Miscanthus vs Elephant Grass
Miscanthus is often called “Elephant Grass” and often confused with the African grass Pennisetum purpureum known by the same name. Miscanthus is also considered to be a biofuel crop because it grows rapidly, has a low mineral content and a high biomass yield.
The automotive industry played an important role in the development of bioplastics. Henry Ford was the first to use bioplastics made from soybeans in the automotive sector.
At the end of the 20th century, disposed cars represented between 8 and 9 million tonnes of waste in the EU. The EU End-of-Life Vehicles Directives (2000/53/EC) imposed financial responsibility on European manufacturers for the end of life of their vehicles so the industry looked for materials that would biodegrade easier and reduce the end-of-life cost.
Elephant grass was already used in industrial applications as it was burnt in power plants as a source of bioenergy. Elephant Grass has a few advantages. It grows without pesticides and fertilisers. The stems can be fermented and distilled, and it requires less drying than other plants. It absorbs a lot of carbon when it grows and it produces 8 tons of biomass per acre.
Elephant Grass Bioplastics
University of Lincoln (UK) researcher, Nick Tucker, was the first to use elephant grass in the production of bioplastic articles in 2001.
Bical Miscanthus Ltd was promoting the use of elephant grass including de-dusted horse bedding. The dust and fibre co-product was mixed by Nick Tucker with either Biopol (bioplastics owned by Monsanto at that time) or polypropylene to make the first elephant grass polymer composites. The maximum ratio reached was about 15% elephant grass.
The advantages of elephant grass dust were low cost and already being dry enough for thermoplastic injection moulding. The moulded products were lighter and stronger than the plastic-only equivalents. Using biopolymers, the biodegradability was not compromised.
The case study component was a car wheel trim. Forty units were made but the product was never commercialised. A group of Austin Maxi owners tried to convince Mr. Tucker to produce some extra wheel trims, but nobody else came forward to use the material for serious commercial production.
The word bioplastics hadn’t been invented when Tucker and his team came up with Miscanthus bioplastics. They referred to it as ‘biodegradable plastics’. It broke down in presence of high concentrated levels of bacteria. The word biodegradable was invented in 1962.
Why was there no breakthrough?
There were several reasons: it was not a patentable concept, there were no end-clients interested and Miscanthus wasn’t the most efficient feedstock to produce bioplastics.
Sugar-based feedstocks (sugar cane and sugar beet) are the most efficient and sustainable crops. R&D and new production processes may have an impact on crop efficiency in the future.
The proximity and availability of a feedstock also plays a role. EU grows more sugar beet than Miscanthus. The EU is the world’s leading producer of beet sugar, with around 50% of the total. However, beet sugar represents only 20% of the world’s sugar production; the other 80% is produced from sugar cane. The largest sugar cane producers in 2016 were Brazil (40,7%), India (18,4%), China (6.5%) and Thailand (4,6%).
However, sugar beets never made it to the bioplastics scene. The EU CAP had a devastating impact on the sugar industry and a polemic appeared that the industrial use of sugar-based feedstock (first generation feedstock) increased the price of food crops. This polemic gave rise to the second generation feedstock.
A dutch firm called NNRGY started the project of growing elephant grass in the Netherlands in 2013. In the meantime, they developed a biodegradable and compostable bioplastic called Vibers. It’s made from elephant grass and potato waste. Vibers is used in several applications such as consumer goods, packaging and concrete. The future will tell us if Vibers becomes a commercial success.
- Special thanks to Dr. Nick Tucker (University of Lincoln, School of Engineering) for his pioneering work and contribution to this article.
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