Monday, March 16, 2009


This picture shows lighting a corridor with the torch sitting upright on the floor.its advantages are-
-100,000+ hours of bulb life.
-Burns 100 times longer than standard Torch light.
-500+hours of pleasant light with one set of three AA size batteries.
-Flat bottom for positioning upright.
-high power focused light.
I have used this light for over six months and found it meets all the above specifications.
More details of this light and other products of this company can be seen at-
A family can buy three torches over a period of time,one for the family head,one for the house-wife,one for the children and meet all their lighting needs in Rs.225.


These pictures show the use of the torch for reading;the torch can be hung from the roof five feet above the book as in the second picture or held in hand as in the others.



A light in the house for three or four hours in the evening is a bare necessity in every home;across many countries the HURRICANE LANTERN with kerosene as the fuel is the most commonly used lamp;while they are sturdy,locally available and above all within reach of the poor,its disadvantages are-
-kerosene often costs a third of the family income
-risk of a fire accident due to spilling of kerosene
-light is dim and not adequate for children to study
-causes indoor air pollution from smoke and other gases and a leading cause of death;over 500,000 die every year from indoor air pollution[IAP] in India.

solar powered lights with LED[light emitting diodes]bulbs are a good alternative to kerosene lamps;these bulbs last for over 100,000 hours;very efficient in light production;however solar powered LEDs run on rechargeable batteries which are costly and not available in our villages;and most such lights in the market are in the price range of Rs.750 to Rs.3000;far above the means of the poor.
A very low cost alternative is the Led torch/flaslight from ANDSLITE for Rs.75/- including the batteries; it gives adequate light for cooking,reading and is sturdy and portable ;it can be used for three to four hours daily for over hundred days on three AA size batteries;these batteries used in transister radio are readily available in all villages for Rs 7/- each or Rs.21.

Monday, February 23, 2009


INSULATION-The rocket elbow and its surrounds should be made with good insulating material;Good insulation is made of tiny pockets of air separated by lightweight non-conducting material.Soil or clay used in traditional stoves is dense and heavy and does not make for good material for stoves;a lot of the heat is absorbed by the stove itself.Using bricks made from a mixture of clay and saw-dust/ rice-husk / hay from paddy stocks will make a good material for rural areas;mix clay and saw-dust,knead saw-dust into the clay thoroughly,then add water;the bricks from the kiln should float in water.
RURAL AREAS-A fixed model with in the house;this can be done with fire bricks made as described above;the stove can be made with sixteen bricks as shown in the video-

Or with available local material-

URBAN AREAS-A portable stove which can be used indoors or outdoors as shown in the videos here can be made with used tin cans and insulation of facing/surface fire tiles/bricks available in the market.

The Envirofit models in the market can be seen here-

Saturday, February 21, 2009


By Dr. Larry Winiarski
1. Insulate around the fire using lightweight, heat-resistant
2. Place an insulated short chimney right above the fire to burn up
the smoke and speed up the draft.
3. Heat and burn the tips of the sticks as they enter the fire to make
flame, not smoke.
4. High and low heat are created by how many sticks are pushed
into the fire.
5. Maintain a good fast draft from under the fire, up through the
coals. Avoid allowing too much extra air in above the fire to cool it.
6. Too little draft being pulled into the fire will result in smoke
and excess charcoal.
7. Keep unrestricted airflow by maintaining constant cross sectional
area through the stove. The opening into the fire, the size of
the spaces within the stove through which hot air flows, and the
chimney should all be about the same size.
8. Use a grate under the fire.
9. Insulate the heat flow path, from the fire, to and around the
pot(s) or griddle.
10. Maximize heat transfer to the pot with properly sized gaps.

Friday, February 20, 2009


Figures from AricMcBay:

"It is easy to construct, and it uses low-cost materials. The rocket stove's main components are:

  • Chimney: a metal box (such as a 5-gallon tin can) or pipe standing vertically and supporting the cooking vessel
  • Fuel magazine: a short length of steel or ceramic pipe fitted horizontally into the base of a chimney
  • Fuel shelf: a flat plate to hold the fuel clear of the bottom of the magazine to allow air to flow underneath
  • Heat exchanger: a tubular metal shield that forces hot gases from the chimney to pass over the sides of the cooking vessel

The chimney and magazine are joined at a right angle, forming the 'rocket elbow', and it is at this junction that primary combustion occurs."

-The heart of the stove is the rocket elbow;small pieces of wood/ twigs are fed on to the fuel shelf in the fuel magazine;wood burning occurs only at the elbow aided by the air flow as shown in the figure;this ensures complete burning of the wood and prevents production of smoke ;smoke is formed when adequate air[oxygen]is not available for burning;
-complete burning results in full release of heat energy from wood and high temperatures in the combustion chamber;the heat energy is conserved by the insulation around the combustion chamber and directly transferred to the vessel on the grate as shown in the figure to the right.;
-the pot skirt ensures heat transfer to the pot both at the bottom and the sides.

-A long combustion chamber prevents smoke but reduces heat to the pot; a short chamber provides more heat but may generate some smoke.
-the gap between the pot and the skirt should be around twelve millimeters to ensure efficient transfer of heat to the pot;heat escapes with a large gap;if the gap is too narrow it restricts air flow.
- wood burns only at the inner end and it should be pushed in as it gets whittled down in burning.
"This stove operates on about half as much fuel, and produces substantially less smoke., compared to the traditional stoves;the stove requires small diameter lengths of wood, small branches or twigs; sufficient fuel for cooking tasks can be gathered in less time, without the benefit of tools, and ideally without the destruction of forested areas."[wikipedia]
The insulation of the combustion chamber is crucial for conservation of the heat generated and several types of materials have been used to achieve this;
Based on these principles several stoves have been designed to cater to all segments of the users;a ready-made stove ENVIROFIT is available in souther states for prices varying from Rs.700 to 2800.we could also build stoves for as low Rs.50 to 100 using local material like in 'Good-stove' ; after a survey of improved stoves the World Bank stated that models that can be constructed by the people with local materials are the ones that are easy for adoption.Stand-alone models are the best for urban poor and for all rural areas.

Thursday, February 19, 2009


The stove seen in the picture is made from a tin can;a 4"x4" window is made on the side near the bottom to place the firewood and a grate on the top to hold the pot all for Rs.6 !cooking is done in the open to avoid smoke in the hut.
For the poor in urban areas and most people living in rural areas, there's little alternative to burning wood and other biomass for cooking food,particularly for theBPL[Below the poverty level]families;biomass is readily available; kerosene and LPG are expensive and not available easily in rural areas; require an investment poor cannot afford;they involve a long transport for delivery to the over 600,000 villages in India;they are non-renewable and likely to exhaust one day;in contrast properly planned, wood can be grown where it is needed,near the villages and being renewable it is inexhaustible;our long term security lies in developing our wood can also be carbon neutral when compensatory planting is done
However biomass burning creates indoor air pollution which kills one person every twenty seconds[WHO];India accounts for 80% of the 600,000 premature deaths that occur in south-east Asia annually due to exposure to IAP.The World Health Organisation estimates that pollution levels in rural Indian kitchens are 30 times higher than recommended levels and six times higher than air pollution levels found in New Delhi. secondly the traditional open stoves are very inefficient and consume high quantity of wood or other biomass.
Tremendous amount of research has gone into making of improved stoves with superior cooking efficiency and no or less smoke; almost all these innovations follow the basic design of the ROCKET STOVE invented by Dr.Winiarski of Aprovecho.The salient features of the design are-
1.complete burning of the wood is achieved by providing for adequate air supply into the combustion chamber;proper burning of wood reduces or eliminates smoke.
2.By providing good insulation to the combustion chamber loss of heat is prevented.
3.The heat is efficiently transferred to the vessel/pot by providing a skirt round the vessel.
these details are presented in the figure in the next posting.