Frequently Asked Questions

What is a Rocket Stove?

The technology we use is called ‘Rocket Stove’, and it’s widely used in various parts of the world. It’s a clever design that mixes air and burning gases together inside a vertical insulated combustion chamber that force temperatures to rise to a point where near-complete combustion occurs. This causes to the smoke to be oxidized and converted to heat energy, which makes the stove both very efficient and clean burning.

Although the basic rocket stove concept does already exist in many formats, it has not previously been applied to the Himalayan context as a heating unit in any meaningful way. There are some programs that use rocket stove technology in clean burning cook stoves – this is a different application of the technology which does not provide heating.

What is the Himalayan Rocket Stove?

The Himalayan Rocket Stove is an innovation of several rocket stove ideas that is adapted to fit the unique context of the Himalayan regions. These stoves need to be similar in shape and size to a tradition Bukhari style of heating stove that is commonly used throughout the Himalayas, in order to fit the Himalayan context.

Height is a primary factor of concern, and this is where the main innovation occurs, as it is relatively easy to make an efficient rocket stove over 3 ft high, and much harder to make one only 2 ft high. The Himalayan Rocket Stove achieves this through innovative use of various design tweaks to optimize performance in a smaller sized format.

What is the distinction between the Himalayan Rocket Stove and Smokeless Chulla?

The Himalayan Rocket Stove Pvt Ltd company is a Social Enterprise with a clearly stated triple bottom line of People, Planet and Profit. It makes products primarily designed for heating (and which can also be used for cooking) to be sold to people of the Himalayas.

The Smokeless Cookstove Revolution not-for-profit project currently operating under the umbrella of the Himalayan Rocket Stove company, which is primarily a training platform aimed at sharing the knowledge behind making smokeless chullas in regions where Household Air Pollution is an issue.

In both projects, the design of the stoves incorporate technology known as “Rocket Stove”, which is an open source concept used in various parts of the world.

How does the Himalayan Rocket Stove work?

The Himalayan Rocket Stove is a heater as well as a cooker due to the design of the movement of gases inside the metal box. We carefully trap the hottest gases inside the box in a way that maximises the efficiency of the heating aspect of the Himalayan Rocket stove, which then transmits to the room through the metal casing. By the time the hot gases finally exhaust out of the flue pipe, there is very little heat left in them.

This is important as most typical ‘Bhukari’ style heaters send the majority of the heat up the flue pipe and out into the atmosphere along with the smoke. A typical Bhukari is about 15% efficient, versus the Himalayan Rocket Stove being more like 90% efficient, due to these 2 aspects: a more complete combustion of the fuel (burning the smoke) and trapping the heat more effectively into the room. 

Who is the Himalayan Rocket Stove for?

The Himalayan Rocket Stove, however, is specifically designed to replace those heater style stoves (bukhari) that do vent outside, but which are less efficient and more polluting. Typically in the Himalayas all stoves vent to the outside, even the nomads in tents have stoves with a flue, so the Himalayan Rocket Stove is as appealing to the nomads and lower income households as it is to the higher income families with larger homes who are also conscious of the cost of heating. 

What is the importance of height in the design of the stoves?

The height is a critical aspect of the design of the stove, in that a Rocket Stove works by drawing the hot gases upwards through a vertical insulated combustion chamber. It’s called the chimney effect, and the taller this vertical chamber is, the more rapidly it will draw the gases through.

The challenge we faced was to keep the height as low as possible due to the way people use the stoves in each of these contexts.

In the Himalayan context, the stove sits in the middle of the room as a feature and the family will sit about the stove, low to the ground. They will need to see over the stove to see each other around the room. Additionally, the cook will be sitting low to the ground while cooking on top, which is similar to how the chulla is used. The cook needs to access the top of the stove from a low seated position in each case.

We had to find a way to keep the height down whilst also keeping the effectiveness of the rocket stove design, which ideally prefers more height. There are various formulas and ratios that are used in the design, and through trial and error we came up with a version that works in both cases. If the context allows us to scale up the height, then we can make larger, hotter and more effective stoves, and we have also done this with several prototypes in Ladakh.

One of our large space heaters is 36 inches high and uses a scaled up internal design accordingly, and is very effectively heating a hall in Ladakh with only a small increase in the fuel input. We will look at producing more of these in the coming year, as the feedback has been very positive with lots of people also requesting we make more of these heaters for larger rooms and halls.

What is the connection with Ladakh?

The test production facility was operational at LEDeG (The Ladakh Ecological Development Group) in their workshop space in Leh Ladakh, from September through to end of November 2016.

The primary purpose was to develop the Himalayan Rocket Stove which is the metal box unit designed as a heater for Himalayan family homes. In the testing of materials for this, we discovered the method for making smokeless cook stoves (chulhas) quite by chance, using the method of adding puffed rice along with cut straw to the clay mix. The straw is added to provide strength to the clay, and the rice is added for the insulating aspect. 

How did you test the stoves in the Himalayas?

After receiving the grant, I set up a test production facility in Ladakh in conjunction with LEDeG (Ladakh Ecological Development Group).

I had a large workshop space and a team of 4 staff who worked full time on the stoves, building and developing the designs I had brought from Australia.

Over this period, around 20 stoves were produced and placed into homes for testing and feedback. Based on the real time feedback from users in a range of Himalayan homes, we tweaked and refined the prototype significantly, and introduced the hot water system into one of the models.

At the same time, we were also exploring the various application of rocket stove technology with a wide range of prototypes being developed onsite. These included large space heaters, hot water systems, a rocket stove clay oven for bread and pizza, and various other ways of working with clay to make highly efficient and smokeless fires.

It was here that we developed an incredibly easy and cost effective system for making smokeless cookstoves (chullas). Seeing the potential to apply this to the issue of Household Air Pollution, I decided to set up a parallel not-for-profit project called the Smokeless Cookstove Revolution, aimed at sharing this technique in a training format.

What is the cost of fuel?

Approximately 10,000 INR ($200AUD) is the typical cost per year for wood for the existing stoves (Bhukaris) if they purchase it. In some cases they collect the wood, so the expense is in terms of labour and time and health risks (usually women and children have this responsibility).

There are other associated and indirect costs attached to this. Each stove using the average of 1000kg firewood per year is depleting the forest by one mature tree each year. This in turn is adding to CO2 emissions and black carbon on the snow and ice of the Himalayas which is increasing snow melt and contributing to water access costs.

There are also health costs associated to respiratory issues arising from pollution.

Who is the team involved with the project?

Russell Collins is the sole founder, CEO and technology developer for the Himalayan Rocket Stove. He is coordinating the project from India and Australia with the support of a media and events organizer based in Mumbai, a production manager on site at the factory in Baddi, as well as distribution partners throughout the Himalayas.

There are also Sales and Marketing Managers in both J&K and HP. As the production capacity grows, so does the team. The rest of the work at this stage is outsourced to the manufacturing partner, who has a factory with dozens of workers. 

What is the projected sales target for 2017?

We are now taking orders from Himachal, (including Spiti, Kinnaur, Kullu Valleys), Ladakh, Shimla, Darjeeling, NE states and Nepal.

As of early 2017, we are just starting to scale up the production so we have been deliberately going slow with taking orders. We are planning to scale up production to deliver 2000 units for the 2017/18 winter season. 

How many model variations of the Himalayan Rocket Stove are there?

Initially we will focus on the standard stove unit that incorporates heating and cooking, also known as the ‘2-in-1’. This will form the base unit on which various options can be added at a later stage.

These options include the Hot Water Unit, which is a stainless steel box that fits onto the back of the Himalayan Rocket Stove, and which will hold approx 18L of water. It takes about 1-2 hours to heat up to boiling, and then it can be used for any normal hot water application, obviously with added cold water to get the desired temperature.

The water box serves an additional purpose. At the end of the evening, with the hot water still in the box and the fire going down, it will also provide another hour of heat to the room without the fire. 

The phone charging module is still in development and is scheduled for release in 2018. There will also be various height options and other options are in development.

What is the impact on indoor temperatures?

When I was testing the stove personally over a month at the beginning of winter in Ladakh, I recorded the temperature outside as down to -5C, and using the standard stove I was able to keep a large room heated to nearly 20C inside a concrete house, which are notoriously cold.

My friend in Ladakh with a more practical earthen house is sending me photos of the thermometer showing 25C inside with -10C outside.

What is the fuel consumption pattern with HRS?

The HRS typically uses less than a kilo of wood per hour of operation and generally likes smaller sticks which are more readily harvested without requiring a whole tree to be felled. Also dried dung works very well, especially when accompanied by some sticks. Coal has not yet been tested, but should work just fine.

Any solid fuel that is prone to release smoke under normal combustion conditions should be ideal for the Himalayan Rocket Stove.

How does a Smokeless Chulla (cookstove) work?

The clay donuts used in the design of the Smokeless Chulla are made of clay mixed with ingredients designed to make them insulating. All Rocket Stoves are based around the simple concept of a vertical insulated combustion chamber and good airflow. These 2 factors combine to give a more complete combustion of the fuel, making them both efficient and less polluting.

Unlike the Himalayan Rocket Stove, the Smokeless Chulla is specifically made for the purpose of cooking, applying heat directly to the base of a pot. There is no intended room heating aspect to the chulla, although of course like any cooking appliance inside the home, there may be some indirect heating. 

Who is the smokeless chulla for?

The smokeless chulla is targeted exclusively at those who would normally use an open fire or a rudimentary chulla that does not vent to the outside. Basically this is an improvement on something that vents smoke into the house. It is not designed to replace something that already vents to the outside, or a clean burning stove such as LPG or electric.

This is typically aimed at the lowest economic strata who collect solid fuel to be burnt in a rudimentary way. The World Health Organisation has identified that approximately 3 Billion people still fall into this category, and around 800 million suffer poor health as a result, with an annual mortality of 4 million globally, one quarter of which falls in India.

How do you use clay for making smokeless cookstoves?

Clay is a thermal mass, which means it soaks up and stores heat. By adding a small puffed grain to the mix, we can change the nature of the clay into something that insulates, which means it will trap the heat. When we fire up a newly built smokeless chulla, the biomass (puffed grains and grass) burns out, making smoke in the process. It becomes suddenly smoke free as soon as the clay is dry and the biomass is all burnt out, usually after several hours.

When all the bio matter is all burnt out, the clay is left with small pockets of gas which is a simple and effective way to make it insulating. This then creates a combustion chamber that traps heat, forcing the temperatures to rise and in combination with properly designed airflow, creates the right conditions for the smoke itself to burn. The burning of the smoke releases additional heat energy and removes the smoke from the exhaust. 

What is the progress of the Smokeless Cookstove Revolution (Smokeless Chulla Project)?

We ran the first workshop in Ladakh with some local students from SECMOL, some Kashmiris who travelled especially for the workshop and a few visiting international volunteers, also from SECMOL. The workshop was a practical hands-on experience where we made various smokeless chulhas, a large hall heating system and the rocket stove oven.

From this experience, we realized the potential to share the core ideas for the smokeless chulha and have since run workshops in Chandigarh at the Punjab University, in Dharwad, Karnataka, IIT Delhi, Kanha Tiger Reserve, Sainik Farms in Delhi and Khampur Village.

There are a number of additional workshops scheduled, and we are taking requests for further workshops. We are also seeking people who are interested to get involved in this project who are willing to act as trainers (or support in other ways) in various regions of India (and beyond). If you are interested, please contact via email.

What workshops have been run so far?


1. Leh onsite at the LEDeG workshop in Leh. We had a group of 3 come from Kashmir especially, about 4 local Ladakhis and a few visiting internationals.

2. Chandigarh at Punjab Uni, about 10 – 20 people in a more casual drop in format I believe (Tanzin and Nitisha were there, I wasn’t)

3. Dharwad in Karnataka, about 20 – 25 people (again with Tanzin and Nitisha)

4. IIT Delhi – about 12 people with 3 specifically interested to become ongoing trainers as part of the Smokeless Chula project.

5. Kanha in MP with Tanzin and Nitisha (March 20170

6. Train the Trainer – Sainik Farms Delhi (April 2017)

7. Trainer practice workshop – Khampur Village


How do you make the smokeless chullas?

The main ingredients are clay (which is easily available throughout the country), straw and puffed rice. Sometimes sand is added depending on the quality of the clay. These are formed into a particular shape that allows for maximum airflow and correct combustion of hot gases resulting in a clean and highly efficient burning of solid fuel.

There is an instructional video on how to mix the ingredients and how to make the chulla on the video page. This is a free resource which you are invited to use and share as widely as possible.

What about changing weather patterns in the Himalayas?

The change in weather patterns over the last 25 years has been dramatic, in particular over the last 10-12 years. Both Spiti and Ladakh are high altitude cold desert regions, where rain was extremely rare. The houses and ancient monasteries are universally made of “mud” (various forms of compressed earth and clay) with flat rooftops. These buildings, some of them over 1000 years old, have stood the test of time. Except that now, over the last 10 years, rain has been a recurring feature of the summer months as the monsoon now climbs higher than before.

I know that this is a new phenomenon as I visited the inside of the ancient Tabo Monastery in 1992, with its fantastically well preserved murals that date back to 996AD. Over many years of repeated visits, I have noticed how these famous murals have degraded due to rainfall and water damage coming through the flat earthen rooftop.

This is also happening to the houses in the village, and they are literally falling apart from the sudden onset of a wet season they previously never had to deal with. 

Paradoxically, this increased rainfall is not adding to their usable water which is drying up as a result of glacial melt and decreased snowfall in the winter, so that now various villages through the Himalayas are barely viable. In fact, I recently heard about a village in Zanskar that lost its water supply and had to relocate.

This change in weather has also meant there have been dramatic and catastrophic weather events in various locations somewhere in the Himalayas, almost every year for the last 10 years. These include massive cloudbursts that lead to devastating floods, mud tsunamis, road washouts, bridges down, passes blocked, villages destroyed and fields wiped out by mudslides.

As a travel operator, I have had a number of close calls where I was blocked or nearly blocked into remote regions with groups due to these events. I have thus decided that the risk factor is now too great for me to confidently guarantee the safety of  people in my care on certain routes. I still oversee a local eco tour for the kids of Spiti to Ladakh, and sometimes organise a fixed location retreat which has a far lower exposure to risk, as there is no remote area travel involved. 

What is the fuel demand in the Himalayas for people using wood stoves?

There are about 50 million people in North Indian Himalayas (HP and J&K) and Nepal. Average housing density is 5 per home, thus 10 million homes.

The wood consumption is based on anecdotes of usage from various regions.In the Kullu / Manali region, the typical usage is about 1000kg per year.

In the upper reaches of the Himalayas, such as the upper Kinnaur region, I have been told they use between 1 and 2 tons of wood per year. In other regions the fuel demand could be lower, so an average of 1000kg per household is probably quite reasonable.

Based on North American firewood calculators, (there are such things) they estimate that a tree with a diameter of 22 inches at chest height provides about 1000 kg of usable firewood. 

What are the mortality rates for Household Air Pollution?

World Health Organisation (WHO) statistics on pollution:

3 Billion still using open fire or rudimentary cookstoves globally

800 million suffering from poor health

Indoor and outdoor pollution combined kills around 7 million globally

Household Air Pollution around 4 million globally, 1 million in India


What is your interest in ecological lifestyles?

In my early 20’s (1990 – 1994) I lived on an alternative community that was completely off the grid. We had to supply all our own infrastructure, including power, water and sewerage. We built our own homes, grew veggies, planted fruit trees and lived close to nature in a beautiful coastal environment surrounded by National Parks and forest. It was here I learnt many skills I have continued to find useful, such as building, working with solar power, storing water, working in the garden and using a composting toilet. Power and water was limited to what we had stored, so I became very attuned to careful consumption of these precious resources.

From this period onwards I have had a heightened sense of the ecological requirements of sustainable living, and have been interested in promoting this wherever possible. My extended periods of work and travel in the Himalayas has naturally overlapped with this interest, hence my involvement in various ecological programs in the mountains.

What impact do you see for these projects and over what timeframes?

In simple terms, our mission with the Himalayan Rocket Stove is to save 1million trees over the coming 10 years. There will be additional side benefits that I hope will be measurable, such as reduced impact on women’s health by reducing the heavy loads of wood they carry. Reduced input of CO2 to the atmosphere, as well as reduced black carbon on the glaciers.

With regards to the Smokeless Chulla Project, the mission is to reduce global HAP (Household Air Pollution) mortality rates by 1 million per year over the coming 10 years, although due to the time lag related to the impacts on health, this figure might take a bit longer to achieve. But we will try!

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