These and other posts would be technical posts in
the blog as compared to my other blogs (refer page links on the side bar). This
particular post was the first topic that drew my attention to how technology
could blend with nature as opposite to going against it. It prodded me to think how
with the convergence of advanced technology worldwide could help us get from Mother
Nature that was so long awaiting to be gifted to us. Alas, our modern
technology though based heavily on Nature's natural laws seems to be day to day going against the very same Mother Nature.
Introduction
Wood
has long been used as a cooking fuel in India and also world over since a very
long time i.e. long before the advent of commercial fuels in the life of the
common man. Obviously, deforestation issues with accompanied climatic shock
events have then been waiting to manifest as has been witnessed all over the
world in the form of floods, droughts, cyclones, mass migration of humans,
riots, etc. The advents of commercial fuels have been a boon to offset such
deforestation issues. Such a push has been partially successful by most
government authorities in the world and incentives have been offered in
addition to educating the common man regarding the safe and viable uses of
commercial fuels such as LPG at least for the purpose of cooking as against
using wood - for the poorest regions however in the rural sector, such imported
fuels with their inflated prices, would still simply be not a viable option).
Alas, however the deforestation issues continue albeit for a different reason
(out of scope for the present discussion and may be ignored) viz. to accommodate
the exponential growing population by encroaching into the forests and displace
the animal/wildlife therein. This was not sufficient that depletion of such
commercial fuels alongwith the said deforestation issues have been now a major
concern not just for India but for all countries intending to solve their own
energy crisis for the coming future.
While
the forests have been long straining under the demand for wood, largely
untapped fuel resources have also existed parallel since a very long time in
the form of agricultural wastes. We know
that the heating value of a fuel indicates the energy available within the fuel
per unit mass – MJ/kg (BTU/lb). The net heating value is the actual energy
available for heat transfer. The difference in available energy is explained by
the fuel's chemical composition, moisture and ash content. For comparison
purposes, the energy content of fuels are reported on a dry basis. For
example, most agricultural residues have heating values that fall in the range
of 14–19 MJ/kg (6,040–8,200 BTU/lb) whereas coal ranges from 17–30 MJ/kg
(7,300–1,3000 BTU/lb). With this known, could we directly use such readily
available agricultural wastes for cooking? No! While these agricultural wastes would
not be suitable directly for use as household cooking fuels, they could be
transformed into a clean - burning charcoal fuel through simple processes. Some
of the benefits of using such waste products as an alternative
cooking fuel would be as follows:
· Unlike wood, charcoal happens
to be a smokeless fuel. The smoke
produced by wood fires in an indoor cooking environment could lead to multiple
respiratory illnesses.
·
Instead of burning
agricultural wastes in the fields, using the wastes as a fuel source could slow
the advance of deforestation by eliminating the need to cut down trees for fuel
wood.
· Charcoal could be viewed as
an advanced fuel because of its clean-burning nature and the fact is that it
could be stored for long periods of time without degradation.
This
post includes a step-by-step guide to converting the fibrous remains of
sugarcane processing, known as bagasse, into charcoal briquettes that are
largely indistinguishable from wood charcoal. The production of charcoal derived from
agricultural wastes and their storage could help evolve a micro- enterprise
wherein any entrepreneur including sugarcane farmers could create bagasse
charcoal briquettes and sell them in the local marketplace for personal
income. In this way, more money could stay
within the community rather than being exported for conventional fuels. By turning something that was previously
unused into a means by which to produce income, the wealth of individual
entrepreneurs and the country in general could increase.
There
is therefore a need for an alternative cooking fuel option in light of the rise
in deforestation and dwindling fossil fuels.
The subsequent sections in this post would describe one possible de - centralized
solution to the problem. If successful in every rural household, the same could
be thought progressively from the point of view of fueling our kitchen in urban/cities
of the country.
The
Process: How to Convert Sugarcane
Waste into Charcoal Briquettes
We know that in every commercial extraction
processes, we have at the least two main outputs for some inputs viz. a product
and a by – product. In the extraction of sugar from sugarcane, the sugar would
be the product and after sugarcane is pressed to extract the sugar contained
within the plant, a large amount of fibrous waste remains. This waste is known as bagasse which would be
either burned in the fields or in more advanced sugar refineries, used to
partially fuel the sugar extraction process.
When bagasse burns in its raw state, heat and thick yellow smoke are
produced. This smoke makes raw bagasse
an unsuitable indoor cooking fuel. Hence,
before bagasse could be used for this application, it must undergo a process by
which the raw fibrous waste could be converted into charcoal briquettes i.e.
charcoal fines be first made from the bagasse for which all of the bagasse needs
to be extremely dry. Sun - dry in the open air until dry to the touch would be
the most economical option. After this would come the process of converting the
dry bagasse into charcoal fines (i.e. charcoal dust) for which a kiln of some
sort would be required. Why the kiln
would be required? This is because a high temperature would be needed for the
ensuing carbonization process i.e. charcoal would be the carbon substance that would
remain when organic matter such as wood or bagasse is heated to a high
temperature but in a low-oxygen environment. Why the low oxygen environment?
Why not simply burn? This would be because bagasse being both the needed fuel
and the material that would be carbonized, which calls for a balance that must
be reached between the two objectives viz. creating heat and creating charcoal
fines with little or no trace of ash mixed with the charcoal dust. Hence, air flow
must be carefully restricted at the optimum time (when the proper temperature
is reached ~270˚C) so that the majority of bagasse remains unburned ready to be
converted into charcoal fines when the kiln then would be sealed such that very
little oxygen would be present inside for the carbonization to take place. The
kiln thus provide with the means for creating this low-oxygen heated
environment.
Normally, most of the literature references on this
already known method suggest the oil drum kiln to be one of the simplest kilns
to construct and use that may need to be modified if other materials such as
peanut shells or sawdust are to be carbonized. A frugal engineering approach
could also be considered at the governmental level to disburse those LPG
cylinders that are unused – on account of growing instances of piped gas
systems/unusable – on account of deterioration of the cylinders, at the rural community
level for re - fabricating the same as a kiln (similar to the oil drum) thereby
incentivizing the community to help start up such alternative cooking fuel ventures.
A detailed description regarding such frugal engineering approach could be
availed in my next coming blog. Please note that the details is under patent
considerations in India and therefore could also be availed from the patent
website (http://www.ipindia.nic.in) in search
tab for the title: Converting
agricultural waste (bagasse) into charcoal briquettes (alternate cooking fuel)
through unused /unusable liquefied petroleum gas (LPG) cylinders employing a
frugal engineering approach and publication date: 06/11/2015.
Now, to continue with our discussion we have the
prepared charcoal fines/dust ready. Again the direct use of such dust would
amount to environment pollution and serious health hazards. Hence, the charcoal
fines need to be introduced into the fire grate as a solid fuel whose ash after
burning would collect on the hearth below. Here, again we employ technology of
composites wherein, we mix the charcoal fines to some locally available binder
and allow it to harden in the open sun that resembles to the age old practice
of collecting cow dungs, kneading them into dough and sticking them on the
walls of the back house/cowshed to dry in the hot sun. Once hardened it
automatically loosens from the walls and collects on the floor.
Since the binder and charcoal fines alone serve
little use as fuel; therefore a composite of the same could help leverage the
benefits of both. So, the enterprise would need to prepare the binder parallel to
the preparation of the charcoal fines. Depending upon the binder material the
time for readying it as binder may vary. It inherently could serve as glue (as the
cow dung does) or it needs to be prepared to serve as glue. In both cases the
binder glue and the charcoal fines need to be mixed in proper composition. A cement
concrete is a composite and we know that improper mix of the cement and sand
particles would lead to a faulty construction. A good indicator therefore that one
has added the correct amount of binder would be when one can easily form some
of the charcoal fines – binder mix into a ball that holds its shape without
falling apart. If it falls apart, then it implies excess of the charcoal fines
present in the binder. If the mixture is very sticky and consequently difficult
to hand-form into a ball, one may have added too much of the binder. After the
briquettes are formed, they need to be dried in the sun for approximately one
week.
 |
| A photograph of one of the larger bagasse charcoal briquettes |
Even though this post concentrates on the conversion of bagasse, other types of agricultural wastes such as peanut shells, coconut husks and saw dust could also be converted into charcoal briquettes by employing similar composite making techniques.
References
[1] D.S Chahal. “Food, Feed &
Fuel from Biomass”, reprint 1991,
pp.23.
[2] N.H. Ravindranath, K. Usha
Rao, Bhaskar Natranjan. “Renewable Energy & Environment”, 2nd reprint 2000 pp.106, 242.
[3] L.A Ekal, S.H Pawar.
“Advances in renewable energy
technologies”, 1st reprint pp.35, 194.
[4] S. Rao, Dr. B.B. Parulekar.
“Energy Technology”, 2nd edition, 1997.
[5] G.D Rai. “Energy Resources”,
3rd edition, 1999.
[6]
http://164.100.24.208/Is/committeeR/Food/27.pdf
[7]
http://bioproductsbioenergy.gov/pdfs/bcota/abstracts/30/z130.pdf
[8] http://
Polystyrene#Environmental impact
[9] www.springerlink.com/index/232k30g002472824.pdf
[10]
http://www.vsisugar.com
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