CHALO, CHALO, CHALO!

The word chalo means 'let’s go' in Hindi and I think perfectly sums up the theme of this month. After weeks of research, I was finally ready to start making some biochar!  The plan was to focus on product development and then community engagement. I had read multiple resources, spoken to many experts in the field and used up most of my mobile data watching Youtube videos of people around the world making their own biochar. Feeling inspired, I was ready! There are multiple ways to make biochar but i wanted to go with something tried and tested.

For water treatment purposes, you want char with high micro-porosity and a lot of surface area for SOCs (synthetic organic chemicals) to bind to. In production, your feedstock needs to reach temperatures between 650 and 950 °C. This removes the naturally occurring tars and oily components in your biomass, while converting the remaining carbon-rich material to a graphite-like structure.

My sketches for the TLUD gasifier

I decided to go with a Top Lit Up Draft Gasifier (TLUD). Using a gasifier is more environmentally friendly than traditional charcoal manufacturing. A number of polluting gases are produced during the pyrolysis of biomass, but in a gasifier these are all burned before they can escape into the environment. At the same time the combustion of the gas provides the energy that drives the pyrolysis, so you don’t need an external heat source.

Put simply this is how it works:

Images sourced from http://www.biochar-bangladesh.org/technology_tlud/

The TLUD gasifier is filled with the sustainable forestry biomass. The portion that contains the feed biomass is called the fuel bed. Air can enter the drum through multiple holes at the bottom (primary air) and at the top of the drum, above the fuel bed (secondary air). The gasifier is lit from the top of the fuel bed. An ignition front is formed that moves down through the fuel producing wood gas and leaving unburned biochar above.  The ignition front is supported by the air (primary air) that enters the bottom of the drum.The wood gas is flammable, and burns at the top of the TLUD. This gas flame is supported with air (secondary air) entering through side-holes near the top of the cylinder.When the ignition front reaches the bottom of the drum, the smoke-producing reaction is complete, and the gas fire goes out. At this point, the process must be stopped by smothering and quenching with water to prevent the biochar from burning.  

Animation showing ignition front in gasifier ( Source: http://www.biochar-bangladesh.org/technology_tlud/)

Back home, it’s easy to get your hands on just about anything if you’re willing to pay for it. Here I do not have that luxury. A lot of things aren’t easy to source, so I’ve been forced to improvise and think of creative workarounds.

The challenge of this project is to make the technology low cost and affordable for local people.I have been inspired by India’s use of circular economy, and I certainly wasn’t going to be purchasing a brand new steel drum. So off i went on a scavenger hunt. This was a challenge and at times I felt frustrated. But with the help of our Local Resource Person, I managed to find an old steel drum in the depths of a local’s outhouse.
Finally, things were looking up! I had the base for the gasifier. The next step was to get it fit with a lid and a flue pipe which would have to be done at a metal works (can’t say i have ever tried welding but now was not the time to experiment!)

Living on top of a mountain has its difficulties, especially during monsoon season. Seriously, it has torrential rained for 8 consecutive days straight! The easiest mode of transport is walking as often the roads are taken out by landslides. Hauling the steel drum to the metal works was a challenge. There are no tuk tuk drivers in the area and taxi drivers didn’t want to put my lovely but dirty drum in their car. I contemplated rolling it 4 km down hill in the rain until a local suggested his motorbike. Yes! Me on the back of his bike precariously balancing the steel drum on the exhaust while gripping onto it with both hands. The things you do in the name of engineering! Thankfully it wasn’t far and at a snails-pace (avoiding all dogs, cows and people on the steep road)  we all made it to the welders safe and sound!

 Once at the metal works, came the task of translating my ideas and sketches to the welder. I realised quickly that he understood what i was trying to achieve and we got carried away chatting about best design. Unfortunately, even though i agreed with his suggestions the cost was a separate issue. So next came the hard talk of compromise. I wanted to compromise on cost by reducing some specification while not reducing the robustness of the design.

It was exciting to see something you have designed be built in front of your eyes especially when it was such an effort to source and transport materials. I think i was a bit of a curiosity to the guys at the metal works. Trying to explain my project to them over chai by the end of the day they were calling me the ‘mad scientist’ I will take that as a compliment, i guess! Haha.  

Outside of work fun .... 

Myself and other interns from Himachal Pradesh and from our other centre in Punjab met in Amritsar this weekend for some much needed sun and to soak in some of the culture. The Golden Temple has been on my India bucket list for ages and i was not disappointed! That night we slept and ate in the gurdwara, which has been a highlight of my India experience.

The golden temple is home to the world's largest free kitchen. Apparently, it can serve food for up to 100,000 - 300,000 people every day! At the Langar (Kitchen), food is served to all visitors regardless of religion or background.

We sat down to eat on carpets on the floor and watching what the others are doing I see that an elderly man raises his hands into a cup shape into which a rapid volunteer drops a hot chapati that he then plops into the metallic tray in front of him. Next to him is an woman wearing a green sari raises her hands next and is offered the same. I do the same. On either side of us are hundreds of others, all seated cross-legged, and all with the same metallic tray.

After some sightseeing, sweat and fierce sun,  I was happy to return to the cooler mountain temperatures. Never thought i would be happy to see some rain! I hope that in my next blog, I’ll have some biochar to show you… wish me luck!