypothesize, but Douglas is correct, stating hypothesize as fact will get you attacked or ignored and you will not be able to get your message out.