Breakthrough - superconductor

[Tim Streater]

V will also be zero. So the current is unknown and will not be determined by the superconductor.

[Jeff Layman]

Basically, Ohm's Law does not apply to superconductors. I didn't realise that it isn't really a law, and there are times when it doesn't apply:

Googling "Ohm's Law" and "Superconductor" will result in many hits confirming it doesn't apply.

[The Natural Philosopher]

OTOH I do write off a technology when its clear it *never will* be economic for anything *but* niche applications...

...as it now seems that wind and solar power are...

[The Natural Philosopher]

And that is in the end the limiting factor. You cannot send infinite current down a superconductor

And you need to keep it cool. So instead of staged transformers you have staged liquid hydrogen....

Current world record is 20kA over 20 meters. At 415V that is 8.3MW. Enough for a couple of wind turbines maybe.

https://home.cern/news/news/engineering/world-record-current-superconductor

V is zero of course.

[The Natural Philosopher]

ohms law is an approximately correct model in metallic conductors at DC only

[Chris Hogg]

I'd just finished reading it when your link appeared here.

He sums it up nicely where he says renewables suffer from low energy density, intermittency and appalling EROEI.

What's to like?

Nuclear, OTOH...

[Tim Streater]

Interesting that it essentially confirms what I was saying about batteries for the grid a few days ago.

[The Natural Philosopher]

Really what we are seeing is the unbridgeable gap between qualitative hand-wavey magic-thinking 'it could work' and quantitative 'but not for very long'

Renewable energy is simply not sustainable.

[Vir Campestris]

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

[The Natural Philosopher]

Hydro is not classed as 'renewable' for subsidies, but strangely it is when totting up the totals for how much is on the grid...along with woodburners...

yes, its the one country in te wprld where windmills make a little sense.

[Chris Hogg]

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.

Norway is 95% hydroelectric, with a capacity of 31GW in 2014. In Iceland, it's about 70% hydroelectric, 30% hydrothermal. The aluminium industry uses 71% of electricity 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.

[Paul]

"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

[Fredxx]

It is possibly a similar breakthrough to a field-effect transistor that was proposed in 1925.

Or wouldn't you consider that a pretty useless device in 1925 could ever result in something like the iPhone?

Sorry, I would say room temperature superconductivity is a breakthrough. There may well be other similar materials that exhibit the same effect at pressures we may be more used to.

[Andy Burns]

if it was anywhere near atmospheric pressure ...

[Jethro_uk]

What effect does removing that energy from the ecosystem have on it ?

[Martin Brown]

More comparable with the very first laser which also required an impressive sized perfect gemstone and a room full of kit to work.

If there were they would probably have been found by now.

Magnesium diboride was the last surprise moderately high temperature superconductor family discovery at 39K in 2001.

Superconductors that will work at LN2 temperatures are about the best we have got right now but they are ceramics and as brittle as hell. Theoreticians are still trying to figure out exactly why they work.

League table is here and up to date:

[Fredxx]

<snip>

For me you've hit the nail on the head. Until we understand why these materials behave the way they do we're just stabbing in the dark.

[Paul]

What's a little flooding here and there ? :-)

You need fish ladders for the salmon to get past a dam. That's if your river has salmon.

The silt tends to fall out, behind the dam. And likely needs to be dredged at some point.

And the reservoir likely has methylmercury in it.

Paul

[Jethro_uk]

TL;DR - not the zero sum game the terminally dim would have us believe.

[Paul]

They do an environmental assessment before building one, so that the cost/benefit is there to see.

I think on balance, compared to the things we could be doing, it's a pretty good solution.

We've run out of rivers to dam, so there won't be any more really big projects, at a guess. Next comes tidal power :-) (Don't worry, there's only one good spot for it... And I don't think anyone is ready to pay for it.)

Paul