BBC News: Molten metal batteries for the grid

[Mike O'Dell]

"pumped hydro" is extremely efficien *at very large scale*.

unfortunately that requires a large lake on top of a very
significant change in elevation over a short distance.

i *believe* the first big pumped-hydro system was done in
Scotland and plays a big role in prime-time TV viewing
on the British Island. With all the commercials concentrated
in one block at the end of shows (at least on the BEEB),
there is a *huge* spike in power consumption when TV goes
to those commercial breaks and the pumped hydro system
is used to bolster the system against those spikes.

Dave Mills, developer of NTP, identified this effect remotely
back when "real time clocks" in computers were driven by
interrupts generated from line frequency. At the specific
times, Dave would see a significant sag in line frequency
and he finally got to asked a UK power engineer about
that and the guy laughed and said, "Sure we know about it.
That's when every household with a television goes into
the kitchen and switches on the electric kettle to make tea."
Electric kettles pull about a kilowatt - times the number
of kettles making tea during Telly - that's a *LOT* of spike!

One of the largest pumped-hydro systems in the US is actually
here in Virginia.

as is suggested, though, people living in Flatland don't
have this option, although there is one project doing the
equivalent by pumping air into underground salt domes
and then letting it back out.

    -mo