Traditional stoves: Traditional stoves in Bangladesh are usually mud built cylinder with three raised points on which cooking utensils rest. One space in between these raised points is used as fuel porting port and the other two for the flue gases exits. The stove may be built under or over ground. In some case, two, potholes are joined together laterally using a single fuel feeding port. The stoves perform sub-optimally due to loss of heat.

Improved cook stoves: Improve stoves are those traditional stoves upon which some modifications have been made to give higher thermal efficiencies. The efficiencies is defined as a fraction of heat content of the fuel fruitfully utilized. If Q is the heat content of the fuel burnt and U the amount fruitfully utilized, then the efficiency E is given as:

E= U/Q
The Institute of Fuel Research & Development (IFRD), BCSIR a number of improved stoves have been developed to suit the requirements in respect of biomass fuel types, shape of cooking pots and cooking habits.

These models may be ground into three categories:

Stove without chimney: This model is just our age-old traditional stove with three modifications: Firstly, the exhaust gap or flue gas exit has been reduced to 1.25 cm, so that convective heat loss, consistent with good burning, is at a minimum. Secondly, a gate has been placed inside the stove at a depth of 15-18 cm below the stove rim. Considering the size of the firewood used, 6-7 holes of 1.25 cm in diameter are made on the wall of the stove just below the grate for primary air entry. This stove 50-55% fuel save when compared with a traditional stove of the same internal diameter. How ever the stove is suitable for fuel-wood, twinges and branches.

Stove with chimney:

A major version of chimney stove is the multi-pots stove where cooking of more than one item is done simultaneously as shown in figure. I n this case fuel is burnt in the first combustion chamber. The stoves are so designed to maximize heat transfer to cooking utensils. Fuel savings of this model, as compared with a traditional one pothole, is about 60-65%. This model decrease the time of cooking and also make the kitchen free of smoke and hot air. It can be easily made with mud. A grate is placed 18-20 cm below the stoves rim. On both sides of the stove, just below the grate, two small holes are made for primary air entry and ash removal.

Multiple stoves can be made in large sized to suit cooking needs in hostels, hospitals, community centers, etc as in figures. Industrial stoves built for streaming twisted years in the textile mill is another variation of this design.

Traditional fuels viz. fuel wood, straws, leaves, bagasse, cow-dung, etc. are being used for domestic use and other heating purposes. In Bangladesh there are also large number small industries which are operated by fuel wood.

Advantages of improved stove:
The improved stoves have many advantages over traditional stoves. Some of the advantages are given below:

1. Save 50-60% traditional fuels
2. Save cooking times 40-50%
3. Keeps the kitchen environment pollution free and thereby reduce health hazards of the users
4. Maintaining proper nutritalive values of the cooked stove.
5. Less blacking of the cooking utensil.
6. Check the fire hazards.
7. Reduces CO2 emissions in the atmosphere, thereby reduce the green house effects.

Future Prospects of Improved stove Technology:

Improved stove save 50-60% traditional fuel as compared with traditional ones. Total amount of traditional fuel consumption in the country is about 39 million tons annually. If improved stoves popularized in the country and if it saves 50% traditional fuel, then annually about 19.5 million tons of traditional fuel will be saved.

The reduction of traditional fuels by improved stoves, therefore have lower emission of green house gases (CO2) in the atmosphere. It also helps to conserve the forest resources of the country.

In reverine Bangladesh it will be difficult to supply natural gas for cooking purpose to the every households of the country. Therefore, improved stoves have bright future in the country. Large scale dissemination of improved stoves in the country can conserve the local forest and change the social life to a great extent.

A MOU has been signed between the World Bank and LGED to address Indoor Air Pollution (IAP). Inception workshop was held on 10 September 2007 at the Hotel Sheraton. Windrock International and VERC are associated with the study. Inception report is available on the REIN web.

LGED has installed institutional biomass gasifier at the Faridpur Muslim Mission in 2006. Main advantage of gasifier is that it could save 50-60% fuel cost.