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How tidal energy works

Did you know we can use the ocean waves to light up our homes? Tidal power could be a sustainable way to help the UK meet its emissions targets. Here’s our guide to what it is and how it works.  

Did you know we can use the ocean waves to light up our homes? Tidal power could be a sustainable way to help the UK meet its emissions targets. Here’s our guide to what it is and how it works.  

Sofia Hutson
Utilities expert
minute read
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Posted 4 MAY 2021

What is tidal energy?  

Tidal energy is a way of harnessing the power of waves and using it to create electricity. It isn’t a new thing – the first tidal energy project was set up back in 1966, in Brittany, France. 

How does tidal energy work?  

Energy exists all around us. You’ll find it in sunshine, wind and the sea. The sea has two forms of energy: heat, which it absorbs from the sun, and movement – in other words, waves. The moon’s gravity pulls the sea up and down, creating tides, and this movement is a form of kinetic energy.  
Tidal power is the process of capturing that energy and using it to generate electricity for our homes. Tidal stations can use the sea’s energy to power huge, underwater tidal turbines. The movement of the water causes the turbines to spin, which then turn power generators to create electricity.  

How do tidal power plants generate electricity? 

There are a few ways tidal power stations can harness the sea’s energy to create electricity. The first involves using a type of dam to create a huge build-up of water. The water is then released, creating enough power to spin the turbine and generate electricity. 
Another type of tidal power station uses currents to power the turbines. That’s why tidal energy works best in places with a large tidal range – that’s to say, a big difference between high and low tide. The bigger the tidal range, the more power can be generated.  

Does tidal energy work?  

Yes! It’s said that tidal energy can power a turbine for up to 22 hours a day. 

What are the benefits of tidal energy?  

There are plenty of benefits to wave or tidal energy: 

  • Tidal energy has zero emissions. It doesn’t create harmful CO2 – unlike gas and oil.  
  • The tides are reliable and predictable. That’s more than can be said for the sun and wind.  
  • Tidal power increases during winter – which happens to be when demand for electricity is highest.
  • Because water’s so heavy and powerful, tidal plants can generate electricity even when the currents aren’t moving dramatically. 
  • Solar and wind farms take up a lot of land – tidal projects don’t. 
  • Tidal turbines live underwater, so it doesn’t matter if they look ugly.  
  • Tidal power plants tend to last longer than solar or wind plants. This makes them more cost-effective in the long run.  

What are the disadvantages of tidal energy?  

As with all forms of energy, tidal energy also has its downsides: 

  • Building tidal power stations costs a lot of money.   
  • Tidal energy can be particularly expensive to harness in places that don’t have the right conditions, like the US. 
  • Tidal energy can be controversial. Questions are being asked about the environmental impact, and who owns the land underwater. 
  • It’s possible that the paints and other materials used to create tidal turbines may pollute the seas. Tidal power stations also create electro-magnetic emissions that could upset marine life. 
  • You can’t build tidal turbines too far from where people live. This is one reason the UK is better suited to them than, say, the US. 
  • Although tidal energy is a growing field, it’s still a pretty small-scale operation. However, the European Commission say that wave power could cover 10% of the EU’s energy needs by 2050. This would see CO2 emissions cut by a massive 276 million tonnes.  

Is tidal energy renewable?  

Yes. As the world looks to find more renewable energy sources, hopes are high that tidal energy could be one of the solutions.  
Tidal energy is powered by the natural rise and fall of the ocean currents. So as long as the tides don’t go anywhere, we should have a power supply on tap.

Do we use tidal energy in the UK?  

Again, yes! The UK is something of a leader in the world of tidal power, thanks to our expertise in oil and gas exploration. Being a small island also gives us easy access to wave power.  
There are currently four tidal turbines off the north coast of Scotland, with plans for more in place. Other big players in the field include France, Canada, China and Russia.