March 23, 2012 - 4:11pm
WFO (Rocket Stoves)
If you have not seen a WFO rocket stove, here's a few videos to learn about them.
A rocket stove is essentially a tall INSULATED vertical pipe that burns any wood or biomas at 2,000 *F with NO SMOKE.
AFAIK A rocket stove uses the least amount of wood to cook than any stove made.
Rocket Bread Oven
No gas reaches the bread!
My friend's rocket stove heats his house.
I helped with this design.Dual Plane Rocket Stove Heater
Energy Conservation with Rocket Stoves in Africa:Aprovecho Research Centre, Southern Africa, Rocket Stoves - Ashden Award winner
Hi Stu, I watched the first video. Looks like a cool oven design. I was a little perplexed though, when he compared it to a masonry oven as needing much more firing. Of course it depends on the size of the oven. The one he was showing was pretty small, and a comparable masonry oven wouldn't need much time for firing either. In any case, interesting post. -Varda
60 pounds of bread with 1 pound of wood is VERY efficient.
If you scale his oven down 10X for 6 pounds of bread, the efficiency would be stunning.
Watch the 3rd video.
This video shows why rocket stoves are encouraged in Africa to reduce deforrestation.
The second video is my friend's setup in Texas.
We have designed a modification that would self feed his rocket stove for 10 hours or more.
If it would self feed, no moving parts, for 12 hours, one would have to feed it only twice each day; say 8 am and 8 pm.
No smoke, no pollution. The 2,000 *F completely incinerates anything that you burn, including painted wood.
Toxic materials are disposed of commercial incinerators operating at 2,000 *f.
Just watched the video and the oven sounds pretty neat. But he mentioned cooking 60lbs of bread with 10lbs of wood, not 1lb. Not sure if that's still impressive or not (I have no experience outside of my gas oven). But it's a magnitude lower than you mentioned.
Sorry, my bad. I make an error.
60 pounds of bread with 10 pounds of wood is very efficient IMO.
A pound of wood contain 7,000 BTU.
Divide by 10 and if it scaled, we could bake 6 pounds of bread with 7,000 BTU (1 pound) of wood.
Since there are 3,413 BTU per Kilowatt-hour of electric power, 7000/3413 or about 2 KWH.
Not too shabby.
Rocket Stove & Dutch oven cooking video.
Akthough this design is very poor, next to the open fire cooking, you can easily compare the smoke.
Note the unburnt carbon build up on the top. Bad design.
Open fires use a lot of wood and they are very inefficient.
BTW - A well designed, loss mass rocket stove/oven will heat up much faster than a high mass brick stove/oven.
The mass in a rocket stove is used to insulate the insides.
The heat does not have to pass though, or heat up the high mass insulation to heat the stove.
In Swaziland, they have developed a form of the Rocket Stove called the Lion Stove (it looks a bit like a lion). It's very efficient compared to what they are traditionally using (open flame, more or less). It was developed for a school feeding program, and can cook up a big pot of mealie pap real quick. Here is a link to some interesting pictures, one of the nice features is that it can be assembled relatively easily from locally availalbe materials.
Thanks, good photos and story.
One thing in common with all the cook top stoves is that they are too short and not as efficient as rocket stoves can be.
However, in third world countries the Lion type stoves and much better than open fires.
My guess is that before you reach the law of diminishing returns, the rocket stove height needs to be about 4 feet tall.
At 4 feet, the combustion is almost complete, and there is no smoke.
Take a look at the Arkansas Rocket Stove and notice the flames and the absolute lack of smoke or steam even though there is snow on the ground.
Rocket stoves have not been made for very long.
The basic "L" design is replicated over and over.
My friend's double plane stove with a vertical feed hopper and with a separate air intake is a breakthrough design.
If I were to build one, that is the design I would use.
rocket stoves after the earthquake in Haiti when a group of Americans was trying to send 1 million of them to Haiti since these stoves use 80% less wood than open fires and there was plenty of small pieces of wood but no big ones and their other sources of fire, electricty and gas were cut off. It saved may folks from dying.
I built my backyard rocket stove using bricks that are just stacked, breaking all the rules of efficiency by not using a steel liner or insulating it with 4" of vermiculite. Mine also uses a side port for air inflow so I can stuff the entire wood loading hole with small pieces of wood to get a larger, hotter fire faster and not have to feed it as often. It works great but by law I can;lt use i very often because of air quality standards. I have also designed a rocket powered oven for bread and pizzas, using two rocket stoves. It will heat up way faster, not require cleaning of the baking area and use 80% less wood than a normal wood fired oven of comparable size. It can also reach much, much higher temperatures of around 700-800 C or so.
Someday, when I can convince myself that wood burning is good for the environment on a personal, non commercial scale, it makes economic sense because I have lots of brush to feed it from my own property that is free and I can convince Maricopa County not have no burn days every weekend and holiday for pollution control to meet EPA air quality standards - I will build it. Her is a pix om my brick rocket stove.
Thanks for your post.
Your stove is step up from the lower height types (no pun intended).
I sure would like a peek at your 2 rocket stove design.
I hope that I am not hijacking my own thread by introducing the following information; but because you mentioned helping Haiti, I feel compelled to publicize the following concept:
As you wrote, a rocket stove uses little wood and it can quickly heat up to 800 *C.
Therefore a rocket stove can easily produce steam.
Haiti, and other natural disater victims, need, first of all, potable water.
In Haiti, there have been thousands of cases of Cholera contracted by drinking contaminated water.
We have an ad hoc team working on a solution to provide clean water, electric power, and heat for cooking.
We can prevent Cholera!
The concept is kindergarten simple:
Use a dry, non lubricated, low pressure (125 psi) steam engine at less than 350 *F, to turn a dc alternator, and drink the concentrate of the distilled water.
You could litrally pee into the boiler, heat it to steam in a rocket stove, and safely drink the condensate.
The dc alternator will charge a car battery, and using a dc/ac invertor you would get electricity for lights, radio/tv, and perhaps even run a small refrigerator.
A machinist that we asked, converted 4 stroke edge trimmer engine to run on steam.
My friend Geo who heats his house with a rocket stove made this video:Homemade Steam Engine Conversion Running
There are literally millions of these engines available for free.
I have also invented a new type of steam engine:Steam Engine - New 2 Piston Single Cylinder Wood Prototype
I hope that this post will inspire others to become involved in this most worthwhile effort.
Lynx Rocket Stove Monotube Steam Boiler
Not the best design, but it shows how it works.
(I know the builder of the rocket stove and the builder of the 3 cylinder engine.)
PM If you want more details.
I stumbled across the rocket stove idea the other day and think that the idea is worth exploring. My current masonry wood oven leaves a great deal to be desired. It started off as a black oven. Unfortunately it cooled too fast, which meant there was only time to bake one load of bread.
Then I added a second firebox underneath. Now the patio slabs I built it on are cracking and it's only a matter of time...
On the upside I learned a lot about what works and what doesn't. Also, most importantly, what I want from an oven.
Now I'm thinking that a hybrid, steel/masonry rocket oven, would give the best of both worlds.