There is increased pressure on the automotive industry to use sustainable materials and decrease its overall carbon footprint. One of the ways to green the industry is to use plant-based products. Hemp (Cannabis sativa L.) is proving to be a great source of fibre and it helps with CO2-reduction.
The plant does not have the psychotropic properties of marijuana but shows great potential for future uses in automotive bodies and batteries.
Hemp produces one of nature’s most enduring fibres. Because hemp is almost impervious to seawater it was and is still used today for ships’ rope and sails, where it holds up better even than synthetics, says E.J.W. Barber, author of the book ‘Prehistoric Textiles’.
In 1941, Henry Ford created a car that has been called ‘hemp car’ or ‘soybean car’ which reportedly used hemp fibre and plastic for an extremely strong body. Even though the Henry Ford Museum refutes that hemp fibre was used, the idea for hemp for automotive use is alive today and growing.
In 2010, Motive Industries revealed the Kestrel, called the first bio-composite electric vehicle. The body material was made from hemp mats produced by Alberta Innovates Technology Futures (AITF) in Edmonton, Alberta. The hemp was infused with polymer resin. The body of the Kestrel was very light, strong like fibreglass and had increased impact absorption.
“We used hemp fibres that were 6” long [15.24 cm]. They look like Shredded Wheat.” says industrial designer Nathan Armstrong, former president of Motive.
There were some problems however using hemp. The cost of the hemp fibre was increased by transporting harvested hemp plants for processing by a decorticator and to the manufacturing facility. Now that there are trucks with decorticators that go directly to the hemp fields, says Armstrong, the cost could be reduced.
Armstrong, who is currently working on new hemp projects, says that there still needs to be more corporate investment in hemp to make the manufacturing process less expensive. Industrial rough hemp is being used for shipping containers, animal shelters and would be good for semi-truck trailers.
Other good uses for hemp are curbs, building materials and sidewalks using a product called hempcrete that absorbs carbon from the air, says Armstrong.
Batteries Can Get a Blast from Hemp
In 2012, Dr David Mitlin PhD has researched hydrothermal synthesis of hemp for nanosheets in lithium-ion batteries.
“We found that the inner bark (the bast) that is leftover from the processing of industrial hemp can be processed and separated into nanosheets similar to graphene used for supercapacitors,” says Mitlin.
“The nanosheets charge faster in high-powered lithium-ion batteries,” adds Mitlin who notes that the material is less expensive than graphene. The Mitlin Group is now commercialising hemp-use for batteries.
New Sporty Eco-Friendly Hemp Bodies
Bruce Michael Dietzen, the founder of Renew Sports Cars, takes the use of hemp for car bodies to the next level with custom-made hemp-bodied sports cars. Dietzen always owned sports cars and he wanted to design his own sports car. After learning about Henry Ford’s plant-based material vehicle, he decided to use hemp.
“Greenhouse gases are not just caused by burning fuel but also by the manufacturing of vehicles,” says Dietzen.
He tells that the hemp-based body of the Renew car is very dent-resistant because natural fibre absorbs energy.
“It’s not just a cool or neat idea – it is inevitable.”
The body is formed from woven hemp that is treated with a bio-based epoxy and moulded. Dietzen calls the hemp-based body material that weighs 47% less than aluminium, Carbon Negative Fiber. Renew rates the material at -12 pounds (5.4 kg) of CO2 as opposed to +188 pounds (85 kg) of CO2 generated to make an aluminium trunk and +213 pounds (96.6 kg) of CO2 generated to make a carbon fibre trunk.
Dietzen hopes in the future to create prepreg hemp-based material that it is like the prepreg carbon fibre used by companies such as Pagani to form carbon fibre supercars. Carbon Negative Fiber has far superior energy dampening characteristics than carbon fibre, says Dietzen therefore that it has the potential to be a superior material for absorbing the energy of a crash.
“It’s not just a cool or neat idea – it is inevitable,” says Dietzen. “We should not be just looking at the miles per gallon of cars but of the carbon footprint of the entire car manufacturing process.”
It may all boil down to the fact that the future greening of the automotive industry could be accomplished with ancient green resources.
“I’m not surprised there is a resurgence in the interest in hemp fibre. It’s easy to grow in many different climates, even over 12 feet tall (3.6 metres), produces pulp fibre much faster than trees, and its fibre is incredibly strong. Archaeological finds show that people have used it for at least 7000 years,” says E.J.W. Barber.
She concludes: “Surely, the usefulness of hemp has withstood the test of time.”