Is it time to rethink our power grid?

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[jdrissel]

I think a good first step would be to define a physical interface. We have what are probably the worst sockets and plugs in the first world. I have given it some thought. It has to be backwards compatible with what we use now, at least for a few decades. It would probably ease adoption if it supports some superset of fast USB charging. I like the principals reflected in the British plug and socket, but we need something smaller. We would not need that much distance between the circuits if we had a ceramic divider that pushed into a slot in the plug actuated by the ground pin. This divider could also serve as a light pipe, enabling smart plugs and sockets to communicate. If there is no comms, the legacy plugs are powered at 120vac when those contacts are engaged. Otherwise the outlet and whatever is connected to it will negotiate a voltage, frequency (0 for DC), and a current limit. The conversion electronics will be in the wall.
So when you plug in your laptop, it negotiates the voltage and current it needs and the outlet supplies it.
The same goes with your phone, TV, audio equipment, network equipment, lamps (lamps may even negotiate lower voltages to implement a dimmer with almost zero parts count.
There are also some cases where we here in America could use some more of that higher voltage and power, such as window AC units, power tools, portable cooking equipment... Now almost everything can plug in anywhere and those junky wall warts and cordbunicles can become fossils.

[wbmgr]

I actually have a reasonable amount of professional equipment that has DC inputs on it. Some of it 48v or 24v fixed but some is auto ranging from 12-24v.

It is very common in the equipment sector that I work in for equipment to either be completely DC powered to be isolated for resilience (so the equipment would runoff a battery bank and the batteries would be charged by a battery charger that was run off a UPS. )

Or, alternatively sometimes you will see a piece of equipment that will use the DC connection as a redundant power source. So it will have in some cases dual AC power supplies and a DC connection as well to a battery bank which has its own charger. Most of our larger network gear is like that.

[VOLKOV]

Your description of power distribution in AC v DC is sort of right but mostly way off. To deliver the same power, if you up the voltage, you lower the current (P=IV). With less current, there's less losses (Ohm's law, which I think you've heard of ;) ). So high voltage actually has smaller losses and is therefore more efficient in delivering the same watts. (This is very distinct from your suggestion that the losses are the same and high voltage can just afford it.) The cool thing about AC is that through transformers, you can kick the voltage up or down with pretty small power loss. So you can pump it long distances at efficient high voltages, and then drop its voltage to safe levels before putting it in homes. With DC, raising the voltage is much harder to implement, as is lowering the voltage losslessly.

[lroy]

No Smiles in Hell for Edison ! The almighty Tesla is the one and true God !

[BlankBrain]

Why doesn't PS Audio offer dedicated solar panels and batteries to power their amplifier rails directly, or with additional regulation? They could add the "Solar" line to their "Stellar" series.
This is only half tongue-in-cheek; I'm considering building an amp with battery-powered rails.
Of course, some AC would still likely be needed to power a tube front-end.

[lroy]

Just putting the HT Lines under ground would be a Huge improvement . How many lines get taken down by storms every year. Vault them save money over time.

[bwithrow]

The transformer steps down the line voltage to 24VAC which is then full wave rectified and filtered to 24VDC.

[siclucealucks]

I would set the DC Voltage std to 24V ...this value can be used by the majority of DC/DC converters. ..sure wouldn't be beneficial for amps with around 50to35VDC(SS Amp). But enough for DACs preamps, CD players..and any other home electronic equipment etc

[exarkunn]

Are you thinking Harries and Izzy? Awesome steak house and the shrimp cocktail is to die for!

[andydelle]

Can't watch the video due to low internal desktop bandwidth where I work, but if we are suggesting DC as a means of long distance transmission, it's been done for many years. One example is the +/- 500kv DC line on the US west coast which runs from Oregon to Los Angeles. Every day driving to work I pass the Sylmar Converter Station in northern Los Angeles on Interstate 5. This is several acres of massive DC to AC inverters. And along the same freeway there is one high tension tower line that only has two wires versus the common multiples of three. That's a DC line from the north. They do this because to spite the cost, complexity, and reliability issues of converting AC to DC then back, it still saves money due to reactance losses on long (hundreds of miles) AC lines.


As for DC distribution at the user level, might actually be practical today. Remember when we had the great Edison/Westinghouse AC/DC war, we did not have efficient switch mode inverter technology. Today we do. So the idea of DC distribution is not that far fetched. Also back in the 1990s Toshiba made a large data center class UPS system that sent 2200v DC from the main inverter to distribution pods in each equipment room. Those then inverted the 2200v DC back to 208/120 three phase 50/60hz AC. Again the claimed benefit was efficiency. Still, I don't see DC distribution at the user level happening anytime soon.

[L.Scott_Music]

The physics of long transmission will keep A/C as our main grid.  But we certainly need to do a number of things to protect our electrical grid from both natural and human threats.  Decentralization and EMP protection are our first concerns.  On a per home basis I can see new homes or home conversions to DC for lighting.  There are commercial solutions that offer 12v or 24v DC for lighting only and 120v AC to outlets.  This is a system that can be implemented fairly easily with proper planning in any new build.  It's a bit more complicated (with dubious financial benefit) for remodels.

[jkbrown]

You kind of run into the same reason that the diameter of the booster rockets on the Space Shuttle are governed by the design of Roman chariots. That is, prior infrastructure governs the cost of later changes. How does a designer of piece of equipment know whether some random DC system will provide enough power, in contrast to the established 120/240v 15/20/30 amp circuits standard in a house today (US). Not to mention the increase cost of higher gauge wiring with high DC amp characteristics. AC only runs at "full power" for a very short time each cycle which mitigates wire heating, etc.

That doesn't mean that there isn't some change coming. I was just reading about the neglected power side of the USB standard and how designers are now exploiting it. This is seen in some phone and laptops that use a USB smart circuitry that can negotiate to provide higher voltages.

[kevenharvey]

Dc voltage would need to be just as high as AC, otherwise you'd need huge cables to be able carry the power, a NA wall plug can carry ~1800W, and sometimes if you're not carefull, the breaker blows. Would be fine for some electronics, but not for all, and at that point, a power supply per item is probably a better idea.

[DodgyBrothersEngineering]

Edison was wrong then, Edison is still wrong now. DC is still not good for long distances due to VD. It may be fine to run low voltage DC inside your house, but it should be stepped down at the house not at the power station, so Tesla remains right. Also there is no thought given to electrocution... With decreased voltage comes increased amps to provide the same nett oomph. So that means making all the wires on the grid substantially heavier to produce the same amount of electricity, not to mention all the heat loss etc etc.

[mfr]

The argument for dc over ac in the home and office, is much weaker now. Th reason is that inefficient iron transformers are not required anymore. Dc/dc and ac/dc switch mode power supplies are about as efficient as one another, so the efficiency advantage disappears. Also in reality, even with a dc source, such as photovoltaics, the voltage has to be changed to the level required by the equipment it supplies, so there is always an "ac" transformation that has to occur. The exception is with small scale simple battery systems that can tolerate a range of input voltages as the battery voltage rises and falls with charge and discharge. Very high voltage dc supergrids, are now being for international transmission. One advantage is the lack of harmonic distortion and power factor issues that plague ac lines.

[Neojhun]

Theoreticaly a DC building network makes good sense. But in reality its just adding complexity to Building Infrastructure which is the hardest, slowest and most costly to manipulate change. If a method could be invented where running DC Circuit around the whole building could be quick, easy & Modular. Only then could a secondary DC circuit be viable.

[christianholmstedt]

No need to make the power grid DC. It's not going to work well. High voltage DC power lines are actually used but it's besides the point.
For home audio it would be possible to setup a DC system. Maybe a ±100V system would be enough.

As a side note. LED can run on AC just fine. They work like diodes.

[chrisvinicombe]

Is that transformer stuck to the circuit board? Why do that when there's plenty of space on chassis?
Stuff like that really annoys me. Means if repairs need to be done, gotta hold a large board with a massive weight in one corner. I consider that to be bad design and have abandoned Acram for just this issue.

[davidchaney]

Can batteries be used to replace power conditioners? Tesla sells battery packs to charge cars and supply houses with electricity.

[swinde]

I don't see how making the grid "DC" could in any way be helpful. Our electronics require as many DC voltages as you can imagine and many require large amounts of current be available such as power amplifiers, toasters, irons, stoves, refrigerators, cloths dryers etc. AC can easily be converted to the exact voltage and current needed in each device. High voltages also have less losses over distance.

If all we had was light bulbs it might have been doable, but the complexity of modern electronics would seem to say no.