Hemp Battery Research: Can Hemp Waste Store Clean Energy?
From hemp hurds to energy storage: a plain-language look at four real studies, their results, and the limits the labs haven't solved yet.
Hemp isn't replacing lithium-ion batteries yet. What researchers are doing is quieter and, in some ways, more interesting. They have found that hemp, especially the leftovers from hemp processing, already has a built-in architecture of layers, tubes and pores. They are putting that architecture to work inside new energy-storage devices.
Three studies have directly explored hemp in energy storage. A fourth, from 2021, supplies the cement-battery foundation that the latest hemp work builds on.
Hemp is used in three different ways:
2013: turn the fibre's structure into nanoscale carbon sheets.
2024: turn hemp hurd (the woody core) into porous activated carbon.
2025: skip the carbon step and mix the hemp fibre itself into cement to build better pathways for ions.
In short: Can hemp be used in batteries? Yes, as a component, in two ways. Hemp can be baked into thin carbon that stores electric charge in supercapacitors, or hemp fibre can be mixed into cement so a cement battery works better. Everything so far is lab-scale.
The Hemp Energy Timeline: 2013 to 2025
2013: The Hemp Supercapacitor
The story: A team at the University of Alberta, Canada, wanted the power of graphene without its price. A supercapacitor is a sprinter: it charges and releases energy very fast but holds little. Graphene works well in one, but the authors say even the cheapest graphene-like material cannot match the price of carbon made from plant waste.
Why hemp:
The authors describe hemp as a fast-growing, low-input crop with centuries of use, though real-world water, nutrient and pest needs vary by variety and climate.
The hemp fibre wall is built in layers, like plywood. The thick middle layer is mostly crystalline cellulose.
Earlier hemp-derived carbons had not been fully tested for energy storage.
What they did: They cooked hemp fibre in dilute acid at 180 °C for a day. This softens the glue between the layers. Then potash (potassium hydroxide) at 700-800 °C pried the layers apart into thin sheets. The paper reports that skipping the first cooking step gave no sheets.
What they found:
The carbon sheets were 10-30 nanometres thick, thousands of times thinner than a human hair.
A single gram had a surface area of up to 2,287 m², close to nine tennis courts (a tennis court is about 260 m²).
The authors estimate a complete device could recharge in under six seconds. This is a projection from their electrode tests, not a measured full-size device.
Its energy, estimated for a whole device, was 12 Wh/kg. For comparison, lithium-ion batteries commonly hold roughly 100-250 Wh/kg (a general figure, not from these papers).
After a small early dip, it kept 96% of its capacity over 10,000 cycles.
Their view of the future: They call the method promising for large-scale production of high-performance carbon, for energy storage and other uses.
Our takeaway: Think of the fibre wall as a book with its pages glued together. The acid cook softens the glue, and the potash opens the pages into separate sheets. Each sheet is so thin that the charged particles only need a short walk. Their own formula says travel time grows with the square of the distance, so half the distance means a quarter of the time. That is why thin sheets charge so fast. And the hemp had to be cooked first, so its structure is a gift but only the right recipe unlocks it.
2021: The Cement Battery, Before Hemp Joined
The story: Researchers at Chalmers University, Sweden, report that no one had investigated rechargeable concrete batteries before, so they built one. It is a sandwich of three layers: an iron layer, a cement middle layer, and a nickel layer. Hemp isn't mentioned. They chose carbon fibre mesh because carbon black and nanotubes are costly and hard to mix.
What they found:
Plating the metals onto the mesh worked far better than mixing metal powder into cement. In their liquid-electrolyte tests it gave about 7 Wh/m² against about 0.5, roughly 14 times better.
Zinc was not suitable as an anode.
The finished battery averaged about 7 Wh/m² and slowly lost capacity over six cycles.
Their view of the future: The energy per square metre is markedly lower than commercial batteries, but a building has an enormous volume, so the total could be large.
Our takeaway: Two lessons here. First, how you build the electrode matters as much as what it is made of. Second, getting ions to move through cement is a likely weak spot. The Chalmers team added a special resin just to help hydroxide ions travel. That is a gap hemp would later try to fill.
2024: Hemp Activated Carbon, Cooked Gently
The story: At Murdoch University in Australia, with partners in Japan, a team asked whether the cheapest part of hemp could do the job. They used the hurd, the woody core.
Why hemp:
Ordinary activated carbon typically needs two high-heat steps around 800 °C, which the authors say raises cost.
The authors say only about a quarter of the fibre from hemp processing is useful.
The outer part of the hurd has connected pores that ions can attach to.
Hemp naturally holds minerals like calcium and phosphorus, which the authors think helped shape the carbon.
What they did: They baked the hurd at 300 °C to make charcoal. Then they mixed it with potash and heated it to just 450 °C for an hour. Keeping a lid on the pot during the first bake kept 38% of the material as charcoal, against 21% with the lid open.
What they found:
Surface area was about 1,196 m² per gram, over four tennis courts.
At 800 °C the honeycomb started to break down, and surface area dropped.
The device is a hybrid sodium-ion capacitor. Hemp carbon works as the negative electrode. The authors found it unsuitable as the positive one, so manganese dioxide fills that role and supplies the high voltage.
In a water-based electrolyte it reached 38 Wh/kg and kept about 91% of its capacity after 1,000 cycles. The hemp electrode alone kept 98.3% after 15,000.
Their view of the future: They say this could replace costly carbon materials and allow economical large-scale production.
Our takeaway: Gentle beat harsh. Hotter was not better, because at 800 °C the melted potash disrupted the very structure they wanted. A water-based electrolyte is cheaper and safer, but water splits apart above about 2 volts, so the device is capped there. And hemp carbon only works well as one side of the device, the negative side, so a second material does the other side. As the 2013 and 2024 papers show, how you cook hemp decides how much useful carbon you keep.
2025: The Hemp Cement Battery
The story: At Tennessee State University, a team added hemp fibre to the cement battery's middle layer. The work appeared in the Journal of Energy Storage (volume 135, 2025).
Why hemp:
The authors call it affordable, renewable and biodegradable.
Hemp fibres tend to add tiny pores and channels in cement.
A cement battery is solid, so its charged particles can only travel through water inside those pores.
Hemp soaks up water. At just 2% hemp, the electrolyte's resistance fell sharply.
What they did: They crushed hemp straw, sieved it, soaked it in potash for three hours, and rinsed it. Then they mixed 2-5% of it into the cement layer.
What they found:
4% hemp was the sweet spot. Ionic conductivity rose about five times, and porosity (measured from electron-microscope images) went from 12.4% to 18%.
Peak energy density was 12.73 Wh/m².
After 100 cycles (about 51 days of testing) it kept 69% of its capacity.
At 5%, fibres clumped and results became erratic.
Their view of the future: The authors picture bridge columns and road surfaces powering their own sensors, so structures can monitor their own health. They also describe "energy-storage-integrated buildings."
Our takeaway: Hemp's job changed. It no longer stores the energy. It builds the roads that the energy travels on. Too little hemp gives too few roads. Too much clumps and blocks them. And more pores means less strength, so a "battery wall" is always a balance between battery and wall. This study measured both electrical and mechanical performance, which matters because a material meant to be part of a structure has to do more than store energy.
The Big Section: What Hemp Brings to the Table
Putting the three hemp studies together, these are the reasons hemp keeps getting chosen:
It grows fast and can be a low-input crop, though real needs vary with variety and climate. (2013)
Waste becomes resource. The woody core and leftover fibres are cheap and plentiful, and the 2013 authors note that even the cheapest graphene-like material can't match the price of plant-waste carbon. (2013, 2024)
Built-in architecture. Layers, hollow tubes, and connected pores are what batteries and supercapacitors need. (2013, 2024, 2025)
A gentler process. The recipe has dropped from 700-800 °C to 450 °C. (2013 to 2024)
Renewable and biodegradable. This is a core reason for the cement work. (2025)
Works in many forms. Carbon sheets, honeycomb carbon, or hemp fibre in cement. One plant, three jobs.
Stays active. The same research group (authors overlap) published more cement-battery studies in 2025-26 using other methods, so the field is moving.
Before the Hype Starts: What the Labs Have Not Proven Yet
Is hemp the whole battery?
No. In the 2024 device the high voltage comes from manganese dioxide. Hemp carbon alone failed as the positive electrode.
Has anyone built this at real-world size?
No. The 2024 electrodes were about 1 cm² with around 2 mg of material. The cement cell was about 25 cm². We found no cost analysis in any of the four papers, though several say "low cost."
Can we compare the numbers?
Not directly. Wh/kg is energy per weight. Wh/m² is energy per area. That is like comparing price per kilo with price per slice. Even within the same unit, the 2013 figure is an estimate for a whole device, while the 2024 paper doesn't account for packaging, so its figure likely reflects active material only. And by our arithmetic, the 2025 hemp cell stores about 31 mWh at its peak, against roughly 58 mWh for Chalmers' larger cell. The hemp cell scores higher per square metre, but the two used different test settings, so the gap isn't a clean like-for-like comparison.
Will it last?
Not proven. 100 cycles is about 51 days, and a building stands for decades. The 2013 device did better at 10,000 cycles, but it is a very different kind of device.
Is hemp the only way?
No. A 2026 follow-up study reported an average of 13.01 Wh/m² by foaming the cement instead of adding hemp. The hemp paper's 12.73 was its peak value, and the two used different methods, so they aren't a direct match. Other 2026 papers explore silica sol, carbon nanotubes and foamed magnesium-sulfate cement. Hemp is one promising way to engineer the inside of energy-storing cement, not the only one.
How strong is the 2013 claim?
The authors say their hemp carbon performs comparably to the best graphene-based electrodes. They do not claim it beats graphene.
A Reflection: The Right Question
In these papers the hemp stalk never changed. The question put to it did. We simply hadn't found the right question to ask of it.
Researchers aren't making a magical hemp battery. They are discovering that a plant we've long treated as a source of fibre also holds architecture that can be repurposed for storing and moving electrical energy. A marvel for the future.
Sources:
Wang, H. et al. "Interconnected Carbon Nanosheets Derived from Hemp for Ultrafast Supercapacitors with High Energy." ACS Nano 2013, 7(6), 5131-5141. DOI: 10.1021/nn400731g
Zhang, E.Q.; Tang, L. "Rechargeable Concrete Battery." Buildings 2021, 11(3), 103. DOI: 10.3390/buildings11030103 (open access)
Minakshi, M. et al. "Synthesis of Porous Carbon Honeycomb Structures Derived from Hemp for Hybrid Supercapacitors with Improved Electrochemistry." ChemPlusChem 2024, 89, e202400408. DOI: 10.1002/cplu.202400408 (open access)
Liu, Z.; Liu, S.; Du, K.; Yin, D.; Armwood, C.; Li, L. "Development of Rechargeable Cement-Based Batteries with Hemp Fibers." Journal of Energy Storage 2025, 135, 118355. DOI: 10.1016/j.est.2025.118355. This is the primary source. Journal details, abstract and highlights were checked on the journal page. Detailed figures were read from the authors' SSRN preprint
Phenomenal Fact
Bhanga/Vijaya has been crowned as a sacred plant among other five, immortalized in Ātharvaṇa Veda, chapter 11, one of the oldest sciptures, where it is invoked to free us from aṃhas.