Analysis: A new research project is looking at how to create a viable, valuable, eco-friendly solution in Ireland for used tyres - Róisín Rafferty, Research Assistant on the EPA funded ENTYRE project at ERI/UCC

In 2022, Ireland collected nearly 63,000 tonnes of waste tyres. However, there is still no sustainable strategy for managing waste tyres in Ireland. Historically, we'd have simply sent them to a landfill, but this practice was banned by the EU since 2003 due to severe fire hazards, pest infestations and toxic chemical leaching.

More recently, tyres have been ground into "crumb rubber" and used in astroturf pitches and equestrian arenas. However, crumb rubber is a microplastic and causes substantial harm when released from these surfaces and fed into our waterways, leading to an EU ban under REACH restrictions in September 2023.

Currently, 93% of waste tyres are exported from Ireland, predominantly to Asia, and are burnt in cement kilns and powerplants. This is also an environmentally unfriendly practice and may not have a future under stricter EU policies.

From Business Insider, how old tyres are turned into electricity

So then, what are our options? This leads us to the ENTYRE project at UCC which is exploring different methods for managing used tyres with the goal of identifying a viable, valuable, eco-friendly solution for Ireland.

The research focuses on two main approaches: recycling and devulcanization. Tyres can be recycled in many civil engineering works, as aggregate in asphalt, concrete or fillers for embankments. They may also be used in pyrolysis, an option currently taking the EU by storm, involving burning tyres in oxygen-deprived chambers to produce oil that could fuel planes and solids that could be recycled back into tyres, among other applications.

The other option, devulcanization, means using various mechanisms to restore the rubber in tyres back to its original pre-processed state. It can be reprocessed in new rubber products, including tyres. Gasification is another alternative under investigation. This is where tyres are heated to extremely high temperatures in the presence of air or steam, or both. This can produce valuable gas, used for electricity, fuels, and valuable chemical feedstock.

From UA Visuals, how OLEXOCRUMB are turning recycled tyres into roads

But these options have limitations. Its use as asphalt on our roads calls into question whether acid rain would result in the leaching of toxins. It is not yet effective in replacing aggregate in concrete and it can go on fire if an embankment is not correctly designed.

Pyrolysis may not produce products with high market value and therefore might not be profitable. Gasification creates nitrogen oxides and sulfur dioxide, that pose huge environmental hazards if not managed properly. Furthermore, breaking the rubber down to its pre-processed state unfortunately is not always very effective. Even with optimum process design, this produces a product that can only ever supplement rubber in new tyres, not replace it.

While it may be difficult to identify a perfect option, the ENTYRE project is using a multi-decision criteria analysis tool to weigh up all the options, considering factors like the environmental impact, economic sensibility, and technology readiness level. Through the course of this project the ENTYRE team will explore all the various options for valorising end-of-life tyres in Ireland, involving stakeholders, reviewing literature and writing policy reports. The aim is to ensure the issue of waste tyres is not just addressed, but transformed it into an opportunity for innovation and economic growth.

The ENTYRE project at the SFI MaREI Centre for Energy, Climate and Marine is funded under the EPA Research Programme 2021-2030. The EPA Research Programme is a Government of Ireland initiative funded by the Department of the Environment, Climate and Communications.