Waste to Energy: Research puts walnut shell into use as battery material

Waste to Energy: Research puts walnut shell into use as battery material

In a novel idea, scientists at Pune-based Indian Institute of Science, Education and Research (IISER) are in a process to find a solution for thousands of tonnes of walnut shells left behind by growers and walnut processors in Kashmir. The idea, a brainchild of post-doctoral student Wahid Malik, who belongs to Verinag in Anantnag (Islamabad) district and currently conducting research at IISER, came into being nine months back when he was visiting Kashmir for a vacation.

Speaking to Greater Kashmir from Pune, senior scientist Satischandra Ogale, under whom Malik is working said the researchers at IISER “processed the nutshell to obtain high-quality carbon which is to be used in the anode part of the sodium-ion battery.”

“These batteries are similar to popular li-ion batteries but are expected to be much cheaper due to the few thousand-fold higher abundance of sodium over lithium in nature,” Ogale said. Battery systems are crucial for all renewable energy resource management and usage, including grid-based set ups, electric vehicles and biomedical or handheld devices, Ogale said.

According to the study of the IISER team, 63,000 hectares of land is under cultivation of walnuts in Kashmir. Of the total 36,000 tonnes of organic waste generated from the farm produce, 15,000 tonnes is contributed by walnut shells alone.

“The crushed shells are first cleansed using acids and then subjected to ‘pyrolysis’ process where it is heated at high temperatures such as 1000 degrees Celsius for about four to five hours. Later the carbon chunks are extracted within the specially created inert atmosphere before it is powered or converted into a paste form,” Ogale said.

Ogale said a major advantage of using the nutshell is its natural composition. He said, “Walnut shell foliage suits the requirements once it is treated chemically, giving an edge over other natural resource substances.” 

“Na-ion batteries are expected to be much cheaper than the lithium batteries and can make the overall setups affordable,” Ogale said. If this technique becomes commercially viable, farmers in the Valley can have an additional source of income, added Ogale. 

The leftover organic waste of walnut is presently used in making packaging products which just utilizes five to ten per cent of the waste while the rest is unattended causing serious concerns to the cultivators, the researchers said. The cultivators even burn it further resulting to air pollution. “At the lab testing stage, the scientists were able to extract about 300 – 400 mg of battery grade carbon from one gram of power obtained from the shell,” Ogale said.

Zain-ul-Abideen, president, Kashmir Food Processors Association said as of now the walnut shell is being used only for cosmetic products such as face-scrubs etc but does not provide the grower enough returns. He said the breakthrough at Pune institute is “worth appreciating” and must be supported by the state governments of Maharashtra and J&K.

“The electrolytic process being undertaken by the Pune scientists can even help to address the electricity crisis in Kashmir. If it is novel and innovative, the technology needs to be brought from lab to field,” Abideen said. 

Bahadaur Khan, president All Kashmir Walnut Growers Association said the walnut shell till now used to be sold outside the state but there is no processing unit in Kashmir which can put the walnut waste to use.

“The news about research is quite exciting and will add value to the walnut industry,” Khan said.