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  • Writer's pictureMao Polosky
    • Mar 10
    • 5 min read

Finding Coconut Shell Ash's Place in the World

Project Summary: Using Coconut Shell Ash (CSA) to partially replace cement in concrete


This week, I've been focused on 2 main areas:

  1. Further investigating coconut shell ash compared to other cement replacements (SCMs).

  2. Tracking the burning of the coconut shell ash

I also had a third minor investigation: Coconut Shell Ash as a glaze in pottery.


Comparing CSA with Other SCMs (Supplementary Cementitious Materials i.e. Cement Replacements)

First of all, let's talk about why we are even investigating CSA in the first place. As seen in the maps below, urban zones are set to continuously grow in the next decades, especially in Africa and Asia (see maps below). Therefore, the demand for concrete for roads, bridges, factories, apartments, etc. will continue to grow as well. Concrete, being incredibly cheap and easy-to-use, is still the best construction material we have, so we have to make it more environmental if we are to balance global development and green goals.



But, through talks with Nick and through my research, it seems that current SCMs won't be enough to meet this coming demand. Nick described how GGBFS (Blast Furnace Slag) from iron production is already being used at capacity, and that new, more environmental arc furnaces don't produce on-specification slag that we usually use to replace cement. On top of that, coal production (producing the SCM Fly Ash), especially in regions besides China, is being ramped down due to global agreements (such as the one made at the recent COP Climate Conference suggesting a transition away from fossil fuels). In fact, at Reuters (https://www.reuters.com/business/energy/us-coal-fired-power-plants-scheduled-shut-2021-10-28/) and the US Energy Information Administration (https://www.eia.gov/todayinenergy/detail.php?id=54559), you can see massive shutdowns of coal plants in the next decade. In fact, concrete makers are already looking at unearthing old landfill supplies of Fly Ash to use instead.


(A small fraction of the planned shutdowns of US coal plants in the next years, https://www.reuters.com/business/energy/us-coal-fired-power-plants-scheduled-shut-2021-10-28/)


(Graph of planned retirements of US coal plants, https://www.eia.gov/todayinenergy/detail.php?id=54559)


For this reason, agricultural SCMs (such as CSA) are being investigated to increase the SCM supply. But how does CSA stack up, environmentally, economically, and numerically? This investigation will continue for the next months, but I'll share what I've learned so far about coconut production.


Origins of CSA: Investigating the Coconut Market

On the economic side, the coconut industry is growing at around 1.6% a year, meaning the production will be around 65,367,000 metric tonnes/yr in 2026. As the data from last week's blog post shows, the main coconut producers are Indonesia, Philippines and India (producing around 70% of all coconuts). The presence of coconut in products such as coconut oil, soaps, coconut water, and processed foods makes it an important export product from some of these countries. The fact that almost all parts of the coconut can be used to create useful products also makes coconut less wasteful than other crops. I plan to do more numerical analysis of CSA compared to other SCMs in the coming weeks.


Fun Fact: "The Coconut Water Market in the US is poised to grow by $2.46 billion during 2022-2026, accelerating at a CAGR of 22.27% during the forecast period” (https://www.technavio.com/report/coconut-water-market-in-us-industry-analysis)


(Some data I found on the global coconut market)


(Uses of various parts of the coconut fruit)


Now, speaking of environmental aspects, there's good news and bad news.


The bad news is that coconut farming usually happens in tropical, biodiverse regions and therefore threatens many species, especially those in the mangrove tree regions, which are very essential habitats that coconut farms can destroy. Per volume of oil, coconut is the worst oil crop of all, but looking at species threatened per hectare of land, palm oil is still worse than coconut oil. This could be partly due to coconut farmers being some of the poorest paid farmers in the world, and therefore not being economically able to implement environmental measures. Also, younger generations are increasingly leaving the farms, creating a question of whether coconut farming can keep up with demand in the future.



On the good side, coconut farming can easily be improved with some environmental methods, such as intercropping (planting other crops between coconut trees) with perennial crops, and cover cropping (planting a ground-cover plant in-between the trees). Cover cropping has upfront costs, but has benefits such as less pesticide/herbicide/fertilizer usage, biodiversity protection, reducing pollution, etc. So, with a bit of support and spreading of this information to farmers, I believe that coconut farming can become much more sustainable. Another good thing is that coconut plants can handle a higher threshold of saltwater than other crops, so as ocean levels rise, and saltwater intrusion increases above and below-ground, coconuts may not be as affected. Coconut trees may also help anchor land from erosion and act as carbon sinks.



I will work to quantize the environmental/carbon impacts of coconuts compared to other crops in the near future.


Good News with the Burning of the CSA

This week, we delivered 4 of the 316-grade stainless steel containers to Nick at Fortera to speed up the burning process, and the burning per week has gone from 3kg to 10kg (or more) per batch. Currently, burning is being done for 9 hours at 750 Celsius, but this temperature may be increased for even more efficiency. This is a huge improvement and means we may be able to hit the 3/21 deadline when we have to have 20-30kg of burnt CSA (40-60kg of original material). 3/21 is when we plan on working with Cemex in Livermore to create molds to test the concrete with CSA additions of various percentages. The 60kg of ash from China has also arrived earlier this week.


Glazing for Pottery: An Interesting Use of CSA

Following the conversation with John at Clay Planet, I've researched a bit on the use of CSA as a pottery glaze out of curiosity. Glazes are commonly powders that add a glassy layer on pottery when baked. I learned that glazes require 3 basic parts: Silica (for the glassy finish), Alumina (helping to shrink/adhere the glaze to the pot) and Flux (other chemicals in the mix to disrupt molecular attractions, lowering melting point). Tree ashes are commonly used for this purpose, but CSA has a similar chemical composition


(Example chemical compositions of wood ashes)


(Chemical Composition of CSA)



In the future, if being an SCM doesn't work out, at least coconut shells could find a niche market as a glaze. I'm also looking into coconut shell's effectiveness as an aggregate (the hard rocks/pebbles in concrete) soon.


Another Small Update (Pie Charts Literature Review):

I also researched and created additional pie charts of Rice Husk Ash and Coconut Shell Ash, based on production values:


To Summarize

This week, I:

  • Confirmed the need for more SCMs as concrete use is set to increase while meeting with Nick from Fortera

  • Literature reviewed the general circumstances surrounding SCM production and coconut farming/production

  • Made sure the CSA-burning was progressing at an accelerated rate (10kg/batch)

  • Explored more markets for CSA (pottery glazes)

  • Continued researching agricultural SCM production to make more pie charts

  • Set out goals for the next weeks

  • Discussed small-scale labs with Dr. B


Thank you so much for reading, and see you all next time!

Max Polosky


Fun Coconut Fact 1: There are 3 variants of farmed coconut palms, namely tall (tall), dwarf (short) and hybrid (hybrid of the two former).

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