Are hemp batteries the new green future? The hemp industry is making a rebound for the first time in decades as the long-held boycotts against the plant’s development lift across the U.S. As cannabis with THC is legalized for medicinal and recreational use across the nation, it is helping to fuel the acceptance of industrial hemp. Though industrial hemp (cannabis sativa) and cannabis (cannabis sativa var. indica) originate from a comparable type of plant, they are altogether different—even though at first glance they look like the same plant. Since the 1950s, the U.S. has grouped non-psychoactive hemp, cannabis sativa, into the same classification with medicinal cannabis and consequently killed the hemp industry. The U.S. now permits restricted development of industrial hemp.
There are a lot of new and older uses for hemp fiber, which grows so fast it can easily outrun a tree for faster, cheaper paper production and support the environment as it grows. Recent research into uses for the hemp plant have found that filaments originating from the inward bark of the hemp plant can pack as much energy and power as graphene, which has been hyped as the model material for supercapacitors. Graphene is a layered growth produced from the decomposition of silicon carbide—an extremely complicated and expensive process. The decomposition produces an atom-thick layer of carbon used to create nanosheets for capacitor electrodes.
Years of research have been done by Dr. David Mitlin, a professor at New York’s Clarkson University, on harvesting hemp as a replacement for graphene for energy storage. The process utilizes the inner bark (bast) of the hemp plant, a waste product from hemp production, which is thrown into the trash by businesses that utilize hemp for garments, development materials and various other items. Mitlin’s research has shown supercapacitors made from this hemp trash have been able to store 12 watt-hours of energy per kilogram—over 2x as high as conventional supercapacitors.
“We’re making graphene-like materials for a thousandth of the price—and we’re doing it with waste. The hemp we use is perfectly legal to grow. It has no THC in it at all—so there’s no overlap with any recreational activities,” said Mitlin
Supercapacitors are energy stockpiling devices that could possibly change the way future hardware is powered. Rechargeable batteries use up their energy in only a few hours. Supercapacitors charge and release in seconds. Their energy density (the amount of energy stored per unit mass) is different from regular/rechargeable batteries (which store a great deal more energy, but release it slowly over time). Analysts have been looking for ways to help produce supercapacitors’ energy density cheaply. Mitlin’s research has created a pathway for how to make better electrodes from certain hemp strands, which can hold as much energy as graphene and are cheaper to manufacture.
The hemp bast is heated for 24 hours at 350 F. Then adding even more heat afterward, Mitlin found he could turn the bast into carbon nanosheets, much like the conventional graphene nanosheets. In a 2014 interview with American Chemical Society, Mitlin noted, “We’re past the proof-of-principle stage for the fully functional supercapacitor. Now we’re gearing up for small-scale manufacturing.” After industrial hemp became legal to grow in the U.S. in late 2018, Texas-based alternative energy storage research company Alternet Systems secured land in New York to grow hemp and hired Mitlin to power motorbikes for its ReVolt Electric Motorbikes subsidiary.
“Our device’s electrochemical performance is on par with or better than graphene-based devices,” Mitlin says. “The key advantage is that our electrodes are made from biowaste using a simple process, and therefore are much cheaper than graphene.”
Research into graphene has been exploring how to exploit its properties to assemble better sun-powered cells, water filtration frameworks, touch-screen innovations and supercapacitors. The main problem with graphene is it’s very costly to make—hemp may just be a much better option. Researchers have suspected for a long time there was more to hemp bast—it was simply an issue of determining the right approach to process the material.
Researchers are constantly looking for sustainable and efficient ways to create battery power. Research into the efficiency of hemp batteries has concluded industrial hemp could be part of the future of battery-powered vehicles. Could hemp batteries pave the way for the next generation of electric vehicles?
Henry Ford’s original Model T was partially composed of hemp “bioplastic” and powered by hemp biofuel. Ford had developed what should have been a revolutionary invention: a car powered by and largely built of hemp. Popular Mechanics described Ford’s work in 1941 as “a step toward materialization of Henry Ford’s belief that someday he would ‘grow automobiles from the soil.’
Supercapacitors form the mainstay in much of the function of electric vehicles. All vehicles need an extra burst of energy when they accelerate from a standstill, and that’s the job of the supercapacitor. Used in braking systems, supercapacitors charge using the energy generated when braking, and by storing this for a short period, they can then deliver the energy required to get back up to speed once the vehicle accelerates again.
With the climate crisis looming, battery-powered vehicles are beginning to displace combustion engines. More recent research has shown that hemp batteries can be more powerful than commonly used lithium and graphene. Researcher and YouTuber Robert Murray Smith discusses the research and experiments in a recent video on YouTube. In Smith’s experiments he observed a Volts by Amps curve of both the hemp and lithium batteries and found that the power underneath the hemp cell was a value of 31 while that of the lithium cell had a value of just 4. Smith said the results of his experiment showed that the performance of the hemp cell is “significantly better” than the lithium cell.
Research indicates that hemp batteries could be an important step toward a more sustainable future. We now know that there is no need to destroy the environment by mining for lithium and the materials that are used in traditional batteries. We can literally grow technology. Is there anything that this underused plant can’t do?