I was talking to Vaibhav, who is building https://www.gocirkla.com/. Cirkla is a sustainability solutions startup that helps brands replace plastics with viable alternatives.
During the conversation, he mentioned how wheat straw that is usually burnt (stubble burning) could be instead converted into pulp and then into molded fiber products. Molded fiber products are compostable and can be used for food packaging & a lot more. Think of Swiggy & Zomato packaging that are home compostable.
While there are existing mills today converting wheat straw agrowaste to pulp, but not at the scale, which can significantly impact stubble burning. This is because today only paper and paperboards are made out of pulp.
He mentioned
Molded fiber is a potential solution after the agrowaste fiber has been converted into pulp. Pulp usually sells for $800-900 per ton in international market, but molded fiber products are sold for $2500-5000 per ton. The increased net revenue per ton can make the reverse logistics of straw collection economical. Export of pulp from India is banned, but molded fiber can be exported.
A typical pulp mill would need ~$20M investment for a 100TPD (tons per day) capacity.
A typical molded fiber plant would need ~$10M for a 25TPD capacity.
Today, India isn’t producing or consuming molded fiber due to higher upfront capex and higher costs compared to traditional plastics since it has to be imported from China, Indonesia, etc.
I don’t know enough, but my first thoughts are that molded fiber can potentially solve for stubble burning and also our plastic waste problem.
I will request Vaibhav to answer if there are any follow on queries.
Vaibhav, what will be the water requirement for this wheat straw conversion to pulp? My question is is it so large that this negates the impact of stopping stubble burning? Also, will the water utilisation be much higher for the traditional plastic, which molded fibre is trying to replace?
There are two major steps of conversion from agrowaste to final product.
Agrowaste Fiber to Pulp - 40 ltr/kg
Pulp to Molded Fiber Product - 3 ltr/kg
So on an average, the conversion process uses 43 ltr/kg of output. This is high compared to plastic production. However, water consumption cannot be the only factor to be looked at when evaluating competing technologies. We need to look at their cradle-to-grave life cycle assessment.
Here is an example of an LCA chart which compares a molded fiber tray to plastic alternative.
Compared to alternative products, the molded fiber product:
Has the lowest impact in 3/6 categories
Ranks in the middle for 2/6 categories
Has the highest impact in 1/6 categories
Another chart compares the Global Warming metric. The cradle-to-grave carbon
footprint of the molded fiber tray is 39% less than an EPS alternative and 47% less than a PET alternative.
We would need to quantify the impact of stubble burning and then compare it with the overall footprint of pulping and molded fiber production. There is a high probability that we would be better off not burning the agrowaste.
@VaibhavGoel While I actively try to not use Plastic as much as I can, I always worry about the plastic waste I generate everytime I order any food from Swiggy/Zomato. It’s great to see that molded fiber products can substitute them economically.
In context of stubble burning, can you also shed some light on the upstream process of gathering of agro-waste? A plant with a 100TPD/day capacity which makes the pricing of these products competitive will require a significant amount of agro-waste as raw materials.
So, are current technologies and machines available to cut wheat/paddy straws effectively at scale?
Secondly, the major reason farmers go for stubble buring is that they want to clear the field as fast as possible for the coming sowing season. Hence, the solution also needs to be fast enough to remove agri-waste to not delay the coming crop. Fast enough to remove 23 Million Tonnes of just paddy stubble that are burnt every year within a short span of just 10-15 days.
@VaibhavGoel Also, you can finance a part of your project through carbon financing as well since you’ll clearly be generating ‘Avoidance Carbon Credits’ for every molded fibrer product that you manufacture.
If you’re not doing this already, let me know. I have been working in the carbon markets space and can connect you to relevant folks to implement it.
We can assume a 1/3 ratio for conversion. So for a 100TPD output, we need 300TPD of agrowaste. Based on our research, farmers have enough time for wheat straw stubble removal (30-45days) compared to paddy (10-15 days). We’ve not yet seen paddy straw implementation for pulp/moulded fibre products yet. However, wheat straw has been implemented in countries such as US at scale. And that would be the initial focus.
We are early stages of evaluating the full scope of a project like this, financing/carbon credits being an area we haven’t touched upon yet. Will get in touch with you at the right time.
@VaibhavGoel can you share how the residua slurry is disposed?
The process of conversion to slurry requires removing lignin from the stubble which requires either washing with sodium carbonate or strong acid. Both of which produce a waste which we call in industry as "Black Liquor"
How would you deal with black liquor at scale
Approximately 7 tonnes of black liquor are produced in the manufacture of one tonne of pulp.[2]
Way back I was called to a paper making factory in barnala by JK, to find solution. But couldn’t come up with anything to work at that scale. How is the solution landscape now? Are there viable, scalable solutions?
I spoke with the MD of Satia Industries Limited, which runs one of the largest pulp mill which uses wheatstraw as an input. They process the black liquor using a caustic soda recovery plant, at scale.
