Why don't we harness tidal, wave and hydro power more?

Qyburn

Scot_39 said:

Still do as AFAIK - as far as I know at least some of the turbines at Dinorwig etc are still being activated / deactivated on a regular basis for impacts of large load changes e.g. so called TV pickup.

Thanks, I'll read those references.  I'm not sure it's quite the same thing, but my involvement was back in the '80s when everything was synchronous, if load exceeded generation the frequency dropped and everyone's throttles opened in response.  Hydros had a steeper and quicker response the steam turbines because of lack of thermal impact.  So they used to like to run some hydros on what I think they called "free governor" where rather than targetting a certain power output they turned up and down as needed.

I don't know if anything like this applies nowadays. For example a lot of wind is connected by inverters so not locked to the grid in the same way, they will pour in power until told otherwise irrespective of grid frequency.

BUFF

I forgot that Drax is planning an upgrade & expansion for Ben Cruachan.
https://www.drax.com/uk/press_release/drax-progresses-plans-to-upgrade-existing-cruachan-power-station/

Apodemus

Qyburn said:

Apodemus said:

No, I can't see it either, but the maximum installed capacity is 400MW, the storage capacity is 3.3 million cubic metres and the maximum head of water is about 210m, so I'm guessing someone with the right set of skills might be able to work it out from that?

I'll bite, although I often wonder whether I've slipped a decimal in these calculations.  Hopefully someone will point it out if I have.

Lifting one kg by 1m is around 9.8 joules, one cu.m of water raised by 210m = 9.8 x 1000 x 210 = 2,058,000 = 0.57kWh That sounds small. Multiply by 3.3 million gives 1,881 MWh.  That's not accounting for efficiency or the fact that 210m is the maximum head  whereas we really want the average.

Oh, well done!  The link that Buff posted suggested 1600 MWh, so that would make the efficiency 85% on your figures, which sounds like it might be in the right ball-park! 

Interesting that Buff's link also says this will be delivered at 210 MW for 8 hours, which is well below the maximum installed capacity in the Planning application of 400MW.

Scot_39

BUFF said:

I forgot that Drax is planning an upgrade & expansion for Ben Cruachan.
https://www.drax.com/uk/press_release/drax-progresses-plans-to-upgrade-existing-cruachan-power-station/

As my post above - they are AFAIK only extending the range of existing generating plant - and asking for a second 600MW second generation plant (blasting out a brand new turbine hall).

But the reservoir - the actual "energy storage" - is not being increased.

So doesn't help with long term storage problem.

It allows them to charge and discharge the current upper reservoir quicker. And so provide more power at peak times.

(The original design took c22 hours to fully empty upper reservoir - the power is already up 40 MW to 440MW at the existing site, they plan to upgrade that further - and also talk of building a new 600MW capacity turbine hall.  They are now talking about a combined 7hr with the upgraded old + new station.)

Apodemus

Scot_39, that's interesting.  I must look up the EIA and see what impacts they predict (if any) that discharging at three times the original outflow rate has on the ecology of the north end of Loch Awe!