I (current / amperes) squared, times resistance (ohms)
100 Amperes @ 100 Volts = 10,000 Watts
2 Amperes @ 5,000 Volts = 10,000 Watts
Wire of 5 Ohms resistance
100 x 100 = 10,000, 10,000 x 5 = 50,000, so you’ll get *nothing* out the other end, in fact, to get 10,000 Watts out the other end, you’ll have to put 10,000 + 50,000 = 60, 000 watts in one end, and you’ll get 84% transmission losses.
2 x 2 = 4, 4 x 5 = 20, so you’ll get 10,000 – 20 = 9,980 watts out the other end. You’ll lose less than a quarter of one percent to transmission losses.
In ZH today there is a story about how 9 substations being taken out would take the entire US grid down, I have mentioned here before that the number for the UK is 6 substations.
so… to transmit electrical power over long distances with minimal loss, high voltage beats high current every which way.
So… DC vs AC…
DC is *a* thing, Direct Current.
AC is NOT *a* thing, 50 Hz AC is one thing, 60 Hz AC is another thing, and 240 VAC is not the same as 240 VDC, nor is it the same as the RMS of 240, 240 / 1.4 = 170 VDC, nor is it the same as anything else, because AC gets you reactance and inductance and skin effects and a whole load of other fun stuff you don’t get with DC.
Part of AC is time, on a 60 Hz AC system the “rise time” from minimum voltage to maximum voltage is 1/2 second, rise time is “rate of change”
Almost everything, most especially everything that is a semiconductor, has a rate of change sensitivity, eg a voltage change of X over 1 second won’t damage it in the slightest, the exact same voltage change of X in 0.0001 second will fry it, dead.
So, you see, it is complex, the AC v DC argument isn’t as simple as frog up or frog down on a UK house / engineering brick.
Some of the things that make AC complex, such as reactance and inductance, also make it easier to deal with than DC, to change (from our opening example) between 100 and 5,000 volts with AC is trivially easy, just use a transformer, but to change between 100 and 5,000 volts with DC is complex, read, expensive.
But it’s not all roses, with DC, being DC, there is no “rise” time, so lots of other things are more robust, read, cheaper.
One of the big problems with DC is there is no “zero” point, as there is with AC, during which you can open or close a switch… 60 Hz AC has 60 “zero” points per second, when no current or power is flowing.
One of the big problems with AC is you can’t just connect two different systems, the “clocks” of their AC cycles have to be *exactly* synchronised, or vast amounts of power start flowing and things go bang.
3-phase works on this principle, each phase is 120 degrees or one third of a cycle, for 60 Hz this means one third of second, out of sync with the next, by bridging between phase 1 and phase 2, or phase 2 and phase 3 in a three phase conductor you can get 220 volts, by bridging between phase 1 and phase 3, you can get 440 volts, if it is 440 V 3 phase.
With 3 phase you don’t just have one clock running at 60Hz (or 50 Hz in Europe etc), you have three, all exactly 1/3rd of a phase out of sync with each other.
DC doesn’t have any of these issues.
Stepping down from a 300,ooo Volt AC line to a domestic 200 VAC supply is no big issue.
Stepping down from a 500,000 Volt DC line to a domestic 24 VDC supply is problematical.
In human terms, DC makes the muscles lock, I used to work on massive DC battery bank systems up to 110 VDC in boats, old school stuff, and it was about a million times as lethal as taking a piss on to a live domestic AC power socket.
You also have to remember that back in the days of Edison and Tesla and Westinghouse, there was no such thing as a semi-conductor, my dad had an ex US army inverter, a *fucking* heavy steel box about the size of a 2 gallon can, you put 12 VDC in and got approximately 200 VAC out, at approximately 50 Hz, inside the box was a DC motor directly coupled to an AC alternator, horribly inefficient, a purely mechanical power intermediate stage, DC power to mechanical motion, and mechanical motion to AC power, back in its day, an awesome piece of kit, because this was the *only* way you could do it.
This, in engineering terms, is the meaning of a legacy system, if you were going to build a national power grid today, you wouldn’t build what we have.
The problem with what we have, is that it is past its use by date, and trying to migrate it to a 21st century system is impractical in the F-35 all purpose but not very good at anything and spectacularly expensive to build and maintain sense.
As an aside, this also applies to our telephone / comms networks, our potable water networks, our sewerage networks, our rail networks, our gas (methane etc, not gasoline) networks, etc etc.
Building new networks is *spectacularly* expensive, Fed QE scale, but at least the money would have gone into the system, not the bankers pockets.
Building new networks means new suppliers and new components and new technologies, everyone working today is working with the old Victorian era shit, they aren’t going to re-tool and re-train on maybes, and in any event, they will want to own market shares, so there will be patent wars and “standards” that are just proprietary ways of locking other people out, rather than doing the job right.
The power grid is just one example, but it is a good one.
The *engineering* solution is to come up with an overall design and set of *engineering* standards that will last another hundred years, that means a fault resilient grid for starters, not one with master nodes that can cause cascade failures.
The *engineering* solution also means you just fucking ignore everything that isn’t a base load generator, eg able to work on demand 24/7/365, so with the exception of hydro all that other shit is out, in grid terms, sure, feed it into small local nodes if you want, but not the grid.
The *engineering* solution means you need a smart network, not a dumb one, at present if say London goes dark, you can’t just plug London back in, the sudden load is too great, and you have no way of turning off all those televisions and refrigerators and water heaters and so on that are just sat there, connected in the “on” position to a dark network, waiting for power…. You need to not just connect localities one at a time, but loads within localities, so not just “OK, bring Marylebone back online”, but “OK, Bring Marylebone street lighting, traffic signals, and hospitals back on line….. waits 360 seconds, OK, now bring on the Domestic lighting circuits”
The *engineering* solution means you don’t get to connect to this new grid, unless all your shit is smart, with a smart central controller, so when the power goes out it shuts off everything in the house, and when the power comes back on it waits until the network tells it that it can now energise up to 300 watts of purely resistive loads, so lights only, no inductive loads like fridge compressors, wait for the signal.
The *engineering* solution says you have a smart system, the smart thing to do is include a UPS, say 250 Ah of 48 VDC (about 8 truck batteries) which itself knows what loads to prioritise, so the 1 watt GU10 LED lights are top priority, the electric kettle and kitchen sockets bottom priority… the smart home system can talk to the smart fridge freezer to monitor how long it can go with the door shut and keep everything fresh….
… “internet of things” sounding familiar yet?
The *engineering* solution is that if we had a grid capable of it, electric cars or true hybrid (no mechanical drive-train) would make more sense, and electric trucks, and so on, and if your electric car is at home, and your home is the suburban home with your own driveway and off road parking, well, that just adds battery capacity to the home UPS, which could at a push on demand feed power into the grid….
Back in WW2 a british destroyer provided the mains electric for a whole indian city.
A true hybrid truck putting out 100 BHP from the generator side of things is 100 x 746 = 74 kW, a street of 100 houses all with true hybrid cars, 30 of whom are home at the time, all putting out 15 BHP from the generator side is 30 x 15 x 746 = 335 kW, third of a megawatt right there.
Not what you would want to be doing long term for efficiency or environmental reasons, but it would fucking *work* while the main grid supply was offline…. and it’s not like the smart systems wouldn’t be able to credit you for the energy used once the downtime was past.
Trouble is, human nature being what it is, nobody is going to build *any* of that stuff while the current grid is up and running.
Trouble is, if the current grid stops running, so does society.
It’s a problem, there is a hole in my bucket, dear Liza…
What we need, they say, is a war, a big one, that takes down the grid and a lot of other legacy shit too, lot of collateral damage and dead bodies in that though.
But, we are still talking about acts of MALICE (as in the ZH article) taking down what we have now.
If there is *anything* you should be taking away from the stuff I write about my day job it is that no acts of malice are required, simple nickel and dime-ing management practices are quite sufficient, all by themselves, to achieve EXACTLY the same effect, and unlike supposed acts of malice, management practices such as these are real and happening every, single, day….
A terrorist event, or an act of god event, they are *****IF***** events.
Management practices causing something to fall below stall speed, they are *****WHEN***** events.
It doesn’t matter one fuck if it is a $1 bullet, or $1 saved on a component or maintenance, they are just triggers, you’ll still be in the dark, and it won’t make the ***slightest*** fucking difference to you that it was $1 saved on a component and not some terr-rist with a $1 bullet that put you there.
Just to be totally fucking clear, terrists and other assorted assholes MIGHT cause it, it all depends, but current business and management practices WILL cause it, absolutely fucking certainly and without any doubt whatsoever gau-ron-fucking-teed.
Worrying about terrists is like worrying about developing the symptoms of lead poisoning after you take a bullet.
What you need to remember, sitting there in the dark, so you won’t be reading this or anything else, because it will all be gone, is this…
By fucking definition, the people and practices that put you there, are, by fucking definition, the least qualified or likely of all people and practices on the entire fucking planet, to fix it.
You’ll need people like me, and boy, our price is going to be fucking brutal, and the above people and practices in red, they’re the new Jews, and we’re the new Dr Mengele’s, and if anything that is understating the case.
It ain’t just a case of charging or demanding what we want, and expecting to be treated like the fabled 0.1% today…. oh no… unless the price is so high it breaks your body and soul and spirit, it isn’t high enough.
Payback’s a bitch, but then, so is physics.