Using cashew shell as a source of energy – Cashew shell uses

Cashew nut is a name that is no longer strange to consumers around the world. However, the part people often use is just the kernel, what about the other parts? Have you ever wondered about their uses? Especially the cashew shell – one of the most toxic parts of the cashew fruit, they are used as a source of energy. Keep reading this post to know how to use cashew shells as a source of energy. 

Does cashew have a shell?

The cashew tree is in the same family as poison ivy and produces a similar oil. The reason cashews are sold pre-shelled is that form a hard wall directly around the seed, cashew shells have a lining that is filled with fluid. This fluid is caustic and can cause burns or rashes to your skin. The part that we consider a “nut” is held between two layers of hard shell containing cardol and anacardic acid

What toxins does the cashew nutshell contain?

Cashews contain a natural toxin called urushiol in their raw, unprocessed state. The toxin is found around the cashew shell and can leach out onto the exterior of the nut itself.

The shell of the cashew nut contains oil compounds that can cause contact dermatitis similar to poison ivy, primarily resulting from phenolic lipids, anacardic acid, and cardanol. Due to possible dermatitis, cashews are typically not sold in the shell to consumers. Readily and inexpensively extracted from the waste shells, cardanol is under research for its potential applications in nanomaterials and biotechnology.

Cashews naturally contain a toxin called urushiol. Urushiol is a substance found in all members of the Anacardiaceae family of trees, which includes cashews, mango, poison ivy, poison oak, sumac, Peruvian peppers, and pistachios. While urushiol resides in all parts of the plant, including the roots, stem, and leaves, it also tends to sit in the oil between the cashew shell and nut inside.

How does the poison in the cashew shell affect the user? 

Coming into contact with urushiol commonly results in allergic contact dermatitis, a delayed skin rash in humans that’s similar to the one you might experience after exposure to poison ivy. An urushiol-induced skin rash appears as bumps or patches on the skin that are itchy, inflamed, and may have secretions, potentially even causing an intense burning sensation or localized swelling

If you were to handle or consume cashews in their raw form, you would likely experience a reaction similar to that caused by poison ivy, such as an itchy and inflamed skin rash that may cause a burning sensation. However, even cashews labeled as raw at the grocery store have been shelled and heat-treated to remove any urushiol residue to prevent consumers from having this reaction.

Energy from a cashew nutshell

Cashew nut shells are one of the most abundant forms of tropical biomass waste which can be used for energy generation. The cashew comprises approximately 30% nut and 60% shell. While the nut is eaten throughout the world, the Cashew nutshells are very hard to peel. Cashew shell is usually 0.4 cm thick, accounting for 60% of the grain weight, including three layers: the outer layer is green, smooth. A honeycombed porous layer, in between the outer shell and the inside containing phenolic oil, known as cashew nut shell liquid (CNSL). The shell is gray in color, very hard, and covered with silk.

The figures below show the overview of cashew nutshell:

The chemical composition of cashew shells includes cellulose, sugar, minerals, protein, ash, carbon, and cashew nut shell liquid…

– For each 1000kg raw cashew nuts, 35-45% cashew nuts will be gained. Assumed that 350kg nuts are harvested, we have the following mass flow of cashew nut processing.

– 25 to 35% of this hard cashew is comprised of Cashew Nut Shell Liquid (CNSL), a vicious and caustic substance. CNSL has a similar quality and heat content to Light Fuel Oil (LFO). Both the CNSL and CNS are used as biomass fuels for clean power generation.

– Biochars are created in the processing of cashew nut shells along with other bioproducts. Biochars have a high carbon content (70-75 wt%) and high heating values in the range of 25-28 MJ kg-1and can therefore be used as an energy source.

– Bio-oils have been shown to have a higher heating value than biochar with 32 MJ kg-1. Bio-oil is not suitable for use in pure form but can be used in mixtures with Diesel. The gas-phase of bio-oil is predominantly CO2 and CO below 4000C with a greater formation of H2.

– Gasification is a thermo-chemical process that converts carbon-containing fuels into combustible gas through incomplete combustion and reduction. The combustible gas can then be used in internal combustion engines or gas turbines, burned directly, or used in the production of methanol or hydrogen.

Produce charcoal from a cashew nutshell

At 2000 degrees Celsius, the oil in the cashew shell began to be gradually removed. Continuing to increase the temperature to 4000 degrees Celsius about 90% of the oil was removed. The shell of the cashew was burned to charcoal: coal has a darker color and darker color. Raise the temperature to 6000 degrees Celsius, charcoal has been heavily modified in structural composition. Appears many burned links in the blue form

Although cashew shell is used as an energy source, we need to be careful in the production process because it can cause many toxic properties.