Cooking

Several engineers and DIY enthusiasts have designed literally hundreds of different types of solar cookers; from simple designs like the solar bowling oven to more complicate ones like the parabolic basket and tin can solar cooker. This expansive variety of options makes it difficult to standardize and evaluate solar cookers, however some critical factors must be met for a design to be successful, some of which are listed below: Cost - must be cheap enough to be viable for implementation into rural areas.

• Convenience - can be built by readily available local materials in a short period of time, as well as being light-weight.SOL
• Safety - heated area must be well protected and no parts should be jutting out.
• Efficiency - how long will it take to cook the food?
• Wind resistance - must be sturdy enough to not be affected by light to moderate winds.
• Heating capacity - sufficient heating capacity based on it's use (water pasteurization vs. cooking food).
• Durability - repairs should be infrequent and easily performed.
• Simplicity of instructions.

The requirements for solar cooking are very simple. You must be able to place the solar cooker in a location that gets sun for several hours and be protected from strong wind. Solar cookers, obviously do not work at night or on very cloudy days. The sunlight is absorbed on dark surfaces that heat up. Food cooks best in dark, shallow, thin metal pots with dark, tight-fitting lids to hold in heat and moisture. To retain the heat created when the black pot absorbs the suns rays some form of transparent cover is needed. This can be as simple as a clear plastic bag or as complicated as evacuated multiple layers of glass. One method to speed the cooking process is to use reflectors to increase the concentration of sunlight on your collector.

A rocket stove is a variety of wood-burning cooking stove with a higher efficiency than other types of traditional ovens due to a better insulation and a better combustion process. They function under a similar principle as rocket stove mass heaters. Most rocket stoves are easy to build, and can be made with low-cost materials (the CCAT rocket stove for instance, costs only USD$84.02).

There is a wide variety of designs amongst stoves included in the 'Rocket Stove' family, but they have the following characteristic features:

• The combustion chamber and interior stove parts are as insulative and lightweight as possible. Heavy materials in contact with hot flue gases absorb heat that could have been used for cooking.
• The combustion chamber is insulated in order to keep the fire hot (above 650 ºC) to burn the wood more completely, thereby reducing smoke (which is fuel that has not burnt completely).
• The combustion chamber is usually in the shape of an elbow or letter 'L', so that wood is placed under a short internal chimney as it is fed into the stove.
• Wood is burned at the tips and is pushed in towards the fire as it burns. Feeding fuel at the correct rate creates cleaner combustion, reducing smoke.

This page refers to stoves using a fuel, usually solid. For solar versions, see Solar cooking

Improved solid biofuel stoves, smokeless stoves or wood conserving stoves are solid biofuel stoves designed to be at least 10% more fuel efficient than regular solid biofuel stoves or reduce the health problems associated with traditional cooking fires. They are widely used in developing countries and are often very simple designs. These designs, when they work as intended, don't fill the home with harmful smoke (through more efficient burning to reduce smoke, and a chimney or venting to remove that smoke), and use less fuel. Several designs have been developed depending on the local materials available, environmental conditions, and community needs.

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  fig 1: A selection of improved cook stoves

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  fig 1a: Open Fire Cookstove

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  fig 1b: Patsari improved cookstove made of bricks and mortar and ruble filling

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  fig c: Lorena cookstove made of rammed earth

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  fig d: Women can design and Manufacture improved cook stoves. ©Simon Ekless/Practical Action

A solar dehydrator (or solar drier) allows the user to preserve food without the energy cost or pollution associated with other drying techniques.

Agricultural and other products have been dried by the sun and wind in the open air for thousands of years. The purpose is either to preserve them for later use, as is the case with food; or as an integral part of the production process, as with timber, tobacco and laundering. In industrialised regions and sectors, open air-drying has now been largely replaced by mechanised dryers, with boilers to heat incoming air, and fans to force it through at a high rate. Mechanised drying is faster than open-air drying, uses much less land and usually gives a better quality product. But the equipment is expensive and requires substantial quantities of fuel or electricity to operate.

'Solar drying' in the context of this technical brief, refers to methods of using the sun's energy for drying, but excludes open air 'sun drying'. The justification for solar dryers is that they may be more effective than sun drying, but have lower operating costs than mechanised dryers. A number of designs are proven technically and while none are yet in widespread use, there is still optimism about their potential.

Reducing your meat consumption can not only improve your health,^[1] make you live longer,^[2] be in line with your ethics, and many more benefits; it can also help solving environmental issues such as deforestation and climate change. This is mainly because meat production requires a lot of land for growing animal feed. Meat production industry is one of the most harmful industries for the environment as it causes a massive amount of greenhouse gas emissions and wastes large amounts of water and grain.

Even though it might be tough, reducing meat consumption will lower the demand for meat, in turn reducing the environmental impact of this industry. Producing plant-based foods generally results in fewer greenhouse gas emissions and requires less energy, land, and water. This is why eating more vegetables, fruits, whole grains, legumes, nuts, and seeds, and less meat and dairy, can significantly lower your environmental impact.^[3]

In addition, you can reduce your impact on the environment by buying local. Buying local products and other goods not only reduces some of the energy consumption involved in the transport of food, it also supports local farmers^[4] and growers in your community.^[5]