Olive Stones Find Afterlife as Carbon-neutral Composite Fillers

The olive tree might have found its way to Greece from ancient Persia and Mesopotamia in the 28th Century BC, but nowadays Spain is the world’s largest processor of olive oil. As such, it is the largest source of olive stones, which are typically considered waste but can be used as biofuels in various forms. The pits can be converted to activated carbon, incorporated into animal feed, or in the case of Malta- and Spain-based company BioPowder, processed into functional fillers for use in plastic composites.

In an exclusive interview with PlasticsToday, BioPowder founder and Managing Director Kathrin Schilling detailed how the company’s capacity of 1,000 tonnes/month of high-grade olive-stone powder is slashing the environmental footprint of various plastic compounds that might otherwise use energy-intensive materials such as carbon fiber, talc, polymeric beads, metals, or even natural fibers such as flax and hemp. “Olive stones are derived from a carbon-neutral ecosystem: You don’t need to grow crops directly because they are a byproduct, nor do you need to chop down any trees,” she emphasizes. Another environmental attribute is that the stones are sourced and processed locally.

Performance advantages

Further, carbon neutrality is accompanied by multiple technical advantages according to Schilling. “They exhibit very high hardness, possess a relatively low density [specific gravity of 1.2 to 1.4kg/l] that makes them suitable for lightweight components, but at the same time they function as reinforcing materials, or texturing materials that can deliver anti-slip [properties] or a surface with a certain type of grip.”

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Powder grades are available in various particle sizes to suit specific applications. Image courtesy of BioPowder.

Powder grades are available in various particle sizes tailored to the demands of the application at hand, with larger particle sizes typically employed to generate surface or visual effects, while smaller particle sizes are used to deliver higher levels of tensile strength and hardness, for example.

Regarding pricing, Schilling notes that the low density of olive stone powder versus conventional fillers that may have densities of up to 2.8 kg/l can potentially lead to cost savings. Further, if the resin matrix is a biopolymer, use of the powder can also reduce overall costs.

Automotive applications

BioPowder is active in the automotive industry, especially when it comes to interior parts, according to Schilling. “In particular, we are seeing interest for applications in bio-based leather or even conventional leather and leather coatings such as for steering wheels, where olive-stone powder can enhance heat resistance and generate more wear-resistant surfaces.” To name further applications, Schilling noted that much of its current business is with masterbatch suppliers and compounders servicing the auto sector.

Besides automotive, BioPowder notes additional potential for olive-stone powders in markets such as shipbuilding, aerospace, rail, appliances, luggage, computer and mobile phone housings, and garment hangers. There is even potential in dental and medical implants, according to the company.