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Thermal Mass Rocket Stoves on our Minds…

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Why Thermal Mass Rocket Stoves are part of This Permaculture Design

Thermal Mass Rocket StoveWe cover the foundations of rocket stove building at every Permaculture Design Certificate (PDC) course we host.
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Whereas wood gasification turns wood scrap into a flammable gas to run engines (generating electricity  power and heat), a thermal mass rocket stove simply turns scrap wood into heat…. lots of heat…with a lot less wood!!!

So, we have included them in our overall design, especially for Earthcamp Village, because they are:

  1. Relavtively simple to understand, construct and use
  2. Inexpensive to build
  3. Beautiful, functional and warm.
  4. Fueled from current sunlight (i.e. wood)
  5. Very…very… efficient at converting wood into clean heat!

Bottomline:  They burn 1/4 of the wood to generate the same heat from a conventional wood stove and the outgases are 90% cleaner as well.

The Key?  They burn the wood, smoke and gasses at very high temperatures…SAFELY!
The exhaust system of Bev and Wayne’s stove before cobbing it over into a bench for heat extraction. More pictures at bottom of this post.

Thermal Mass Rocket Stoves Explained

Not long ago, our friends and neighbors, Bev and Wayne, started to build a thermal mass rocket stove in their living room.  Wayne took one of our PDC courses and was inspired by the rocket stove concept (See the illustration and links below).

Bev and Wayne have been sharing their adventure with us and we are very excited about the possibilities.

Imagine having a wood burning stove in your home that:

  1. Burns less than 1/4 the amount of wood you typically burn
  2. Keeps you as warm or warmer
  3. Allows you to easily burn sticks, twigs and branches instead of just large chunks of firewood.
  4. Burns cleaner than any wood stove ever made

The big thing for us, living here on the prairie in Illinois surrounded not by woods or forests but by corn and bean fields, is the very real shortage of easily available firewood.

What I am talking about are the large hardwood trees with trunks and large branches which are typically chainsawed to length and then split to fit into a wood burning stove.  All of this tonage of wood then needs to be hauled out of the woods, dumped or stacked somewhere, then loaded back into a truck for delivery to be driven to someone’s home (a lot more energy) and then unloaded and stacked again for winter use.

Up-to-date Picture of Above Stove at Bottom of this Post

About the Thermal Mass Rocket Stove…

When fired up properly,  the stove can make a quiet sound, similar to that of a “rocket” as the high temperatures uniquely created within the stove pull in more and more air and burn off the hot gasses from the burning wood.  
In this stove, you burn not only the wood but also most of the smoke and gasses coming off of the burn to get more heat and a much cleaner exhaust.  Much Less Pollution…!!!

Click on the photo below to read a great article about these stoves.
It is written by Paul Wheaton of Permies.com 

Cross Diagram of Thermal Mass Rocket Stove – More found at Permies.com

 

RMH_Cover-ThumbHere is a link to the most popular book on rocket mass heaters written by Ianto Evans and Leslie Jackson.  It talks about how you can build one for yourself in a weekend for less than a hundred dollars.

This book explains in detail exactly how to build one, then how to use it in a range of applications.

They discuss materials: where to find them, what to pay and how to make use of found and recycled parts.

The section on fire and fuels is thorough but simple.

With the use of traditional firewood, we are talking about the consumption of a lot of fossil fuel (gasoline and oil) as well as the need for a good amount of human labor (time). 

So, imagine for all of us prairie or rangeland dwellers that there would be an option to be able to grow and harvest the wood we need to keep warm in the winter within 2-3 years, instead of waiting 10-20 years for a tree to grow large enough to harvest.  These thermal mass rocket stoves can easily burn 1-2 inch diameter branches which can be grown in a short time and harvested with just loppers or pruning shears.

No longer would we need to harvest firewood with a chainsaw, log splitter, gasoline and truck.

Hayden could harvest our annual firewood needs with a pair of loppers and pruning shears.

This is big…big…big…news…!!!

When the price of fossil fuels and electricity begin to soar, so will the price of firewood.  With an increase in the demand for firewood comes the risk of harvesting too many of our trees and the potential to further disrupt the ecological balance on our planet. Besides, a full size tree takes a couple of decades to grow. Will we really have time to wait?

With the use of a thermal mass rocket stove, our annual supply of firewood could be harvested with a pair of loppers, pruning shears and a garden cart.

Photo: Bill Hogarth, an English expert Coppicing Hazelnut

Quite literally, farmers will be able to convert some of their prime (and not so prime) farmland into the raising of selected firewood brush using the long honored art of coppicing.  For example, a farmer could grow hazelnut bushes for the nuts.  Once every 7-10 years, it’s a good practice to coppice the hazel bush  (cutting it completely off, close to the ground) thus harvesting the perfect firewood for a rocket stove.  The next season the hazel bush springs back to life and will begin producing nuts again in another 2-3 years.

This is why permaculturalists have such a passion for food forests.  In a food forest we not only grow the foods we need to eat, we can also produce fuel and fiber while simultaneously building topsoil.  Food forests improve the land and water with every successive generation of farmers.  Traditional row-crop farming however does just the opposite.  We loose massive amounts of topsoil every year worldwide and especially on industrial farmed soils.

So, the implications of the widespread use of this stove and a new firewood harvesting system are substantial:

  1. Decreasing our need and use of polluting fossil fuels
  2. Harvesting the energy from current sunlight instead
  3. Repairing damaged farmland
  4. Providing income and right livelihood for farmers and growers
  5. Harvesting CO2 out of the atmosphere and storing it into wood and soil
  6. Minimizing flooding (woodlands hold much, much more rainwater than farmland)
  7. Creating habitat for wildlife
  8. Providing greater homeland security
What is not to like here?  These are some serious solutions we are looking at and it costs very little to implement.  We are talking about some clay, sand, brick, a couple of steel drums and some duct work, and we can change the world…!!!

Cheers…. Bill Wilson

Here is how Bev & Wayne’s stove looked in the early days of the build. The cob is being built up around the exhaust system. They still have the finishing work to do.
Here we are looking down into the burn chamber. Notice how the fire is burning “sideways”. As the rocket stove heats up, it draws air into itself which keeps smoke out of the room and gives the stove a “rocket” sound.
The Finished Stove. And they love it…!!! Heats their home with very little wood.

 

Here is a Link to a fun article from ‘Morning Chores’ with:
21 Free DIY Rocket Stove Plans for Cooking Efficiently with Wood

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