"Pancho" wrote in message
...
On 20/01/2020 08:16, Chris Hogg wrote:
On Sun, 19 Jan 2020 20:17:29 +0000, Pancho
wrote:

On 19/01/2020 14:42, Chris Hogg wrote:
On Sun, 19 Jan 2020 13:37:34 +0000, Chris Hogg wrote:

On Sun, 19 Jan 2020 13:17:14 +0000, Pancho
wrote:

On 19/01/2020 12:53, Chris Hogg wrote:

Lots of 'potential' storage solutions, such as compressed air into
underground caverns, trundling very heavy weights on rail tracks up
mountains, Tesla-type batteries everywhere and so on. But none of it
comes near to pumped storage in terms of capacity, and that's very
dependent on the right topography, most of which has already been
used. Those other solutions may be OK for very short term
peak-lopping, but none are capable of storing the amounts of energy
needed to run the country for a several days at this time of year,

OK, I was seeing quotes of hydrogen storage providing months energy
supply as opposed to a few hours for pumped storage. The main
difference
being hydrogen is 40% efficient where as pumped is 80% efficient.


But how and where are they going to store a month's worth of hydrogen?
The volume would be absolutely huge, even if compressed. The phrase
'greens don't do sums' is occasionally trotted out on this NG. That
looks like a classic example of just that.

AND:

Where is the capacity coming from? Unreliables, supported by nuclear?
Bear in mind that whatever unreliable is being used as the primary
generator, when the 'battery' (in whatever form that might be) gets
substantially discharged, not only will the primary generators have to
supply the ongoing day-to-day demand, they will also have to recharge
that 'battery' PDQ, in anticipation of another generation-free period
in a week or so's time. How much extra generating capacity that might
need, I don't know, but substantial, I would think.
That problem doesn't arise with nuclear.

A large battery gives plenty of time for a battery to recharge, two
months is a big battery.

I don't understand what you're saying there. A large 'battery', of
whatever type, would take a long time to recharge from flat, when
speed would be of the essence in time for the next lull in the weather
with no generation from unreliables.

The idea of a battery is to smooth out variance. To allow for supply to
match demand. With a big enough battery we just need average energy
production to match average energy demand. Without a big enough battery we
need overcapacity. Hasn't this point been made many times?


Actually the problem does occur with nuclear, too. You need rapid
dispatch to counter the variability of demand.

But nuclear is dispatchable; not ideal (they're best run flat-out
AIUI), but it's not difficult.

Yes, but is it optimal? You would need enough nuclear capacity to match
maximum demand, also turning it down can cause difficulty.

At some point it might be cheaper to have fewer nuclear power stations
generating full all the time. When they have spare capacity they generate
hydrogen, in periods of high demand they use the hydrogen to fuel rapid
dispatch generators.

The french system proves that you dont need the hydrogen,