Will Hemp Batteries pave the way for the next generation of electric vehicles?
The benefits of the hemp plant are varied and numerous. A companion crop of migrating tribes since the rise of our species, hemp went from the primitive uses as fiber and clothing to refined paper and biofuel. Recently, hemp batteries made from discarded hemp fiber have helped slow mining for rare minerals, and may pave the way for a more sustainable future.
Hemp Batteries are Supercapacitors
A capacitor is an electronic component that stores an electric charge for a short amount of time. Supercapacitors have a higher capacitance than a standard electrolytic capacitor, large reservoirs of energy that can be dispensed quickly to get things moving.
Supercapacitors form the backbone in much of the function of electric vehicles. When vehicles accelerate from a standstill, the lack of kinetic energy means that all vehicles need an extra burst of energy while they accelerate. That’s the job of the supercapacitor. Used in regenerative braking systems, supercapacitors charge using the energy generated when braking, and by storing this for a short period, they can then deliver the extra energy required to get back up to speed once the vehicle accelerates again.
Conventional lithium-ion batteries store energy and expend it slowly. On the other hand, supercapacitors rapidly discharge their entire load to provide high quantities of energy. These typically work together in getting and keeping a car in motion. Hemp batteries operate like supercapactiors in that they expend energy quickly and are not currently able to store a big reserve of energy, like a lithium battery would.
Hemp Batteries Innovate From Waste
While many think that such hi-tech electronics would come from precious metals buried deep in the ground, the raw material for this new form of supercapacitor is much closer to the surface.
Waste fibers from the hemp crop are ideally suited to forming the thin sheets of substrates that line the inside of a supercapacitor. With the bark of the hemp plant converted into carbon nanosheets, the resulting supercapacitors work as effectively as the industry-standard graphene material, which is much more expensive and less environmentally sound.
A study published in 2014 outlined a new method of recycling hemp waste to manufacture supercapacitors. Researcher Dr Mitlin, who headed the study, described the conversion process of the inner bark from the hemp plant that’s typically thrown out. Essentially, hemp fiber is ideally suited to making large sheets with a high surface area, and the resulting material is stronger than diamonds and more conductive than copper.
To obtain the sheet, manufacturers first dissolve the lignin and cellulose, leaving pure carbon nanosheets. By transforming these sheets into electrodes and adding an ionic liquid, the resulting supercapacitor rivals alternatives in terms of both energy density and operating temperature range.
The Hidden Cost of Mining Rare Earth Minerals
There are many cases of human rights abuses across the globe in the quest to mine the rare minerals used in commercial and industrial electronics. Hemp batteries, therefore, provide much promise to anyone concerned with sustainability.
In a study published in the journal Resources (2014), lead researchers expressed concern about the continuation in the growth of rare earth element mining despite the existence of viable alternatives, such as hemp batteries. The study cited the “growing social and environmental concerns” in China regarding the growth of mining and mineral processing. It also questioned the lack of adoptable alternatives. Overall, the research underscores the necessity of a more circular supply chain; and one that follows the industrial and ecological principles of reuse and recycling.
Using plant waste to manufacture batteries is nothing new in the energy sector. In fact, researchers from the University of Alberta in Canada successfully converted banana peels into the dense blocks of carbon used in battery anodes in both sodium-ion batteries (NIB) and lithium-ion batteries (LIB).
Bio-waste offers entrepreneurially-minded individuals with opportunities to nudge society forward in a sustainable manner.
The Drawbacks of Hemp Batteries
While many are quick to proclaim the benefits of hemp, including CBD oil, there’s usually more to each of these benefits than meets the eye. Supercapacitors, while immensely useful across a variety of applications, aren’t actually batteries in the ordinary sense. They don’t provide that longer-lasting mode of storage that lithium does. Rather, hemp batteries provide temporary storage of a charge you can harness quickly. This is why electric cars typically need to recharge over long road trips. So, at this time, hemp batteries can’t replace lithium-ion batteries.
There’s still a ways to go in developing hemp batteries, but advances and continual refinements will come. Meanwhile, early research indicates that hemp batteries could be an important step towards a more sustainable future.
Ali, Saleem. (2014). Social and Environmental Impact of the Rare Earth Industries. Resources. 3. 123-134. 10.3390/resources3010123.