Big Steps In Building: Change Our Wiring to 12 Volt DC

Strangely, whilst shaving this morning under the 12v lighting in my bathroom, I had this same thought. Most of the electrical needs in my flat are low voltage (between 12v or fluorescent lighting, electronics, and so on).

However, what happens with large appliances? Are there 12v washers, toasters, and fridges? Would we have to purchase new appliances in all regards or would it just be a matter of replacing motors and compressors?

Also, would this mean one could have a big 12v battery sitting in one's home that would act as a buffer in power outages (rather like a UPS for the neighbourhood)? Would one's electric car play this role?

To make a long story short, AC won over DC because it made (and still does) more sense. AC can be transmitted longer distances than DC, and this was the BIG REASON that Edison lost. Remember, Tesla used to work for Edison, and Edison was a maniac when it came to protecting his products and ideas.

Contrary to the Economist article, AC at higher voltages loses less power than DC over the same distances, thanks to the equation P = V*(I squared). Using higher voltages and lower amps is superior to the reverse.

Also, when the DC/AC War was being fought, people didn't have solar panels or windmills that generated electricity. Finally, with regards to all the different electrical standards, etc., companies create electronics products first, and THEN worry about a power source. Electronics engineers don't start out with a standard power source and then ask "What can we build around this?"

I fail to see the thrust of your article, other than that you begin with the assumption that big centralized power plants are inherently "bad". I propose that this kind of setup won't change for the next century or more.

LA: the thrust of the article has less to do with transmission issues than it does about the waste within our houses by over-wiring for obsolete technology. It would not be a stretch to have electronic engineers agree on a common voltage and build around it.

the guy above me is right. AC won over DC for good reasons a long time ago. I think having some sort of centralized and standardized DC power distribution is a cool idea, though.

I agree with most of the points except copper usage. As you decrease voltage you increase amperage (for a give amount of power -- watts). Higher amperage means higher "line losses" (due to the resistance of the wire). 120VAC/12VDC = 10 times the amperage. Ever try plugging too many high-power things into a small extension cord? It will get very hot = power lost.

The only way to counter this is to use MUCH larger wire, 10 x in this case (wire cross section area, not diameter). That is ALOT of additional copper (or Aluminum). This is why they use such high voltages for cross country power lines. Also why solar is going with higher voltages coming from the PV array(s). Conversely, also why the wiring between solar storage batteries is so large, usually bigger around than a persons thumb.

The basic rule is that for any given amount of power: lower voltage = higher amperage = larger wire higher voltage = lower amperage = smaller wire.

Other than that, keep up the great work -- you and JL are two of my favorites on TH.

Lew W

Been there.

Left there.

I've been off the grid since the late 1980s. At first almost all my 'stuff' was 12 vdc. Inverters were expensive and somewhat inefficient. 120 vac was used only when there was no other option.

I'm still off the grid. I 'make' my power at 24 vdc. It's too expensive to ship the power at 12 v. (48 v would be even better.)

But inverters have greatly improved and mine stays on 24/7. Everything in my house is 110 vac. I ran the numbers for low voltage super efficient refrigerators vs. 'Energy Star' and buying more solar panels and batteries.

I bought a Kenmore.

The author has a great point (I think) about standardizing stuff that runs on low voltage DC. Running a second set of outlets (where needed) for those devices makes a lot of sense to me. And we could get some 'smart' cubes that have a very low draw 'stand by' mode rather than a constant draw.

But switching the world to DC?

Forget it.

For what it would cost to rewire, replace almost everything electrical, and rework the grid (actually set up a parallel grid) we could create bunches of green power sources. We could go basically wind/solar/tidal and have money left over.

(BTW, I don' think the AC/DC transmission stuff is correct. I think the choice of AC had more to do with the equipment available at the time. I believe Europe is installing/getting ready to install some high voltage DC transmission lines as they are more efficient than using AC.)

i'm really lost on #4. how does reducing the number of outlets really reduce the amount of copper use? the power still has to get to every room. and now we're talking about adding a second circuit that runs parallel to all the existing wiring. sounds like *more* copper to me, not less.

what makes more sense to me is keep the existing AC wiring, but in places where a bunch of DC is needed, like a computer station, or a home theater, have one DC power supply that all the components can draw from come off the existing power. DC isn't so hot for transmission, but having tons of different transformers next to each other is redundant.

and if North America really wants to save on copper, we should just switch to 220-240v.

This is a bad idea. The amount of copper required would be staggering. I will explain…

For household type loads, resistance of a meter of wire is proportional to its mass. A load powered from a 12v source will require 10 times as much current as one powered from a 120v source. Nothing wrong with that, just two different solutions to 'power = voltage * current'. The problem comes when you address wiring losses. The voltage drop across a wire is its resistance times the current. If my current goes up by a factor of 10, the voltage drop in the line will also go up by a factor of 10.

An example:
My cabin has 12 gauge wire at 120v. The wire to the water pump is 50 feet long, which is really 100 feet since the electricity has to go there and back, two wires. The water pump draws 700 watts when it runs. 12 gauge wiring's resistance is 1.588 ohms per 1000 feet, or 0.16 ohms for my 100 foot path. 700 watts at 120v means 5.8 amps of current. The voltage drop in the wire is 0.93 volts. Not bad, I'm losing a little less than 1% of my power to wiring losses, 99% efficient is good.

Now lets switch to a 12v pump, same wire. The wattage will be the same, it takes the same amount of work to pump the water. 700 watts from 12v takes 58 amps of current. 58 amps through a 0.16 ohm wire is a voltage drop of 9.28 volts. I'm going to lose 75% of the power heating up the wire. But not for long, we are far beyond the rated capacity of that wire, the insulation will melt, the wires will short circuit, and the breaker will blow. What we need is bigger wire.

I use a wire size called 0000 for the DC battery bank at my cabin, lets try that to run the pump. 0000 has a resistance of 0.049 ohms per 1000 feet, or 0.005 ohms for our wire. That will give us a voltage drop of 0.29 volts. Not great, but not too bad. We'll still have 11.7v at the pump. 2.5% loss, 97.5% efficient.

The problem is a 0000 conductor is 1/2 inch in diameter, and we needed two of them for the pump. At 1.56 feet per pound we need 64 pounds of copper to get power to the pump. With 12 gauge wire at 50 feet per pound we only needed 2 pounds of copper. There is probably not enough copper in known reserves for americans to wire their houses this way.

Our efficiency gets bad in a hurry as we work at lower voltage because the current goes up, causing a larger voltage drop and that voltage drop is a larger percentage of the original.

Andy Thompson's minihome works because the distances are very short, and he is using small loads.

The motivation for this was to address wall wart. There are better solutions.

Wall warts come in two varieties, AC/AC and AC/DC. The AC/AC ones are used to reduce the voltage to a safe level before feeding it into a device that isn't built to the kind of safety standards required for lethal voltages. You might find these on some lighting products. This need would go away in a 12v world.

AC/DC converters are more common. These are the warts which we loathe. They take the 120v AC and convert it to whatever voltage the device needs. That is the key. Digital electronics needs 5v, 3.3v, and sometimes lower. Disk drives need 12v in addition. A stereo amplifier probably needs 30v and -30v. A single lighting LED might need 3.8v and a big LED fixture might need 24v. Switching to DC wiring in the house will replace all these AC/DC converters with DC/DC converters.

A DC/DC converter is something like 85% efficient and draws negligible power with the load is off. This is slightly less efficient than a well made AC/DC converter. But that is the real problem… it is possible to make a cheap AC/DC converter that is not only low efficiency, but bleeds power even with its load turned off. You know these devices. They are the wall warts that feel slightly warm even when nothing is plugged in. It is also possible to built an AC/DC converter that is high efficiency and does not bleed appreciable power without a load, but these cost $3 more to produce, and even though consumers will save $4/year over the cheap one, they will buy the one that is $3 less expensive so that is what manufacturers make.

The good news is that regulatory agencies have stepped up to this. There are standards in place to limit how horrible a power supply can be sold. It looks like from 2007 going forward you can expect your warts to have less than a 1w idle load and be at least 84% efficient which is pretty good. There is a synopsis at http://www.phihongstarproducts.com/WorldwideStandards.htm

At 1w I don't think you will feel the heat coming off an idle wart. I just groped a couple of mine. The older ones are warm, the newer ones are cool. I think regulation may have taken care of the wall wart phantom load.

At 1w you can figure each wart is costing you $1/year. Add up your warts, divide by your annual power bill. If it is a significant percentage, then maybe you need to think about unplugging them when not in use.

You can look up the capacity of wires at http://www.powerstream.com/Wire_Size.htm.

LA: I am not talking about running pumps, I am talking about modern electronics and lighting that draw very small loads.

My answer has always been a hybrid approach. Leave the AC transmission system in place and start with all new builds requiring another tap on the transformer at each building for a 12v line as well as the 120/240 wires coming in. Then you recify and filter and regulate that at the panel and run 12v around to some places in the house where low voltage devices couple be plugged in eliminating the wall transformers. Since you have a transformer already outside dropping the transmission voltage own to the 220/center tapped 120v you simply add another tap. Then you only have one rectifier/regulator which can be made.
I'm running 12v lines a couple places in my house and am standardizing on the anderson power pole which is popular for ham radios and utiliizing automotive power distribution panels. So I'm combining a couple existing standards which keeps the cost low. Currently I'm just using a seperate transformer and will eventually switch it in and out using the low voltage disconnect of a solar charge controller, just put that part and the solar panel on hld until we move.

Distance seems to be the underlying hurdle here.

Thanks to all those who already pointed out the problem of wire size with copper and corrected the confusion of AC/DC with high voltage/low voltage characteristics. This article could certainly have done with some peer review first, but I think its heart was in the right place.

As someone who has been trying to specify a new computer from scratch finding really power efficient chips, power supplies and other components is really hard. It was as hard as six years ago when my goal was quiet - there is just a real lack of solid information on efficiency and power consumption. It should be as clear and available for all components as it is with food information!

The big thing I see is waste of resources to build all these wall warts - so many are transformer based think of all the iron and copper that goes into them. If designers were forced to work around some well defined power standards and connectors like computers it would be easier - we could have interchangeable high-efficiency wall warts, or even ones integrated into DC only power strips.

Jason: large appliances draw lots of power and would not work in this, one still probably needs AC for that.

anon: I confused this article by bringing distribution in, and should have left that story for another post. My real interest here is the internal distribution.

Greenovator: I am fully aware that large loads need larger wires at low voltage, but most of the things we power at 12V do not. The wires running from the wall-warts are small because the loads from electronics are small.

mdpdb: If there is only one outlet per room for vacuuming, you need a lot less copper and a lot fewer circuits.

eugene: I agree about the pump, and thanks for the long and knowledgeable answer.

how about a longer cord on the vacuum?

Everyone's 120VAC motors also grow by 10X when dropping to 12V - Refrigerators, compressors, vacuum cleaners, power tools. FYI, that is why portable power tools are increasing voltage to get greater power in the same size package.

Maybe if we are going to set new AC and DC world standards. Let's consider what Boeing and Airbus consider to be the most efficient and less weight. 400 cycle, 120 volt, 3 phase power uses less copper and all components are much smaller and lighter.

Also use the standard 12 volt airline armrest outlets or computer internal power connectors instead of automotive cigarette outlets. A DC power strip would cover most uses for computer or entertainment centers rather than running 12 volt wiring where it's not needed.

New distributed energy power generators located on site would provide power for apartment and office buildings, hospitals, commercial centers, subdivisions, etc. This would eliminate the requirement to build new large power plants and power lines and provide much more redundant sources of power to help eliminate blackouts in the future. This will also be a priority for homeland security.

We are currently designing a new high technology turbine and generator that will compete directly with large diesel generators in price and fuel flow, which is about half what a new turbine generator costs and consumes. This breakthrough technology will be perfect for the distributed energy market when it arrives.

http://www.BackupPowerSystems.com

I like the idea of using the electric car as a backup battery, esp. since it would ideally only be used for longer trips and hauling stuff. Theoretically you could survive an outage for some time while relying solely on walking and biking.
As for the more power-hungry appliances, I think the article is saying that right now the option is only to mod what you can in some cases, and invert power in others. The author is suggesting that we need to get this big enough that market demand drives innovation, and appropriate plug-and-work devices become the result.
Oh, and that the first step is a universal standard. I think settling on 12V DC is easy enough, most are familiar with it. Settling on the right plug, however, could be challenging. I would recommend using the ubiquitous auto outlet (the one that originated as a cigarette lighter). Besides familiarity, it already has a huge supply of devices designed for it. Plus you would only ever need one cell phone charger.

The standard 12v plug for cinema and video equipment is the XLR (usually the four pin version, though I think sometimes the three pin switched round male/female from audio gear to avoid accidentally frying one's recorder or microphone). The cables are insulated, durable, and readily available.

The four pin version can (I would suppose) simultaneously carry two voltages; so it could have both 12 and 24 volts in one plug.

Speaking of audio gear, we regularly carry both an audio signal and power over the same microphone cable (phantom power). If we were building a distributed system with electric cars acting as buffer batteries and so on, could the power cables carry data back and forth between power providers and users (e.g I plug in my car and set a timer that says how long it will be plugged in and when it should be charged by; the car sends signals to the power provider saying, "I have a 75% charge right now, need to have 100% by 6:30 AM. Wait till you have surplus power to charge me; in the meantime, use the power I have on hand for lighting in the neighbourhood.") Every charged device could do this. My laptop could charge in the middle of the night when more power is available and the power plant would not have to outlay excess energy when it's not needed.

Something else to consider isn't just the wire (which has been explained earlier). The circuit breakers and other components have to be much more robust, because DC maintains an arc much easier than AC. This is because AC is already, by definition, dropping to zero voltage multiple times every second, so it breaks the arc. This is important in circuit breakers and when you unplug the vacuum cleaner by accident before you turn it off. In both cases you get a big arc - especially dangerous when its between the plug and outlet. Breakers need to be bigger (one rated for 120V AC is only rated for 40V DC, if its rated for DC at all), and the interface between outlets and sockets needs to be specially designed so the arc is broken before the plug comes all the way out and you are exposed to the arc.

Far better for the environment would be to force all of our appliances to 240V, like in much of Europe. We already have 240V distribution to all homes, its mostly a matter of building new homes to the spec. Older homes will convert over time as 240V appliances become cheaper. The advantage? Less copper used in every home, since the wire sizes can be made smaller.

I agree with Lloyd. We should be moving toward standardizing 12VDC in the home for most outlets (and making the rest some other specified higher voltage DC standard like maybe 48V or more) and converting the electric grid to DC.

AC is NOT inherently better than DC - just the opposite. DC is INHERENTLY better for a large number of reasons. The ONLY reason that AC won over DC at Edison's time of history was because AC voltage could be stepped up and down in voltage whereas DC voltage could not. It had nothing to do with high voltage AC being better than high voltage DC - it had to do with the fact that high voltage AC was possible then whereas high voltage DC WAS NOT. But high voltage DC IS possible NOW. It is not AC vs DC. It was and still is about LOW voltage vs HIGH voltage - whether it be DC or AC. A number of people have correctly brought out the equation Power = Voltage times Amperage and used this to show why AC is better. But this equation has nothing to do with AC vs DC. All it shows is VOLTAGE and AMPERAGE and WATTAGE. This equation holds equally true for BOTH DC and AC. It can be Power (Watts) = DC Voltage times Amperage or Power = AC Voltage times Amperage. I hope this clears up confusion. AC won because it could be converted to high voltage, thereby reducing line losses through electrical 'friction' and thereby enabling use of small copper wire. The same goes for high voltage DC, but unfortunately back then the technology to transform DC to high voltage and back down did not exist, so use of DC BACK THEN would have required huge wire thickness (gauge) to ensure minimal losses of electricity due to electrical friction.

'AC can be transmitted longer distances than DC.'
---DC can be transmitted the same distances as AC with as little or as much electrical energy loss. Take AC down to 12V and it will lose basically the same amount of electrical energy as 12VDC over the same wire gauge and distance. Actually, one correction: DC can be transmitted longer distance than AC. Why do I say this? Because as very cursorally mentioned in the main text of Lloyd's article, AC tends to GROUND whereas DC does NOT. That means AC wire lines leach electrical energy when in close proximity to the ground whereas DC does NOT. And the higher the AC voltage, the more leaching that occurs to ground if the wire is maintained at the same distance to the ground. This does NOT happen with high voltage DC. The way this AC leaching problem is overcome is to keep high voltage AC lines high away from the ground. And the higher the AC voltage, the higher off the ground the wires must be - in other words: super tall electrical towers. This is the fundamental reason AC wires are kept high off the ground and why one can see different tower height sizes. It is also the main reason why homes powered by AC run DC wiring under the ground to reach their garden lighting and many outdoor electrical gadgets. It is also why some EXTREMELY long distance high power high voltage lines are run at DC: it is impractical to run such long line distances at high voltage AC because the tower heights required to stop leaching to earth would be ridiculously and prohibitively HUGE. This is the key reason that some in Europe are considering switching their AC grid to DC. Because by switching to DC, they can send electricity relatively easily from any corner of Europe to any other corner of Europe with minimal losses and without need for stratosphericly tall AC towers.---
'AC at higher voltages loses less power than DC over the same distances, thanks to the equation P = V*(I squared). Using higher voltages and lower amps is superior to the reverse.'
--- As mentioned above, this statement is wrong. Yes, using higher voltages and lower amps does lead to less electrical energy loss, but this has nothing to do with AC vs DC. High voltage DC has basically the same electrical friction (and loss) over the same size wire gauge and distance as does the same level voltage of AC.---

'Also, when the DC/AC War was being fought, people didn't have solar panels or windmills that generated electricity.'
--- This is off topic, but you are mistaken. They did not have PV, but they did have DC wind power which charged DC electrical batteries. If my memory serves correct, Edison(?) himself had an off-grid home at that time powered by DC wind generator and batteries (as did Ford I think). Of course, the number of individuals with such homes could be counted on your fingers (and they were all filthy rich).---

'Finally, with regards to all the different electrical standards, etc., companies create electronics products first, and THEN worry about a power source. Electronics engineers don't start out with a standard power source and then ask "What can we build around this?"'
---Again, you seem to be significantly mistaken. Engineers DO have a power source in mind when they design most products. First, think of all gadgets run by common AAA, AA, D, etc, batteries. That is the power source and the product is designed around that power source. Then their are rechargeable batteries for specific gadgets, like your laptop. The battery often or usually (maybe always) comes first and the laptop energy use system has to conform to the battery - not vice-versa since the battery technology is more difficult to modify than the laptop. And what about all of the products that run directly off 110 or 240 AC that don't require a wall-wart. Do you think those are first designed without thought to the energy source and it just so happens that they got lucky and the appliance just happens to use 110 or 240 AC? No, most designers DO take energy source into consideration when designing an appliance. They DO ask: This is the power-source, what can we build around it?---

'I propose that this kind of setup won't change for the next century or more.'
--- This kind of setup is ALREADY changing. DC grids are ALREADY being developed. If what you mean is that you don't expect to see an overnight change from a generalized AC grid to a generalized DC grid within the next century, you are right. Actually, you will NEVER see it because it will never happen overnight. But if you mean that you don't expect to see any gradual changes to the AC grid within the next 100 years that eventually lead to a generalized DC grid, then you are wrong because those changes are already underway.---
'Also why solar is going with higher voltages coming from the PV array(s)'
---All sources of electrical generation, whether PV, wind, nuclear, coal, etc., that are located far from end users will transmit the electrical energy in high voltage for the reasons mentioned. The question is whether they will do it in DC or AC. PV is inherently a DC energy source. The energy created by the photons knocking loose electrons in the PV layers is continous or, better said, DIRECT. PV can NOT make AC electricity unless they have an inverter attached. And all you have to do to make high voltage DC come from a PV power plant is to wire enough strings of PV panels in parallel to produce the desired voltage. Converting this high voltage DC to high voltage AC leads to electrical energy losses. Of course, at some point this conversion does take place because most of the grid is AC. But the conversion could either take place at the PV power plant or thousands of kms away near the end users where the PV lines connect to the grid.---

'Conversely, also why the wiring between solar storage batteries is so large, usually bigger around than a persons thumb.'
---This has nothing to do with the batteries being DC. It has to do with the batteries being low voltage. If you had two 1000VDC batteries connected together, the connecting wire could be as thin as one of your head hairs.---

'For what it would cost to rewire, replace almost everything electrical, and rework the grid (actually set up a parallel grid) we could create bunches of green power sources. We could go basically wind/solar/tidal and have money left over.'
---It wouldn't cost anything to rewire and rework the grid. To convert an AC grid to a DC grid does NOT require rewiring and reworking the grid and would NOT require a parallel grid. The same electrical lines that already exist, can be used to transmit either high voltage AC or high voltage DC - but not both at the same time. The only thing that does need to change is the equipment at the transformer stations. Take out the stuff that transforms high voltage AC to lower voltage AC and put in equipment that transforms high voltage DC to lower voltage DC. This is a far cry from what you have just stated would be required. Yes, some changes would be require and it would cost money, but nowhere near the 'everything needs to be redone' scenario mentioned. Futhermore, all those green sources of power (wind/solar/tidal) would be sending out high voltage DC energy for one reason or other. Sources out at sea (offshore wind, tidal, wave) would be running wires underwater and therefore they would not be AC - they need to be DC. PV farms produce in DC, as I have already mentioned. ---
' The circuit breakers and other components have to be much more robust, because DC maintains an arc much easier than AC. This is because AC is already, by definition, dropping to zero voltage multiple times every second, so it breaks the arc. This is important in circuit breakers and when you unplug the vacuum cleaner by accident before you turn it off. In both cases you get a big arc - especially dangerous when its between the plug and outlet. Breakers need to be bigger (one rated for 120V AC is only rated for 40V DC, if its rated for DC at all), and the interface between outlets and sockets needs to be specially designed so the arc is broken before the plug comes all the way out and you are exposed to the arc.'
---This is true. DC does maintain an arc much easier. And safety circuit breakers need to be more robust, but I have both 240VAC circuit breakers and 12VDC circuit breakers in my house and can tell you that there is neither much difference in size nor in cost. But the statement that it is especially dangerous to have a 12VDC arc going from outlet to plug if inappropriately disconnected is both correct and misleading. Yes, the arc is likely. But at 12VDC, it is not dangerous. Take a look at the US NEC and see what kind of safety regulations they have for 12VDC wiring - they are minimal and tend to be quite lenient. Why? Because getting shocked by 12VDC is a nuisance - NOT life-threatening.

I live in an off-grid home that provides its own electrical energy through PV and wind generator. I designed the electrical system myself. Installed it myself. And maintain it myself. I have my wind generator and PV and batteries at 24VDC. I have a step down converter that takes that 24VDC down to 12VDC which feeds my lights, pressure pump, vent fans, plus a number of 12VDC outlets so that I can run appliances that use 12VDC. I also have an inverter than converts my 24VDC to 240VAC. My AC runs my fridge, washer and many other appliances. I must say that the 12VDC runs do require larger copper wiring than the 240VDC runs in my house, but I save more electrical energy in my 12VDC runs than I do in my 240VDC runs. This is for several reasons. Some mentioned by Lloyd. My 24VDC-12VDC converter does a much more efficient job of transforming the electricity (about 95% efficient) whereas my 24VDC-240VAC inverter is much worse and the efficiency greatly fluctuates depending on capacity use. If the inverter is close to max capacity, it is about 90% efficient, but that percentage quickly drops as the capacity use of the inverter goes down. And at idle mode (when not in use - in detection mode) it uses over 200W a day. Furthermore, many of my appliances that use wall-warts lose a lost of energy. Example: my laptops wall-wart takes some 300W of AC energy and transforms it to 60W of DC energy for use by the laptop. Sound efficient to you? Luckily I have a DC-DC transformer cable for computers so that I can hook the laptop straight to a 12VDC plug in my house, and then its more like 80W being converted to 60W. Luckily, I can power some of my stuff directly from the 12VDC outlets, but many of these gadgets with wall-warts are practically impossible to do so.

To summarize, DC is better for both long distance grid transmission and better for end use. It should be promoted and we should be making faster moves to change over to it. The current pace of change, in my opinion, is too slow.

People seem to be on the right track; for the same power flow, increasing line voltage decrease line current which decreases power loss in the line.

ANON IS WRONG !!!!!!
anon states "AC can be transmitted longer distances than DC" this is totally WRONG.

So, why is power transmission done using ac and not dc?

Here are the main reasons:
1. AC can be stepped up/down using mutally coupled inductors, transformers, where as it is virtually impossible or not efficient for dc
2. Generators naturally output ac
3. Very easy to convert ac to dc but to convert dc to ac requires more complicated circuitry.

Also if you are not in the power industry you probably dont know about our power interconnect system. The western interconnect, includes: wa, or, ca. It includes 2 500Kv lines from the gorge in wa to LA, ca.

The nice thing with DC lines is that you only need 1 line to send power, the other line, return line is not needed because it is typically earth grounded.

The longer the ac line, the more resistive inductive/capacitive and other losses come into play. So for a certain length, ac transmission is more economical, and there for very long lines dc is more economical, because with dc one really has to worry about resistive losses. Just to let you know complicated ac/dc converters are used in the dc line.

Invention is a wonderful thing. It's been my main activity for decades. Having said that, "inventors" with ideas like this would save the whole community a lot of time and wasted effort if they would simply get some up-front advice from someone experienced in the field. In this case, it's electronics, and I'm one of those experienced people (one of many, so I'm not blowing my own horn). Anyone with a few years experience (and training) doing hands-on electronic repair could have spotted this as a no-go, waste of time in a millisecond. A number of previous posts explained that fact pretty well, but for some unknown reason people who would not dare work on anything mechanical, somehow think that even without training, electronics/electrical is something they are adept at. Go figure..... Unfortunately, most of the alternate energy/free energy/zpe (etc.) web sites are currently peppered with things like this that defy simple theory (and also hands-on experience) - especially where electronics/electrical is concerned.
Yes, I once had unworkable ideas like this - but that was long BEFORE I received electronic training. So, the point of this long rant is, that the alternate energy community needs to avail themselves of prior knowledge and experience by checking out these kind of things before they hit the web page. It's easy, so where is the problem? In this case even a small amount of reading on electrical/electronic theory would have squashed this idea to oblivion. It's electronics 101 - or less.
Wasting web space on half-baked ideas that haven't been checked out simply makes the whole community look like a bunch of flat-earthers and "crack-pots".
Sorry to rant on, but it needed to be said.

GB,

I am assuming that you did not read my post. Because if you had, you wouldn't have made such an inappropriate statement. All you did was show me that you yourself need to pick up a book and some equipment and learn and get some real experience. You went and decried a ridiculous something that is ALREADY in use and coming more into use. You've made yourself look like a complete 'crack-pot' to me, at least.

Tesla may of developed AC for long distance transmission through wires.

But he also developed single wire systems and of course his Magnifying transmitter

These systems ran on PULSED DC. Tesla abandoned high frequency AC and only worked with Pulsed DC for the far superior capabilities of Pulsed DC

Tesla used Spark Gaps, Capacitators and transformers to develop systems where the is no back emf, the electricity only flows in one direction.

Energy input could be amplified for a Larger Output than was originally input.
Hence 'Magnifying' transmitter, using pulsed DC

GB, I do not usually respond like this, but I found your tone patronizing. I am a licenced architect who has been building houses for twenty-five years and know exactly how they go together and how much copper is in them. Furthermore I did electronics 101 in University.

I have spent a lot of time in the Minihome learning how 12 volt systems work and a lot of time at home building computers. I do not consider myself a crackpot, nor am I inexperienced.

I think it is a serious proposal.

Let's all step back a bit (and this pertains to many of the posts I'm seeing here on Treehugger) and work on speaking positively in our comments. If I want contention and sarcasm, I can go to any number of commentators or forums who mock environmentalists as a "bunch of confused idealists" (or something of that nature).

We don't have to agree in lockstep with every idea posited here; but let us take all in consideration and weigh pros and cons sensibly--rather than attacking the intelligence of like minded people who are sincerely seeking solutions to the issues we face collectively.

I'm coming here for ideas and to contribute to other's ideas. You or I may only have some miniscule part of a larger solution; that's why we post comments to discuss. I certainly don't have the overarching solution to any of these problems; to think otherwise implies either genius or too much ego. (If only Tesla were here now to explain half the things he was thinking of; we'd probably be in a much better situation.)

read up on Mpathx wall wart eliminator. They are trying to do what you talk about here!

i nearly jumped in with the same punches as everyone else, thankfully i decided to read the comments first.

my contribution is that we've simply opted for the wrong AC power. rectifying single (or 180 opposing) phase AC power is a loosing battle, it requires huge arsed caps to maintain voltage differential during the cycle's zero crossing phases.

there are two solutions:
the first is increasing switching frequency, which reduces the length where your ac doesnt have much differential.

the second is using multiphase power, typically three phase, where when one line is going towards 0v the following phase is ascending towards its maximum. some nasty transitional draw issues aside (rectifier hand off is much more abrupt when your 70v and dropping line goes no-load and the follower 70v and rising line goes from no-load to on-line), you end up with something much more closely resembling DC power without any capacitors at all. although it requires four wires of power, the three source lines can have considerably reduced cross sectionals.

i've always wanted 3 phase so i could build massive amplifier for dirt cheap. audio amps are 2 parts amplifier and 7 parts power supply, since single phase power blows chunks for making dc power.

the first solution would do the most towards getting rid of wall warts, the second solution would do the most for any high draw power device.

Hi it seems to me that you are all neglecting a much better source of saving. Frequency . Higher frequency transformers are much more efficient, the switch mode power supply in a computer is a good example small ferrite core transformers running at higher frequency can make huge savings.

Simple question, need an answer: If I have a standard 12volt fully charged car battery, how long can I run a110ac device on it (Not a wall wart device, but say a normal radio, light...etc)? Yes I have read all of your comments and this is why I am asking this question.

I read some good ideas. I read some correct electrical knowledge from most writers. I read some incorrect electrical knowledge from most writers. You all need more study of the technology before real value will be found on this topic in these pages.