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, as grip for safety. Solvay invented HDS for tires in the 1990s and continues to innovate with new grades and production processes, supporting its customer’s move to sustainability.
Traditionally, HDS material is derived from sand but Solvay has identified alternative circular raw materials like waste sand and rice husk ash. “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 silicon dioxide 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 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.
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.”
CO2 emissions cut in one third
This circular-based silicate process is achieving an overall 35% reduction in CO2 emissions per ton of silica. This will make the Livorno plant Europe’s one of the best-in-class silica production sites in terms of carbon footprint per ton.
“In 2025, Solvay is the first company to claim to produce circular HDS at a European site,” says An Nuyttens, President of Solvay’s Silica business unit. “This commitment reinforces our position as a market leader, providing our customers with a much-needed sustainable solution.”
Solvay 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.”
Circular silica goes global
Solvay has big plans for circular HDS and this launch is just the beginning. “Starting production in Livorno is a first step. We're implementing a global circular silica roadmap, tailored to regional raw materials, that will enable us to offer a circular solution to tire manufacturers and other industries around the world,” says Marie.
In Asia, we announced shifting to circular silica produced from ISCC+ certified waste sand. This initiative, starting in 2026 at our Qingdao (China) and Gunsan (South Korea) plants, could make over half of our regional HDS capacity circular. To follow, a worldwide rollout is planned from 2026 onwards.
In addition, this circular transformation comes with the roll out of our decarbonization roadmap as the implementation of low-emission technologies, such as electric furnaces, to reduce the product carbon footprint of silica worldwide.
For circular highly dispersible silica, a promising future awaits. Stay tuned!