Power-to-gas in practice: hydrogen for municipal mobility

1. The Challenge

The municipality of Sonneberg wanted to store renewable energy locally while also enabling zero-emission mobility. To achieve this, hydrogen had to be produced, stored, and made available for vehicles on a decentralized basis. Traditional solutions would have either utilized only the excess electricity or enabled refueling—but not both within an integrated system. Additionally, the oxygen produced was to be put to good use in the wastewater treatment plant. What was needed, therefore, was a technically sound solution for true sector coupling under real operating conditions.

2. The sera Solution

As part of the LocalHy project, a power-to-gas system was installed at the Sonneberg wastewater treatment plant that converts renewable electricity into hydrogen and oxygen via pressure electrolysis. The hydrogen is stored on-site and made available to municipal vehicles via a hydrogen refueling station from sera Hydrogen. A dry-running piston compressor with an electro-hydrostatic drive is used for compression, compressing hydrogen up to 1,000 bar. The system is designed to prevent any contamination of the gas and to meet the vehicle manufacturers’ high purity requirements. The oxygen produced during electrolysis is used in the biological treatment stage of the wastewater treatment plant, where it improves the process.

3. Customer Benefits

• Local utilization of surplus green electricity through conversion into hydrogen
• Emissions-free refueling of six municipal vehicles directly on-site
• Additional benefits of the oxygen in wastewater treatment
• Practical proof of effective sector coupling in municipal infrastructure

4. Brief Summary

The project in Sonneberg demonstrates how hydrogen production, energy storage, and mobility can be meaningfully combined in an integrated system.