Do you think AC will ever be widely replaced with DC?

[sdifox]

Every meal is a tour around the farm. I'd enjoy the meat more if it wasn't for the 4 weeks of 14 hour days.

But it is Damn tastey here

<--- Lived in Buenos Aires for 7.5 years.

I miss the food. Alfajores, Mantecol... and the bread.

 

[kranky]

Never going to happen. Who is going to want to pay to change all the wiring in their house to DC wire? Let alone all the distribution systems that use AC wires now.

Although it would be nice to have plugs with just one prong so you wouldn't have to make sure you turned them the right way to match the outlet, it's still not worth the cost to redo all the wires and plugs for DC.

 

[ichy]

Once photovoltaics and windmills improve, every household can be fully self sufficient, using DC.

Until the sun sets and the wind drops!

 

[ichy]

Never going to happen. Who is going to want to pay to change all the wiring in their house to DC wire?

:facepalm:

 

[PottedMeat]

:facepalm:

i smell a business opportunity

 

[ichy]

Direct Current Monster Cables!

 

[kranky]

Never going to happen. Who is going to want to pay to change all the wiring in their house to DC wire? Let alone all the distribution systems that use AC wires now.

Although it would be nice to have plugs with just one prong so you wouldn't have to make sure you turned them the right way to match the outlet, it's still not worth the cost to redo all the wires and plugs for DC.

:facepalm:

Too subtle?

 

[bruceb]

No, DC will not replace AC. DC motors need to be bigger than the AC counterparts, compressors for air conditioning and refrigerator do not work on DC. Also DC can not be sent a long distance from the power generation facility. They do use DC for subways, where the motors need to provide high torque. But they also have rectifier stations every few train stations so the dc voltage and current stay high. Also the third rail is extremely big to handle the current. With AC, the voltage can be stepped UP, so the transmission lines can be smaller and the voltage goes a lot further to the users.

 

[edro]

Never going to happen. Who is going to want to pay to change all the wiring in their house to DC wire? Let alone all the distribution systems that use AC wires now.

Although it would be nice to have plugs with just one prong so you wouldn't have to make sure you turned them the right way to match the outlet, it's still not worth the cost to redo all the wires and plugs for DC.

 

[Rubycon]

RE: Arcing, this is why one cannot use the same (AC) rating of a switch when used in DC. It's significantly less, otherwise you risk greatly shortened (contact) life and potential fusing of the contacts!

Especially designed switches for high current DC will feature an action with very fast (snap) open to limit the arc. (still hand power range)

For years I've thought Neutrik Speakon type connectors would make great plugs and wall sockets. They have high power ones that can certainly handle the VA but the code doesn't allow it.

 

[jagec]

compressors for air conditioning and refrigerator do not work on DC. Also DC can not be sent a long distance from the power generation facility.

Neither of these things are true. Sure, standard AC compressors don't work if you plug them straight into DC, but that's kind of obvious. DC compressors are available, and inverter AC systems (which are more efficient anyway) convert to DC as a first step before converting back to variable-frequency AC to control the motor speed.

HVDC is also the most efficient way to send power over large distances, now that we have the electronics to allow efficient conversion back and forth.

 

[Red Squirrel]

Why do I have a feeling an elephant is going to die soon?

AC is actually more efficient for transmission because of transformers. You cannot easily convert a DC voltage to another DC voltage. You can use voltage dividers and stuff but it's not as efficient as a transformer.


I do think there needs to be a nema DC standard for household items though. Lot of items run on DC so instead of these devices needing their own rectifiers, they would plug into this specially designed plug. Various light fixture sockets could be made as well for this. Obviously would not happen overnight, but new construction could start having it introduced. Basically it could be a 4 prong outlet for regular items and also have a light socket version. Each prong would be a different voltage. Ex: prong 1: negative, prong 2: 5v, prong 3: 12v, prong 4: 48v. All this would lead to a central power supply next to the electrical panel which feeds a DC electrical panel with it's own set of breakers for each DC circuit. 5v and 12v would be for smaller stuff like LED lights, and most things that have a wall wart. 48v would be for bigger things like computers, very bright lights, etc.

Could use 12/4+gwd wire to feed so that gives you enough watt capacity for most small/medial DC items. 12 awg is good for 20 amps. That's 960w at 48vdc which would actually be enough for a computer, so really quite a lot of DC stuff could run off these plugs.

 

[IHateMyJob2004]

history called

it want its bong back

And it's knowledge of power distribution.

 

[IHateMyJob2004]

Epic troll is Epic.

OP only did the OP and disappeared.

/thread

 

[jagec]

AC is actually more efficient for transmission because of transformers. You cannot easily convert a DC voltage to another DC voltage. You can use voltage dividers and stuff but it's not as efficient as a transformer.

You seemed to have missed the development of switch-mode technology.

There is a reason why HVDC exists and is the preferred technology for certain power transmission applications.

 

[SagaLore]

I think it should be. AC is more wasteful and ultimately more expensive because

Okay I had to stop there because you already revealed you're FOS and don't know what you're talking about.

 

[Phynaz]

Are you a dropout?

 

[shortylickens]

Oh look, its this thread again.

 

[Mark R]

You seemed to have missed the development of switch-mode technology.

There is a reason why HVDC exists and is the preferred technology for certain power transmission applications.

HVDC, despite the advances in technology, is still a very niche system.

The cost of the inverters is immense - so HVDC is only viable where the lines are of exceptional length and capacity; or where 2 independent (i.e. not synchronised) AC grids must be connected. The breakeven point is roughly 1000-2000 miles of length. For shorter legs than that, AC is significantly cheaper.

 

[Jeff7]

I shouldn't give a serious answer to a dumb question, but....

If we discover superconductors that work at room temperature then you might see DC being used a lot more. It's obvious that the OP has no understanding of this though.

I see cheap room-temperature superconductors as being a huge deal, on the level of the widespread use of electrical power. New types of motors, drastically reduced losses in power transmission, insanely fast processors, and lots of fun with magnetic levitation.

On a side note, could nuclear waste be used to generate power for a house? I assume there's still energy left when it's scrapped. Could that be distributed to individuals for use?

Nuclear waste could be reprocessed to extract more energy, but the US has a ban on reprocessing out of concern of proliferation. (I'm sure that secret government projects will follow that law to the letter if they really want some top-notch nuclear weaponry. ) And Europe and Japan do reprocessing,and they have yet to launch ICBM strikes on anyone.
Current reactors extract just a small portion of the possible energy from a given quantity of uranium.

Some of the Gen IV reactor designs are targeted to have efficiencies of >90%, whereas current tech is somewhere around 1%, in terms of the quantity of uranium fuel that actually undergoes fission. And these future reactors would also be able to consume existing nuclear waste as fuel, since there's still so much useful material left in it.
They're quite a ways off though. :\

 

[PowerEngineer]

HVDC, despite the advances in technology, is still a very niche system.

The cost of the inverters is immense - so HVDC is only viable where the lines are of exceptional length and capacity; or where 2 independent (i.e. not synchronised) AC grids must be connected. The breakeven point is roughly 1000-2000 miles of length. For shorter legs than that, AC is significantly cheaper.

Pretty much this. While advances in power electronics has made rectifier/inverters somewhat cheaper, it hasn't really changed the breakeven point for DC transmission very much.

It is true that a conductor insulated to withstand a certain maximum voltage will deliver more power using DC simply because the DC voltage can stay (nearly) at that maximum value all the time. This can mean lower right-of-way costs and also contributes to lower line losses which explains why it can make sense to use DC transmission for long distances. (So does the fact that there are obviously no reactive power requirements.)

As others have pointed out, the ability to use transformers to raise and lower voltage (and thereby minimize power losses over distance) gives AC a huge advantage. Just as important, AC motors are much cheaper and more reliable than DC counterparts. Sure, you can use a DC motor to run a compressor or a wash machine; but you'd be silly to want to.

People have been proposing DC circuit breaker designs for decades, but I'm not aware of any actually in service at transmission voltage levels (although perhaps one or two have slipped by me). In any event, DC breakers are perhaps possible but far from being proven as practicable.

The big advantage to AC for switching and circuit breakers is that by AC's very nature the current passes through zero 120 times a second. As the current passes through zero, the arching current across the opening contacts is extinguished. If we can clear the ionized atoms from between the contacts quick enough, then the insulating strength of the material between the contacts may be enough to prevent the current from restriking (in the reserve direction) as voltage builds toward the peak value. Doing that is what AC circuit breaker design is all about. You don't get any natural current zeros with DC (and voltage is always high too). That's what makes DC switching so challenging!

I think we will eventually see homes built with a single central DC rectifier that feeds a parallel set of DC outlets throughout the house, which should be more energy efficient than having scores of small rectifiers in all of our electronic devices. Now if we can just get all the manufacturers to agree on some industry standards...

 

[herm0016]

I think we will eventually see homes built with a single central DC rectifier that feeds a parallel set of DC outlets throughout the house, which should be more energy efficient than having scores of small rectifiers in all of our electronic devices. Now if we can just get all the manufacturers to agree on some industry standards...

This is my plan when i go off grid. solar/wind/whatever is available. water tower for water pressure and power storage, along with batteries. Regulated 12vDC and pure sine 120vAC outlets throughout. if I must, I can build simple solid state voltage regulators for specific things. wood/coal/geotherm for heat.

 

[disappoint]

I haven't read those articles posted and I will when I have more time but I'll just quickly go over why AC is used over DC.

For long distance power lines you want to minimize power loss due to heat. That is you want to minimize current. In order to carry the same amount of power with less current you must increase the voltage.

P=IV, or Power = Current x Voltage.

If you need to deliver a certain amount of power, and you want to reduce energy loss due to heat by reducing the current flow, then you need to increase the voltage.

That is why high power lines over long distance have very high voltage. It reduces power loss.

AC makes stepping that high voltage down to lower voltages easy using transformers. Transformers do not work with DC because in order to induce a current in the secondary, the primary coil's current must be changing. It's the change in current of AC that makes transformer use possible.

 

[jagec]

HVDC, despite the advances in technology, is still a very niche system.

The cost of the inverters is immense - so HVDC is only viable where the lines are of exceptional length and capacity; or where 2 independent (i.e. not synchronised) AC grids must be connected. The breakeven point is roughly 1000-2000 miles of length. For shorter legs than that, AC is significantly cheaper.

You and PowerEngineer are both right, of course. My point was only that Red Squirrel's claim of AC being inherently more efficient than DC for power transmission was not universally true, DC voltage conversion had moved past mere voltage dividers, and in fact good switch-mode DC conversion can approach or in some cases exceed the efficiency of transformers (but certainly not at the same price-point!).

 

[ALIVE]

DC will replace the AC at least at homes and town distribution.
More and more devices are using DC. So it is a logical change. Maybe we will have something 30-40V rail in the house to minimize the amber in the cables. And use dc-dc converters to get the voltage down right.

Television dc
computer dc
fridge there are dc models already

so electric kichen is one question??
use a line of 200-400v to minimize the amber??

after all dc motors is know technology thus we can replace ac motors with them.
A unification at 24volt will be nice. Since 24volt is already an industry standard.

Given that now we have solar power it is getting ridiculous
solar panel dc convert to ac 80% efficiency to transport to convert again at 80% to use at home dc devices thats 64% so we are loosing around 36% now.

So investing at transfering Dc at hight voltage low amber will solve some issues.