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Cooking, lighting, smoke and pollution. Established in April 2007, CleanAirSIG connects all those engaged in indoor air quality and household energy in developing countries.

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Options to Reduce Smoke

Introduction

Exposure to smoke and other products of incomplete combustion in the household kitchen is a complex product of the three subsystems making up the household energy system: source (direct emissions such as a stove), living environment (dispersal of emissions such as air currents in the kitchen), and the user (behaviour and habits such as cooking without pot lids or the use of combined cooking and sleeping places). Interventions in any of these inter-linked areas will influence exposure levels.

A wide range of intervention options exist within the three subsystems and in any given setting it is likely that a combination should be considered. Source interventions include improved cooking devices (stoves with and without chimneys) and alternative fuel-cooker combinations (charcoal, kerosene, LPG, biogas etc.). In addition interventions that reduce the need for the fire could reduce emission sources (examples include solar water heaters, partially precooked food and efficient housing reducing the need for heating). Interventions at the level of the living environment subsystem include ventilation (hoods, fireplaces, windows and ventilation holes) and improved kitchen design (for example a stove lifted to waist height would reduce the need for bending over the fire when tending and possibly reduce exposure for children playing on the ground). Interventions focused at the user subsystem are essentially behavioural. With dissemination of appropriate information, users may be encouraged to keep children out of the smoke and follow practices that may reduce exposure (alternatives include more thorough drying of fuel, use of pot lids to reduce necessary stove power, and good maintenance of the stove and flue where present).

A number of socio-cultural factors that impact profoundly on exposure include cooking habits, gender differentials, food preferences, family size, income and family needs, and ventilation. Gender differentials in particular have a strong influence on exposure. Women usually perform the majority of household work and spend the most time in the kitchen (WHO 1992), and therefore, much as one would expect, women are exposed to particulate levels many times those of men. For example, a study in rural Kenya young and adult women were found to have high absolute exposure levels, and between 2.5 and 4.8 times that of males in the same age group (Ezzati et al 2000b). The importance of these socio-cultural factors is further illustrated by findings from the ‘Macro-Scale Experiment’ in the village of Qalabotjha, Villiers for the South African Department of Minerals and Energy in 1997, where 80 % of the 500 randomly selected respondents strongly agreed with the statement ‘a fire or coal stove in the home brings and keeps my family together’ (van Niekerk 1998). Interventions in the household energy system may go to the very centre of life, as claimed by van Niekerk.

Options for reduce smoke

There are only a few approaches to alleviate smoke:
  • Reducing the need to burn fuel
  • Keeping away from the smoke
  • Venting the smoke from the cooking environment
  • Burning the fuel cleanly
  • Using an alternative fuel that is easier to burn cleanly

Within these classifications are a vast range of technologies and interventions, so the information below is not exhaustive. Note also that some of the technologies can also reduce the risk of burns - a major problem with some traditional fires. The costs identified are relative and a bit subjective.

Reducing the need to burn fuel

Insulating walls

Useful where space heating required and walls are either "dry stone" or could be further insulated.

Examples Practical Action adopted.

Cost Household can achieve without it costing anything.

Retained heat cookers

Otherwise known as "hayboxes". These can be really successful as they allow those with limited funds to use bottled gas (expensive) to heat foods up cleanly and then insert them into haybox to continue cooking. (How safe is keeping food warm for prolonged periods? Households tend to access them through the evening - rather than sealing the lid till all is used - but very well liked).

Examples Used all over the world. Examples include:

Cost Households can achieve this without costing anything.

Another type of retained heat cooker is the Sarai cooking system developed by Appropriate Rural Technology Institute (ARTI), India.

Sarai is a stainless steam steam cooker. It is a non-pressurised cooker, into which you put about 150 ml of water and then lower into it a wire cage, which holds three cookpots, one on top of another. The steam pot has a lid which is kept closed while the food is being cooked. The heat is provided by a charcoal burner, which is designed to hold just 100 g of charcoal Beans, rice and vegetables of a family of 4 to 5 are cooked with just 100 g of charcoal briquettes. It takes between 45 minutes to an hour to cook the meal.

Details about this cooker are available here

Solar water heaters

These are useful technologies varying from wheelbarrow type plates with zig-zag water-filled tubes that can be moved around to chase the sun, to low-cost black plastic bags that are hung up in a sunny place to catch the sun.

Examples See: Consumer response to mobile solar water heating in the low-income sector South Africa

Cost Bags can be purchased by most households without credit.

Communal ovens

Mainly seen in refugee camps,institutions and schools, or making staple food for sale, providing income and preventing cooking being done in the kitchen.


Examples See:

Cost A high cost purchase that is often donated, but may require some form of credit for those on low incomes.

Solar Steam cooking is a very promising option for reducing the need to burn fuel and thus reduce smoke in the kitchen. This application works well in the community kitchens. According to Deepak Gadhia, Managing Director, Gadhia Solar Energy Systems Pvt. Ltd,” If only 3% Indians were to cook with solar cookers, we would save 3.2 MT (million tonnes) of wood per year and reduce CO2 emissions by 6.7 MT per year.”

Examples See


Cost Solar cooking is a good option for community kitchen and it is expensive to set up. Support from charitable organizations is needed.

Reducing the size of the food being cooked - eg grinding pulses or grains

Can be used if long cooking times and extreme fuel shortages come together - but culturally difficult under normal situations.

Cost Households can achieve this without costing anything.

Orienting house to pick up solar gain

Only appropriate to new-build.

Examples See Energy Efficient Housing to Benefit South African Households

Promoting low-cost cleaner lighting eg clean-fuel or hurricane-type lamps

Some groups leave the fire alight for lighting - and some people adopt highly polluting kerosene wick stoves for lighting at night, particularly if enclosed stoves are promoted.

Example See the Ethanol Noorie Lantern http://nariphaltan.virtualave.net/lantern.htm

The existing Noorie kerosene and alcohol lanterns have efficacies of 2.03 and 2.82 lm/W respectively. With better thermoluminescent materials, the liquid fuel lamps can have efficacies surpassing those of the electric bulbs. Hence, efficiencies of liquid fuel lighting will be at par or even exceed those of electric lighting.

Cost This can be purchased at low cost by most households without credit at about INR450 or 11 US dollars

Keeping away from smoke plume

Keeping infant from smoke

Can only be done where a safe place is available for child.

Examples http://ehs.sph.berkeley.edu/krsmith/Publications/Chapt%2018%20IAP%20from%20Soid%20Fuels.pdf

Cost Households can achieve this without costing anything.

Cooking out of doors or in a separate room

Although the cook is exposed, the rest of the family is much less affected indoors.

Examples Protecting Children from Indoor Air Pollution Exposure Through Outdoor Cooking in Rural South Africa

Cost Households can achieve this without costing anything.

Sleeping in another room to the stove

In Kenya (elsewhere?) children often sleep in the kitchen where a smouldering fire is left on... possibly to get rid of mosquitoes.

Examples Project data - available if required

Cost Households can achieve this without costing anything.

Keeping face away from fire - particularly during fire lighting

The highest levels of pollutant are found when the fire is relatively cool and thus the combustion reaction is not fierce enough for all the smoke particles to turn into CO2. Needs awareness-raising.

Costs Households can achieve this without costing anything.

Using a chimney stove or smoke hood

See below - a chimney stove draws the smoke out of the house and no smoke should be rising towards the woman (if it works), whilst a smoke hood stops the woman putting her head where the plume of smoke is rising.

Examples See below

Cost A high cost purchase that may require some form of credit for those on low incomes.

Venting the smoke

Chimney stove - traditional

The chimney stove (usually made of mud or metal) has a flue (base of it shown at rear) which is integral with the body of the stove and vents the pollutants through the roof. Mud stoves tend increase the amount of smoke as the mud all needs to be heated up - if the flue is kept clean this is fine, but often not the case and additional smoke gets into the room. Metal stoves heat up more quickly (good) but tend to make the room very hot indeed as the heat radiates out through the metal. Metal needs to be high quality or very short life. For both, difficult to control heat as the flue (when not blocked) creates a suction which can make fire burn very fast - so getting the geometry right is critical, and often this is overlooked.

Example -
Image
Chimney Stove - Traditional


Cost A high cost purchase that may require some form of credit for those on low incomes.

Chimney stove (improved)

The newer "rocket type" stoves get round this by insulating the walls of the firebox, ensuring that the hole for feeding in fuel is small so wood has to be the right size, there is a channel for primary air to reach the firebox.

Example
Image
Chimney Stove - Improved


See: http://www.cato-projects.org/ArLivre/RocketStove2.htm

and Increasing Fuel Efficiency and Reducing Harmful Emissions in Traditional Cooking Stoves

Cost A high cost purchase that may require some form of credit for those on low incomes.

Smoke hood

An inverted funnel with side and rear walls to the floor that allow traditional stoves to be used. The smoke vents upwards through the roof and the woman is less inclined to lean over the fire as the front of the hood is in the way. Very effective in Nepal, but requires subsidy. Can afford greater tolerences and allows the fire to be "seen".

Examples See:
Image
Smoke Hood


Cost A high cost purchase that may require some form of credit for those on low incomes.

Eaves spaces

Making a window above where the stove is burning allows the smoke to be vented out of the space rather than curling back into the room. Can remove substantial amounts of smoke at very low cost.

Cost This can be achieved at little or no cost by most households without credit.

Burning the fuel cleanly

Cutting the wood into smaller, uniform, pieces

This allows air to reach the wood more freely and thus combustion is more complete. However, it has implications for the cook who will need to cut the wood into small pieces. People may not have the choice of using small evenly-sized pieces of wood... they may only have access to dung, sawdust, low-calorific value residues such as rice straw etc.

Examples See: http://www.bioenergylists.org/en/stoves

Cost This can be achieved with no cost to the household but it is time consuming.

Raising the combustion area

Grates which raise the fire off the ground using a grid are vital with coal - but with wood, care should be taken as they can make combustion too rapid.

Cost This can be purchased at low cost by most households without credit.

Providing a route for ashes to escape where low calorific value fuels are used

Low calorific fuels produce a lot of ash which can "drown" the flames by blocking off the oxygen. There are a range of effective stoves for small low-calorific residues such as rice husk, which allow the ash to drain away.

Examples Eg Rice husk stove: http://www.bioenergylists.org/en/taxonomy/term/22

Cost This can be purchased at low cost by most households without credit.

Gasifier stoves

If you use a fan to blow air into the fire, you can create a gas which is burnt separately to the fuel, it is called gasification. The gas burns as cleanly as bottled gas, leaving a residue of charcoal. Several designs have been made - usually for larger scale cooking. Philips launched an excellent household model last year (it is expensive though).

Examples See: http://www.bioenergylists.org/en/taxonomy/term/112 and http://www.research.philips.com/newscenter/archive/2006/060227-woodstove.html

Cost A high cost purchase that may require some form of credit for those on low incomes.

Using a fuel that is easier to burn cleanly

Liquified Petroleum Gas (LPG)

Gas burns cleanly - and usually produces less greenhouse gases than burning biomass in a traditional stove. However, refilling the gas bottles can be expensive, particularly if people are paying off a loan for the gas stove and bottle, or if they have gathered fuel "for free". It may be cost effective if people can use their time savings for income generation. It is a fossil fuel, and if not produced within a country, can be damaging to the import / export balance - and may be taxed. However, it is well liked by those who adopt it and and can afford to run it. It can be used to heat up food to put into a retained-heat cooker.

Examples Widely available and used.

Cost A high cost purchase that may require some form of credit for those on low incomes.

Alcohol fuels (Ethanol and Methanol)

Ethanol can be made from biomass residues such as sugar cane residues, and methanol is generally made from fossil fuels, and can use the gases wasted in the production of LPG. Thus, the fuels can be made within a country and using sources which are either renewable or would otherwise be wasted. Unfortunately, they can also be used as an automotive fuel (or additive for blends), and this has led to massive production - to the detriment of forests (forest clearing for agricultural production). Locally sourced and ethically produced ethanol and methanol can provide excellent fuel for clean cooking stoves.

Examples See Project Gaia and ProjectGaia Commercializing a New Stove and New Fuel in Africa

Cost A high cost purchase that may require some form of credit for those on low incomes.

Fuel oils

Bosch is taking an interest in these - often using the fruit from oil plants that cannot be used for food. Unfortunately, they can also be used as an automotive fuel, and this has led to massive production in some cases - to the possible detriment of forests.

Examples See: Plant-oil Cooking Stove for Developing Countries and http://www.bsh-group.com/index.php?109914

Cost A high cost purchase that may require some form of credit for those on low incomes.

Contributors

Last edited by Miriam Hansen .
Page last modified on Friday September 24, 2010 12:05:41 GMT.
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