Firewood cooking was virtual slavery but gas and electric cooking are easy and fun
Posted on March 11th, 2013

Dr Hector PereraƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚  London

Back home in Sri Lanka, in the early days our servants cooked our meals on firewood stoves. When you really think about their hard work, you would realise how difficult it was to prepare the meals on firewood stoves. Not many people think and appreciate their hard labour to get the meals on time to the table.

Burning fire wood fire is a type of chemical reaction, in which wood burns with oxygen, the products will be carbon dioxide (CO2), carbon monoxide (CO) water vapour (H2O), ash and charcoal that slowly burns away. Very often any chemicals from different kinds of wood as well form the cocktail of gases in the kitchen.

Suffering and cocktail of gases

In a kitchen they burn so many kinds of firewood, such as coconut leaves, husks, shells, cinnamon, cashew, rubber or any kind of dry wood and we burn or chemically we call, oxidized. Sometimes biomass fuels or fossil fuels, the main by-products are the same, heat, smoke, carbon dioxide and monoxide. When food is cooked inside the homes with firewood, dung, coal or with other solid fuels, it creates high level of indoor air pollution. Say for example a mixture of different firewood such as rubber, cinnamon, cashew or coconut leaves, husks and shells are burned in cooking rice, curries and frying dry fish in open fires; it gives a cocktail of nasty smelling gases including smoke. They say, ƒÆ’‚¢ƒ¢-¡‚¬ƒ…-No smoke without fireƒÆ’‚¢ƒ¢-¡‚¬ƒ”š‚ but it smokes before it catches fire then, fire and smoke come out. If it didnƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢t catch fire, some people use some kerosene from the kerosene lamp or blow several times into the fire. ƒÆ’-¡ƒ”š‚ Just imagine the heat on the face, eyes and the hair. How would these kitchen servants stop inhaling these gases, while trying to light fire because they are so near the stove? Sometimes they cough several times continuously, tears and nose drooling, sneeze then need to blow out the wet and blocked nose several times to unblock the nose while sweating. I know it because I also cooked in open fires to see the actual situation? The servant woman was a not residing there; she comes in the morning and goes in the afternoon. I worked in this firewood kitchen laboratory for few weeks when we went on a holiday. I must say, itƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢s not a pleasant experience, I do not recommend to any students this kind of experience. How would I describe this? You smell like a smoked mackerel, haddock or bacon or dry fish or ƒÆ’‚¢ƒ¢-¡‚¬ƒ…-JardiƒÆ’‚¢ƒ¢-¡‚¬ƒ”š‚ when sweat mixed with, dust, soot and ash on hair, face and on clothes, black soot and ash on hands and on clothes, looks like wearing a mask, too much to describe. I am wondering how some of these people undergo this suffering every single day, many hours in the open fire kitchens? It is still happening in Sri Lanka because of the energy poverty.

If you really look at carefully, all this hassle is to get fire for cooking, nothing else. We expect our servants to cook our meals in the middle of these problems, am I correct? Suppose if we got the fire in a different way such as by gas or electric or even by solar power then how would be cooking? Honestly it would be easy and fun.

Rich and wealthy in cold weather countries

These so called wood burning stoves in the sitting room are now limited to rich and wealthy class in England but to my surprise itƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢s a way of life to some poor people in Sri Lanka. Of course they are not trying getting comfort by warmth but to cook breakfast first then keep on going to cook meals for the rest of the day to a whole family. Yes the wood burning stoves may keep you warm and cosy in the shivering cold winter, but they may also be hazardous to your health, especially if you have certain health conditions.

All these toxic gases are absolutely unhealthy. It can lead to a number of chronic obstructive pulmonary diseases such as angina; it is the name given to symptoms (usually chest pain or chest discomfort) produced when the heart muscle is in a state ofƒÆ’-¡ƒ”š‚ ischemiaƒÆ’-¡ƒ”š‚ – that is, when the heart muscle is not getting enough blood flow. Angina is most commonly produced by blockages in the coronary artery. Then emphysema caused by damaged lung air sacks or alveoli and asthma. The point I am trying to say is these are happening due to pollutant toxic gases emitted by burning firewood.

ƒÆ’-¡ƒ”š‚ Some advantages of using LPG

If the people could economically afford to use LPG then most of the problems arising due to use of firewood can be dealt. It is important to note where I stated, to use gas economically that means most people use gas carelessly. The reason could be the fact that they are unaware how to use them economically.

The long term health condition is most important and the authorities must take this into serious consideration. I am not asking them to cut the gas prices or give them for free but must educate them how to get the maximum benefits of PLG by various means. Definitely if LPG gas is available at an affordable price then itƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢s a good start then educate them how to use gas efficiently, show the benefits of using of LPG and the dangers of using firewood for daily cooking.

If LPG can be used efficiently then there would be less air pollution, less money spent on gas, food can be cooked faster and it would give tastier food.

CH4(g)ƒÆ’-¡ƒ”š‚ + 2O2(g)ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ CO(g)ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚  +ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ 2H2O(l)


The equation shows that methane undergoes full oxidation to give carbon dioxide and water or steam but in the absence of enough oxygen it forms carbon monoxide.

methaneƒÆ’-¡ƒ”š‚ +ƒÆ’-¡ƒ”š‚ oxygenƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ carbon monoxideƒÆ’-¡ƒ”š‚ +ƒÆ’-¡ƒ”š‚ water.
2CH4(g)ƒÆ’-¡ƒ”š‚ + 3O2(g)ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚  ƒÆ’-¡ƒ”š‚  2CO(g)ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚  +ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ 4H2O(l)

TheƒÆ’-¡ƒ”š‚ incompleteƒÆ’-¡ƒ”š‚ combustionƒÆ’-¡ƒ”š‚ ofƒÆ’-¡ƒ”š‚ natural gas asƒÆ’-¡ƒ”š‚ methane.

If there isƒÆ’-¡ƒ”š‚ notƒÆ’-¡ƒ”š‚ enoughƒÆ’-¡ƒ”š‚ oxygen available for all theƒÆ’-¡ƒ”š‚ carbonƒÆ’-¡ƒ”š‚ to turn intoƒÆ’-¡ƒ”š‚ carbon dioxide then some orƒÆ’-¡ƒ”š‚ allƒÆ’-¡ƒ”š‚ of the carbonƒÆ’-¡ƒ”š‚ turns toƒÆ’-¡ƒ”š‚ carbon monoxide. This happens with anyƒÆ’-¡ƒ”š‚ hydrocarbon. Here we shall takeƒÆ’-¡ƒ”š‚ methaneƒÆ’-¡ƒ”š‚ as an example.

DuringƒÆ’-¡ƒ”š‚ incompleteƒÆ’-¡ƒ”š‚ combustion, methane gasƒÆ’-¡ƒ”š‚ burnsƒÆ’-¡ƒ”š‚ with a yellowƒÆ’-¡ƒ”š‚ flame (unlike the clearƒÆ’-¡ƒ”š‚ blueƒÆ’-¡ƒ”š‚ flameƒÆ’-¡ƒ”š‚ seen inƒÆ’-¡ƒ”š‚ complete combustion). CarbonƒÆ’-¡ƒ”š‚ particlesƒÆ’-¡ƒ”š‚ (sooty marks) may also be seen.

Carbon monoxideƒÆ’-¡ƒ”š‚ is aƒÆ’-¡ƒ”š‚ very poisonousƒÆ’-¡ƒ”š‚ gas.
It cannotƒÆ’-¡ƒ”š‚ beƒÆ’-¡ƒ”š‚ seenƒÆ’-¡ƒ”š‚ orƒÆ’-¡ƒ”š‚ smelt andƒÆ’-¡ƒ”š‚ poisonƒÆ’-¡ƒ”š‚ theƒÆ’-¡ƒ”š‚ airƒÆ’-¡ƒ”š‚ in every year,ƒÆ’-¡ƒ”š‚ people dieƒÆ’-¡ƒ”š‚ fromƒÆ’-¡ƒ”š‚ carbon monoxide poisoning. I have seen is some so called modern flats, have nice large glass windows but the kitchen windows are sealed. The only way to ventilate is by the extractor fan, do you think it is right?

I have witnessed in many British TV cooking programmes by so called celebrity cooks, they carelessly cook with gas on full blast, never talk about energy efficiency, energy saving or any science of cooking. In that case our servants at back home can cook better due to sheer years of practice.

Adiabatic flame temperature (constant pressure) of common gases/Materials such as methane is much higher than in wood flame.

That means wood burning temperature is much less than that in LPG gas flame.ƒÆ’-¡ƒ”š‚  Wood burns to give a temperature around 500 to 300C0 but the LPG gas flame is around 1950C0 or 3542F0 that is much hotter than the flame from firewood. Have you heard some people can walk on this red hot amber? Yes people do that in special religious places such as in Kataragama devalaya, Carli Kovil in Chilaw, of course with faith.

Clay pots are poor conductors of heat

Food is bad conductors of heat that means heat go through them quite slowly, so when we cook food, we must not use intense flame because most of it goes waste as radiated energy. In LPG the flame can be controlled but in firewood it is very difficult to maintain a constant temperature. Quite often in Sri Lanka, clay pots are used in firewood cooking for rice and curries. The clay has very low thermal capacity so most of the heat is radiated to warm the kitchen than in actual cooking. The stainless steel vessels with thicker bases retain heat for a longer time. I think only in specialised shops have quality cooking vessels.

When I cook rice, pasta or spaghetti or even chicken curry or any vegetable curry, I make use of the principles of science for cooking. That cannot be explained in a few words, even if I did that would sound like double Dutch to some people. Let me put it this way, when you tried to learn driving a car, did the instructor went into explaining all the mechanisms involved in the car? He just told you what to do then show by driving it as well but never attempted to take the engine into pieces and explain all the mechanics then it would have been double Dutch to you. Here I would keep my scientific explanation only to the authorities who wanted to find details of my scientific energy saving but to any other, I will demonstrate how to save energy and time.

I am confident to explain in simple terms so that even any secondary school age child can use my method to cook confidently, save time and energy. Only secondary school age children but not the primaries are allowed to handle fire in a chemistry laboratory. Here in the kitchen laboratory follows similar rules. Would you like to try and find any food stuff that has no chemicals, all foods stuff including spices are made up of complicated chemicals?

I will certainly demonstrate how to cook efficiently by gas or even by electricity, then one would believe me how easy and fun is cooking. Sometimes I prefer gas because the intensity of the flame can be visually seen.

I understand there is a cocktail of cooking aroma that would give out while cooking and there is a possibility of depositing some of them while cooking. Who would like to walk about smelling like a mobile kitchen? When the University students have to live away from home, why most the students prefer to eat takeaways because they are totally ignorant about home cooking and also because they think itƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢s an insult to know cooking. I asked one of my Advanced Level chemistry students in Sri Lanka, ƒÆ’‚¢ƒ¢-¡‚¬ƒ…-You know how to cook riceƒÆ’‚¢ƒ¢-¡‚¬ƒ”š‚? She emailed me, ƒÆ’‚¢ƒ¢-¡‚¬ƒ…-No Sir, itƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢s awfulƒÆ’‚¢ƒ¢-¡‚¬ƒ”š‚. I totally agree with her but that can be changed if cooking was done scientifically that saves energy and less time is spent in the kitchen. Any comments please,


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