Archive for Wood

Hand operated briquette press – utilizing waste paper and sawdust

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Firewood dependence for cooking in the developing world has resulted in forests being depleted at a rate of 2.5 to 3% per year. It is here in the poorest parts of the world that villagers spend a good portion of their time gathering wood to cook, heat and make charcoal. To counter this dependence on wood, efforts were made in the early 80’s to come up with alternatives. One such alternative being explored was making fuel briquettes from non-woody biomass for cooking. Dr.Bryant and students at the University of Washington in the USA developed a novel low-cost briquette making process using non-woody agricultural residues, ordinary water and a hand-operated wood press.

“Anyone can make briquettes from their own leaves, grass, straw and paper”

The briquette process was simple and could be established in poor rural communities, requiring little technology and very little money. With a small effort villagers could now create their own fuelwood from agricultural residues. To make a briquette, ordinary leaves, grass and straw would be chopped and mashed into a paste. This paste would then be compressed into round cakes and dried. The resulting briquette would be sold as a fuelwood- and charcoal substitute at the local market. In 1994 the Legacy Foundation, USA, picked up on Bryant’s briquette making process and extended the outreach activities. Today, Legacy Foundation’s training and online media services have spread the briquette technology and process into eleven other countries, such as Haiti, Uganda, Mexico, Nepal, Kenya, Mali and Tanzania. The foundation has also released 8 technical/training manuals on all known aspects of briquette making.

Vuthisa acquired the rights to promote and extend this technology into Southern Africa. The Legacy Foundation have now launched their new Ratchet Press to replace the wooden presses and its now manufactured in South Africa.

 

The Ratchet Press is designed to fold away when being transported and once erected in a few simple steps provides the necessary power to compress sawdust and paper mixed in a wet slurry into medium density fuel briquettes. Using common tools and skills, the Ratchet Press can work for an individual or full time commercial briquette production facility. Though it is compact and portable, it can deliver nearly the same force as their larger Mini Bryant compound level wood press. They have launched 3 Ratchet Press manuals namely; Ratchet Press Construction, -User, and -Marketing manual which explains in detail how to construct (unless an actual press ordered from Vuthisa is preferred) the press, arrange and prepare materials and operate the press successfully.

Watch this demonstration video of our latest Ratchet Press:

Vuthisa have also started manufacturing the Test Briquette Maker (TBM) under license so visit our online shop for prices. Quite a large proportion of people that buy the user manuals never commit themselves to building the actual presses, possibly due to time or money constraints or they lack workshop tools and/or technical know-how. Order this “Press Kit” to get familiarized with the concept behind their hand operated wooden and metal, low-pressure briquetting machines. “Like” our Facebook Fan Page and receive a FREE PDF download link to the “Test Briquette Maker”:

“The Test Briquette Maker can be built for under $125 (USD) and requires almost no maintenance…”

The Test Briquette Maker can be built for under $125 (USD) and requires almost no maintenance, with only basic drilling and welding (10 cm at most) work required. If you’re looking to attract funding to roll out a program using this technology, this press will be most suitable to that end. As mentioned a FREE download link to the “Test Briquette Maker Construction and User Manual” will be supplied with every manual purchased on this site.

Watch this demonstration video of the Test Briquette Maker:

Also visit our Instagram account for more pictures: https://www.instagram.com/vuthisa/

Order the Ratchet press here (minimum order of 2):

For more information on the briquette process and to access their electronic How-To Manuals kindly visit this page:

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Sneak preview of our new IP

by Kobus Venter

Well done to Troy Manufacturing for again being able to translate our drawings into workable solutions. Most components are laser-cut, but many add-ons are hand made. The quality of the welding is also top class. All components are in direct contact with fire so none will be painted. They all come together to form a single Biochar kiln to be used in the Vuthisa Biochar Initiative, sponsored by the Energy and Environment Partnership Southern and East Africa (EEP-S&EA) fund.

Visit https://vuthisa.com/2013/12/23/the-vuthisa-biochar-initiative/ for updates on the project.

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The Vuthisa Biochar Initiative

By Kobus Venter

Welcome to the ‘Vuthisa Biochar Initiative’ blog page. On this page you will learn more about our project and what we hope to achieve. The project officially kicked off in December 2013.

The project actually has many outcomes, but the primary goals are:

Create Employment – Up to 30 workers will be employed in year one. Unemployment is rife (>50%) in the rural areas of KwaZulu-Natal especially with a minimum wage now being introduced for farm workers. The feedstock for the Biochar project will be secured by ‘Vuthisa Charcoal Projects’ through a contract signed with the Department of Environmental Affairs, Natural Resource Management Programme, that pays the wages of our workers.
GroupPhotoEPWP
Eradicate Invasive Alien Plant Species and restore the Natural Biodiversity of the land – We intend to clear over 300 hectares of Wattle in this area and restore the land back to virgin grassland. The main culprit being Acacia mearnsii (Black Wattle) and Acacia decurrens (Green Wattle). Unmanaged Wattles in KwaZulu-Natal has now reached more than 300,000 hectares in extent, according to the Agricultural Research Council (ARC) report commissioned by Water Affairs, 2010. Left untouched, this alien vegetation would spread at an average rate of one percent a year, threatening water and food security.  Concerted efforts are being made to prevent the further spread of these invasives especially in water catchment areas and it is estimated that R 34 Billion ($ 3.4 Billion) will have to be made available over the next 25 years to stop this spread.

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Increase streamflows and reduce erosion – The Wattle trees spreads vigorously through the seed it puts out and these typically germinate in or near river systems, reducing filtration into underground aquafirs and streamflows. At the onset of the infestation when the trees are young, only 500 mm of water is preserved within a typical annual rainfall area of 1200 mm. As the invasives spread, after 24 years only 25% of the entire potential water yield namely 300 mm of water will become part of water supply into the local catchment.

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Develop Emission Reducing Biochar Kilns and reduce greenhouse gas emissionsAcacia mearnsii is a hardwood species and makes excellent charcoal.  Conventional pyrolysing tecnologies in South Africa however are less than 20% efficient.  Our first goal is to achieve a minimum of 25% wood to biochar conversion efficiency. Using more efficient methods to produce charcoal (or Biochar) has the potential to save about 100 MtCO2 per year in Sub-Saharan Africa (See http://bit.ly/I0KIXl).  CO2 production from Emission Reducing kilns has not been quantified, but a 5 to 10% reduction in GHG’s is expected. We plan to produce 150 tons of Biochar in the next two years and we expect that 20% of this will be bought indirectly by fertiliser companies which could result in at least 30 tons of carbon being sequestered back into the soil.

Kiln_Complete

Develop Biochar Eco-fertilisersBiochar as a soil amendment will allow rural folk to improve their subsistence agriculture. Mixing biochar with soil or a good active organic compost before it goes in the soil will soak up its full compliment of water, nutrients and microbes so that it can make those available immediately to the plants as soon as it is added to the soil. Ultimate concentrations after some time of repeated applications of these eco-fertilisers (chemical free) will work up to about 8 to 10% biochar by weight of the soil content.

biochar trials

See this Google Earth map below of precise location of the clearing operation:

What is Biochar?Biochar is charcoal mixed with compost and applied to the soil as a soil amendment and has the same benefit to plants than chemical fertelizers. The act of burying the Biochar in the soil, removes carbon from the air (CO2) and sequesters carbon into the soil for thousands of years and prevents the release of Methane from harvested plant material into the atmosphere. Methane is a key fuel component to providing the heat into the retorts and in the Biochar forming process.  Venting un-burnt Methane into the atmosphere contributes 26 more times to the greenhouse effect than CO2 alone.  For more information on biochar, feel free to research the many references to Biochar on Google or read more on our Biochar web page: https://vuthisa.com/biochar/
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Harvested IAPs ready to be charred

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Biochar Retorts being primed for firing in Guatemala

Please donate to the project.

The Energy and Environment Partnership fund for Southern and East Africa (EEP-S&EA) have kindly stood up and agreed to fund 50% of the Project Management fees, Site Preparation, Tools and equipment and Administration fees. The EEP Programme in Southern and East Africa is jointly funded by the Ministry of Foreign Affairs of Finland (lead donor), The Austrian Development Agency (ADA) and the UK’s Department for International Development (DFID). For further information visit: http://eepafrica.org/ or http://eepafrica.org/portfolio-item/vuthisa-biochar-initiative/#tab-id-1

EEP_Logo2EEP_Biochar

To donate to the project please get in touch with us.  We offer branding opportunities on Hippo Water Rollers, send out T-shirts and give shout outs on Social Media. Contact us here to find out more.

We accept SWIFT payments whereby money is wired into our project bank account.  Please approach your local bank’s FOREX department and request the appropriate procedure and instructions to follow to expedite this type of payment.

Contact us here for our bank details.

Donate via PayPal (pay with a credit card):

Please Donate

 

Donate via EFT:

PayR100

PayR1,000

PayR2,000

PayR5,000

PayR10,000

Please indicate in your bank reference which activity you wish to sponsor.

What will the money be used for?

We will have the following expenditures:

1 –  Water and Sanitation

Instead of purchasing large stationary water tanks to supply drinking water from rainwater harvesting, we thought it would be cool to use Hippo Water Rollers and collect water from the nearby fresh water vlei. Each water roller can hold 90 litres of water. This presents branding opportunities for companies out there, by having their name or logo printed on each Hippo Roller. Visit the website for Hippo Water Rollers here for more information: http://www.hipporoller.org/ The cost of each Hippo Roller is R 1,500 ($ 136) including delivery to the site. We require a minimum of 4 Rollers and a total of R 6000 (± $ 544).

The cost of purchasing and delivering 2 x Portable toilets to the site is R 14,000 (± $ 1,272), and we’ll pay for the fortnightly servicing of the units.

[0%] of “Water and Sanitation” funded to date.

Reviewed on: 20 January, 2015

2 – Cooking Stoves

The cooking stoves we require are special portable wood- and charcoal fuel saving stoves and because we are re-sellers of this product we can provide them at cost to our workers. We require 8 of these stoves to offer the staff with a means to cook their food safely or to boil water. More information here: https://vuthisa.com/news/stovetec/
The cost of delivering 8 stoves to the site is R 3,880 (± $ 352).

[0%] of “Cooking Stoves” funded to date.

Reviewed on: 20 January, 2015

3 – Protective Clothing

To ensure our workers are operating safely and are fully kitted out, we need to supply them with adequate protective clothing (PPE). These include Two-piece overalls, T-shirts, Rainsuits, Gloves, Chainsaw operator safety gear, Goggles and Masks. The most recent quotation revealed that we need R 22,560 (± $ 2,051).

[60%] of “Protective Clothing” funded to date.

Reviewed on: 20 January, 2015

4 – Tools & Equipment

The basic tools and equipment required for the project include Hatchets, Loppers, Knapsack sprayers, Combi-cans, First-aid kits, a Fire extinguisher and Spades. This will cost R 14,500 (± $ 1,318). We have already paid for 2 chainsaws worth R 11,300 (± $ 1,027).

[65%] of “Tools and Equipment” funded to date.

Reviewed on: 20 January, 2015

5 – Biochar Kilns

The specialized Biochar kilns have been developed over many years and are professionally constructed by a light engineering company in Mkondeni, Pietermaritzburg. The cost of each kiln ex-factory is R 9,000 (± $ 886) and we require 3 to start off with for a total of 27,000 ($ 2,658).

[18.5%] of “Biochar Kilns” funded to date.

Reviewed on: 20 January, 2015

6 – Environmental Impact Assessment consultancy cost

The planned activities for the biochar project and charcoal activities will require an Environmental Impact Assessment (EIA) and an Atmospheric Emission License (AEL).  The entire process is expected to take 11 months to complete.  Cost: R 329,543.22 ($ 32,954) including VAT.

[57%] of “EIA” funded to date.

Reviewed on: 20 January, 2015

When everything is tallied up we need R 87,940 (± $ 7,995) PLUS R 164,771.61 (± $ 14,979) for the EIA and AEL.  The EIA and AEL will be funded from biochar sales, but any donation towards this cost would be very much appreciated.

[33%] of “Vuthisa Biochar Initiative” funded to date.

Reviewed on: 20 January, 2015

In conclusion we would like to thank everyone for their support and that we will do everything in our power to meet the goals of the project.

Or for more information contact us here: https://vuthisa.com/contact-us/

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Vuthisa Biochar Trials Ivory Coast – Part 1

By Kobus Venter

Here we have Ivoire Consommation from Ivory Coast (Cote d’Ivoire) using the Vuthisa 3-Drum Biochar Retort. A concerted effort was made by Kouamé Bahfi (owner of Ivoire Consommation) to make Biochar and promote it as a soil amendment in his region. In this video Gmelina was carbonized (bought in), using twigs and bamboo as the fuel of choice to heat up the retorts. Later on however, it was found that bamboo placed inside the retorts made excellent Biochar and it worked out cheaper as well. I have it on good authority that he will be trying an Adam Retort, built from adobe bricks next. Watch this space…









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Vuthisa Biochar Trials Guatemala – Part 1

Herewith Part 1 of the trials and tribulations of starting a Biochar project in Guatemala. Emphasis is on manufacturing Biochar from invasive alien species in the forests of Guatemala, without creating excessive air pollution. Using a retort system means that gaseous products that are normally vented unburnt are in fact now utilised to provide the heat back into the retorts, creating exothermic conditions, providing its own heat for carbonisation. Efficiencies are higher and the final conversion to Biochar (as opposed to making charcoal conventionally) should be around the 25% mark. The ‘3-Drum Retort’ system, whereby lower quality and smaller diameter feedstock is burned as fuel to provide the heat into the internal retorts is in the Beta phase and these types of testing will yield valuable lessons. There were many challenges in getting the kiln on to the farm in question. First it travelled by road on the back of a pickup truck and then by boat some 400 kilometres.

Transport

Then it had to be carried on foot to the burn site. Some innovative approaches are adopted, including the use of bamboo sticks to carry the pieces through the bush.

Other challenges we foresee would be to try to get hold of clay to seal the kiln off and this seems to be in short supply. The humidity is high and the first test burn resulted in creating torrefied wood only, so the burn will have to be extended to allow moisture to be driven off. We suggested placing wood piles close to the kiln to dry pre-dry the wood and to consider two subsequent burns: one burn to create the torrefied wood and a second to turn that into Biochar.

To be continued…








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What is a Rocket Stove?

By Vuthisa

Dr. Larry Winiarski, now Technical Director of Aprovecho, began developing the Rocket stove in 1980 and invented the principles of the Rocket stove in 1982. The Winiarski Rocket stove’s simple design and use of common materials make it easily modified for optimal performance. In the last 29 years, variations of the Rocket stove have been built in over 20 countries. The Rocket elbow can be made from different materials such as sand/clay (Lorena), pumice/concrete, heavy steel pipe, 430 stainless steel or refractory ceramic. Find a comprehensive list of Websites, Videos, Downloads and Manufacturers at the bottom of this page with regards to building, using or purchasing a Rocket stove. Click here to go to References


What’s wrong with an open fire?

An open fire, as shown above, is often 90% efficient in turning wood into energy. But only a small proportion (10% to 40%), of the released energy makes it into the pot. Improving combustion efficiency does not appreciably help the stove to use less fuel. On the other hand, improving heat transfer efficiency to the pot makes a large difference. Improving the combustion efficiency is necessary to reduce smoke and harmful emissions that damage health. Improving heat transfer efficiency can significantly reduce fuel use. Fire is naturally good at its job, but pots are not as good at capturing heat because they are inefficient heat exchangers. In order to reduce emissions and fuel use, the stove designer’s job is to first clean up the fire and then force as much energy into the pot or griddle as possible. Both of these functions can be accomplished in a well engineered cooking stove and a Rocket stove. A Rocket stove is a type of stove combining the air-intake with the fuel-feed slot in an opening into the combustion chamber extending into an “internal chimney” before exiting through the vertical chambered heat exchanger.  Some models have the chimney located in a different location, drawing emission gases along a horizontal path (sometimes below cooking points) before exiting through the vertical chimney.

Click on image above to play GIF animation

Or download image here.

A Rocket stove is signified by ease of construction and simplicity of building materials while accepting small-diameter fuel such as twigs or small branches, yielding high combustion efficiency and directing the resultant heat most effectively. A Rocket stove achieves efficient combustion of the fuel at a high temperature by ensuring that there is a good air draft into the fire, controlled use of fuel, complete combustion of volatiles, and efficient use of the resultant heat.  As the fuel burns within the combustion chamber, convection draws in new air from below ensuring that any smoke from smoldering wood near to the fire is also drawn into the fire and up the chimney. The chimney should be insulated to maximize the temperature and improve combustion.  The design of the stove means that it can operate on about half as much fuel as a traditional open fire and can use smaller diameter wood. Some models can accept whole logs, with only the tips combusting. In horizontal feed magazines the fuel has to be pushed into the combustion chamber at regular intervals. The advantage of this system is that the heat output can be adjusted as required, but the disadvantage is that if left unattended the fire will extinguish.

Rocket stoves are usually insulated and some are raised up from the floor which reduces the danger of children burning themselves. For space heating purposes the heat is transferred to a heat store which can in some cases be part of the structure of the house itself. The exhaust gases then pass out of the building via the chimney. The use of a cooking hood is recommended as the hood and chimney combination does not influence the rate at which air is introduced to the fire. The “internal chimney” creates the optimum amount of draft for fuel-efficient combustion.

A Rocket stove’s main components are:

Fuel magazine: Into which the unburned fuel is placed and from where it feeds into the combustion chamber. The fuel magazine can be horizontal where additional fuel will be added manually or vertically for automatic feeding (gravity feed) of fuel. The fuel magazine can be simple steel piping or even ceramic pipe. Fuel shelves serve as the platform for the fuel that is used with the stove. This slightly raised platform makes it possible for air to flow over and under the fuel source.

Combustion chamber/Internal chimney: At the end of the fuel magazine where the wood is burned. Internal chimneys are mere extensions of the combustion chamber and may be constructed from a larger tin can to piping and provide the required draft to maintain the fire. The top of the combustion chamber/chimney serve as the support for the cooking area. Some Rocket stove designs have chimneys in a separate location to the combustion chamber.

Chimneys: Located above the combustion chamber or to one side or can be part of the hood extraction system.

Heat exchanger: To transfer the heat to where it is needed, i.e. the cooking pot. From the chimney the heat passes into a suitable heat exchanger to ensure the efficient use of the generated heat. For cooking purposes the design keeps the cooking vessel in contact with the fire over the largest possible surface area by use of a pot skirt to create a narrow channel which forces hot air and gas to flow along the bottom and sides of the cooking vessel. The pot is usually encompassed by a fixed or adjustable pot skirt. The pot skirt functions as a shield to force the emission gases to pass close to the container holding the food. The gap between the skirt and the pot is also known as the pot gap. The pot gap calculation is crucial to the performance of the stove and excel spreadsheets are usually used to calculate this gap.

Rocket stoves are found more commonly in third world countries where wood fuel sources are scarce but it has been introduced in the United States in recent years. Some of them are small for portability with insulation inside a double-walled design with a chamber for partial biomass gasification and additional mixing to increase power output and provide a cleaner, more complete burn. In some models, as the wood is converted to charcoal, it falls through a grate for later collection and carbon sequestration. Since the Rocket stove is a wood burning cooking stove, obtaining fuel while on a camping trip is easy. Unlike a campfire, the Rocket stove will function very well using small branches and limbs that tend to litter the floor of the woods. This means there is no need to chop larger sections of wood into smaller sections in order to feed the fire.

References:

Websites
http://en.wikipedia.org/wiki/Rocket_stove Definition of a Rocket stove
http://www.bioenergylists.org/stovesdoc/Still/Rocket%20Stove/Principles.html Larry Winiarski’s Rocket Stove Principles (Dean Still)
http://www.bioenergylists.org/stovesdoc/Design/Design.html Biomass Cookstove Design and Testing
http://www.ehow.com/how_2265305_build-winiarski-rocket-stove.html#ixzz1H5MC0jJa How to Build a Winiarski Rocket Stove
http://www.ehow.com/how_4507160_build-rocket-stove.html How to Build a Rocket Stove
http://www.ehow.com/how_6550436_make-rocket-stove-camping.html How to Build a Rocket Stove for Camping
http://www.rocketstove.org Where you go on the web to find (or to learn how to make) Rocket stoves that work (Peter Scott)
http://www.treehugger.com/files/2009/03/rocket-stoves.php Rocket Stoves: Build Your Own Ultra-Efficient Cook Stove (Video)
http://www.mnn.com/your-home/at-home/stories/rocket-stoves-tips-for-designing-your-own Rocket stoves: Tips for designing your own
http://www.rocketstoves.com/ Website of the Book Rocket Mass Heaters
http://www.pyroenergen.com/articles08/eco-rocket-stove.htm PYRO-Eco Stove for Cooking on Rural Areas (Junji Takano)
http://bioenergylists.org/en/taxonomy/term/ Rocket stoves (9 web pages)
http://www.appropedia.org/CCAT_rocket_stove Campus Center for Appropriate Technology (CAT) Rocket stove
http://www.squidoo.com/rocketstoves Rocket Stoves – Cool Name, Hot Stove
http://www.rootsimple.com/2007/11/our-rocket-stove.html Our Rocket Stove
http://solarcooking.wikia.com/wiki/Rocket_Stove Rocket stove
http://www.wonderhowto.com/how-to-build-and-understand-rocket-stove-331886/ How to build and understand a Rocket stove
http://mdulastove.wordpress.com/ Holey Roket (as in Rok+et) : a biomass briquette stove type by Rok Oblak
http://www.stoveteam.org/ Home to the Ecocina Rocket stove
https://vuthisa.com/news/rocket-stove/ Examples of Rocket stove installations in South Africa
http://www.meadowforge.co.uk/DK_rocket_stoves.htm The DK Rocket stove (UK)

Videos
http://www.youtube.com/watch?v=XSMR2ANIZ7E How to Make a 16 Brick Rocket Stove
http://www.youtube.com/watch?v=235m0EzZF4U DRTV Rocket Stoves
http://www.youtube.com/watch?v=LfKHVoCY2so 12 Rocket stove mass heaters – efficient wood heat
http://www.aprovecho.org/web-content/media/rocket/rocket.htm How to build a Rocket Stove
http://video.google.com/videoplay?docid=797446823830833401# How to make a Rocket stove by Vavrek
http://www.youtube.com/watch?gl=IE&hl=en-GB&v=eqUsUMlyIeQ Coffee can Rocket stove by Rich
http://www.youtube.com/watch?v=gO-vPyCShLg&feature=player_embedded#at=94 How to Make a Tin Can Rocket Stove by Larry Winiarski
http://www.rocketstove.org/index.php?option=com_content&task=view&id=42&Itemid=93 How to build an institutional Rocket stove – Part 1 to 8 by Peter Scott
http://www.youtube.com/watch?v=YIMi0DVDvqw&feature=player_embedded Build a Rocket stove by Aprovecho
http://www.youtube.com/watch?v=CsDjcv5vO4c&feature=related Operation of the StoveTec Combo Two Door Stove by Dean Still
http://www.richsoil.com/rocket-stove-mass-heater.jsp Rocket stove mass heater – website containing various instructional videos
http://www.youtube.com/watch?v=GmEiLMT56L0&feature=player_embedded Redneck Rocket Stove using cinder blocks
http://www.youtube.com/watch?v=vJ7WjwAqeX0 How to assemble special bricks into a Six Brick Rocket Stove with Ken Goyer by Aid Africa
http://www.youtube.com/watch?v=9uh2VExcdbY&feature=player_embedded#at=221 The principles of a Rocket stove and how to build one – Institutional type
http://mdulastove.wordpress.com/holey-rocket/holey-roket-making/ Holey Roket Making (as in Rok+et) by Rok Oblak
http://www.youtube.com/watch?v=2fmp23SdS2Y Ecocina step by step
http://youtu.be/9CM4K5K-TiI Happy Rocket stove users in South Africa
http://wn.com/Rocket_Stove_Workshop World News now hosts many YouTube videos on Rocket stoves

Downloads
http://stoves.bioenergylists.org/stovesdoc/apro/Institutional_Rocket.pdf The Institutional Rocket Stove Designed by Dr. Larry Winiarski
http://www.bioenergylists.org/stovesdoc/Pcia/Design%20Principles%20for%20Wood%20Burning%20Cookstoves.pdf Design Principles for Wood Burning Cook Stoves
http://stoves.bioenergylists.org/stovesdoc/Still/AprovechoPlans/Rocket%20Stove%20Design%20Guide.pdf Rocket stove design guide
http://www.bioenergylists.org/stovesdoc/Scott/malawi/Malawi%20Repor1.pdf (See page 9 for fire brick recipes) Introduction of Rocket Stove Technologies (Institutional stoves, Household stoves and insulative refractory bricks) Into Malawi, March- July 2004
http://stoves.bioenergylists.org/stovesdoc/Scott/malawi/Malawi_ReportAug05.pdf Malawi Report
Feb 1st – April 11th, 2005
http://stoves.bioenergylists.org/stovesdoc/apro/guide/HOUSEHOLD%20Stoves%20Construction%20Manual%20Nov%202004.pdf MINISTRY OF ENERGY AND MINERAL DEVELOPMENT Energy Advisory Project HOW TO BUILD THE IMPROVED HOUSEHOLD STOVES
http://www.rocketstove.org/images/stories/chimney%20tool/IRS%20Assembly%20Guide%2010%2027%202010%20new.pdf Institutional Rocket Stove (IRS) Assembly Guide Designed by Peter Scott
http://www.rocketstove.org/images/stories/chimney%20tool/IRS%20Calculation%20Sheet%2010%2026%202010.xls Pot gap calculation

Manufacturers
http://www.stovetec.net/us/index.php – StoveTec
http://www.envirofit.org/cookstoves.html – Envirofit
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330431124275
http://www.speedreading4kids.com/rocket3.htm
http://www.rocketstoves.org/

http://www.stockstorage.com/The Grover Rocket Stove
http://www.meadowforge.co.uk/DK_rocket_stoves.htmThe DK Rocket Stove

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Is it better to burn wood or charcoal?

By Kobus Venter

Is it better to burn wood or charcoal? Half the World’s population of nearly six billion people prepare their food and heat their homes with coal and the traditional biomass fuels of dung, crop residues, wood and charcoal  (Inheriting the world: The atlas of children’s health and the environment, by Bruce Gordon, Richard Mackay and Eva Rehfuess, WHO 2004). In China, India and Sub Saharan Africa, up to 80% of urban households use biomass fuels for cooking. Wood fuel usage is the most predominant with charcoal a close second. What is their respective influence on global warming? Sorry, but this post will not attempt to discuss this complex issue, because the reality is that for most people struggling with energy security, saving the environment is not exactly high on their list. The following paragraphs will instead focus briefly on the burning characteristics of wood and charcoal, because in many cases availability and affordability of the fuel type will dictate which fuel type is being used.

Typically wood has an energy value of between 14 and 18 MJ/kg when burned. Charcoal has an energy value of around 29 MJ/kg, in other words charcoal burns hotter than wood, but when not insulated or not receiving sufficient air supply (including secondary air), the absence of flames or fast flowing CO2 gases will result in less efficient cooking due to a lower heat transfer efficiency (HTE). In other words with conventional charcoal burning (glowing embers) the pot will receive radiant and infrared heat, with the pot positioned close to the coals. Wood burning flames (especially from open fires) tend to ‘lick’ the pot and transfer heat more effectively, but contain products of incomplete combustion (PIC), also known as ‘particulates’, that are harmful to humans when inhaled. In many instances households cannot afford to purchase or install chimneys that remove the smoke. The flames (yellow colored) will also tend to blacken cooking pots. Indoor smoke inhalation gives rise to pneumonia and other respiratory infections – the biggest killer of children under five years of age. Indoor air pollution (IAP) is responsible for nearly half of the more than 2 million deaths each year that are caused by acute respiratory infections (ARI). Good ventilation and improved cooking stoves can dramatically reduce children’s exposure to smoke. Vuthisa currently promotes the StoveTec stove which is very fuel efficient (conserves wood) and emits 70% less smoke. Visit https://vuthisa.com/news/stovetec for more information.

Charcoal is preferred over wood as a cooking fuel in many parts of the world because it does not produce smoke, is easier to transport and ready to use in a convenient dry- and broken-up form. Charcoal burning however produces large amounts of Carbon Monoxide (CO) which is harmful to humans when exposed to very high levels. Increasing air flow through the charcoal emits more CO, so if you don’t mix secondary air with the CO and insulate the fuelbed to raise temperatures to spontaneously combust that mix, you’re better off with a glowing ember burn. Most charcoal stoves (i.e. Ceramic Jiko) are not designed around this principle and won’t be much different to your barbecue, whereby you vent all the gases first and then cook on the glowing embers. There is anecdotal evidence that family members have succumbed to CO poisoning, but families using charcoal are very aware usually of it’s dangers and allow for adequate ventilation. Why is CO harmful to humans? Let me explain: The effect of high levels of exposure to CO can be lethal, but even low levels of exposure can have harmful effects. CO diffuses rapidly via blood vessel membranes. Once it’s present in the bloodstream, CO binds to hemoglobin 200 times more readily than oxygen. This forms carboxy-hemoglobin (COHb). COHb reduces the oxygen carrying capacity of the blood and impairs the release of oxygen from hemoglobin. The neurobehavioral effects include impaired coordination, tracking, and driving ability. Cognitive performance is impaired at COHb levels as low as 5%. During exposure to a fixed concentration of CO, the COHb concentration increases rapidly at the onset of exposure. This levels off after about three hours, and reaches steady state after 6 – 8 hours of exposure. Headaches, nausea and loss of consciousness occur at COHb levels of 25-40%. Permanent brain damage and death follow if COHb levels exceed 45%. Vuthisa developed a safe charcoal stove over the last few years to address this very issue.

I don’t advocate charcoal usage over wood, because of the wasteful manner in which charcoal is made and the charcoal trade destroys naturally occurring forests and contributes to global warming. There are signs that governments are trying to regulate the industry by introducing more efficient charcoal-making kilns and establishing plantations to ensure sustainability of the timber source. In Namibia, millions of hectares of encroachment bush is being converted to charcoal and sold to neighboring South Africa as barbecue charcoal. South Africa itself (according to the most recent South Africa Yearbook) is plagued with alien plant infestations, totaling more than 10 million hectares, about eight percent (8%) of the country’s land surface area. The rate of spread is alarming and their numbers are projected to double over the next 15 years.  More recently Vuthisa Technologies started to convert slashed invasives into charcoal and biochar using Emission Reducing Biochar kilns in a project known as the Vuthisa Biochar Initiative.

My verdict: It seems there is no clear winner, just spare a thought for the millions of people that rely on either wood or charcoal for their day to day survival.

Visit our Online Shop to view some wood and charcoal stoves as well as other fuel efficient stoves and cookers.

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