| Boiling Point No. 20- December 1989 |
by Keith Bennett, Energy Systems Analysis (Consulting Croup), UK
This article considers coal, gas, kerosene and electric stoves as the alternatives to biomass cooking for the developing countries.
Interesting comparisons are drawn with the transition from biomass fuels in Britain.
Whilst walking in an oak wood in South Shropshire, England, last weekend, a friend drew my attention to a small flat area on an otherwise rather steeply sloping hillside. That, he said, is the remains of a charcoal burner's kiln and sure enough a little scraping away of the ground revealed blackened soil and small remnants of char.
In Britain, an early transition was made away from the fuelwood economy. Firstly, around 300 years ago there was a transition to coal, as forests were cleared and fuelwood became scarce and had to be hauled increasing distances to the towns. However, as many urban dwellers in Southern Africa are now finding, coal is not an easy cooking fuel. Especially as a direct substitute for wood, coal is difficult to kindle and has an unpleasant smell. Another problem is the very high ash content compared to wood which tends to block up the grate. Inadequately maintained coal and coke stoves can also be dangerous and there have been reports of carbon monoxide poisoning fatalities in South Africa townships, due to the build up of this lethal gas in poorly ventilated kitchens.
Coal requires a specially designed stove or cast iron multifuel cooker of the Rayburn or Aga type. Even today, in certain rural areas of Britain, a significant proportion of households burn wood in one or other of these domestic solid fuel cooking ranges. This is due to the availability of cheap, or in many cases free, wood logs in the more wooded parts of the countryside. The woodburning households may not rely entirely on wood however, and in most cases the kitchen is also likely to include a gas or electric stove and probably even a microwave oven. The most appealing feature of the woodburning cooker is its efficiency as a space heater. Cast iron construction ensures that the body of the stove convects and radiates heat to the kitchen on cold days. The stove is often kept on overnight with a heavy log kept burning slowly by the closed down chimney and air dampers, to avoid the inconvenience of starting up the stove with paper and kindling, often a slow and frustrating business on a cold day with a damp chimney.
This requirement for space heating is an important consideration in the transition from biomass to non-biomass cooking. The often stated claim of fuel substitution programmes or policies in developing countries is to reduce the consumption of wood and charcoal and save the forests. Where space heating is required (in upland areas of Africa for example), it is estimated that 20% of fuel consumption is for heating, so even if people are encouraged to switch to say kerosene or LPG then they are likely to continue to use a wood hearth to keep warm, especially in the mornings and evenings. For example, women in Zimbabwe who started to use massive mud stoves because they found them more convenient, found that they were using significantly more wood because they needed to keep the central wood burning fireplace going in order to keep the family warm. However, they were prepared to spend the extra time collecting more wood in order to enjoy the benefits of the new stove. Massive mud stoves are not particularly effective space heaters because the construction materials have a low thermal conductivity and the outside of the stoves never get very hot compared to cast iron stoves. Some heat is stored in the body of the massive stoves, but this does not compensate or compare with heat from the open fire. Modern electric storage heaters give out heat which has been stored at night using cheap rate electricity. In the same way as gas and oil central heating systems, in order to be effective, these heaters depend on the house being well insulated and air draught from gaps around windows and doors being minimized; conditions not found in rural housing in the Third World.
The pattern of cooking in rural areas of Britain still bears some similarity to that in certain urban areas of the Third World. It is quite common to find a middle or higher income family in say Khartoum or Delhi, using wood, charcoal, kerosene, gas and electricity for cooking (although not necessarily at the same time!). The reasons are as they would be the world over, for maximum convenience, comfort and economy. An additional factor in the developing countries for retaining many stoves is also security. If wood becomes scarce there is always the kerosene stove. If kerosene supplies dry up perhaps bottle gas will still be available and so on. Electricity is notoriously unreliable due to the poor management and need for investment by the developing counties. The supply will need to be improved before people are likely to depend on it for cooking.
A wood stove is often the only one which will allow the cook to use the family rice or sauce pot. These pots are simply too large to fit onto a gas or electric stove and even when they can fit, cooking is too slow. Meals which require the food to be grilled, some meat and fish dishes for example, cannot be cooked on a simple one or two plate gas or electric stove; a charcoal fire is needed. Conversely, to light a wood stove in the morning to boil water for tea or porridge is a dreadfully slow process compared to using a small bottle gas stove.
Despite particular cooking needs which are not met by the cheaper gas, electric or kerosene cooking stoves, these stoves offer many advantages in terms of controlability, cleanliness and speed compared to biomass stoves. Especially in the large urban areas of developing countries, their use would be more widespread were it not for financial, economic and technical problems.
On the economic side, a policy is needed to encourage a switch to say kerosene or LPG if this is to occur. In colonial times, kerosene cooking stoves were popular in towns all over the Sudan, when a reliable supply was maintained. The government is now planning to improve the supply of both kerosene and LPG in an effort to stem the huge demand for charcoal which has decimated forests to the south of Khartoum. There have been examples where urban populations have made a significant switch to kerosene when the price was low enough. In India, a major switch to kerosene and LPG has occurred where these fuels have been priced attractively compared to wood. This contrasts with other areas where wood is still cheap and plentiful. In one town in Sierra Leone, where a survey was conducted, it was found that despite average family expenditure on wood being 30% of income, the majority would not consider a switch to kerosene for reasons including food taste, perceptions of safety and the wider range of cooking methods that are possible with an open fire. In Zimbabwe, kerosene stoves are mass produced from thin tinplate and sold at a fraction of the price of many improved woodstoves.
However, their use is limited by the size and output of the stoves which would be slow in heating anything but a small kettle. These stoves are of the wick type and rely upon a reservoir of fuel with a fabric wick sucking up the fuel to a flame. A more efficient, cleaner and less smelly type of kerosene stove is the pressurized model, such as the primus stove. These stoves have a fuel tank which can be pressurized with a hand pump and the fuel is pre-heated and vapourized through a nozzle and mixed with air for efficient combustion. These models are extremely expensive and require sophisticated manufacturing compared to the wick stove which can be artisanally produced at minimal cost.
The term entry cost is used to describe the investment needed to switch fuels. Clearly the entry cost for woodfuel can be either minimal as three stones can be found anywhere, or can be significant, if an improved stove is purchased. Likewise for kerosene, depending on the available stoves. For LPG (bottle gas) and electricity, the entry cost is invariably high. To get started with bottle gas, at the very least you need the gas tank, regulator valve and burner head. For electricity, even a single plate stove is relatively expensive and the consumer is also likely to incure connection charges, if a supply is not already connected and standing charges in addition to the cost of the electricity. In many urban areas of Zimbabwe, electric cooking is actually considerably cheaper than wood or charcoal once the appliance is installed. However, since safety regulations for domestic appliances insure that very cheap (and highly dangerous) electric stoves with ceramic element holders and exposed elements of the type found in some countries are not available, the high cost of a stove constrains many potential users.
Amongst the development professionals, much has been made of the cultural barriers to the adoption of improved cooking stoves and the same arguments have been applied to duel switching. Whilst it is certainly true that for example, polygamy tends to invalue the need for separate cooking facilities and that certain benefits may be attributed to the presence of smoke (insect repelling, preservation of timber etc.) the attraction of gas and electic cooking should not be underestimated. Certainly in urban areas there are few cultural barriers to the adoption of modern clean, efficient stoves, it is rather the financial and technical constraints that deter people from switching.
Environmental factors are also important where policy options are being considered. Certain Chinese and Indian towns for example cannot be seen on landsat photographs, as their presence on the satellite pictures has been completely obliterated by the pall of smoke from biomass combustion, largely from domestic cooking fires. In Africa, large areas of woodland are being cleared by woodfuel businesses in order to supply urban areas with cooking fuel.
However, electricity can be generated from biomass and this option is now receiving some attention in Britain as a partial alternative to the use of non-renewable fossil fuels. It has been proposed that farming land presently surplus to requirements be turned over to mechanically coppiced wood energy crops, which are then gasified and used to dry generators. The carbon removed from the atmosphere by the growing wood is returned to the atmosphere on combustion (with little sulphur or NOx pollution) resulting in no net gain or loss in the atmospheric carbon dioxide; but the real benefit is in the fossil fuel ea. coal or oil that will be saved. This is an attractive option given the political climate of increased environmental awareness. It appears that with the privatization of electricity in the UK, there will be increasing opportunities for smaller scale power generation feeding into the national grid. Farmers may be able to install fully automatic generating equipment and export the electricity through existing power cables. The process is made all the more attractive by the fact that the winter harvesting period for the coppice wood coincides with the lowest period of activity in the farmers year and with the peak seasonal demand for electricity.
In Britain and the other industrial countries, economic development fuelled growth in income which enabled families to afford improvements in the kitchen including the switch to modern fuels with all their advantages. All the factors which combine to keep poor countries poor also ensure that families are unable to switch to safer, more convenient and clean cooking methods.