sasfasaf

Yes, I am aware of the difference between high and low level fuel and the stew of different half lives of the constituents of higher level fuel.

There's 47 k tones of high level waste in the US alone [1].So I think it's fair to assume that your 80 000 tonnes world wide was high level waste.

Which has to be kept far apart from each other since they decay and at the very least generate heat. Therefore, apartness is an integral part of repository design. Yucca Mountain has a capacity for 70 000 tonnes. That is, its not big enough to store the world's waste despite nuclear power having a small fraction of the overall worldwide power production over the last 60 years.

[1] https://en.wikipedia.org/wiki/High-level_radioactive_waste_m...

"Which ones?"

Cascading failures. Those are very effectively blocked by power islands connected by HVDC lines (like Texas is). A power outage like the North East in 2003 is unlikely in Europe because of your mild weather being unlikely to put your infrastructure to the test.

"the last major customer-visible nation-wide outage was in 2006 [...]."

You're comparing Germany (?) to the US more than six times as populous and far larger in extent and far lower density? The last outage that impacted me in my corner of my continent was back in 2003.

Europe literally has the most benign weather on Earth. Barely any tornados. Barely any hurricanes. Barely any Blizzards. Heck you don't even have good thunderstorms - trust me, I grew up in Europe, there's no good thunderstorms there.

"Meanwhile, the US has outage reports every few months, including such absurdities as rolling outages to prevent wildfires from shoddy unmaintained networks. Or the shit that went down in Texas, which refuses interconnections to avoid federal regulations."

You really have little appreciation of the scale of California and Texas. Cali is 30% larger than Germany, twice as long, with taller mountains, little to no water, and full of combustible material.

Texas' outage had nothing to do with its interconnections. A rare weather event froze the gas pipelines at the same time they were supposed to pick up the slack from derated renewable generations. Texas' neighbors had no electricity to give (and in fact, the neighbors complained that Texas stopped exporting power - Texas IS connected to the rest of N. America).

Now, you could point out that Texas should have been better prepared for rare weather. I agree. So should have the Rhine Valley Region.

"If the conversion losses were as high as 10%, why did anyone bother using HVDC for e.g. a mere 85 km stretch in the Trans Bay Cable?"

1. Because AC also has transformation losses (2-3% per transformer. You need at least three (medium voltage, high voltage, medium voltage, low (house) voltage).

2. The answer is in the name, ain't it? It's underwater.

AC coupling in a dielectric increases losses very significantly. The longest underwater line AC line in the world is only 135 km, in Greece, for this very reason. The Greeks probably couldn't afford the capital to instal a DC line instead and settled for higher losses.

You pay for more expensive HVDC lines for three major purposes:

1. Underwater cables - see dielectric loss

2. Cheating on the synchronization

3. Long AC lines. This has many reasons:

- Take the speed of light, and divide it by 200Hz (50Hz * 4) = 300 000 km/s /200Hz = 1500 km. That's as long as an AC line can be before you start to deal with impedance reflections.

- Lowering losses. AC was famously adopted to lower ohmic losses by adopting high V. But, AC lines are coupled to ground (they're a massive capacitor to ground), so at a certain length you have to consider AC coupling losses that don't exist in DC

"But even if they were 10%, that’s a multiplier not an adder so it makes a difference of 10% to final energy prices, it wouldn’t break anything (though it might shift the minima to batteries, as those are also cheap and getting cheaper)."

I love how eagerly ppl dismiss 10% loss. I'm aware its a multiplicative - it's also an 11% increase in the amount of panels needed (1/0.9 = 1.1). You have to think of your losses in the inverse - how much added land you have to cover (and loose CO2 sinks to photosynthesis)

The things that are "cheap and getting cheaper" are things at a certain scale. Everyone loves things getting cheaper at scale, but forget that things also get more expensive at scale. Batteries don't get cheaper once you start running against the bounds of how much electrode material is available.

"I think you’re overestimating how much the losses matter. You only lose half your power from 20,000 km, adding an extra 10,000 km from wiggling around a bit takes you down to 34% of original generation"

so from you're original 50%, to 34%, a loss of 34/50, implying an increase in land covered of 50/34, or about 50% more land you have to cover.

50% more land if I accept your hand waving argument that you'll only need an extra 10Mm to get from point to point.

"“I am not qualified to discuss them” absolutely is not the same thing as dismissing them."

"I'm not qualified to discuss them" absolutely is used, de facto, as a license to ignore. It maybe the most common human rationalization.

"But my main point is more of we don’t need to tile the Sahara (or any single particular place), so it shouldn’t even come up in the first place."

You have to tile something. The Sahara makes most sense lacking vegetation. But sure, tile Ireland and see how much the local appreciate it.

Ok, but I want numbers. How good can ICEs get?

Mercedes claims their 1.5L F1 engine - designed for power, not efficiency - is over 50% thermally efficient. An EV can't match that. Not with the gas cycle efficiency and all the line power losses.

I'm not arguing that 3GD wasn't stupid, just that it generates an insane amount of power.

Either way, no more of them will be built - there are not many more gorges like that left.

"Which is going to be a fixed amount regardless of distance"

Sure, but knock off another 10%

"I would expect HVDC to be a dead end already if it made a difference to my conclusion."

I didn't get that. Could you re-phrase?

"Surely a web is the best topology? "

My point you're underestimating the line length since you cannot connect generation to consumption with a straight line. Also, the hub-spoke or a web network would need the connections to be much larger than needed for that city (since the city would also need to transmit to it's neighbors)

"While true, I’m not even going to try to play at global geopolitics; [..] worsen the performance of my opinion and give your criticism the best possible chance."

You cannot dismiss cultural concerns. Look what happened in Kabul last week!

Ok, look, I'd rather not talk about "football fields 10 meters deep". But going by that number your 80 000 metric tonnes of spent fuel has an average density of 740kg/m^3. So does your football field include the empty space necessary to keep the rods far apart (to keep them cool and not critical)?

But never-mind the technicalities, you cannot dismiss the geo-political implications. We have barely existed as a species in the time length nuclear waste decays. We have only 5000 years or so of statehood, the vast majority of them since collapsed.

Unless you propose burying the waste in the Marianna trench (I think there is merit there), I really need to see the stability concerns addressed.

EDIT: And yes, I am "aware". I stated my undergrad in a nuclear eng program, and switched to physics after a few courses. I still have friends in the industry and to say morale is low is an understatement.

Sorry let me re-phrase

"Nope. Germany averages about 6% of transmission loss"

I wasn't referring to ohmic losses, or transmission losses. I was referring to consumed along the way. The power generated in Vladivostok doesn't reach Germany not because the line losses are real, but because there'a country of 150 million inbetween.

"We have this in Europe ffs. Almost all of Europe, parts of Asia (Turkey) and North Africa (Morocco, Algeria, Tunesia) run in a synchronized-phase grid, and we have interconnection links to the insular ones (UK, Nordic countries, and a small one tying us to Russia). The entire former Soviet Union runs on a synchronized-phase grid"

Indeed you do (and there's problems with that), and it's not the impressive frankly (N. America has the same, with HVDC interconnects). But the OP was (clearly?) suggesting transporting all the power needed in Europe in, say, the Gobi desert. That's a scale of grid capacity that you do not have.

A fairer comparison is comparing the CO2 emissions caused by putting all that precious lithium and rare earths in one electric car vs. putting it in several light trucks.

The workman's hybrid Ford Maverick or hybrid Ford 150 replacing a pure gas powered Tesla is far better for the environment. There's a reason why hybrid technology debuted in massive machines - they're the ones who benefit the most

That's not obvious to me.

Sure, using the numbers and technology we all learned about in thermo class 20 years ago (best ICE efficiency of a car is 20% usually gets much worse), I agree.

But the hybrid drivetrain throws all the assumptions of that common wisdom in the air. Namely:

- Throttle can be open all the way when power is needed, the engine turned off otherwise

- Engine can be made for efficiency, not power density

- Engine can be sized to average power, not worst case scenario over the lifetime of the car

On top of that, in the last 20 years, the power electronics revolution has made recovery of the energy in the exhaust stream possible (see F1).

I'd love to have an ICE expert tell me why ICE efficiency can't be double what common wisdom tells me what it is. I suspect it's environmental laws regulating NOx emissions (thus putting a hard upper bound on compression ratios). I really doubt an electric car can beat the carbon emissions of a natural gas powered ICE that achieves 40% efficiency. Not with our current energy mix anyway

It's a lot greener than little generators you'd buy at Costco.

But don't dismiss neighborhood scale generation. It can approach efficiencies of large scale plants, while providing free heating/cooling. All whilst being very robust.

" and produces 1% of China’s power."

It produces 1% of the electricity used by CHINA the premier industrial and most populous country in the world and you dismiss it? Three Gorges was a mistake, but it generates power used by 13 million people. That is a ton of power.

Most gas plants are in the 300 MW size, i.e. the 3GD is about 80 of them.

". I have no idea how much a multi-gigawatt HVDC line costs per kilometre,"

Well there's the crux, ain't it? They're bloody expensive.

Also, to your 3.5% loss / 1000km line loss add in the transformation losses. Then consider that a 20k line must be a DC line (to avoid reflection losses).

Also, why did you use 20k km? Such a curious number, half the world's circumference, that I suspect you mean to propose to wrap the world in power lines to get power at midnight from noon elsewhere

Well 20km for your loss calculations is not nearly enough since you cannot connect two sites in a straight line. For starters the earth' topography won't allow it. But then there's the issue that you won't connect every city to every generating site, but have a hub-spoke model (like ethernet). To give you an idea of the added distance compare the straight line distance of Atlanta to Pittsburgh to the interstate distance (520 mi to 680 mi).

Finally, the proposal of connecting two sites on opposite ends of the earth is fundamentally hegemonist. What are you going to do with the fiercely independent people that tend to live in deserts when they oppose you wallpapering their desert with panels? When the Bedouins of Algeria are blowing up the electricity needed in Japan, will the EU send storm troopers to punish the locals?

" a grid that has enough capacity to distribute power across continents."

That's easy to write, but very hard to envision the scale. The grid transports very small fraction of the consumed power over large distances, most of the power gets consumed along the way. But what you are proposing involves transmitting all the power that a far away community consumes several time zones away

Well there are breeder reactors that significantly transform waste to less harmful products, and the Russians have basically commercialized them.

But they're still a bad idea. Nuclear waste implies a strong, competent, and stable state that is able to secure it for millennia. Fifteen years ago when I arrived to the US the Americans I spoke of couldn't conceive their hegemony collapsing or the US state becoming incompetent.

This, I think, is the strongest argument against (current) nuclear power - in time it appears that all regimes collapse, geographic areas fall into anarchy and chaos. Human society simply doesn't have the proven long term stability to secure nuclear power.

Probably not. Super conductors don't really solve any problem because they loose their super conductivity at high B fields; i.e. when they transport large currents. Case in point the highest field magnets are not made w/ superconductors but water cooled copper pipes.

So you'd have to transform the electricity to high voltage, low current. But we already do that to pretty much arbitrarily lower Ωlosses on high V lines - the USSR made a transcontinental line back in the sixties with MV (yup, mega volts).