Rocket stoves: Tips for designing your own
Ideal not just for their social and environmental benefits, rocket stoves have economic benefits as well.
Wed, May 19 2010 at 3:06 PM
SIMPLE SOLUTION: Rocket stoves can be made into any size to accomodate any need. (Photo: fishermansdaughter/Flickr)
They may sound high-tech, but rocket stoves (named for the way air moves through them) are anything but.
Designed to increase fuel efficiency without increasing harmful emissions, rocket stoves are helping people become more self-sufficient, slowing climate change, and saving lives in developing countries where fuel wood is scarce and traditional open fires are polluting indoor air.
They are ideal not just because of their social and environmental benefits, but also for economic reasons: they’re cheap and easy to build, and they require very little fuel.
So whether you’re looking to save money, build an affordable, portable and efficient camping stove, or just have a backup in case of emergencies, a rocket stove is a no-brainer.
What is a rocket stove?
The rocket stove is a wood-burning outdoor cooking stove that was developed by Dr. Larry Winiarski in the 1980s as a safe, effective, environmentally conscious alternative to open fires for impoverished people in developing countries.
Compared with traditional open fires (also called “three-stone fires”), rocket stoves can be healthier and more efficient.
They reduce smoke and harmful emissions, use less fuel wood, and increase the amount of energy from the wood that is turned into heat energy.
In countries like the Democratic Republic of the Congo, energy-efficient rocket stoves reduce air pollution, allow for more efficient cooking, provide employment opportunities, prevent widespread deforestation, and help refugees and internally displaced people cook meals when fuel is not readily available or is not safely procured.
Beyond that, rocket stoves can be an inexpensive means of slowing climate change.
According to the Aprovecho Research Center, which pioneered the use of rocket stoves, “It takes only about three ARC rocket stoves to offset one average American’s driving habits for one year ... or just 13 stoves to offset an American’s entire annual footprint.”
Elements of a rocket stove
A basic rocket stove consists of just a few components:
• An insulated rocket elbow, formed of a horizontal fuel chamber that fits into a vertical combustion chamber (also referred to as a “chimney”)
• A stove body that surrounds the elbow, made of sheet metal or some other inexpensive material, with a small opening
• A fuel grate, placed inside the fuel chamber, on which the fuel wood rests
• A pot skirt, a sheet metal shield that surrounds the cooking vessel, creating a gap, to ensure that more heat from the flue gases enters the vessel
How does a rocket stove work?
In open fires that are not carefully maintained, only a small percentage of the heat energy released from the burning wood makes it into the cook pot.
With a rocket stove, only the tips of the fuel wood are burned, eliminating that waste (and, in an added benefit, eliminating smoke).
Rocket stoves can use most any dry plant matter, not just wood — leaves, twigs, and brush will work as well.
Fresh air enters the fuel chamber from beneath the burning wood resting on the grate, allowing the air to be preheated before it enters the combustion chamber, which in turn leads to cleaner combustion.
The small fuel entry not only demands less fuel wood, but also limits the amount of cold air that can get in.
The combustion itself is confined to a small, insulated space, so most of the energy in the wood is converted to heat for cooking.
The cook pot sits directly on top of the combustion chamber, so the hot gases contact it immediately after combustion, reducing smoke.
The pot skirt that surrounds the vessel further improves efficiency by increasing the temperature of the flame that contacts the pot, and by directing the gases to scrape the sides of the pot as well as the bottom, increasing heat transfer.
Building a rocket stove
The process of building a rocket stove is a simple one, and instructions are available online (some sites require a donation to access plans).
A basic rocket stove, used for cooking food or boiling water in a single pot, can be built in a couple of hours with a few cheaply purchased or found/recycled materials: sheet metal, refractory bricks, vermiculite and cement (to secure the combustion chamber in the stove body), and steel poles for pot supports.
Want a rocket stove but aren’t keen on building one yourself? Don’t worry; they can be purchased.
If you do build your own, be sure to test it before using it; for instance, with a water-boiling test.
- Check out how to build a rocket stove on sustainablog.org
- Design Principles for Wood Burning Cook Stoves, including In Field Water Boiling Test
- Video Instruction on How to Build Your Own Rocket Stove
- CCAT Rocket Stove
- Larry Winiarski’s Rocket Stove Principles
- Aprovecho Research Center
- StoveTec Retail Store
MNN homepage photo: fishermansdaughter/Flickr
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