disadvanages

• Setting up tidal barrages uses large amounts of concrete

  
• large amounts of concrete and this contributes to carbon emissions.

  
• Smaller tidal stream turbines don't use so much concrete or cause as much carbon emissions in their manufacture.

  
• Tidal barrages can block sewage

  which needs to go out to sea

  
• Boats may not be able to

  get past the barrage.