Batteries offer a growing hope as the world transitions away from non-renewable sources of energy, like natural gas and coal, to a more sustainable energy grid. Lithium-ion batteries now power a rising number of electric vehicles and even allow homeowners with solar panels to store power while the sun is shining and use it when darkness falls. However, there is a downside to batteries. Lithium mines can leak toxic chemicals into the soil and water of surrounding communities. Could hemp batteries be a better solution?
Hemp-based batteries are an exciting area of research that may one day play an important role in the future of renewable energy. What exactly are batteries made from hemp, and could hemp batteries be better than lithium?
What Are Hemp Batteries?
The concept of hemp batteries was first launched into the academic world by ACS Nano. Research conducted in 2013 demonstrated how scientists were able to pull carbon from hemp to create “unique interconnected partially graphite carbon nanosheets.”
In plain English, the researchers used fibers from industrial hemp to form thin sheets of what is known as substrates, which line the inside of a special type of battery called a supercapacitor. The exciting findings from the paper were that the carbon nanosheets made from hemp worked better in some regards than graphene, the current material used in batteries.
The bottom line is that hemp could be used to make a better type of supercapacitor.
How Are Batteries Made from Hemp?
It’s tempting to imagine an entire battery made out of a hemp plant, with leaves, stalks, and hemp flowers all compacted into a battery shape. In reality, hemp plays a very specific role in making a supercapacitor.
Waste fibers from hemp, known as bast and hurd, are heated over a long period of time in order to extract carbon molecules from the cellulose of the plant. It is this carbon that ends up playing a role in the battery. The carbon from the hemp plant is used to make carbon nanosheets, which conduct electricity.
Hemp Batteries vs. Lithium-Ion Batteries
It’s exciting to think that hemp-based batteries may one day replace lithium-ion batteries, but it isn’t exactly accurate to perform a direct comparison of hemp and lithium batteries. In actuality, hemp batteries operate differently than lithium-ion batteries.
We’ve referred to hemp batteries as “supercapacitors.” Think of a battery-powered car or truck. They need a steady amount of electric energy as they drive down a country road. However, if that car stops at a red light, the battery will need a big burst of energy when the light turns green to get going again.
Lithium-ion batteries are great at storing energy for a long time and expending it slowly. However, they are not so good at rapidly releasing a large amount of energy, like what a car needs when a red light turns green.
Guess what is good at performing that function? Yep, supercapacitors. These types of batteries can discharge their entire load of energy quickly to provide a big boost of energy. That’s exactly what an electric vehicle needs to accelerate quickly. While supercapacitors don’t hold a charge for long, they can absorb regenerative energy from braking.
Although hemp batteries can’t replace lithium-ion batteries, they can work together to make vehicles and many other electric-powered machinery work better and more efficiently.
The Benefits of Hemp-Based Batteries
How might batteries made from hemp be better than current supercapacitors that use graphene nanosheets?
- High Energy Density: Energy density refers to the amount of energy a battery can hold based on its weight. The higher energy density a battery has, the stronger the battery. A 2016 study conducted by Carbon found that hemp-based batteries contained an energy density of 19.8 Watt-hours per kilogram.
- Cost: One of the benefits of using hemp over graphene is that hemp batteries can be made using hemp waste that hemp farmers don’t need. This makes hemp both easy to find and much cheaper than graphene. Over the next decades, the world is going to need a lot of batteries to power its vehicles, homes, and cities. Cheaper batteries made with hemp could keep the cost of this transition much lower.
- Availability: Graphene is a versatile “it” material that is finding its way in everything from silicon chips to solar cells and, of course, batteries. However, one of the biggest downsides of graphene is that it is difficult to make in large quantities. Hemp, on the other hand, can grow to maturity in a few months and is known for its ability to grow in many different types of soil, including soils that cannot sustain other crops.
- Superconductivity: Batteries need to conduct electricity with as little resistance as possible. The more resistant a material is to conductivity, the less efficient the battery will be. Hemp-based batteries showed extremely good conductivity.
- Temperature Resistance: The conductivity of hemp batteries remains high even in hot and cold temperatures according to the original study on hemp-based batteries. This is especially important when considering that this technology could one day find itself in vehicles that need to function in searing summer heat as well as icy winter weather.
Will We Someday Have Batteries Made of Hemp in Our Vehicles?
How likely is a future filled with hemp batteries? As of now, the idea is still in the early development stages, but one of the authors of the original study Dr. David Mitlin said, “We’re past the proof-of-principle stage for the fully functional supercapacitor. Now we’re gearing up for small-scale manufacturing.”
It really isn’t so odd to think that hemp may one day power our cars. In fact, there is also growing excitement around the idea of hemp fuel.
These days, CBD and CBG farmers have an increasing number of options when it comes to creating a secondary income stream from their hemp biomass. That hemp could be used for hempcrete, hemp plastic, and even – someday – hemp batteries!