Torrefaction can be the inexpensive technique for biochar production, as the biomass is treated using indirect heat (like steam) in this process with the temperature range of 200-300°C and residence time could be less than one hour.

I've used a muffle furnace under oxygen-free condition. I worked on fast pyrolysis but you still can use it for slow pyrolysis. From my point of view, it is an economical method and easy to be conducted.

Dear Zubia Anwar

I recommended you to kindly study the gasification methods about your query. In this we have different types of equipment with their own properties. like downdraft gasifier, updraft gasifier, cross draft gasifier.

regards.

One of the cost effective way is digging a cone hole on the ground and putting materials little by little. The key factor is cone shape of the hole. It's not precise method, but of course cost effective and practical. Here is a link to YouTube which explain how it works:

https://youtu.be/h9J7J4fQHpo

@ Shaima Alsaidi

Thanks for giving me suggestion related to the biochar production methodology.

Can u assist me by sharing your methodology used for biochar production by using muffle furnance.

Looking forward to hearing back from you

Zubia Anwar