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.

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.

UK nukes were designed to do baseload. They were never designed to be
dispatchable. PWR is a different matter.

"For many years, load-following requirements have been specified in
standard terms of reference. For example, most PWR plants are capable to
follow loads in a power range of 30-100% at rates from 1 to 3% per
minute. Exceptional rates of 5% per minute or even 10% per
minute are possible over limited ranges"

( http://www.templar.co.uk/downloads/0...et_Nuttall.pdf )

The problem is xenon poisoning of the reactor elements if reduced rate
recations are sustained. The French get around this by modulating
reactors with fresh fuel rods: once they are getting on, they use them
for baseload.

Faster rates of change are available with other recator types

Certainly an all nuclear grid would be able to cope with diurnal shifts,
and by moving maintenance and refuelling into the summer when demand is
lower, as long as the ~3GW of hydro/pumped power were there to cope with
unplanned outages.

I would imagine some gas would be retained for STOR purposes too.


You wouldn't build a nuclear power station just to cover 6 extremely
cold winter days..


--
Religion is regarded by the common people as true, by the wise as
foolish, and by the rulers as useful.

(Seneca the Younger, 65 AD)