Marocco is currently connected with mainland EU with 1400 MW AC. Another connection is discussed with Portugal. I've heard about the plans to connect UK, but I don't know if that really makes financial sence.. It would be more than twice the length than the HVDC that connect Norway and UK.

And not to be the wiseguy here, but You are actually wrong on HVDC (High Voltage DC). HVAC has inherently higher losses due to the alternating part of it, which causes dielectric losses the to capacitance, and inductive losses the to inductance - both being dependent on frequency. Thus HVDC has lower losses than HVAC.

But you are right on the oart of voltage since losses are directly proportinal to the square current (I, Amps). So higher Voltage, less losses and vice versa.

And HVDC have been around since 1950's and is still developing. HVDC is very common now, and a lot of links are continously beeing installed ot just since it's more effective but also give other aspects to a grid. And yeah, I am actually an engineer

And drive 2 EV's - none of 'em Teslas though.


Thinking of it - my first and Only post and has NOTHING to do with music.... kinda bizar...

 

Last edited: Dec 21, 2021

Don't buy, share -> car sharing

 

Interesting.. could you elaborate more?

I'm certainly not an Engineer,
but I studied preparatory school of Technology and they taught me the usual narrative of DC = Bad for transmission..

And well, this are hardly reputable sources,
but it seems it's also common understanding:
https://www.designingbuildings.co.uk/wiki/Alternating_current_and_direct_current
http://www.electricalterminology.com/advantages-of-alternating-current/
https://winnerscience.com/2014/08/13/8-advantages-of-alternating-current-over-direct-current/
https://greengarageblog.org/10-pros-and-cons-of-alternating-current

In short..

Spoiler: Pros & Cons

Easy to step-up
High voltage is required to economically transmit large amounts of electrical energy over long distances.
In DC systems, it is impossible to obtain a high voltage above a certain value for various reasons.
Alternating current generators can be made to produce higher voltages than direct current generators.
AC can be relatively easily and economically stepped up or down with a transformer to suit the application.
DC cannot be wired through a transformer.

Easy to step-down
AC can be increased to high voltage levels for transmission over large distances, then stepped down to safer levels for consumer use.
The increased energy needs to be reduced for measurement and usage purposes.
Thanks to the alternating current, it is also possible to measure and use the energy with high accuracy.
Alternating current energy meters and home appliances can be produced in small sizes.

High efficiency
The efficiency of alternating current generators is over 95%, and their power is greater than direct current generators.
Thus, larger production units can be established and the efficiency of the turbine generator system increases as the efficiency of the turbines increases at high rotation numbers.

Low cost
AC is cheaper to generate than DC.
Multi-phase alternating current asynchronous motors are easy to produce and are about half the cost of an equivalent direct current motor.

Less maintenance
Besides, AC motors require much less maintenance than direct current motors.

Conversion to direct current is easy
Direct current used is first produced as alternating current.
Alternating current is brought close to the place of use and is converted to direct current with rectifiers or motor-generator groups. Although alternating current can easily be converted to direct current with rectifiers, it is not so easy to convert direct current to alternating current. Moreover, converting AC to DC is cheaper than converting DC to AC.

Small cable diameters
A.C voltage is generated in power plants with the help of big alternators.
This A.C voltage is increased by transformers to reduce the losses that may occur in transmission lines.
When the voltage is increased and the current is decreased, the diameters of the conductors used in transmission lines are also reduced.

Heat energy generation
To talk about the heat effect of electrical energy, it is first necessary to dwell on the resistances of the conductors.
Each conductor has a resistance associated with the diameter, length, and resistivity of the material from which it is made.
When the electric current passes through this conductor, if the conductor shows too much difficulty for the current, this difficulty generates heat energy on the conductor.
Alternating current is used not only in conventional heating devices but also in arc furnaces and induction furnaces operating with three-phase current.

Multi-phase options
In the AC system, we get three phases, which is a desirable property as we can feed different areas with different phases, and if any problem occurs only in a single phase then the other two will keep on working and total power cut will not occur in all areas connected to the same supply.
(And also the phase cancellation that I mentioned for excedent currents..)

Safety
With AC, it is really easy and safe to interrupt the current due to the current going to zero naturally every 1/2 cycle.
For example, a circuit breaker can interrupt about 1/20th as much DC as AC.
Also, AC generates less electrical arc when interrupting the current.

Disadvantages:
Alternating voltages cannot be used for certain applications e.g. charging of batteries, electroplating, electric traction etc.
At high voltages, it is more dangerous to work with AC than DC.
The Shock of the ac is attractive but the shock of dc is repulsive. (although I heard contradictory arguments on this)
Need for insulation
Need for Inverters

So yeah, I won't say I'm totally wrong, as this is common knowledge..

But in this specific HVDC case things seems to be actually Reversed,
and is exactly for that reason that I was quite surprised to find out...

And now you Confirm it.
Is it really all that different when talking over such long distances?
What kind of voltage/intensity are we talking about for HVDC?

Interesting..

And what about the typical story of DC Burning power lines if made too intense,
and thus needing more intermediate stations..?

I guess since DC cannot use transformers to step the current up/down,
and there's considerable energy losses on long distances due to Heat generation,
super Thick-ass wires would need to be used, which increases cost.. no?

Wouldn't this Thick wires cause higher resistivity losses?

And what about the phase cancellation of excedent currents? or the lack of multiphase?
Is there an equivalent system for HVDC, or how are they dealing with peaks/stuff?

I can definitely see what you comment about Inductive losses, or at least inductive Interference,
as AC is more of a voodoo thing that likes to fly around in electro-magnetic fields.. lol

So yeah, I'm not saying you're wrong,
but could you tell us more?


Here's the official Morocco-UK Xlinks site:
https://xlinks.co/morocco-uk-power-project/

 

Last edited: Dec 21, 2021

If we get to something like that scenario describes, it's basically a churn. Doesn't matter what you have or don't have very few people will actually be able to hold on to any of it as it will be taken from them by meaner badder people. Let's not get ahead of ourselves and all think we are mean, bad people that will do the taking instead of having our stuff taken and then thanking the baddies for it. Safest mode of transport in such a situation is using your own two feet.

Freedom and convenience can exist when you convince the meaner, badder people to not be mean or bad because life will be better for them and everyone else if they don't make us all live in the stone age. That reasoning of social compact is the foundation of the difference between Afghanistan and Haiti or the United States.

From personal experience having been around a lot of human from monsters in my old line of work, if you get angry a lot or are cranky you are probably not a mean baddie. They tend to be very stable and mid range emotionally, violence for them is just something that you use on everyone. Kind of like toilet paper is for wiping your but, killing people and taking their stuff is how you get food or whatever you want, no emotional investment or turmoil required.

Now outside of doomsday scenarios there isn't much to argue about there. The question was if you could afford different kinds of chocolate what flavor would you choose. I don't understand why everyone needs to justify their choice or convince others that they choose the same as them. Freedom is the ability to choose, who can one have more freedom with limited choice.

 

Thanks to both of you. My well out of date appreciation of the engineering and economics of elec supplies got a nice update from reading this. Comments below are a mix of what I already knew, realising it was out of date, and what I just learned.

The competition between transmission via AC and transmission via DC has been with us ever since humanity learned to harness electricity. Factors like practical engineering feasibility, safety, and economics all contributing to the squabble.
Fascinating how this tit for tat, pros and cons, has enabled both AC and DC to prevail in different circumstances.
Nice intro to the history is here https://en.wikipedia.org/wiki/War_of_the_currents

@Ŧยχøя, Like you, I kind of got lulled into thinking that AC wins for bulk transmission and that the killer arguments were...
- Bulk transmission requires insanely high voltages (for efficiency)
- Stepping up and down between essentially-high transmission voltages and essentially-low domestic voltages is viable, simpler, cheaper, with AC but too elaborate, too costly with DC.
Therefore (and for other reasons) AC wins for bulk transmission.
Edison's DC lost, Westinghouse's AC won - game over - but that's only cos my history knowledge was naive.

AND my view of bulk transmission was parochial. We think of bulk transmission as being our national grids and for those we take it for granted that AC has won the contest.

But today, for 'really bulk transmission', where the game is to use 'power super highways' to transfer really huge power between (even incompatible) AC transmission networks, the engineering and economic benefits of using DC for those connections is apparently viable and attractive.
Hence for underground, underwater, 'really long' bulk transmission, the balance tips back to DC.

My scruffy summary above leaves out only 99% of the interesting techie details
i.e., the stuff that actually matters and that goes over my head.

I won't paraphrase extracts but I just learned some interesting stuff from reading these links...
https://www.quora.com/When-and-why-...now-What-are-its-advantages-and-disadvantages

https://en.wikipedia.org/wiki/High-voltage_direct_current

---

@Ŧยχøя, I will just pull your leg though...

you know you got that bit arse about face - right?

 

This always comes to mind when I see posts like this

 

Don't need an Electric Vehicle! You will Eat the Bugs! And Live in a Pod. You will Own nothing. "Eco-Friendly"

 

Good stuff
Exactly what I needed.

It's one thing to have a bunch of massive articles and books that explain the stuff in detail.

But it's not that easy to have a bunch of experts/ppl who know what they're talking about,
Summarizing the whole thing in a few clear/efficient paragraphs..

 

Last edited: Dec 22, 2021

I'mma let yall finish but where do were do we put all the dead batteries, and if you have street parking how do you charge your car?? you have a few years to figure it out in Cali so don't worry

 

That's very true,
In practical terms, to have an EV you need to have your own Garage (hardly possible in big EU cities), or a Parking lot with current.

Otherwise I guess one could recharge the car on the weekends,
or leave it chargin in the stations in the afternoon/night..

But you lose one of the benefits which is all that freedom..


Batteries can be recycled or refit,
it's still an emerging/evolving thing so it's got room to improve.. and manufacturers play a big part in that.

But the industry is moving in that direction too, so it's doable to a certain extent

https://cen.acs.org/materials/energy-storage/time-serious-recycling-lithium/97/i28
https://www.nature.com/articles/s41586-019-1682-5

 

Last edited: Dec 22, 2021

Someone drives into town to work in the morning and parks their car. A car takes about 8 square meters. It just stands there uselessly all day until evening. People in cities suffer from air pollution and noise. We need other intelligent transport concepts. Playgrounds, benches and vegetable gardens should be built where the cars were. Here is an article that is worth reading:

Paris mayor bans cars and wants to completely rebuild the city
A city for the citizens and not for the cars - that is what Anne Hidalgo promises. Should it be re-elected, pedestrians and cyclists have absolute right of way and the car will become the slowest mode of transport. We present the plans. Who does street space in cities belong to? In Germany you just have to look out the window and you know the answer: The road belongs to the motor vehicle - all other road users are pushed to the edge and are tolerated at best. But more and more cities are rethinking - in Scandinavia for a long time. There you can enjoy the results of a real traffic turnaround that is only conjured up in Germany: The number of children, pedestrians and cyclists killed by drivers has fallen dramatically - in some large cities to zero. (Read about this: "Helsinki reports zero dead cyclists and pedestrians in traffic") But the mayor of the French capital, Anne Hidalgo, has also wanted to tame the traffic juggernaut Paris since 2014.
www.france24.com/en/france/20210514-paris-mayor-steps-up-green-city-goals-with-latest-car-ban-plan

 

There are about 1.446 billion vehicles on Earth in 2021. About 21% of those vehicles are in the United States.
https://hedgescompany.com/blog/2021/06/how-many-cars-are-there-in-the-world/

• All my adult life, I have taken it for granted that I have access to a personally owned car, available for me to use any time I want.
• There are approx 7.9 billion people on the planet.
• Assume all 7.9 billion people adopt the same stupid entitled attitude as mine - it's not viable - we are all screwed.

I will continue to use a personally owned car almost every day.
I will cheer if and when we finally get rid of this insane addiction.
It has to change. Ideas like the Paris Mayor above are vital; individual choice won't make it happen.

 

Last edited: Dec 22, 2021

The biggest polluters are not cars, but ships on the oceans, airplanes and the military.

Maybe sails and gas for the container ships instead of oil, maybe hydrogen for the planes.
Maybe we exterminated ourselves at the end of the century, global warming, water shortages, food shortages, viruses and wars.

 

It's up to the environment you live in..

In Barcelona for instance, I use mainly a road bike to move around..

It's only if I'm on a hurry, or have to move far that I would take public transport,
but there's a considerable choice in there..

I could take the Bus, Taxi, Metro, Tram, or even Train to move around in the city.
(all of them at a 5 minute distance from my door, or less..
and at 5 minute distance from my final destination..)

And If I needed to move around the region, or even the entire country,
I could do it very easily just by taking a Train and then maybe a Bus if the place was isolated or something..

That's not true for smaller cities, or less developed countries,
or countries that have a different mentality/way of doing things..


I imagine in USA one Needs a car,
because cities or suburbs are made with a different mentality.

There's not as much Trains connecting cities and suburbs,
and I imagine the Bus is a secondary option as it is here..

So I imagine if you live in a Suburb and need to go downtown in LA or whatever,
you need to have a car, or use the bus..

Ofc you could potentially go with a bike, or even walking..
But you'd need a good dose of patience/morale, or even an armor (lol),
if you had to walk all through those distopian Long/Wide straight-ass streets that go away towards the infinite lol..


Also the culture is different,
afaik (or at least as far as TV/Cinema has told me),
it's very common in USA to have the Parents pay for the driving License of their kids when they are 16yo..

And they will be driving the car at 16, and even drive to School which is unimaginable here..

Here only the rich/mid-high class families will pay the driving license, but that will be at 18-20 or more..
and usually families have One single car.. only the most rich ppl will have two cars.

So yeah it's a different mentality, and it's a direct result of how society is organized, and cities/terrain laid out.


In many African countries you also Need a car, and better if it's a 4x4.

Or just a good old/real motorbike (not a 49cc scooter),
just like they do in many Asian countries too..

In Barcelona you can also use car or motor-bike,
but it's not really all that necessary, only more practical in certain situations.. that's what I 'm sayin

 

Last edited: Dec 22, 2021

Agree and agree.
But even if the cars were 100% non-polluting, the idea that every individual on the planet can own one is a fantasy that has served only privileged entitled people during a brief period of human history. A world with 8 billion privately owned (pollution free) cars would still be dystopian.
Although I drive a car most days, I do prefer to regard my life as a healthy pedestrian as far more important than being a privileged motorist.
A village/town/city full of pedestrians/cyclists is infinitely more attractive than thousands or millions of cars.
It has to change. Cities are where the major mind-set changes are required first.
None of this is news - it just needs to gain pace.

 

Last edited: Dec 22, 2021

Example Africa, the worker transports oil crops from the field to the company where the oil is pressed. He has a bike and drives from the field to the company 3 times a day. When he has saved enough money, he buys a scooter with which he can take his child to school and drive from the field to the company 6 times a day. If he has saved enough money, he can buy a car and drive 20 times from the field to the company.

 

And of course we can't argue with that logic for those circumstances.
BUT
Assume that every individual can provide 1,000 entirely valid reasons why he/she NEEDS to have a car.
It still holds that 8 billion of us can not all own cars - that is dystopian.
Scenarios like these are very classic clashes between the interests of individuals and the interests of society.

An individual cannot be expected to solve this.
That's why society needs to re-organise around not needing private cars - not easy!

This is just a classic example of a 'tragedy of the commons' scenario - they come in millions of guises.
They do not get solved by listening to every individual (like me) saying "well hey mate - I NEED a car"
and then pretending that I'm right because I can offer entirely valid personal reasons.

It's easy for me to identify my needs. It's harder to own up to being part of the problem.

 

Last edited: Dec 22, 2021

Right - I want to add, who actually benefits from the car and who makes sure that little changes? The state has tax revenues, the oil companies, and many jobs depend on cars. There are always alternatives, some young people do car sharing because they no longer consider it a status symbol.

Oil is the engine of every modern industrial society. Only if you can earn money with environmental protection will there be environmental protection. In other words, money is made with e-cars and pollution rights. As a large oil company, you paint yourself green. But only the winnings count.

As @Ŧยχøя χøя already described, it is important to have good traffic concepts that citizens can then adopt. Car pooling and car sharing also take the strain off traffic significantly. Oil would have to have a fixed price that would become more expensive. Then companies could also convert their production.

 

Last edited: Dec 22, 2021

I worked as a commissioning engineer in several plants around the planet, I can roughly tell you how is made the distribution chain (the biggest plant I saw):

- generator(s) 15kV AC ->
- step-up transformer (there can be more than one stage) to 132kV AC(SF6 gas insulated ducts!) ->
- substation(s) with step-down transformer(s) to 11kV ->
- various distribution substations with step-down transformer(s) to 400V AC (380V) and / or ->
- distribution cabins to final commercial user (380V or 230V AC).

The SINGLE smallest generator I dealt with was 80MVA hydrogen cooled (fucking dangerous!!!) and the biggest 750MVA (demineralized WATER cooled, inside stator windings).

DC is not very efficient for long distance distribution, and there are special substations within plants that deal with that (example the charging stations for backup batteries in case of failure of main supply) or for example for trains and subways where they use (now) electronic converters to regenerate AC for motors.

One small example: in plants are extensively used remote transducers of all types, typically any physical source measurement (e.g. 0 to 100°C) to 0-10VDC or physical source to 4mADC-20mADC.
Volts are suitable for short or very short distance, instead for long distance mADC are used, because the transducer will supply whatever voltage enough to drive at 20mADC for, let's say, 200m (this is written in tech specs), current is the same no matter the circuit lenght.
If you used V reference, 10V at 1m is still 10V, but at 200m could be, let's say 4V, leading to a huge error (40°C instead of the real 100°C).
AFAIK ethernet is replacing all this.

 

Last edited: Dec 22, 2021

Couldn't agre more
I'll try to reply to some of Your comments.

Well, that depends on what we mean with transmission. If we speak about our grid as a whole, there is today NO practical/technological/financially feasble way to replace an entire grid structure (generation - transimission - load) to DC. Just take a look at the EU grid for starters. https://www.entsoe.eu/data/map/

Besides, AC has certain advantages as you mentioned, and when we speak about the transmission AC has advantages over DC
-AC is extremelly fault tolerant - i.e we could loose a transmission line, but the electricity will nonetheless work within the syncrounous area since the electricity will per definition just flow another way. This is ofcourse dependent on the network structure, and in some cases a fault in an overlaying grid may cause to much power to flow to a underlying grid potentially causing severe damage and outages.
-AC is easily transformed (which you mentioned). This is an extremely important issue since the losses are proportional to the square of the current, which is the very reason we use HVAC for long transports.

However, if we by transmission mean point to point, HVDC has some clear advantages over HVAC.
-Lower losses as I mentioned above due to the fact that only HVAC.
-Modern HVDC links can be used for black starts of parts of the grid (HVDC VSC can create it's own since wave at the receiving end thus it's not dependent on a sine-wave at the "revieving end" to work. Older thyristor based HVDC could not do that however)
-In HVDC-substations you can control the phase angle between the current and voltage. This is one of the important quality aspects of any AC grid, and since we have more and more inductive load (voltage ahead of current) an HVDC link could actually be used to ease that effect. In general this is what media reports as "reactive effect", but from a purely physical perspective it's a matter of the phase between current and voltage.
-You can connect different syncrounous grids (when you think of this - it is a very important since larger grids are more resilient, think W/Hz when it comes to frequence regulation)

Back in mid 2010 the 1100 kV level was reached by ABB (now sold it's division to Hitachi) and Siemens also had the same just a while later (if I remember it correctly). The power is well in the GW range for HVDC, and I think the Changji-Guquan link in China with it's 12 GW over 3000 km still has is the largest. This IS the main advantage HVDC has over HVAC.

Actually, it's the oposite - almost.... I wire with a larger area will have less resistivity - BUT.... For AC there is an effect calle the skin-effect that casues the current density to be highest close to the surface, and then decline rapidly towards the center of the cable. This is due to the eddie currents that are created by the alternating magnetic and electric fields in the AC. Since HVDC isn't alternating, the skin-effect does not apply.

DC doesn't have any phases per se. The three phase system we have in AC thus has no bearing on DC. The station in each end of a HVDC converts the incoming 3-phase AC to DC and at the oterh end vice versa. And to be precise, the ctual flow of power can be directed in both directions in a HVDC.



But the Marocko link to UK.... Well... The North Sea Link interconnecting the Nordic syncrounous area to UK is 700 km (Norway - UK) and a ~2 Bn Euro investment. The capacity of that is 1.5 GW at ~500 kV. 3800 km is doable with HVDC, but all subsea ?? It would be truly amazing if built, but I see a lot of issues with potential faults and how this will be handled. There are other simliar ideas (Australia for instance) but they are yet to be realised. Somewhere there is a financial analysis to be made, and right now... I'm not sure the cost of transfered energy is good enough. But I hope I'm wrong !!!