Chris Hogg wrote:
On Mon, 19 Oct 2020 21:34:44 +0100, Vir Campestris
wrote:

On 19/10/2020 14:48, The Natural Philosopher wrote:
Renewable energy is simply not sustainable.
Hydro electric power _is_ sustainable. You can keep catching the rain
and making power from it indefinitely.

What it _isn't_ is a solution for all our power needs - there just isn't
enough rain falling in enough mountain valleys.

AIUI wind/hydro works quite well in New Zealand, where they have lots of
wind and rain in a hilly country with low population density.

There is of course the Banqiao problem. Orders of magnitude more deaths
than have ever ben caused by nuclear power.

Andy

In NZ, 54% of the electricity is hydroelectric, 20% gas, 10%
geothermal, only 7% is wind. But total usage is low. Total capacity is
only about 10GW; average output 5GW.
https://en.wikipedia.org/wiki/Electr...in_New_Zealand

Norway is 95% hydroelectric, with a capacity of 31GW in 2014.
https://en.wikipedia.org/wiki/Electr..._consum ption

In Iceland, it's about 70% hydroelectric, 30% hydrothermal. The
aluminium industry uses 71% of electricity production.
https://en.wikipedia.org/wiki/Electr...and#Production

All of which is fine if your electricity consumption isn't high and
you have the topography and geology to support it. Not may places
have, so it's not widely applicable.


"More than 70,000 MW of hydropower have already been developed in Canada.

Approximately 475 hydroelectric generating plants across the country
produce an average of 355 terawatt-hours per year."

And Three Gorges is 22.5GW. It takes quite a few nukes
to match something like that.

Itaipu Dam in Brazil is 14GW.

These are pretty good sources. It would take a fair number
of nukes to match them.

And some (not all) hydroelectric projects last a while.
The tiny station downtown (generates less than a megawatt),
it probably lasted a hundred years before it was closed.
The building is still there, but the water flow is reduced.
They're in no rush to take it apart, because that would
cost money :-)

The local watershed, has around 35 stations, piddly things
not worth counting. They dam everything around here. That's
how the count gets to 475.

At the old river we used to go tubing in, the head end
of the river is a generating station. With a rather
substantial whirlpool up near the exit gate on the
station. If you stick your truck tube in the water
there, you'll spin around forever. There's a sign there
to tell people to not do that, but no complex fences or
gates to keep you out. And during Tubing Festival, the
generating station output is adjusted to make tubing fun.
(You don't want to be running a rapids when drunk, so the
water rate is turned down to a laminar flow.) All sorts of
people blasted out of their minds, riding down a river on
inner tubes. Hippy heaven. Wearing apparel is
"swim trunks and wine skin".

Having rivers all over the place, is great.

Paul