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Reducing the carbon footprint of tires with… rice!

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Bio-circular silica for eco-friendlier tires

Highly dispersible silica (HDS) is a key ingredient in tires. It ensures low rolling resistance, which leads to lower fuel consumption for thermal engines and extended battery range for electric vehicles, and it also provides high wear resistance, leading to longer tire life.

Traditionally, this material is derived from sand. But an alternative with a better environmental profile exists: burnt rice husks! “To produce silica, you need a source of silicon dioxide,” sums up Marie Gaube, Silica Market Manager at Solvay. “Today, this source is sand, but it’s well-known that rice husk ash is the vegetable ash with the highest SiO2 content,” so we have decided to make the switch. Let’s explain.

A first in Europe

As a leading global provider of HDS, but also as a company that is strongly committed to its ambitious environmental objectives, Solvay is launching its first unit of bio-circular highly dispersible silica at its site in Livorno (Italy) - in fact, we will be the first company to produce silica from rice husk ash in Europe, implementing a proprietary technology to do so. This new generation of bio-based HDS provides the same performances as sand-based silica, while having a much lower carbon footprint; what’s more, our sourcing will be 100% local.

There are several environmental benefits here. Firstly, the raw material is bio-based which answers a strong demand from customers in the tire industry. What’s more, according to the Ellen McArthur Foundation’s definition, rice husk ash is a circular material because it’s a byproduct of agricultural activities that gains much higher value thanks to this application, along with having an extended period of use, as the silica stays in the tires for years.

Secondly, the manufacturing process is less energy intensive. “Currently, the precipitated silica made in Livorno is obtained by transforming sand into silicate in an oven, then the silicate is precipitated, filtered and dried to obtain silica,” explains Marie. “With rice husk ash, the production process of silicate is different: it’s a chemical transformation, which allows significant energy savings.”

An Nuyttens



“We are the first company to commit to producing circular highly dispersible silica at a European site. This commitment reinforces our leadership position, providing our customers with a much-needed sustainable solution.” 
An Nuyttens, President Silica, Solvay 

CO2 emissions cut in half

This circular-based silicate process will be coupled with the implementation of a biomass boiler at the plant, achieving an overall 50% reduction in CO2 emissions per ton of silica. This will make the Livorno plant Europe’s best-in-class silica production site in terms of carbon footprint. Production is expected to start by the end of 2024, and bio-circular HDS is set to gradually replace sand-based silica in our Zeosil® portfolio over the following years. 

“Solvay is the first company to commit to producing circular HDS at a European site within a concrete timeframe,” says An Nuyttens, President of Solvay’s Silica business unit. “This commitment reinforces our leadership position, providing our customers with a much-needed sustainable solution.”  

Our bio-based HDS will significantly increase the use of sustainable raw material and reduce the CO2 footprint in the tire industry. “Silica is essential for the high performance of our tires, and with Solvay’s bio-circular silica, they will at the same time become more sustainable,” says Claus Petschick, Head of Sustainability at Continental Tires. “It reduces the overall carbon footprint and increases the share of renewable materials in our tires. Soon, Solvay will take us one step closer to our goal of 100% sustainable materials by 2050 at the latest.”



Beyond tires, this new generation of precipitated silica will also be able to address other needs in the mobility industry, for example in electric vehicle batteries, as well as in other markets such as Home & Personal Care and Feed & Food, where silica is used in products ranging from toothpaste to animal feed.

Bio-circular silica goes global

Solvay has big plans for circular HDS: this launch is only the beginning. “Starting production in Livorno is the first step in our roadmap that will enable us to offer a circular solution to tire manufacturers and other industries around the world,” says Marie.

In effect, plans have been made to build a new facility in North America that will also use bio-based, circular and local raw materials, and we are investigating similar projects in Asia and South America. For bio-circular highly dispersible silica, a promising future awaits.