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University Switches To DC Workstations

CmdrTaco posted more than 3 years ago | from the direct-and-to-the-point dept.

Power 468

An anonymous reader writes "Researchers at the University of Bath, UK are undertaking an in-depth study of energy consumption within the new network, with the aim of demonstrating that running a large network of devices on DC rather than AC is both more secure and more energy efficient. AC electric power from the grid is converted to DC and runs 50 specially adapted computers in the University Library. Students using the system have noticed that the new computers are more compact and much quieter than the previous systems. The immediate advantages of the new system are not only for the user but for the energy bill payer and the environment."

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So... what? (2)

MobileTatsu-NJG (946591) | more than 3 years ago | (#35574530)

They switched to laptops?

Re:So... what? (5, Funny)

somersault (912633) | more than 3 years ago | (#35574586)

Tesla is giggling in his grave

Re:So... what? (1)

AndyAndyAndyAndy (967043) | more than 3 years ago | (#35574592)

Edison was a hack!

Re:So... what? (5, Interesting)

ShakaUVM (157947) | more than 3 years ago | (#35574922)

Edison: "Genius is one percent inspiration and ninety-nine percent perspiration."

Tesla: "If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found the object of his search. I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety percent of his labor."

Re:So... what? (5, Insightful)

danlip (737336) | more than 3 years ago | (#35575074)

Truthfully both approaches are valuable, and we would be a poorer planet without either of these men. It's a shame they disliked each other so much.

Edison: "Genius is one percent inspiration and ninety-nine percent perspiration."

Edison contracted out all his perspiration. That's genius.

Re:So... what? (1)

pnewhook (788591) | more than 3 years ago | (#35575184)

Truthfully both approaches are valuable, and we would be a poorer planet without either of these men

Without Edison there would have been a lot less tortured puppies, cats horses and elephants.. Edison arguably invented very little, instead taking the inventions of people who worked for him and claiming then as his own.

Re:So... what? (0)

Anonymous Coward | more than 3 years ago | (#35575164)

If Tesla had half Edison's ability for self-promotion and half of George Westinghouse's business sense and some say, crookedness, we might have had "Telsa Electric" and the "Telsa Genius" prize.

Whenever I think of Telsa's story, it just breaks my heart.

Re:So... what? (1)

crank-a-doodle (1973286) | more than 3 years ago | (#35574726)

Good one!:P

Re:So... what? (5, Funny)

Opportunist (166417) | more than 3 years ago | (#35574876)

Too bad, if he was rotating it would probably generate some power.

Re:So... what? (5, Informative)

Junior J. Junior III (192702) | more than 3 years ago | (#35575162)

Tesla was the one who advocated for AC power. Edison was the one who argued for DC as the safer choice, and publicly electrocuted horses and other animals using AC to show how unsafe it was.

No really? (0)

scuzzbunny (1818528) | more than 3 years ago | (#35574552)

They needed to do a study to figure this one out?

Re:No really? (0)

Anonymous Coward | more than 3 years ago | (#35574798)

You need a study to demonstrate that it a. actually works; that the various parts are available, that there aren't unforseen problems, etc., and b. the benefits are worth the effort.

Re:No really? (1)

MightyYar (622222) | more than 3 years ago | (#35575248)

They needed to do a study to figure this one out?

I'm glad that they shared their experience with the rest of us, to save us from duplication of effort.

Tesla v. Edison (0)

Anonymous Coward | more than 3 years ago | (#35574574)

Tesla and Edison fought this out 100 years ago. DC is great for short distances only. AC is great for killing dogs.

Re:Tesla v. Edison (2)

Corporate Troll (537873) | more than 3 years ago | (#35574642)

AC is the tool for killing Elephants though. linky [youtube.com]

Re:Tesla v. Edison (1)

jshackney (99735) | more than 3 years ago | (#35574648)

Westinghouse and Edison?

Re:Tesla v. Edison (1)

jshackney (99735) | more than 3 years ago | (#35574674)

oh, duh! disregard.

Re:Tesla v. Edison (0)

Anonymous Coward | more than 3 years ago | (#35574848)

Tesla worked for Westinghouse; it was Tesla's AC system that was opposed to Edison's DC.

Actually DC is great for long distances too (2)

Viol8 (599362) | more than 3 years ago | (#35574868)

Its the voltage that matters when transmitting over long distances, not the type of current. In fact DC is slightly more efficient for a given voltage though you'd have to ask a physicist why.

secure? (3, Insightful)

Hazel Bergeron (2015538) | more than 3 years ago | (#35574612)

There is no evidence or reason for DC to be more "secure". If some lame argument about it being harder to bring your own power source / utilise their outlets when you have a custom system is put forward, then, well... no.

I can understand the efficiency argument to a certain extent, although if a workstation needs enough power that a fanless AC PSU is unsuitable then the more efficient AC PSUs will be enjoying enough load to reach over 80% efficiency. Are the centralised rectifiers + wires + in-computer DC-to-DC converters as efficient?

Re:secure? (1)

adonoman (624929) | more than 3 years ago | (#35574718)

I think they're referring to secure meaning less downtime - the individual computers are less likely to have power supplies die, since there aren't any moving parts. Also, part of the system involves a UPS - so less issues there than previously (although there's no reason you need DC for that to work).

The thing that confused me was the statement that the system was "faster". Maybe they're just talking about the fact that they got new computers? The whole article reeks of badly uninformed reporting, glossing over the important parts and seizing on, and exaggerating, little trifles that the reporter happened to understand.

Re:secure? (1)

g0bshiTe (596213) | more than 3 years ago | (#35574824)

I dare say in my 13 years of IT, I have replaced far more worn out UPS batteries than I have bad PSU's.

Re:secure? (1)

Onuma (947856) | more than 3 years ago | (#35575054)

Definitely true. Battery banks tend to need regular, and often costly, maintenance. And you can still cause lots of damage to them by tripping them or incorrectly swapping switchgears/breakers, etc. I've done my time repairing those, and concur.

Re:secure? (0)

Anonymous Coward | more than 3 years ago | (#35575102)

I'm sorry, secure just does not mean less downtime.
Oh, do you mean secure as in security blanket?
Do the new computers come with Teddy Bears?
That'd make people feel more secure.

Re:secure? (1)

vlm (69642) | more than 3 years ago | (#35574760)

There is no evidence or reason for DC to be more "secure".

In this modern post 9/11 post columbine world the words "secure" and "inconvenient" have merged and very few non-philosopher types can tell them apart.

In this case it means that its inconvenient but typing the word secure is shorter and creates warm fuzzies in morons brains.

Are the centralised rectifiers + wires + in-computer DC-to-DC converters as efficient?

Yeah, generally the more you spend the higher quality the design. Its not that you can't design build and sell a 99% AC supply, its just you can't do so and survive in this weird confuseopoly market where the only thing that matters is price, none of the UL or FCC listings are real, and its all made by our enemies in China.

Re:secure? (1)

gad_zuki! (70830) | more than 3 years ago | (#35575024)

Oh course its secure! The $300/hr "Security Consultant" we hired said so and here's his checklist from the audit!

*DC power
*Use Passwords, change weekly
*Use Control-Alt-Delete
*Blame sysadmins for everything

Re:secure? (1)

bromoseltzer (23292) | more than 3 years ago | (#35575032)

The system is arguably less secure. You have 50 systems depending on one AC-DC converter (or a small number of them), and that introduces a single point of failure.

When our data center installed a nice shiny big UPS system to help us solve some problems about unreliable AC supply, I (correctly) predicted the next data center outage would be from the UPS.

Re:secure? (1)

Palpatine_li (1547707) | more than 3 years ago | (#35575204)

I thought the security argument is about the grid, no? And the efficiency argument is also about the grid. It really doesn't make a big difference when you switch to DC only locally.

DC is more secure? (1)

snowraver1 (1052510) | more than 3 years ago | (#35574616)

How is DC more secure? The only reason I can think of is because of the increased difficulty connecting a stolen computer to your home power supply.

There is a small deterrance factor, but I think that by the time most theifs would have figured this out, the computer would already be stolen.

Re:DC is more secure? (1)

Shisha (145964) | more than 3 years ago | (#35574712)

They meant to say it's more reliable, because there are fewer parts inside the computer that could fail.

You could argue in the opposite direction: if the main ACDC converter fails, all the computers go down, not just one. Swings and roundabouts I guess.

OT (1)

Opportunist (166417) | more than 3 years ago | (#35574978)

Update your sig. It's outdated by like 3 months.

AC? (5, Interesting)

Anonymous Coward | more than 3 years ago | (#35574628)

The only thing inside a computer that actually runs on AC is the computer's powersupply. The powersupply regulates this to DC voltages! The powersupply is also quite bulky and noisy compared to the other components.

"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."

Yes, I'm sure it'll generate less heat when most of that heat comes from converting AC to DC, but why the hell would it run faster when everything else in the computer is still the same?

Re:AC? (1)

spidercoz (947220) | more than 3 years ago | (#35574700)

MOD PARENT UP!

So glad someone else knows this fact.

Where did the heat go? (2)

DeadCatX2 (950953) | more than 3 years ago | (#35574714)

They just move the AC/DC conversion somewhere else. All of the heat will go along with it.

Re:Where did the heat go? (2)

tomhudson (43916) | more than 3 years ago | (#35575076)

From TFA:

Also:

the project team moved the one tonne AC converter through the University library and into the roof space, removing and rebuilding walls to transport it

It would have been cheaper to just use 50 energy-efficient laptops. You'd get even more power savings, and if you wanted to completely remove the heat from the transformers, just put them all in a cabinet that vents outdoors, and extend the DC power plugs.

And you wouldn't have to also invest in another ton of batteries.

Re:AC? (1)

doconnor (134648) | more than 3 years ago | (#35575002)

"why the hell would it run faster when everything else in the computer is still the same?"

Don't modern computers slow themselves down if they are getting to hot? With the AC to DC conversion moved somewhere else, the computer are cooler and slow themselves down less.

Re:AC? (1)

tomhudson (43916) | more than 3 years ago | (#35575044)

The only thing inside a computer that actually runs on AC is the computer's powersupply. The powersupply regulates this to DC voltages! The powersupply is also quite bulky and noisy compared to the other components.

"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."

Yes, I'm sure it'll generate less heat when most of that heat comes from converting AC to DC, but why the hell would it run faster when everything else in the computer is still the same?

Because they're comparing it to a previous (older) system, not the same system but powered with a local ac/dc power supply. An apples and oranges comparison.

TFA is so fact-free it could have been submitted by Florian Mueller.

Re:AC? (1)

Xacid (560407) | more than 3 years ago | (#35575096)

"but why the hell would it run faster when everything else in the computer is still the same?"

Just a guess but it might allow for running the CPU faster as there's less external heat bringing up its temperature.

Question tangent to that: I'd imagine SSDs run MUCH cooler than HDDs - with that said, does anyone know first hand?

Re:AC? (1)

jesseck (942036) | more than 3 years ago | (#35575104)

The speed comes from the new computers. Generally, when you purchase new computers, the hardware is better than the previous ones. Add to that you don't have the Windows bloat of years of updates and installs / uninstalls, and possibly running Windows 7 versus the old XP, and you get a faster machine.

When people ask me if they need a new computer or would the one they have work, I respond that any new computer will seem better. After the honeymoon period, though, when something breaks or you install the same programs, that old system may seem faster. I tend to see this with more with persons who bought their last computer in line with their needs, and want to buy a new computer on the cheap.

Dumb idea (2)

Animats (122034) | more than 3 years ago | (#35574632)

There's something to be said for DC distribution within data center racks, but building a plug-in DC infrastructure seems like a PR stunt. They need a whole rack of power conversion gear to serve 50 desktop computers.

Google at one point proposed that rackmount computers should be built to run on 12VDC only, so you could have a single 12VDC supply in the rack and get rid of the individual power supplies for the server. Whatever happened to that?

Much industrial automation gear and military equipment runs off 24VDC. That's low enough that you don't have a shock hazard, but high enough that the wire sizes are reasonable.

Re:Dumb idea (1)

Bert64 (520050) | more than 3 years ago | (#35574844)

A lot of networking/telco gear can run on DC, but very few servers seem to have that option...

Re:Dumb idea (1)

Onuma (947856) | more than 3 years ago | (#35575114)

That's because the military truck batteries are 24VDC. You can run all of their equipment off a truck's alternator, if it is wired up properly. Alternator --> UPS --> Further Distribution.

It makes sense to have the same voltages across the board, so that you can reduce the need for variants of hardware.

can a dell take a plug in DC to DC psu in the AC t (0)

Anonymous Coward | more than 3 years ago | (#35575182)

can a dell or others take a plug in DC to DC psu in the AC to DC slot?

More Secure? Regionalism, maybe? (4, Interesting)

rwade (131726) | more than 3 years ago | (#35574646)

Selective quotes from TFA [bath.ac.uk] :

Researchers at the University are undertaking an in-depth study of energy consumption within the new network, with the aim of demonstrating that running a large network of devices on DC rather than AC is both more secure and more energy efficient.

The new DC network also offers greater security. DC power supply units have a simpler design, with fewer parts that could fail and need replacing. The system at the University also charges a number of batteries when usage levels are low to allow the system to run independently from the grid for up to eight hours should a cut in power be experienced.

The above two paragraphs are the only I could find in TFA that mention security. I gotta ask -- can anyone speculate how centralizing the PSU would lead to a more secure system? Is it possible that there is a regional definition of "secure" to mean "very reliabile" or "very available." As in, we have "secured" a constant municipal water supply?

McCumber cube? (1)

oneiros27 (46144) | more than 3 years ago | (#35574754)

If you're looking at the McCumber cube [wikipedia.org] , then yes, availability is one of the three aspects we're trying to protect in security (along with confidentiality and integrity).

Most "security" obsessed people these days come from the "keep the bad people out" mentality, even if it's at the expense of making it so obnoxious for the authorized users to actually be able to do their job, but a complete model of security is that people who are supposed to be able to use the system are able to use it when they want.

(but I wouldn't have said 'secure' ... I'd have said 'reliable', as 'secure' has connotations of restrictiveness and secracy)

Re:More Secure? Regionalism, maybe? (5, Funny)

xs650 (741277) | more than 3 years ago | (#35574810)

"Is it possible that there is a regional definition of "secure" to mean "very reliabile" or "very available."

Yes, it's regional, as in "The wankers will stop nicking the computers if they can't use them at home."

Re:More Secure? Regionalism, maybe? (1)

Shisha (145964) | more than 3 years ago | (#35574860)

The whole article is full of strange statements.

Consider the following part:

Not content with lowering power usage and reducing energy loss, the University hopes to extend the environmental credentials of the new network by installing mini wind-turbines or solar panels, both of which output a DC current and therefore don’t require inefficient conversion from AC to DC.

My school physics may be a bit rusty but I would assume wind turbines produce either pulsating DC or AC and hence the current has to be converted before use by electronics.

Re:More Secure? Regionalism, maybe? (1)

Going_Digital (1485615) | more than 3 years ago | (#35575174)

What they really mean is that they don't need expensive phase converters so that the AC supply produced is in phase with the mains electricity. Much easier and cheaper to put the output into a rectifier.

Re:More Secure? Regionalism, maybe? (0)

Anonymous Coward | more than 3 years ago | (#35574910)

Yeah, I think they mean 'reliable'. The article is dumbed down to the point of being nearly free of content, so I'm forced to speculate about what they left out. I suspect that they are looking at the complexity and cost of providing UPS power for each computer. If each computer had a separate stand-alone UPS, replacing them with a central battery backup would be simpler and more reliable. Converting DC battery power to AC at the output of each UPS, and then converting it back to DC at the front end of each computer power supply adds complexity. If you consider battery backup a requirement, then it makes sense to build it into the computer's power supply like a laptop, or use a centralized backup and distribute DC.

Re:More Secure? Regionalism, maybe? (0)

Anonymous Coward | more than 3 years ago | (#35574998)

This, this here. By secure, they are meaning stable, reliable power. It is a rather strange phrasing that is somewhat popular here in the UK.
Similar to the popular "how" instead of "why" confusion in a lot of younger kids.

One of the main reasons of it being more secure is, of course, because they are converting it to DC.
This tends to remove a lot of the noise from power lines that can seriously degrade and damage equipment.
Power balancing equipment for power lines are usually seen as over-expensive crap, but if you run a lot of electrical stuff, you're better off getting one, it could save you a huge amount of money if something bad were to happen, like spikes, lightning, etc.
They aren't even that expensive either. There are even ones for small-scale use that you can plug straight in to sockets that run for prices of your average surge protectors.

Re:More Secure? Regionalism, maybe? (0)

Anonymous Coward | more than 3 years ago | (#35575008)

Selective quotes from TFA [bath.ac.uk] :

Researchers at the University are undertaking an in-depth study of energy consumption within the new network, with the aim of demonstrating that running a large network of devices on DC rather than AC is both more secure and more energy efficient.

The new DC network also offers greater security. DC power supply units have a simpler design, with fewer parts that could fail and need replacing. The system at the University also charges a number of batteries when usage levels are low to allow the system to run independently from the grid for up to eight hours should a cut in power be experienced.

The above two paragraphs are the only I could find in TFA that mention security. I gotta ask -- can anyone speculate how centralizing the PSU would lead to a more secure system? Is it possible that there is a regional definition of "secure" to mean "very reliabile" or "very available." As in, we have "secured" a constant municipal water supply?

Well, when bits are made from DC they have a firm identity of what they are. AC leads the bits to be more morally relativist, constantly changing sides. Therefore, bits made from AC are more likely to be swayed by Al Qaeda or Chinese propaganda, whereas DC bits are solidly 'merican and patriotic.

Edison & Tesla (0)

Anonymous Coward | more than 3 years ago | (#35574656)

Didn't Edison & Tesla argue this out a few years back? Has electricity changed so much since then?

Re:Edison & Tesla (1)

Qubit (100461) | more than 3 years ago | (#35574932)

Has electricity changed so much since then?

It's funny that you'd bring that up. Yes, actually Physicists and noted researchers are observing subtle but significant changes in the way that electricity flows through conductive materials. Electrons used to be so-called "longer" a few decades ago (end to end, mind you), so you'd actually get a fewer number of them traveling through the wire to you per second.

Now that the magnetic poles of the earth are shifting, and we're (slowly) approaching the geomagnetic "pole-arity" reversal (a little physics humor there...), electrons flowing through wires are shortening and approaching the shape of a sphere rather than an elongated sausage. You'll see this happen more strongly during the night, when your part of the Earth is facing away from the Sun and isn't experiencing as much solar radiation and bombardment of charged sub-atomic particles.

So yes, it is a good time for the University and other large groups to reconsider the way that they power their computers. Note that they'll need to install an inverter once the poles actually do reverse, however usually the reversal takes over a thousand years. That being said, taking precautions isn't a bad idea, as Wikipedia does point out [wikipedia.org] :

...geologist Scott Bogue of Occidental College and Jonathan Glen of the US Geological Survey, sampling lava flows in Battle Mountain, Nevada, found evidence for a reversal that took only four years.

I'd be happy to consult with any University or Company that is considering a move to DC power or other "green power" initiatives.

For more information about the latest in advanced power tech and the influence the shifting poles has on inter- and intra-electron measure, please see the wikipedia page on such topics here [wikipedia.org] .

Re:Edison & Tesla (1)

ArhcAngel (247594) | more than 3 years ago | (#35575190)

Physicists and noted researchers are observing subtle but significant changes in the way that electricity flows through conductive materials. Electrons used to be so-called "longer" a few decades ago (end to end, mind you), so you'd actually get a fewer number of them traveling through the wire to you per second.

Ah! but DO the electrons flow through the wire or just shuffle back and forth as the holes flow through the wire? I've seen these very same people get into fist fights over that question too.

Re:Edison & Tesla (1)

TheRaven64 (641858) | more than 3 years ago | (#35575222)

Electricity hasn't but transformers have. It used to be very cheap to do voltage conversions with AC and very expensive (and lossy) with DC. That's a lot less true now.

AC vs DC (2)

prakslash (681585) | more than 3 years ago | (#35574658)

The major drawback to DC power is in the wiring. Direct current requires larger gauge wiring than AC power, which increases material costs considerably. In general, DC power is economical only if the wiring between the computers and the DC source is less than 35 feet in length. More than that, AC power becomes more economical.

Re:AC vs DC (4, Funny)

TDyl (862130) | more than 3 years ago | (#35574728)

I guess I could swing either way on this one.

Re:AC vs DC (0)

Anonymous Coward | more than 3 years ago | (#35574976)

Tell that to power companies,

http://en.wikipedia.org/wiki/HVDC#Advantages_of_HVDC_over_AC_transmission
http://en.wikipedia.org/wiki/Skin_effect

DC transmission does not require larger wires, it require smaller wires. And no, you can't compare a 12VDC with 240VAC. The point is that higher voltage DC (240VDC) can be more "dangerous" but that can be mitigated be using better circuit breakers. On the other hand, unlike AC, DC does not cause RF noise to be emitted from every single circuit in your house. When you are not using power, the circuit is energized but "quiet".

The only problem with DC is inability to use power transformers. DC-DC conversion is more expensive, but I believe today this is mainly due to less application in DC-DC conversion especially with higher voltages than 50VDC.

Re:AC vs DC (3, Informative)

Muad'Dave (255648) | more than 3 years ago | (#35574982)

I'm not sure how you came to that conclusion. AC suffers from several effects that make it less efficient and/or more expensive over long distances.

For DC, the power delivered is V*I. For AC, it's similar except the V is really Vrms - you must insulate for Vpeak, but you only get Vrms * I power. For sinusoidal AC, the difference is a factor of 1.414.

With AC circuits that have non-zero reactance, you must choose a conductor that can carry Imax, but the power delivered to the load is only Vrms * Imax * cos(phi), phi being the phase angle between the voltage and current.

AC circuits suffer from the skin effect [wikipedia.org] where the power travels more on the surface of the conductor rather than equally throughout its cross-section. This requires a larger solid or stranded conductor than would be required for DC.

AC has a few things going for it - the ease with which voltage can be transformed, the ease of generation with rotating generators, and ability to drive large, multiphase motors efficiently.

Re:AC vs DC (0)

Anonymous Coward | more than 3 years ago | (#35575010)

Not necessarily... Most/all the computers I ever owned would run quite happily on DC with cable no thicker or shorter than AC. The secret is to feed them with approximately 310 Volts. No modification needed unless you want to remove a couple of diodes from or bypass the rectifier (don't try this at home) and make them useless on an AC supply. This is more highly recommended if the computer's power supply doesn't have power factor correction (assuming you DC supply does).

Re:AC vs DC (1)

Viol8 (599362) | more than 3 years ago | (#35575048)

"Direct current requires larger gauge wiring than AC power,"

No it doesn't. Its the voltage that matters, not the type of current. It just so happens that most industrial DC applications - eg metro trains - use lower voltages that their AC equivalent which means higher currents for the same power delivery and hence thicker cabling.

Re:AC vs DC (1)

tomhudson (43916) | more than 3 years ago | (#35575126)

The major drawback to DC power is in the wiring. Direct current requires larger gauge wiring than AC power, which increases material costs considerably. In general, DC power is economical only if the wiring between the computers and the DC source is less than 35 feet in length. More than that, AC power becomes more economical.

FTFA:

the project team moved the one tonne AC converter through the University library and into the roof space, removing and rebuilding walls to transport it

Somehow, I suspect that the cable run to the individual machines is more than 35 feet.

Re:AC vs DC (1)

bromoseltzer (23292) | more than 3 years ago | (#35575230)

Not really. It depends on the current drawn through the wire. For power P (constant for the computer, more or less) required at a voltage V, you need I=P/V amps. You're not going to distribute 3 V or 5 V, which is what your ICs want, I hope! You could distribute 120 V DC with the same size wiring you use for the usual AC connection. You could send around 1,200 V (DC or AC) and use 1/100 the copper. (Power lost to heating goes as I**2.) The high voltage limit is set by safety and cost of DC-DC converters.

Con Edison (3, Informative)

The Grim Reefer2 (1195989) | more than 3 years ago | (#35574668)

I guess Con Edison should have waited [nytimes.com] just a few more years. Apparently 125 was not quite enough.

Re:Con Edison (1)

kiehlster (844523) | more than 3 years ago | (#35575068)

It was before its time, I guess. This article reminded me of the same thing. Con Edison offered reliable, safe and efficient power. It won't kill you like AC power when you accidentally touch the wire.

Silence is golden... (0)

Anonymous Coward | more than 3 years ago | (#35574678)

I'd imagine there would be certain efficiencies gained by off-loading the work of the switching power supply to one central location, then just powering the workstations like you would normally power internal computer components. You'd still need to cool internal components, but if you were looking for really silent operation, you could offload this to liquid cooling, and cool the power supply and components at the same time - leaving the lab nearly silent. Of course, if the main power supply futzes - your entire lab is down, versus just one workstation.

DC-DC conversion? (1)

cdrguru (88047) | more than 3 years ago | (#35574680)

In a single room or even perhaps a floor of an office building I guess I could see DC distribution. It would tend to reduce the power supply losses. Laptops are already doing total DC-DC conversion for the different voltages they need and there probably isn't much of a reason you couldn't run 12 volts to each computer and have it convert it over to 5 and 3.3. I would think your benefits would be significantly less if you were running 100 volts DC and requiring it all to be downconverted as DC-DC conversion isn't anywhere near as efficient as AC-DC conversion.

The big question is when do the wiring costs exceed the power supply losses. If nothing else you need to have a completely different parallel distribution network run with very, very incompatible outlets. You would NOT want to plug just anything into a DC supply, even if it was 12V. DC at 100V would destroy a lot of things and the load something like a shredder or even a desk lamp would be damaging.

Another factor I would think is redundancy. Today if you blow a power supply (one of the most common computer failures) you lose one computer. If you blow the power supply for the office floor you might lose 100 or 200 computers.

Re:DC-DC conversion? (0)

Anonymous Coward | more than 3 years ago | (#35574788)

Another factor I would think is redundancy. Today if you blow a power supply (one of the most common computer failures) you lose one computer. If you blow the power supply for the office floor you might lose 100 or 200 computers.

That seems to be an argument for the opposite position: you only need x power supplies to provide x redundancy, instead of 100 or 200 times x power supplies?

Re:DC-DC conversion? (4, Informative)

vlm (69642) | more than 3 years ago | (#35575122)

Today if you blow a power supply (one of the most common computer failures) you lose one computer. If you blow the power supply for the office floor you might lose 100 or 200 computers.

For reasons which are a long story, I have had several servers up and running on 12V for many years now. The powerstream guys are pretty much the gold standard of ATX 12 volt power supplies, as far as I know:

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

Note that these are "honest wattages" not the "marketing wattages" seen in the AC power industry. The price of a 300 watt DC supply seems high compared to a 100 watt AC supply from China that has a sticker claiming 300 watts. However its not too bad compared to a AC supply that actually only provides 300 watts despite having a sticker labeled 800 watts or a million watts or whatever marketing felt necessary. Also the powerstream supplies, to the best of my knowledge, are some of the few computer power supplies you can buy that do not have forged FCC and UL registries, which is worth something to me. In summary, expensive, but strongly recommend based on years of experience.

Anyway, what happens when the primary rectifier goes down, is my battery bank will run the asterisk PBX and friends for something like half a day, during which time I can source a generator and charger, or perhaps casually purchase a new supply, etc. Also I have multiple supplies any of which could theoretically power the whole works (at a cost of high heat and much shorter capacitor lifetimes, etc). So you Y-cable them to run multiple plants off one supply. Guess what, the same Y cable can be used to run multiple plants off one battery, if one fails. Etc.

Theoretically, I could run the entire phone system off an idling car, assuming you have enough gas in the tank. Unfortunately my entire plant draws just a little too much for the cigarette lighter plug, probably 15 amps total. If I could invest in new phones / new servers / etc and get total plant draw down to 5 amps, not only would my batteries be 1/3 cheaper or last 3 times longer in an outage, but I could also run the works conveniently off a car cig lighter port.

Obviously if you have zero battery capacity then you are instantly in deep doo doo, but given three or so figures of amp-hours you're good to go for a very long time.

Wire everything in Amphenol power poles, exactly like the ham radio guys so you can use their DC products, and keep a stock of extension cords and Y cables and other gadgets. Use fuses, and as a subset of that rule, only use automotive fuses because they are infinitely available. Use 12 volts as your standard because you probably own a mobile 12 volt generator (aka your car). Perhaps if you're in the .mil and have a 24 volt humvee, do 24v instead, whatever.

A DC powered system is frankly pretty straightforward and simple.

Telecom has known this for a while (0)

Anonymous Coward | more than 3 years ago | (#35574692)

I believe the telecom industry has known this for years. Since telecom equipment in COs can be run on both DC based and AC based power, consumption levels can be monitored between the AC and DC based offices. AC/DC - Rock on.

Re:Telecom has known this for a while (1)

tomhudson (43916) | more than 3 years ago | (#35575156)

I believe the telecom industry has known this for years. Since telecom equipment in COs can be run on both DC based and AC based power, consumption levels can be monitored between the AC and DC based offices. AC/DC - Rock on.

Not exactly - it's because of the requirement that equipment operate during power failures. Hence the large banks of lead-acid batteries in older switching centers.

UDC anyone? (1)

srijon (1091345) | more than 3 years ago | (#35574696)

We've got USB, what I want is UDC - some kind of in-the-wall intelligent DC outlet standard so that we can get rid of all those wall-warts and reap some of the advantages this article mentions. Of course, the one-tonne AC converter is a bit of a problem...

I think I speak for us all when I say "Huh???" (2)

$RANDOMLUSER (804576) | more than 3 years ago | (#35574702)

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.

If you mean "much cooler", you already said that. If you mean "much faster", you should probably sign up for that physics (or electronics) course.

The new DC network also offers greater security. DC power supply units have a simpler design, with fewer parts that could fail and need replacing.

So you don't mean "security", you mean "reliability".

Decarbonisation will increase electricity consumption by 2030 and possibly more than double it by 2050.

I wonder how much carbon was released refining all the lead in all those batteries...

Re:I think I speak for us all when I say "Huh???" (1)

pz (113803) | more than 3 years ago | (#35574856)

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.

If you mean "much cooler", you already said that. If you mean "much faster", you should probably sign up for that physics (or electronics) course.

I'm betting the new systems were much faster because they were, well, newer than the old ones, and the fact that they ran faster is completely unrelated to the fact that the cable running into the box that provides power carries DC rather than AC. But what do you expect from a propaganda-laden puff piece released by a university PR department, scientific accuracy and truth?

Re:I think I speak for us all when I say "Huh???" (3, Funny)

adonoman (624929) | more than 3 years ago | (#35574900)

running much faster

With DC power, the electrons get to run laps, and every time they get to your computer, they can do a little bit of work, spreading it out among all the electrons. With AC power you got those electron thingies racing back and forth and back and forth, but never getting anywhere. Only the few electrons near the computer actually do any helpful work, and they get worn down really quickly, so they stop working as efficiently, and the CPU slows down, and it's just generally bad.

Re:I think I speak for us all when I say "Huh???" (1)

maxume (22995) | more than 3 years ago | (#35575056)

They switched to new computers, so nothing terribly impossible is being described. It also isn't very amazing, imagine, newer computers being more energy efficient than older ones.

Re:I think I speak for us all when I say "Huh???" (1)

Lehk228 (705449) | more than 3 years ago | (#35575098)

I am more worried about the carbon used to fuel steam shovels for all the bullshit

Edison will triumph in the end! (1)

John Hasler (414242) | more than 3 years ago | (#35574720)

He tried to tell you AC would fail. Take that, Tesla.

why not just spec a decent normal power supply? (1)

Chirs (87576) | more than 3 years ago | (#35574738)

It's not clear to me how this is any better than specing normal machines with a decent power supply. Anything rated at "Gold 80 Plus" will convert to DC with 80-90% efficiency depending on the power draw.

Is this just a matter of replacing old inefficient noisy machines with newer efficient (and thus quieter) ones?

Re:why not just spec a decent normal power supply? (1)

zill (1690130) | more than 3 years ago | (#35575086)

My W510 draws only around 50 watts, but its power brick is rated for 120 watts. My desktop is likewise over-provisioned as well to account for power consumption spikes.

However by combining the AC to DC conversion of 100 computers, the over-provisioning factor can be much much less, because it's very unlikely that the computer enter into power spikes at the exact same time.

makes sense in a library (0)

Anonymous Coward | more than 3 years ago | (#35574750)

Fewer fans means less noise, if you put some batteries in between you can use a power source designed for the *average* power required instead of designing it for the *maximum*, plus provide 30 seconds "save your documents right NOW" UPS functionality. The power conversion can be done ventilated with outside air so you save on airco. Good idea for concentrated PC groups like libraries and offices, bad idea at home...

wow, newer = faster and smaller, big deal (2)

alta (1263) | more than 3 years ago | (#35574756)

Ok, so people have 'noticed' that these NEW computers are faster, quieter, smaller and just magically better than the old system.

This is obviously not very scientific, I'd venture to say if they replaced the entire old system with a new AC system, it would still be faster, quieter, smaller, etc...

Yes, DC may be great, but these observations can be said about any new vs old setup.

I would love to make the conversion (1)

erroneus (253617) | more than 3 years ago | (#35574758)

My server at home is begging for a DC conversion, for example, as are my switches and other gear.

The idea is great, but like so many things, we are entrenched in our AC power systems. So until we come up with a common implementation of the "AC to DC" power supply for everything and everything comes with an option to plug in "DC" I will have to wait.

There are DC power systems for servers and such today, but such things are pretty much special order and expensive. I hope that it catches on at a level which enables me to run my stuff on DC sooner rather than later.

How was the "emission" tested? (1)

MrKevvy (85565) | more than 3 years ago | (#35574768)

TFA: Initial tests show that the system in Bath emits approximately half as much energy as heat

Switched mode power supplies are on average about 94-95% efficient, so why half as much energy as heat? It should have been a mere 10% reduction.

Simple answer: without a fan, the heat is trapped in the case. Not much of an improvement.

Poor Nicola (0)

Anonymous Coward | more than 3 years ago | (#35574790)

Tesla must be rolling in his grave - at 60Hz

Re:Poor Nicola (1)

$RANDOMLUSER (804576) | more than 3 years ago | (#35574952)

Tesla must be rolling in his grave - at 60Hz

Too bad they didn't think to bury him in a stator.

Back in (the) Black (2)

demonbug (309515) | more than 3 years ago | (#35574828)

So they went AC-DC to try and get back in (the) black?
My concern is that the initial conversion would cost a touch too much, and it ain't no fun waiting for the energy savings to cover the investment - the down payment blues.
Still, in my experience the power supply is often the point of failure that finally kills the whole computer, so goodbye & good riddance to bad luck.

This is interesting (1)

kamakazi (74641) | more than 3 years ago | (#35574834)

It has taken a while for the economical advantage of this to trickle into user space. Electronic devices are almost all DC in nature, and the efficiency improvements here are not actually the computers, they are the lack of individual power supplies. Other poster have made comments about laptops, but normal laptops are actually no more efficient than desktops. They use less power, but that power brick is not any more efficient than a good desktop power supply.

What they get to do here is run one big, presumably very efficient power supply, and run it outside of populated space, moving the noise and heat generation to where it can be more efficiently controlled.

Of course telco types will say "Umm, yeah?" because a lot of telco heavy iron has been DC forever, for the same reasons TFA is bragging up this system.

This doesn't apply very well to consumerland, because houses don't lend themselves well to special DC wiring that doesn't easily move when you rearrange the room.

And before people start asking "Why don't the power companies just use DC?" Electricity transmission over distance is much more efficient as a high voltage/low current AC than DC current, especially since you can't use transformers on DC.

But I can very easily imagine datacenters utilizing a rack sized high efficiency DC power supply to run row(s) of server racks. This would tie in very nicely to Googles battery-in-every-server method.

Re:This is interesting (1)

Elder Entropist (788485) | more than 3 years ago | (#35575040)

Electricity transmission over distance is much more efficient as a high voltage/low current AC than DC current, especially since you can't use transformers on DC.

Not entirely true. High voltage DC (HVDC) is more efficient for long distance transmission. It's more that AC is most economical for medium distance with lots of tap-in points. http://en.wikipedia.org/wiki/High-voltage_direct_current [wikipedia.org]

OLD NEWS (1)

LOTHAR, of the Hill (14645) | more than 3 years ago | (#35574884)

DC datacenters have been around longer than AC. All major telco's globally use DC distribution for their networking and communications equipment. They always have, and likely always will. The newer datacenter companies are just having to learn for themselves why it makes sense.

Bad reporting. (1)

gstrickler (920733) | more than 3 years ago | (#35574888)

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.

So, they run faster and produce much less heat, which means they're not running the same CPUs, etc. as before. Therefore, it's an apples-to-oranges comparison.

I have no doubt that a single large DC power supply can power multiple systems with better efficiency, especially if the AC/DC power supply is located in a separate room or outdoors where it can be cooled without contributing heat to the room containing the computers. Of course, that's not necessarily desirable in cold environments, but that's a separate issue.

AC is used for power distribution because it's far more efficient for distributing power over a distance. Even a few mi/km, DC loses are significantly worse than high voltage AC. AC is far easier and more efficient to transform to/from high voltages, making high-voltage AC far more efficient than high voltage DC for distribution. DC isn't practical until you get to the final few hundred feet.

My University... (0)

Anonymous Coward | more than 3 years ago | (#35574898)

It's kind of strange reading about this on Slashdot, seeing as I am an undergraduate in the CS department at Bath. I don't think I've even seen these PCs - possibly because they put them on the 5th level of the Library, and I am too lazy to walk up that many stairs.

Not a panacea (1)

StikyPad (445176) | more than 3 years ago | (#35574948)

...running a large network of devices on DC rather than AC is both more secure and more energy efficient. AC electric power from the grid is converted to DC and runs 50 specially adapted computers in the University Library.

Computers already run on DC -- the only question is where the conversion takes place. The downside to having a single converter (rectifier) is that you have a single point of failure, but obviously you can place it away from the actual computers to reduce noise and such.

As for efficiency, it all depends how efficient the individual power supplies are/were for each PC. There's nothing inherently more efficient about converting once for all PCs vice converting once for each PC. In fact, your losses might even be higher depending on your distribution network. Additionally, there's the not-insignificant monetary and environmental cost of installing DC-DC power supplies for each PC, upgrading the transmission lines, etc. Depending on how long the network is used and the actual efficiency gains, if any, those investments may or may not pay off over time.

Why Isn't This Done More Often? (1)

organgtool (966989) | more than 3 years ago | (#35574984)

Just a couple of days ago I was talking with a friend about how my company already does this with some of its servers.

I know that we use AC for transmission because it loses less power over long distances than DC, but is there any reason why we don't have DC converters installed in the electrical panels of homes other than the fact that many appliances currently require AC? More and more appliances seem to be using DC lately, requiring wall warts. If we could convince more manufacturers to produce DC appliances, it would assist people transition their homes to DC power. This would be great because it is safer than AC and it would be more efficient to convert it in one place rather than through the use of the many wall warts and computer power supplies we currently have.

Quieter and cooler? I'll volt for that! (1)

sehlat (180760) | more than 3 years ago | (#35575082)

(just sayin)

universe being damaged from workstation in DC (0)

Anonymous Coward | more than 3 years ago | (#35575092)

that's crazy? we can only goof things up here at home, so far?

Possible "security" (0)

Anonymous Coward | more than 3 years ago | (#35575170)

If these computers run on DC only, they won't work in most homes when a student inevitably tries to steal it.

The Prius Effect (0)

Anonymous Coward | more than 3 years ago | (#35575238)

Only Gasoline goes in but somehow it's a hybrid. Here we have an extra conversion loss but somehow it's better. From the Superman alternate universe?

The systems also come with a Teddy Bear (0)

Anonymous Coward | more than 3 years ago | (#35575254)

Which makes people feel more secure. This has nothing to do with secure as in SSH, this is secure as in Linus' blanket.

WTF? (1)

zoomshorts (137587) | more than 3 years ago | (#35575256)

"both more secure and more energy efficient"

MORE SECURE!!!! What a crock of shit.

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