Appropriate Technology: Cooking Intro

Our daily nourishments and cravings require quite an energy input for cooking. Food processing/ preserving and the electric tools of the kitchen are found in other articles.  This article covers several technologies for heating foods for prolonged periods at varying heats; cooking.  Because it is an energy input, no matter which one you choose, choose one that is efficient because we will be drawing on resources to cook. For example,

fuel wood

processed acacia branches at Sadhana Forest, India, 2009 after a cyclone brought these invasive down. cooking fuel

even if it is through the sun that you are cooking, the solar stove still contains a lot of embedded energy in its construction.   With the elements presented below, their placement is critical to take advantage of sectors like the sun but also their input of wood needs to be adjoined with another element such as wood storage in relative location.  And then where do you get the wood from?  Do you have coppice woodlot or better yet a variety of elements to meet the important function of fuel wood.  Lastly, I have seen across the world, ironically enough, examples of huge forests that were once charcoal producing zones (La Garotxa near Barcelona) or a more green countryside in general, i.e. Dominican Republic vs Haiti because of the gas propane bottle. Areas that once provided fuel wood or were deforested, now are able to grow because of the fossil fuel input. So again if wood is to be used, make sure it is burned efficiently and it is being sourced from multiple elements.

Rocket Stove 

This super efficient cooking system uses small diameter wood that employs a rapid draft for clean burns thus producing intense heat. The name rocket refers to the sound that the draft creates, which allows for maximum oxygen to hit the fuel. They are built with varying materials from bricks to cob but the stove should use an insulated space around the burn chamber to radiate maximum heat rather than absorbing it through thermal mass like a cob oven. In fact the simplest form of the stove can be made from varying sized coffee cans and a soup can.  The coffee can rocket stove makes a great choice for backpacking and camping trips while the rocket stove forms a cornerstone of the outdoor kitchen/social space. Remember to site firewood nearby as well as a countertop to aid in the overall cooking process. Zone 0-2.

Cob Oven

These ovens are thermal mass and insulation combined and often form a cornerstone of an outdoor kitchen. The thermal mass is warmed by burning wood inside and the insulation layer that envelopes it helps to retain the heat for maximum efficiency.  They do take quite sometime to heat up yet hold heat for an extended period of time.  Consequently, it is good to have several baking projects lined up if you are going to fire your cob oven.  A low level heat is even retained for about 12 hours making dehydrating or super slow baking possible.  The construction these is labor intensive but pretty straightforward with Kiko Denzer’s book being a great resource; Build Your Own Earth Oven.  Ensure that you build the foundation so that the height of the oven is at a good working height as this will machete more likely that you will have pizza parties, bake breaks, roast vegetables, and kookiest slowly.  The waste ash can be spread back into the fields and make sure you have tools to use in the cob oven space for taking things in and out of the oven.

Solar Oven 

With the driving force of the sun’s energy and glass, this cooking device often also incorporates a reflective material to further power this appropriate technology.  The suns rays enter through the glass and are trapped giving a warming oven effect. This oven cooks slowly foods that could either be boiled on a stove top or put into an oven. Alternative systems are present other than just a box idea with companies also using the evacuated tubes (GoSun) that are used in solar thermal units creating an extremely efficient elongated edge.  This element can drastically reduce your firewood, electricity, or gas input and is one of the elements that supports the important energy function of cooking. They are sighted in year round sunny locations but are in relative location to the kitchen so usage is frequent. Zone 1-2.

Biogas Generator 

Through employing a fermentation (anaerobic) process to breakdown organic material in a specially built chamber, a production system of natural gas is realized. Human wastes, animal wastes and plant residues can be combined in a chamber that creates the right conditions for fermentation and the subsequent capture of the gas.  The gas is then stored and distributed for on-demand use. The other output of the biogas process is a sludge of organic matter that can be utilized in the landscape or composed first. System size is being developed for smaller and smaller units but can be scaled up for small communities or industrial wastes. They are usually sited right outside the house or near a barn where animals are kept or food is processed or waste streams are brought in.  Zone 1-2.

homescale Biogas station

Biogas station in relative location from kitchen, Terra Alta, Portugal, 2018

Hay Box

This low tech insulated box saves energy by bringing something up to temperature and boil first, no matter what fuel source, and then wrapping that into an insulated box that fits the cooking pot snuggly. This was traditionally hay or straw but has been updated to modern insulations like styrofoam. The even lower tech version is simply wrapping wool blankets, high insulation material, around the heated pot.  This draws down the cook time with fuel and while it may take some minutes longer is actually quite efficient in saving precious fuels whether it fossil fuels or wood.

hay box cooker schematic

Appropriate Technology: Cooking Conclusion

Cooking really is a massive daily energy input so be prepared to have multiple elements for this important function as the seasons ebb and flow with tides of space and time.  You can’t say you are off the grid until you sort this one out for sure!  Electric cooking with renewable electric production is a possibility but it will have to be a big system as electric cooking is quite energy intensive.  But build these diverse systems slowly and enjoy the nourishment that comes!

Written by Doug Crouch

Header Art by Nathan Maggard


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