Originally published 2019-10-17.
Are hemp batteries really more powerful than lithium or graphene? Not in the way the viral headlines suggested. What exists is solid research showing that carbon made from waste hemp fibre can form excellent electrodes for supercapacitors, and a home-lab video in which a British experimenter found a hemp-carbon cell delivering more power than a small lithium cell in his test. Both are genuinely interesting. Neither shows that hemp has replaced the lithium-ion battery in your phone or car.
This guide explains where the claim came from, what the 2014 university research found, why "power" and "energy" are not the same thing, and where hemp-derived carbon could realistically be useful.
Where the viral claim started
In 2019 a wave of articles reported that "hemp batteries" beat lithium. Most traced back to a video by Robert Murray-Smith, a British chemist and inventor who runs a popular YouTube channel about materials and energy experiments. He built a cell using hemp-derived carbon and compared its current–voltage curve with that of a lithium cell.
In his test, the area under the hemp cell's power curve came out at roughly 31, against about 4 for the lithium cell, according to reports of the video. Murray-Smith himself was careful: he presented this as a demonstration, not as proof, describing the hemp cell's performance as "significantly better" in that comparison. You can watch his experiment here:
A single bench test, with one lithium cell of unknown age and design, cannot rank whole technologies. It is a useful prompt for curiosity, but the stronger evidence comes from peer-reviewed lab work published years earlier.
The 2014 hemp supercapacitor research
In August 2014, chemical engineer Dr David Mitlin presented research at the American Chemical Society's national meeting in San Francisco. The work had been done at the University of Alberta in Canada; Mitlin was by then moving to Clarkson University in New York, which is why some reports placed the whole project in the United States.
His team started with hemp bast fibre, the fibrous material from the plant's bark that Canadian hemp processors often discarded. They heated the fibres for about a day at a little over 175°C (350°F) and then at much higher temperatures, which split them into extremely thin carbon nanosheets. Those sheets became the electrodes of supercapacitors, with an ionic liquid as the electrolyte.
The results were impressive for a waste material. The devices reached energy densities of up to 12 watt-hours per kilogram, two to three times higher than the commercial supercapacitors they were compared with, and performance on par with or better than graphene-based devices. They also kept working from freezing point to above 93°C (200°F), a wider range than typical commercial units.
Why the graphene comparison caught attention
Graphene, a single layer of carbon atoms arranged in a honeycomb, is one of the most celebrated materials of the century. It is extremely strong, conducts electricity superbly and has a vast surface area, which makes it attractive for electrodes. Its big drawback is cost: producing high-quality graphene at scale remains expensive.
That is what made Mitlin's work stand out. Hemp nanosheets share some of graphene's useful properties, such as a thin, highly porous structure, but they are made from cheap agricultural waste using a fairly simple heating process. Press coverage at the time described hemp carbon as costing a tiny fraction of graphene; the exact ratio depends heavily on which grade of graphene is being compared, so it is safest to say "far cheaper" rather than quote a precise multiple.
Supercapacitors and batteries do different jobs
The biggest source of confusion in the hemp story is the word "battery". The 2014 devices were supercapacitors, and supercapacitors are not drop-in replacements for lithium-ion batteries.
- Energy is how much charge a device can hold. Lithium-ion batteries store roughly 100 to 265 watt-hours per kilogram. Supercapacitors typically store around 0.5 to 15, so even an excellent one holds a small fraction of a battery's energy.
- Power is how fast that energy can be delivered or absorbed. Here supercapacitors win comfortably, often by a factor of 10 to 100.
- Lifespan also differs. A supercapacitor can survive hundreds of thousands or even a million charge cycles; a lithium-ion battery usually manages hundreds to a few thousand.
A simple way to picture it: a battery is a large tank that releases water steadily through a tap, while a supercapacitor is a bucket you can fill and empty almost instantly. That makes supercapacitors ideal for regenerative braking in buses and trains, cranes and lifts, camera flashes, and backup power for memory chips, where short bursts matter more than long runtime.
From lab to motorbikes?
Mitlin said in 2014 that his team had moved past proof of principle and was preparing for small-scale manufacturing with a Canadian start-up. In 2018, Alternet Systems, a Texas company with an electric motorcycle unit called ReVolt, reportedly announced plans to work with Mitlin on hemp-based energy storage. Public information on how far that partnership progressed is limited, so it is best seen as an announced plan rather than a product on the road.
Hemp-derived carbon remains an active research topic, alongside carbons made from coconut shells, wood and other biomass. The appeal is the same in each case: turning cheap, renewable waste into high-value electrode material.
Common myths about hemp batteries
"Hemp batteries are eight times better than lithium." That figure, taken from the 31-versus-4 result, comes from one home test of power, not energy, and cannot be generalised.
"Hemp will replace lithium in electric cars." Current hemp-carbon devices are supercapacitors with far lower energy storage. At most, they could complement batteries by handling bursts of power.
"Hemp carbon is graphene." It is not. It is a different carbon nanomaterial that can rival graphene in some electrode uses at much lower cost.
Why hemp is worth watching anyway
Industrial hemp is a low-THC variety of cannabis grown for fibre, seeds and oil, and it already finds its way into textiles, paper, building materials such as hempcrete, food and bioplastics. Since the United States removed hemp from its list of controlled substances in the 2018 Farm Bill, more farmers can grow it legally, which means more by-products looking for a use.
Turning those leftovers into energy-storage materials will not make lithium obsolete, but it could make some parts of the energy transition cheaper and cleaner. That is a more modest headline than "hemp beats lithium", and a much more believable one.
Sources: ScienceDaily / American Chemical Society: hemp-based supercapacitors, August 2014; BBC News coverage of the 2014 research; Wikipedia: Supercapacitor (energy and power comparisons); Wikipedia: Hemp; Robert Murray-Smith's video experiment on YouTube.
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