This is a simple version of a home-made fuelless cooker, which as the name suggests, uses residual heat.
The principle is that the heated food is placed, in its pot or saucepan, into a well-insulated box, the box lid which is also insulated is put in place and that’s it!
The food takes about 4 times longer to cook completely within the box and may need to be reheated prior to serving but usually the only energy consumed has been that needed to get it to the initial boiling point. The ‘box’ part of the system provides safety, neatness and the possibility of transporting.
Our version comprises two cardboard boxes of different sizes and a small panel of Holzflex wood fibre/wood wool, purchased at our local eco builders' merchants for 3 euros/dollars/pounds. However, there are many types of insulation you can use, including the original hay or you could use layers of corrugated cardboard!
There are several reasons why a simple cardboard cooker like this could come in very handy:
- you are going on a long journey and want a hot home-cooked meal
- you are experiencing power outages and want to keep food and liquids hot or cold
- you have a wood cooker, so can save fuel and provide cover for the times you may not want to light a fire
- you like slow-cooked, pastured meat
- you eat organic, gluten-free or any other specific kind of food and go on long journeys, often without certain hope of finding a suitable restaurant
- you are transporting raw milk or frozen foods
- it's fun!
Two Cardboard Boxes - one smaller than the other Supplies will obviously depend on what size of cardboard boxes you can find but to give you an idea, I used two readily available food cartons from my local store measuring:
Length 12" (305mm)
Width 9" (230mm)
Height 6½" (165m)
Length 15½ (390mm)
Width 11¾" (300mm)
Height 10" (250mm)
So, because I was able to find cartons whose sizes differed by about 2¼" (60mm) - I could use:
1 Single Panel of Wood Wool Insulation 1⅛" (30mm) thick (around $3,00)
Extra Cardboard - boxes or sheeting (whatever you can find for free!) to make the lid and inserts. As mentioned above, you could also use cardboard as the insulation.
Old Carving Knife
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Step 1: A Little History
The Hay-box or fuelless cooker was a very popular item around the turn of the 19th to 20th century, particularly during the World Wars and the Great Depression when people were often displaced and the price of fuel rose steeply and/or was rationed. Many cookbooks of the period had a chapter on recipes suitable for this type of cookery, so it's well worth a visit to a secondhand bookshop to see what you can find!
Ideal meals of this period were stews made from cuts of meat which were cheaper and needed slow, low temperature cookery but which, with the hikes in coal and coke prices and the short supply of fuel, paradoxically had become expensive to cook. There was also the problem of food rationing, which made it ever more important to avoid spoilage and waste. Fuelless cookers used less water and as the precious foodstuffs were cooked at an even temperature and by residual heat, this meant the food had no chance of burning nor becoming tough and inedible. There was also an added and even more important factor, in that nutrients were retained through longer cooking times and lower temperatures, thus even smaller amounts of meat, eggs, milk, fruit and vegetables for example, gave maximum nutritional value.
The popularity of hay-boxes and fuelless cookers however went much further back in history to a time of the great emigration periods of the early and mid 1800s, when people travelled vast distances and often only had time to light fires and cook in the evening and before they started their journey each morning. The slow-cook method using residual heat allowed them to get their stews and crockpot meals ready in the morning and cook them throughout the journey so as to have a hot meal at mid-day.
Step 2: Choices of Insulation
As previously mentioned, I used wood wool, which is easy to find here but I have made several hay boxes and have used various media all of which were non-toxic, some of which were free and the rest were low cost. However, the choice is yours, use what is readily available.
My choices, shown above comprise, from top to bottom:
ORGANIC LUCERNE HAY
ORGANIC TRITICALE STRAW
ORGANIC VEGETABLE FIBRES
ORGANIC HEMP AND LINEN
HOLZFLEX WOOD FIBRE
ORGANIC SHEEP'S WOOL
Step 3: Construction - Box
If you are using a panel of insulation: this needs to be cut to line the four sides and base of the larger box.
Begin by cutting the insulation for the bottom of the larger box, I used an old carving knife for this.
Place the smaller box into the larger and measure and cut insulation to fit the spaces between the two boxes.
If you are using loose material such as wool, hay or straw start by covering the bottom of box with a layer to the required depth, so that the smaller box sits level with the larger when placed inside it.
Now place the smaller box inside the larger and then fill the spaces between the two boxes with insulation material.
Keep in mind that it is the air spaces between the fibres that provide the insulation so don't compress the material too much.
Step 4: Construction - Lid
To make the lid to the Hay Box cut two rectangles of cardboard to the size of the larger carton and make a ‘sandwich’ with the insulation between them.
Hold the lid together together with broad masking tape, starting with the corners.
Adhere the tape around the perimeter of the lid so as to seal in the insulation.
Step 5: Fitting the Pan
When the saucepan is put into the box, fill the voids at the box corners with triangular-shaped pieces of cardboard (a bit like ‘Toblerone’ boxes) or stuff with tea towels/dish towels, ideally any kind of insulating material which will reduce heat loss due to convection currents.
This also avoids any movement of the pan during transportation.
Step 6: Hay Box Films - 'Making Of' and 'Seaside Picnic'
So there you have it a cheap, quick and easy way to create a cooker from cardboard.
Hope you'll make one!
All the very best and thanks for reading and watching,
Organikmechanic aka Andy
This is an entry in the
Cardboard Speed Challenge