Making biochar and cooking with a homemade rocket stove

It has been awhile since I did anything worth blogging about. Here’s my latest rocket stove build, designed to cook and make biochar:

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Most of the biochar I’m making is for a charcoal gasifier, though I probably will set some aside for gardening next year. Being able to use the wood gases released to cook food or heat a house increases the overall efficiency of such a system.

Here’s a couple snapshots of the rocket stove in case you are interested in building one yourself:

IMG_0369Note how the back is made with three hollow blocks. On either side at the base, you have another hollow block set slightly offset. The sides and front of the heat riser are made with solid blocks.

IMG_0370All the broken blocks you see in the above picture can be replaced with a full solid block. To get better results, level the dirt beneath the stove. If you have any concrete blocks or bricks laying around, see if you can build a rocket stove. I think you will be impressed.

This design is perfect for cooking with, since you do not have to continually push in fuel. I find that a small load of wood provides a hour of good cooking heat.

For those who have had questions on my rocket stove DVD, I have decided to simply upload the series to Youtube, due to lack of interest. I’m running behind on the project, so be sure you are subscribed to my channel.

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DIY Rocket Stove Data

I’ve been analyzing the heat output and efficiencies of my DIY rocket stove. Here’s the first video I’ve published on the subject:

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I did this video to represent what the average end user seems to do with the commercial models they purchase.  If I get enough interest in a efficiency video, I’d be glad to illustrate the proper usage and the benefits of proper stove use.

So get on Youtube and Google+ and let me know what you think, both about the data presented here, and if you are interested in seeing more details.

Thanks for all the support and interest in my projects so many of you have shown!

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DIY Rocket Stove – No Welding Required!

If you haven’t noticed, rocket stoves aren’t cheap to buy. Often, they aren’t cheap to build as many designs require expensive tools. I’ve just built a DIY rocket cookstove that uses common tools most people already have.

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Please note that I had to adjust the feed shelf from what is shown in the video. Here’s a picture of the shelf in action:

Rocket Stove Feed Shelf
Rocket Stove Feed Shelf

There is still a bit of tweaking to get optimum burn efficiency, but it boils water very nicely as is. Since the L tube is made from exhaust pipe, it should last for quite some time.

If you have been wanting to get into building rocket stoves, there is no excuse not to now. This stove is a perfect DIY project that the average home owner can put together with tools already sitting in their tool box.

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Waste Vegetable Oil Lamp / Space Heat

Alcohol fuel is expensive, so I turned to a source of heat that I had been saving for awhile – waste vegetable oil. We don’t fry foods often, but when we do, I try to save the oil for various projects. Waste vegetable oil has between 110,000 and 125,000 btu per gallon, compared to ethanol at around 76,000 btu per gallon. Waste vegetable oil is free, ethanol cookstove fuel ran me $16 per gallon.

To make a simple oil lamp, I took a pimento jar and using a box cutter, cut a slit in the lid. The wick is made from a single cotton ball unrolled and flattened. Oil is added to the jar, which is absorbed by the wick. Lighting is simple and only takes one match. The corners of the wick are lit, and the flame spreads across by itself. Here’s my simple oil lamp in action:

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Oil lamps are nothing new, in fact, they have been used for several thousand years. This is just a modern interpretation produced from cheap household things.

To take it to the next level, I decided to turn it into a personal space heater that can double to heat water for beverages. I took a normal 15 ounce can and drilled 4 holes in the top side wall, and ultimately drilled 8 in the bottom for better performance. The intense heat from the lamp is absorbed by the can and radiated at a lower temperature over a wider area. Here’s a demonstration of the simple heater in action:

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As you can see, the immediate area around the heater is quite warm. A metal camp type of cup would be better for making tea than the coffee cup I used in the video. I was very surprised at how clean the lamp burned, as evidenced by the inside of the can.

If used in combination with a space blanket, a small heater like this could keep you quite warm in an emergency. Drinking warm liquids heats you from the inside and the radiated heat will keep you warm on the outside.

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Using the Alcohol Stove Indoors

Using a couple bricks and a floor tile, you can provide a fire resistant environment for using your alcohol stove indoors with relative safety. Here’s a video that demonstrates using it as a heater as well as boiling a quart of water:

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As with candles, oil lamps, or other forms of indoor combustion, such a setup needs to be attended at all times.

As you can see in the video, the heat output is quite good. From the color of the flame, you can tell it isn’t the most efficient alcohol stove out there, but it is easy to build out of common materials. Another benefit is its good performance with rubbing alcohol.


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DIY Alcohol Stove & Wick Making

Being able to produce heat and cook food during a power outage is important. While wood is often the go to source of emergency heat and cooking fuel, sometimes it is not practical for using in all situations. Alcohol is more energy dense, quicker to light, and easy to store.

I’ve built a high output alcohol stove out of a old yeast jar and cotton balls. Store bought wicks just didn’t work as well as I’d like them too, so making them out of cotton balls not only saves money, but also yields better results. Here’s how I did it:

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I’ll be doing a video in the near future that shows a better pan / pot setup than the cinder block in the above video. I’ll also show how to turn it into a space heater.

Fuel options are quite good with a stove like this. Denatured alcohol, methanol (heet), and rubbing alcohol all burn well with this stove.

If the stove is used indoors, be sure you have a smoke detector, carbon monoxide detector, and water or a fire extinguisher handy. Another benefit of using alcohol as a fuel is the ability to use water to extinguish fires. Methanol and denatured alcohol are the preferred fuels to burn indoors. Rubbing alcohol seems to produce more fumes and soot.

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Trimmed down woodgas stove

My old woodgas stove cooktop design was too tall to be really practical. I have trimmed it down, making it much easier to pack around. It also heats better with the cook surface being closer to the fire. Take a look at it now:

Woodgas stove with cooktop

The cooktop now only adds 2 inches of extra height to the overall setup. By comparison, the old design amounted to two coffee cans stacked on top of each other. Here’s the internals of the entire system:

Parts of the woodgas stove

On the front row left to right, you have the feed ramp and intake blower. The forced air induction boosts the heat output by a significant margin and is easily powered by a 9v battery. I normally just use my alum battery when I use it in my backyard. On the back row left to right, there is the cooktop, the burn chamber, and the outer shell. The cooktop is made from a cut down coffee can and the outer shell is made from a coffee can with a hole cut in the top for the burn chamber and another hole in the side for the blower.

The burn chamber is made from a quart sized paint can with 1/2″ holes drilled at random in the bottom and sides. To give an idea of how long these things can last, I’ve been using this same can for a year and a half. This slides into the outer shell. The blower forces air into the area between the outer shell and burn chamber, preheating the combustion air. The end result is a fairly efficient camp stove that is suitable for outdoor heat and cooking, all smoke free.

Another important part of this design is the feed ramp. Most woodgas stoves run in batches, so if your food isn’t cooked or your water boiled, you have to remove the pot, add fuel, and get the fire going again. With the forced air induction and feed port, you can keep the fire going as long as you like. The feed ramp ensures that the fuel goes into the burn chamber:

Woodgas stove feed ramp

In the above picture you can see how the feed ramp extends downward leading to the burn chamber. The fuel is fed through the port and down the ramp. There are 4 ports at 90 degree angles to each other. This enables 4 people to sit around the fire and enjoy a lot of warmth while food is being prepared on top. The ports are also great for roasting hot dogs or marshmallows.

Smoking trout and keeping warm around the woodgas stove

As you can tell, there is a lot of heat output. On the top, I have my smoker with a couple trout being prepared for dinner. You can see 3 out of the 4 ports going full blast. If you don’t want to produce extra heat, feed it just enough fuel to prevent the flames from going out the sides. For those of you that haven’t seen my fish smoker, check out the following video (which shows the old cooktop):

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Using a woodgas cookstove

There are a lot of ways you can use a woodgas cookstove. With a little ingenuity, you can take a pile of cans and create stoves that can do nearly anything. Let’s see how fast you can boil water with it:

You can produce heat for those chilly days:

By adding forced air and a cooktop, you can add fuel without choking the fire like in the simpler designs:

The cooktop radiates heat, so it can be used for warmth. You can dry out wood on top, making it easier to keep the fire going when it is wet outside. Another neat application is to make a simple smoker for fish or small game:

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How to make a woodgas cookstove

Ever go camping and forget the firewood or run out of propane? With a small woodgas stove, you can forget the fuel and use readily available sticks to grill, smoke, boil, etc. Here’s how I built one out of some old cans, a pair of aviation snips, and a drill:

Another benefit of the woodgas stoves is the lack of smoke. No more smelling like a campfire, alerting game animals of your presence!

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