So it’s been, let’s see, wow – a couple of weeks already since Tim Barker led a two-day workshop (a first for him and us) on how to build simple rocket stove combustion units for such uses as water heating, ovens, and mass heating. It was a fantastic workshop, hosted by the wonderful Michael and Lisa Jackson at Yandoit Farm, and we wanted to share a few photos and a bit of know-how, here on the oven, with further reports to come on the hot water unit and Megan’s mini-rocket cooker.
Now rocket stoves are super exciting for a few reasons. As noted by Tim:
- They offer complete combustion of the wood
- They can reach very high temperatures
- They can use wood typically considered too small to bother with
- They are easily built from common materials.
In other words you can knock these suckers up in a day or two, and they turn twigs into heat way more efficiently than most wood stoves and with way less cost to set up. If you are good at scavenging bits they can cost virtually nothing to build, and when you prune your fruit trees you can get the fuel you need to cook dinner, heat your home, and enjoy a nice hot shower.
Tim kicking off in the Yandoit Farm hayshed.
We started with a little bit of theory (the workshop was about 95% hands-on) with Tim, who got across the key points of difference between rocket combustion and normal combustion. This is all Dan’s possibly muddled recollection, but the main difference is that rocket combustion is complete. Because the compounds released from the wood heated when added to the rocket stove are sucked into the flames, unlike a normal fire, combustion is complete, meaning no smoke. That’s right – smoke mean incomplete combustion, or wasted energy. It was really weird looking down the flue of our first rocket unit at the workshop and feeling the hot air but seeing zero smoke. For we are culturally trained to associate smoke with fire, but with rocket stoves it is true that sometimes when there is no smoke, there is still fire! The second difference is that rocket stoves focus on ensuring complete combustion and only then use the resultant heat. Conventional wood stoves and often use the heat before combustion is complete. The combustion chamber of the rocket stove is heavily insulated to prevent premature heat loss.
Anyway, enough theory, let’s jump to practice, as we did on the Saturday morning.
Whilst Tim showed us how to make the base rocket stove unit from old bricks…
VEG’s Carey and friends (Chris, Brielle & Paul) constituted the poo collection crew. 20 minutes into the workshop and they were shovelling shit!
Which we mixed with subsoil to make a cob mix
With some relatively clean feet..
But not for long!
Work that cob!
Consider it worked.
Relatively unclean feet..
Beautiful cob blobs
And such fun to make!
Securing the base layer
Reshaping the base unit (feeder tube, burn tunnel, and riser)
Praise to the rocket gods
Blob on the cob
Coming up beautifully!
Here’s one I prepared earlier 🙂
Frame was attached…
A quick chat about the immanent fate of these nice blue barrels…
Revving up the grinder (nice one Megan!)
Brielle aka The Permaculture Terminator
Fitting the outer to the inner skin.
Sitting on the frame.
“I am Geoffrey, the badger hunter. Let me tell you the story of my people” – a comment from sculptor Dean.
Pyromaniac Tim getting ready to fire the rocket!
The puff that turns it from a normal fire into a rocket
Ladies and gentlemen, we have lift off…
This is what complete combustion looks like – look mum – no smoke!
Tim going for the giant-bong look…
Yandoit farm resident and exceptionally wonderful human being Chris who finished off the stove all by herself in the two weeks after the workshop…
And who would have thought something so rough and ready and functional could be so beauuutiful!
Recycled old supermarket shelves
Finishing off dinner in the oven which we can say lives up to its rep and cooked about seven pizzas and finished off these pies effortlessly and quickly on bugger all wood.