Edison's final victory over Tesla? British university installs a DC power network.

[Commie Pinko Dirtbag]

http://www.bath.ac.uk/news/2011/03/21/first-dc-network/

Britain’s first local DC computer network installed on campus
^{21 March 2011}

When students returned from their Christmas vacation this year they found a new suite of computers on the fifth floor of the library.

These were faster, smaller, quieter and generally better to use. Little did students realise that they were also part of a demonstration of a new method of distributing energy.

These computers are powered using direct current (DC) electricity rather than alternating current (AC). The supply network is unique and will act as a showcase for future projects of this type. (...)

Initial tests show that the system in Bath emits approximately half as much energy as heat than the previous AC powered system while running much faster. This results in a double energy saving – initially from energy efficiency rather than emitting heat, and secondly in avoiding the need to power the fans in machines or utilise air conditioning units. (much more at link)

[RC]

1. OK, th e computers still need different voltages internally to function.

Work being done by the computer will still produce heat. The next generation of chips run cooler because they use a little different technology.
Basically I think what they did was to externalize the power supplies and used a big, healthy one to run all of or at least a bunch of the computers from it. So of course the computers themselves will run cooler.
All computer run off of DC anyway, so pardon the yawn here.

[Statistical]

18. The different voltages in PC is trivial problem.

Most power supplies today use DC to DC switching to supply different voltages. Technology advancement has made DC conversion far more efficient. To meet energy star requirements most (all but the cheapest) power supplies use DC to DC.

So 120V AC gets rectified to 12VDC and then some of the 12VDC is converted to 5V & 3.3V. CPU today use lower voltage but they are converted from 12V connection to the motherboard.

Honestly there is little need for 5VDC supply anymore. CPU at one time ran at 5V directly from powersupply but those days are long gone. Hard drives still use 5V but are moving to 3.3V. Likely some future version of ATX standard will drop 5V to improve efficiency further.

[itsrobert]

27. England runs on 220-240V AC

You probably know that.

[sdfernando]

2. There is no question

that DC is more efficient, but it is problematic to transmit over long distances.

[Tesha]

12. It's not problematic to transmit DC over long distances.

It's problematic to transmit low voltages. And it used to be
problematic to transform low voltage DC at the generation
point to high voltage DC for long distance transmission and
then back to low voltage DC for utilization. AC was much simpler
in this regard.

But modern semiconductors have eliminated that problem so
now our most-efficient, easiest-to-manage power transmission
lines use *VERY* high voltages of DC. There's one through my
area that's carrying hydropower from James Bay in northernmost
Quebec down to Ayer, MA; it operates at +/- 500 KV (so one
million volts line-to-line).

Tesha

[hobbit709]

14. There are some advantages in long distance transmission

but disadvantages in local transmission.

[Tesha]

15. Yes, but fewer and fewer as it becomes cheaper and cheaper to...

...use high-frequency switching technology to "transform" DC.
The high-frequency converters are much more efficient than
line frequency transformers, they can be remotely "supervised",
and can respond to overloads more intelligently. Distribution of
DC also uses the conductors more-efficiently so can be done
with fewer insulators, less metal, etc.

You may yet see DC make big inroads into distribution as
well as transmission (where it is clearly superior in almost
every way today).

Tesha

[Statistical]

16. Really?

High Voltage DC has many properties that make is superior to AC for long distances and wattages.

The only thing that held DC back was technology. The technology to efficiently change DC voltage didn't exist 200 years ago. Changing voltage for AC is trivially easy. You can build a transformer by hand (and they did).

If no electrical grid existed today (no need for legacy compatibility) and you were building one from the ground up likely any system would be a AC/DC hybrid. Powerplants would be DC and connect to HVDC long distance transmission and local distribution would be AC (to save cost on expensive DC to DC converters). Possibly in another 100 years if you were building a powergrid from ground up the technology might make a purely end to end DC system the best choice.

[Tesha]

21. The real win is in "system stability"

Without any concerns for phase or even frequency,
it's far easier to control an HVDC transmission system,
even over a very wide geographical area. And it's far easier
to force the power to flow in the direction(s) you want it
to flow and not in those occasionally-surprising wrong
directions.

(Statistical, I realize you know this; I'm saying it for
everyone else reading here.)

Tesha

[FLPanhandle]

3. So all they did was move the transformers from the computers to the building

Hard to see why this even merits a news story.

[Commie Pinko Dirtbag]

4. It's simple, it's a new idea, and it saves energy. That's news worthy enough for me. -nt

[RC]

5. Not really new.

They have been doing this for years with rooms full of blade servers. Main supply buses as big as your arm.

[Statistical]

19. Exactly direct DC has been common in high density server rooms for a while.

Companies didn't do it to be green they did it to save $$$. Improving the thermal efficiency of servers allows them to be tighter packed and reduces cooling costs.

[Wilms]

6. This seems like a wonderful idea.

I'm glad they took this on.

[david13]

7. No way. There are many applications that use dc. dc

Oh, dc, that's me.
No, I mean direct current. Any battery is dc. Diesel locos are dc. Tho' they are now making some of them ac.
And many others.
dc (me)

[Tesha]

13. Diesel locos aren't DC anymore.

The main generator is an alternator these days; simpler
and more reliable. Its output is then rectified to DC and that
is fed to the "traction inverters" which convert it back to
variable-frequency AC to feed the induction or synchronous
AC traction motors. Again, these AC motors are much simpler
and more-reliable than the DC machines they replaced,

Tesha

[david13]

20. They are starting to replace. I don't know what percentage they

have already replaced.
Like cars on the road, not everybody has the new model.
The dc motors always had a stalling issue. I been on one that stalled, more than once.
dc

[Motown_Johnny]

8. Sorry, IMO Edison doesn't hold a candle to Tesla.

and never will

[sendero]

9. Agreed..

... Edison was a hack, Tesla was a genius.

[Shining Jack]

10. Absolutely.

:thumbsup:

[Kat45]

11. Check out the rock band Tesla's song "Edison's Medicine"

http://www.youtube.com/watch?v=-2zwBRa0YhA

[SidDithers]

17. No Edison / Tesla thread is complete without the Drunk History version of their rivalry...

http://www.youtube.com/watch?v=3gOR91oentQ

Warning: There is puking in this video, but it's still funny :)

Sid

[slackmaster]

25. LOL!

Thanks for that, Sid.

[cbayer]

22. I want one!!

I currently have to convert my DC to AC to charge/run my computer. I DC driven computer would save me tons of energy and I would love it!

[hunter]

23. They are pricey.

Laptops:

http://www.powerstream.com/ADC.htm

Desktops:

http://www.powerstream.com/DC-PC-12V.htm

(This is just what came up first for me at google, not an endorsement...)

Some computers will refuse to charge with anything but their own name brand power supply. There's a proprietary chip inside the charger that does nothing more than broadcast "I'm a Dell Charger!" (for example.) If the computer doesn't see that chip it may run but it will refuse to charge the batteries. If you are comfortable hacking such things and you can find the chip, you can transplant one from a broken name brand charger into a no name D.C. power supply.

Unfortunately there are also companies in Asia that make counterfeit power supplies that identify themselves as genuine. These may simply fail prematurely or they may catch fire because the UL approval is also fraudulent. They might also be perfectly fine power supplies equal to or better than the original.

[cbayer]

24. I have a mac. I am going to look around and see if their are any dc charging adaptors

out there.

Thanks for all the great info!

:hi:

[Tesha]

28. The situation on Macintosh is more complicated.

Apple very carefully patented the "Mag-Safe" power
connector and they are aggressively defending their
patent. As a result, you won't find many third-
party charging solutions (and some that do exist
exist by recycling your old Apple Mag-Safe power
connectors!).

But all the Apple chargers will operate on moderate-
voltage DC (somewhere between 170 and 340 volts)
as I mentioned in a reply above. You could probably
Google up some details if you're really interested.

Tesha

[Tesha]

26. It's a little-known secret that most modern computer power supplies...

...will run just as happily on somewhere between
170-340 VDC as they will on 120 VAC. They have
no input transformer and simply either directly
rectify or voltage double the AC input, converting
it (ultimately) to about 320 Volts DC which they
then convert onwards to the utilization voltages
(3.3 VDC, 5 VDC, 12 VDC, etc.)

The same thing is true of many newer cell phone
chargers, etc.

This doesn't mean you should blindly and blithely
plug your computer into DC, but it's generally
true nowadays.

Tesha

[cbayer]

29. I am not sure about this. We run our DC power directly from our 12 volt batteries.

You are way over my head here!

:hi:

[CabalPowered]

30. Thanks for posting this

:thumbsup::thumbsup:

I wish LEED would consider adding some spec for these concepts. It would certainly help in spurring more research.