Along those lines the National Hydropower Association presented a report to the Senate here in the U.S. showing that there is as much as 12 gigawatts of hydroelectric power that could be generated from existing dams. That would be a 12% increase in hydroelectric power generation.
http://fuelfix.com/blog/2011/04/05/study-new-hydropower-could-add-12-gigawatts-without-any-new-dams/  

Comprehension is not understanding. Understanding is not wisdom. And it is wisdom that gives us the ability to apply what we know, to our real world situations

So...  They're exporting about 4GW all the time to some other district?

Steven Fahey, CET

California, mostly.   

David Castor
www.cvoes.com

All of Spain's network

Realtime Demand https://demanda.ree.es/comparativa_curvas.html

Make up (curve with pie chart format. move the mouse around the curve and the pie chart changes... cooler than Bigfoot scat in January hay)
https://demanda.ree.es/demanda.html

Make up (depth chart format)
https://demanda.ree.es/generacion_acumulada.html

you can also see how closely they can follow the actual demand by ramping up/down various plants and units.
   
 

Let your acquaintances be many, but your advisors one in a thousand'  ...  Book of Ecclesiasticus

Quote:

you can also see how closely they can follow the actual demand by ramping up/down various plants and units.

They don't really much choice.   

David Castor
www.cvoes.com

There's always a choice, or better said, an "alternative".  It could be a catastrophic possibility, but few cases are so limited that there is really one, and only one, path forward.

Let your acquaintances be many, but your advisors one in a thousand'  ...  Book of Ecclesiasticus

Should read "They don't really HAVE much choice."

I suppose the "choice" to not match generation to load has always existed, but that is not really the point.

The point is that generation - no matter what the source - must always continuously vary to match the load in order to maintain system frequency and voltage.  This seems to be lost on a lot of wind power advocates.  Looking at the BPA data, there are many instances of sharp peaks in wind turbine output during low load periods.  This requires rapid load cycling of their large hydro generators and this is something they were not designed for.   

David Castor
www.cvoes.com

but ... they (the generators) have no choice.  

Let your acquaintances be many, but your advisors one in a thousand'  ...  Book of Ecclesiasticus

Sure, there is a choice, dump the wind.  They scream bloody murder, but it really does no harm to anything except the pocket book of the wind operator to dump wind power at times of low load that is exceeded by the minimum hydro output.  In many cases the river flow must be maintained and spillway usage is discouraged (fines, etc.) as it increases the dissolved gasses in the river.

Interesting.  Is that because it adds "flat" water from deep dark places behind the dam, poor in gas (O₂ content, to the river, thus diluting the overall gas content, or some other reason.

Let your acquaintances be many, but your advisors one in a thousand'  ...  Book of Ecclesiasticus

No, it's that the water over the spill-way dissolves too much Nitrogen. At least in this part of the world, the needs of the fish come ahead of power generation "optimization" considerations. If wind had to compete on its own economics it wouldn't matter much, but heaven forbid that they have to give their precious tax credits.  

I don't understand that.  Seems like O should also be taken up in nearly the same ratios as what's in the atmosphere, so no river, stream or lake would ever have a chance to get better aeration than that in the natural world.  In general, aeration should be a good thing because of the O added.  I think it may be a different reason.

Let your acquaintances be many, but your advisors one in a thousand'  ...  Book of Ecclesiasticus