The curse of 'white oil': electric vehicles' dirty secret

[ajdelange]

The one I liked the most was smelting and melting of metals only when there is huge surplus of energy.

It's just not practical to build an aluminum smelting plant that only works a few hours a day or that must be shut down if the wind calms.

I got interested in this and a little more digging revealed that it is not only impractical. It is impossible. You cannot shut down an aluminum smelter for more than a couple of hours (with out damaging the pots) but what you can do is feed more or less bauxite for load leveling! I think that's pretty neat. Thus on a sunny but cool day in NY when the solar production zooms but the A/C load is low they don't have to dial back the big hydro plants up here (Quebec). They just ring up one of the many smelters and tell them to make more aluminum using the juice they can't sell to NY (and which they make available dirt cheap). IOW there is always a huge surplus of energy here in QC (and lots of smelters). Water that goes over the spillway instead of down the penstock represents wasted solar energy.

More to the point of the discussion re solar is Australia where evidently this technique is used extensively. What do they do when the sun shines and the battery banks are charged? Ring up the smelter. A lot of speculation on my part here. I don't really have any details on the Quebec or Australian mechanisms. But I always have wondered how the manage the "duck back" in places that don't have pumped storage. Now I have another idea.

 

[ldjessee]

Power cables are in the air because air is a powerful insulator. It's simply cheaper to suspend them in the insulating mixture which is 'air' than to dig a deep trench, cover them in special insulating material, and keep water and roots out of it.

We bury cables in many places, but pretty much only in the most densest areas or places which have chosen to make this expensive step - usually places with groun cheap to burrow in without many deep-rooting plants.

The water system we have locally is mostly not burried. Many water systems don't even have covers! We call those canals.

-Crissa

People say digging is expensive, but when these aerial power lines start forest fires that burn millions of trees releasing tons and tons of carbon into the air... Not sure I think that equation balances the way many used to think it did.

2-3 times a year, my power is cut because a car or truck misses the curve and takes out a pole.

They keep putting wood poles up, because they said if they put the metal ones up, it will most likely kill the people in the car and they still will have to replace it anyway, because it is damaged....

And I understand it might not be practical to start a huge project to just systematically bury power cables now, but as you do construction, improvements, expansions, etc this work could be done then.

But I am no expert... I also question why our electrical grid backbones are not superconductors. We can make superconductors that require a temperature warmer than liquid nitrogen... Just not sure where the power needed to keep them cool balances with the power saved from power loss due to resistance... has to be a lot with the main lines coming from power sources... (most power, most losses from resistance, right?)

Then when it gets to one of those stations, it moves back to normal power lines...

I mean, I cannot have been the only one to thought of this... (quick google search) Nope, Germany did it in 2014. 1 KM long superconducting powerline between two transformer stations in the city of Essen.
"For a sense of how important that could be, consider that in America something like 6% of all electricity generated is lost to inefficiency during transmission. In 2005, that was around 250 million mega-watt hours, or about $20 billion in monetary value."
I have not checked this article for accuracy, but it does show that I am not the only one who thinks this could be practical. And I assume superconducting cable is easier to keep underground.

If canals were covered by solar panels (as that project in India is doing), it would save loses from evaporation...

 

[Crissa]

Yep, they're liable when people slam into metal poles.

It's pretty ridiculous.

The forest fires have all started in weather that is outside the historical record. Very difficult to build for a climate that wasn't predicted.

I'm not saying that we shouldn't have underground utilities. We should. But getting them built would take a massive undertaking larger than the highway-building effort of the twentieth century.

Handwaving that it can be done - we need to accept the costs.

-Crissa

 

[ajdelange]

Are you the only one thinking of this sort of thing? No, of course not. The people that built that experimental line are thinking of this sort of thing. Is it practical at this stage in its evolution.? No, not by a long shot but by experimenting they may learn something which will bring it to the point of being practical some day but "may" should really be in bold letters.

Yes, most of transmission losses are associated with warming of the conductors by current flowing through them though some energy gets converted to sound (the buzz and crackling you hear near a high tension line), some is radiated, some is lost in the cores of step-up and step-down transformers. Taking your 6% total transmission loss figure I'd guess 4% goes to heating the wires and 2% to the transformers (i.e. the other losses are insignificant). Definitely a practical super conductor would transform the industry. The efficiency of a transformer wound with superconductors would be better as well as the savings in the lines themselves. But so would a generation/storage system that obviated the need for long range distribution.

 

[Crissa]

Nearly none is lost in changing the voltage of AC power. That's a major advantage of AC power. The losses are so small they're not generally calculated beyond the copper length.

-Crissa

 

[ajdelange]

. (most power, most losses from resistance, right?)

Yes and the losses are proportional to the square of the current so the obvious approach to transmission is to get voltage up thereby reducing current. The reasonTesla and Westinghouse beat out Edison is that this is relatively easy to do with AC and, with the technology of the time, very difficult to do with DC. Power generated at about 4 kV can be transformed up by a factor of 177 reducing current by the same factor and loss by a factor of 31,217. Of course there is a spoiler in here and that is that all the current in a AC system is not active (delivering power). Some of it is reactive. This doesn't transfer any power to the load but does to the line conductors and transformer windings it flows through. Reactive current flows across the insulators one sees on power lines and from the conductors through the air beneath them to the ground. This is particularly problematical in buried systems as the conductors are often only inches away from the earth.

So why am I going on about this? Yesterday we were driving in the country and I spotted this out the window.

Did a double take, swerved and went back to take the picture. No, Mrs did not think I was nuts. She well knows I am. So what's wrong with this picture? Some of you may, from the drift above, already figured that out but I'll bet that very few of you have ever seen a pylon like this one before though you may have seen thousands of normal ones. What's wrong with this picture is that there are only two sets of conductors on it and all the towers you have probably seen have 3 (I had never seen something like this outside of a GE lab and that was over 50 years ago). This is a DC transmission line (Edison must be chuckling in his grave) which transmits 2000 MW at ± 450 kV from James Bay to Boston (with taps for Montreal)..

DC transmission has its own set of problems associated with voltage conversion, conversion from AC to DC and back and switching, of course, and DC lines are rare but reactive currents are eliminated.

2-3 times a year, my power is cut because a car or truck misses the curve and takes out a pole.

This problem is not eliminated. In 2004 some whackos from the Resistance Internationaliste tried to knock one of this lines towers down (not far from where the picture was taken) with explosives placed at the pylon's base.