A floating tidal stream turbine undergoing testing in Orkney, Scotland. Steve Morgan/Alamy Stock Photo
The UK’s annual electricity demand is expected to more than double by 2050. To meet this daunting target without relying on fossil fuels, the government is betting big on wind power – one of the cheapest forms of renewable power available.
But in August and September 2021, calm weather caused wind energy generation to drop 60% below the seasonal average. Planned and unplanned outages of nuclear power plus high demand for natural gas compounded the problem, resulting in network operators restarting coal power stations and energy companies raising prices.
As hosts of COP26 in Glasgow – the 26th UN climate change summit – the UK has framed the negotiations as a chance to show that “science and innovation can deliver climate solutions”. Established energy sources such as offshore wind will play a big role in decarbonising the economy and slowing climate change. But how can a fully net-zero grid guarantee electricity when the wind drops again in the future?
There’s another way of generating clean energy that the UK has so far failed to exploit: tidal stream power.
The UK has two high tides and two low tides each day. This movement of water is created by the gravitational force of the Moon and Sun and the rotation of the Earth. In places like the Pentland Firth in northern Scotland, islands funnel and speed up these tidal flows. Tidal stream turbines are designed to work in these turbulent waters to generate electricity.
Tidal stream turbines work in a similar way to wind turbines – they even look alike. Wind turbines use the wind blowing over their blades to create a lift force, behaving like an aeroplane wing. One end of the turbine blade is connected to the hub of the rotor, so the lift force on the blades causes them to rotate. This turns a generator, producing electricity.
Tidal stream turbines do the same thing underwater using tidal flows instead of the wind. Most tidal stream turbines that have been installed so far sit on the sea floor, but some designs connect the turbines to a floating structure, making it easier for engineers to maintain them. The Conversation - link - Danny Coles - link - more like this - link
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