# Why isn't tidal power used more? **URL:** \ **Category:** Factual Questions\ **Created:** [July 10, 2014, 2:01am UTC](https://boards.straightdope.com/t/why-isnt-tidal-power-used-more/692737 "2014-07-10T02:01:15Z")\ **Posts on this page:** 8\ **Page:** 2
**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\ **Post date:** [July 11, 2014, 4:21am UTC](https://boards.straightdope.com/t/why-isnt-tidal-power-used-more/692737/21 "2014-07-11T04:21:13Z")
I suspect tidal power is one of those things that pays off only the course of many decades and is immensely expensive at first, hence is hard to persuade the public to build at first. Even if it saves billions of dollars over the course of 70 years. ---
**Author:** ![needtoknow](https://avatars.discourse-cdn.com/v4/letter/n/f9ae1b/32.png) [@needtoknow](https://boards.straightdope.com/u/needtoknow)\ **Post date:** [July 11, 2014, 4:47am UTC](https://boards.straightdope.com/t/why-isnt-tidal-power-used-more/692737/22 "2014-07-11T04:47:22Z")
> **[Home - ORPC](https://orpc.co/)** > > \[vc\_row css\_animation=”” row\_type=”row” use\_row\_as\_full\_screen\_section=”no” type=”grid” angled\_section=”no” text\_align=”left” background\_image\_as\_pattern=”without\_pattern” el\_class=”banner\_section show” css=”.vc\_custom\_1671525759144{background-image:... ---
**Author:** ![Ken001](https://avatars.discourse-cdn.com/v4/letter/k/43a26b/32.png) [@Ken001](https://boards.straightdope.com/u/Ken001)\ **Post date:** [July 11, 2014, 11:40am UTC](https://boards.straightdope.com/t/why-isnt-tidal-power-used-more/692737/23 "2014-07-11T11:40:48Z")
Here is tidal power in action - built in France way back in 1966. It does work. > **[Rance Tidal Power Station](https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station)** > > The Rance Tidal Power Station is a tidal power station located on the estuary of the Rance River in Brittany, France. > Opened in 1966 as the world's first tidal power station, it is currently operated by Électricité de France and was for 45 years the largest tidal power station in the world by installed capacity until the South Korean Sihwa Lake Tidal Power Station surpassed it in 2011.\[unreliable source?\] > Its 24 turbines reach peak output at 240 megawatts (MW) and average 57 MW, a capacity fa... China now has a larger one but mostly the idea has been ignored. Sad. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [July 11, 2014, 3:18pm UTC](https://boards.straightdope.com/t/why-isnt-tidal-power-used-more/692737/24 "2014-07-11T15:18:09Z")
the tide can be harnessed where the large water flow is channeled through a small area. there are a few natural locations where this occurs. you otherwise would need to build large containment for this. it would be a large expense. it would impede shipping and boating. it would alter the coastal environments changing a fast uniform water flow to a slow graduated flow. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [July 11, 2014, 4:15pm UTC](https://boards.straightdope.com/t/why-isnt-tidal-power-used-more/692737/25 "2014-07-11T16:15:40Z")
> [@Ken001](#): > > We are slightly confusing each other because there are three main methods to generate electricity from the ocean > > 1. Wave power which harnesses the up and down movement of waves. Scotland seems to be the leader. > > 2. Ocean currents which flow through underwater impellors. > > 3. Tidal power which requires a barrage (dam) and turbines at the entrance to a large estuary. > > Number 3 is what I think of when tidal power is mentioned because 1 and 2 do not require tidal flows in order to work. I agree with your breakdown of the types, but wouldn’t the one proposed in Scotland go under method 2? ---
**Author:** ![Ken001](https://avatars.discourse-cdn.com/v4/letter/k/43a26b/32.png) [@Ken001](https://boards.straightdope.com/u/Ken001)\ **Post date:** [July 12, 2014, 4:01am UTC](https://boards.straightdope.com/t/why-isnt-tidal-power-used-more/692737/26 "2014-07-12T04:01:14Z")
Ah - I see what you mean. The MeyGen Pentland Firth project does indeed use water currents but it isn’t operating yet. I was instead thinking of the Pelamis Wave Power system which started in 1998 and is the best known wave power technology. It was producing commercial electricity by 2004 and the concept has been watched globally. Unfortunately wave power cannot generate a lot of electricity and is limited to a range of wave heights. Too calm is no good and violent storms can wreck the array. ---
**Author:** ![Ken001](https://avatars.discourse-cdn.com/v4/letter/k/43a26b/32.png) [@Ken001](https://boards.straightdope.com/u/Ken001)\ **Post date:** [July 12, 2014, 4:10am UTC](https://boards.straightdope.com/t/why-isnt-tidal-power-used-more/692737/27 "2014-07-12T04:10:05Z")
Incidentally there was another project using strong currents which was absolutely novel but can’t find a reference and it may have failed. Anyway the concept was to use a venturi pipe to drive a wind turbine. One end of the pipe was placed in the strong current under the Golden Gate Bridge. Water rushed across the mouth of the pipe and sucked air from inside the pipe - the sort of setup you can see in a school science lab. The other end of the pipe was on land and had a fan in the mouth. The fan turned as air was sucked in. Brilliant, simple, controllable, predictable, very few moving parts, and all that was in the water was a pipe. ---
**Author:** ![Absinthe\_Anecdote](https://avatars.discourse-cdn.com/v4/letter/a/f6c823/32.png) [@Absinthe\_Anecdote](https://boards.straightdope.com/u/Absinthe_Anecdote)\ **Post date:** [July 12, 2014, 2:24pm UTC](https://boards.straightdope.com/t/why-isnt-tidal-power-used-more/692737/28 "2014-07-12T14:24:01Z")
> [@Ken001](#): > > Incidentally there was another project using strong currents which was absolutely novel but can’t find a reference and it may have failed. > > Anyway the concept was to use a venturi pipe to drive a wind turbine. One end of the pipe was placed in the strong current under the Golden Gate Bridge. Water rushed across the mouth of the pipe and sucked air from inside the pipe - the sort of setup you can see in a school science lab. > > The other end of the pipe was on land and had a fan in the mouth. The fan turned as air was sucked in. Brilliant, simple, controllable, predictable, very few moving parts, and all that was in the water was a pipe. It probably worked, but was only capable of generating small amounts of power. The East River project in NYC is ridiculous when you look at what they put into this effort and what they will get out of it. [http://energy.gov/articles/turbines-nyc-east-river-will-provide-power-9500-residents](http://energy.gov/articles/turbines-nyc-east-river-will-provide-power-9500-residents) If they are gaining significant knowledge, it might be justified, but I don’t think they are learning anything they don’t already know. [Previous page](https://boards.straightdope.com/t/why-isnt-tidal-power-used-more/692737.md?page=1)