All aboard the bus to a better LIFE!

Passengers waiting to board the V3 bus in Barcelona, Spain, which runs from an industrial estate on the outskirts to the city's docks, have little idea they are taking part in a pioneering EU-funded LIFE project which could revolutionise public transport across Europe.

A sign on the front proudly proclaims: 'This bus is powered by biomethane produced from eco-waste sludge.' In other words, the LIFE NIMBUS experimental bus is fuelled by biomethane generated from human poo at the city's Baix Llobregat sewage treatment plant. The results are promising: one bus travelling 14 000 km per year on biomethane fuel cuts greenhouse gas emissions (GHGs) by 28 tonnes and boosts biogas energy recovery by 68%.

That's important not just because biomethane is a sustainable fuel that emits 80% less CO2 than natural gas, but because methane released during conventional sewage treatment also contributes to climate change. With biomethane production a priority for RePowerEU, the recently-concluded 5-year, €1.9 million LIFE NIMBUS project uses biomethane from municipal sewage to do just that.

'We proved that wastewater could be turned into biomethane to power a bus,' says LIFE NIMBUS project coordinator Alessandro Solimeno. 'We've learned valuable lessons from the pilot, and these insights are helping us refine our processes to ensure the bus can run hundreds of kilometres on biomethane as we move forward. We're hoping to demonstrate clearly that biomethane derived from wastewater can be scaled up into a viable, cost-effective solution for public transport.'

The passengers on the V3 route may not care how their bus is powered - like millions of other EU citizens, they simply want to access sustainable transport regardless of income, location, gender or abilities. Sustainable, accessible public transport was the focus of the 2025 European Mobility Week , which invited participants to 'rethink every journey and ensure mobility for everyone!' - and that's certainly what LIFE NIMBUS is doing.

LIFE NIMBUS is just one of hundreds of LIFE projects dedicated to mitigating the impacts of climate change and helping EU citizens adapt to global heating. The project is aligned with the goals of the European Green Deal, EU Climate Adaptation Strategy, 2050 Long-term Climate Strategy and the EU Mission on Adaptation to Climate Change. It also supports the Energy Efficiency Directive, the Fit for 55 package and the Renewable Energy Directive.