17 May 2017 Last updated at 16:55 BST
A set of 32 of these new massive wind turbines have been turned on at Liverpool Bay, in the Irish Sea.
They use the power of the wind to make electricity to power homes and businesses.
Called the Burbo Bank Extension, the energy windmills are 195m tall and 80m wide.
But how much does size matter? Watch Leah's report to find out.
These are the biggest and most powerful wind turbines anywhere in the world, and they're in the UK.