Pollutionwatch: Olympic flame is a warning sign for hydrogen future

Burning the fuel in the cauldron symbolised its zero-carbon properties - but it does cause air pollution too

The hydrogen flame above the Tokyo Olympic Stadium was symbolic of a zero-carbon future but illustrated a warning too.

Hydrogen, created using zero-carbon methods, looks set to play a big role in decarbonisation as energy storage and fuel. It can then be used in fuel cells to generate electricity or burned in boilers or generators. One option to decarbonise home heating is to inject hydrogen into the existing natural (fossil) gas pipelines. Studies are under way to reduce the explosion risk from hydrogen leaks, but less attention is being paid to the air pollution from combusting hydrogen.