Cooling Data Centers Could Prevent Massive Electrical Waste

June 27, 2008 By Timothy B. Hurst 35 Comments

AC-DC?

For electricity flowing all the way from power plants to the wall socket, alternating current is far superior. But for the short transmissions inside those computers DC power prevails. The search for ways to convert AC to DC more efficiently is leading some data center companies to consider a DC-centric approach.

It’s easier to transmit AC over long distances; DC requires thick copper cables or bars, instead of comparatively lightweight wires. But DC becomes a more serious possibility for power once AC reaches a building.

Converting from one form of power to another in a computing environment may not be performed efficiently, especially at the server level, and even then, the resulting waste heat may be deposited in the rack or computer room at a point that requires further effort to dispose of it with the air handlers. Unfortunately, there is disagreement in the community over how to address these inefficiencies.

DC advocates argue that plugging servers into AC power is inefficient, and switching systems to DC would cut down on waste heat and component failure.
Proponents argue that using DC outside the server removes some of the inefficiencies of power supplies that convert AC electricity to DC. Servers without such power supplies don’t have to contend with as much waste heat and attendant component failure.

But according to NPPL, substituting DC power in data centers as a replacement for conventional AC power has not yet made significant inroads into many data centers because the technology is unfamiliar to many facility engineers.

Despite the wide-spread use of DC power in telecommunications, there is reluctance within the computer industry to switch to new technologies without field experience showing that the switch could be done safely and would have operational and economic benefits without causing unanticipated problems.

If DC would in fact be a more efficient type of power within servers themselves, might it be possible to site server farms to take advantage of the DC provided by integrated renewable energy generating systems such as solar PV and wind?

Photos:1.© Eimantas Buzas | Dreamstime.com; 2. Versageek via Flickr under a Creative Commons License

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Filed Under: Energy Efficiency, Other Clean Technologies Tagged With: data centers, dc power, dc servers, direct current, waste heat, web servers

About Timothy B. Hurst

Tim is the founder of ecopolitology and the executive editor at LiveOAK Media where he writes regularly about the politics of energy and the environment, green business and clean tech.

When not reading, writing, thinking or talking about environmental politics with anyone who will listen, Tim spends his time skiing in Colorado's high country, hiking with his dog, and getting dirty in his vegetable garden.

Pingback: Yahoo is Crowing Over New Energy Efficient Chicken Coop…Er, Data Center, That Is – CleanTechnica
http://google.com/zsxdg sandrar

Hi! I was surfing and found your blog post… nice! I love your blog. Cheers! Sandra. R.
http://google.com/zsxdg sandrar

Hi! I was surfing and found your blog post… nice! I love your blog. Cheers! Sandra. R.
LH

I’m interested in the liquid metal cooling idea. I know of a company called nanocoolers that proposed a cooling system that used gallium as the coolant. They couldn’t get any traction with the idea and have since gone out of business. Is there someone else that’s working on it again?

Also the industry is working very hard to promote and improve energy efficiency. There are two relavent industry agencies: ASHRAE (American Society of Heating, Refrigerating and Air Conditioning Engineers) technical committee 9.9 and The Green Grid. T.C 9.9 has published several books: Best Practices for Datacom Facility Energy Efficiency, High Density Data Centers – Case Studies and Best Practices, Liquid Cooling Guidelines for Datacom Equipment Centers which can be purchased at the ASHRAE.com bookstore. They are also hosting 5 free workshops in NY, http://www.ashrae.org/pressroom/detail/16615. The Green Grid’s website is thegreengrid.org.
LH

I’m interested in the liquid metal cooling idea. I know of a company called nanocoolers that proposed a cooling system that used gallium as the coolant. They couldn’t get any traction with the idea and have since gone out of business. Is there someone else that’s working on it again?

Also the industry is working very hard to promote and improve energy efficiency. There are two relavent industry agencies: ASHRAE (American Society of Heating, Refrigerating and Air Conditioning Engineers) technical committee 9.9 and The Green Grid. T.C 9.9 has published several books: Best Practices for Datacom Facility Energy Efficiency, High Density Data Centers – Case Studies and Best Practices, Liquid Cooling Guidelines for Datacom Equipment Centers which can be purchased at the ASHRAE.com bookstore. They are also hosting 5 free workshops in NY, http://www.ashrae.org/pressroom/detail/16615. The Green Grid’s website is thegreengrid.org.
Al

A couple of quick points:

1) While industry is using some sub-optimum AC/DC power supplies, the limit of power supplies efficiency may not be at 75% that you referenced.

“Power-converter efficiencies are in the upper nineties and quickly approaching the magic 100% barrier.” (Hearst Electronic Products Monday June 30th 2008, LOU PECHI Power-One, Camarillo, CA

http://www.power-one.com)

2) A more easily achievable goal would be to increase the server use from “6%”. Virtualization is available for most server platforms and increase the usage factor significantly. This approach to reducing the heat load in a data center is true heat savings (Planning figures are about 10 to 1, that is one virtualized server can handle 10 current servers load).

3) New technology hard drives, i.e. solid state drives (SSD), decrease the heat load in a data center by reducing the power needed to turn drives. While still fairly expensive compared to conventional drives, SSDs can quickly pay for themselves by reduced power and heat. If I remember correctly they require about 10% of a conventional HD.
Al

A couple of quick points:

1) While industry is using some sub-optimum AC/DC power supplies, the limit of power supplies efficiency may not be at 75% that you referenced.

“Power-converter efficiencies are in the upper nineties and quickly approaching the magic 100% barrier.” (Hearst Electronic Products Monday June 30th 2008, LOU PECHI Power-One, Camarillo, CA

http://www.power-one.com)

2) A more easily achievable goal would be to increase the server use from “6%”. Virtualization is available for most server platforms and increase the usage factor significantly. This approach to reducing the heat load in a data center is true heat savings (Planning figures are about 10 to 1, that is one virtualized server can handle 10 current servers load).

3) New technology hard drives, i.e. solid state drives (SSD), decrease the heat load in a data center by reducing the power needed to turn drives. While still fairly expensive compared to conventional drives, SSDs can quickly pay for themselves by reduced power and heat. If I remember correctly they require about 10% of a conventional HD.
http://redrocksdatacenter.com Tom Nats

This is a great article and it shows how the times are changing.

We are currently undertaking a air-side economizer project for our data center. You can read more about it here: http://redrocksdatacenter.com/green and we’ve started a blog to cover the construction: http://ae.redrocksdatacenter.com

In addition, we’ll begin construction on a new building next year that will be 100% DC. We sit on over 85 acres and are planning on putting up > 30Kw of solar arrays. These are fun projects and hopefully other data center owners will take notice.

Tom Nats

Red Rocks Data Center

rrdc_info @ redrocksdatacenter.com
http://redrocksdatacenter.com Tom Nats

This is a great article and it shows how the times are changing.

We are currently undertaking a air-side economizer project for our data center. You can read more about it here: http://redrocksdatacenter.com/green and we’ve started a blog to cover the construction: http://ae.redrocksdatacenter.com

In addition, we’ll begin construction on a new building next year that will be 100% DC. We sit on over 85 acres and are planning on putting up > 30Kw of solar arrays. These are fun projects and hopefully other data center owners will take notice.

Tom Nats

Red Rocks Data Center

rrdc_info @ redrocksdatacenter.com
Jimmy Dolittle

The hospital I work for has spent a LOT of money on HVAC for their server rooms. I am talking a LOT of moola.

JT

http://www.FireMe.to/udi
Jimmy Dolittle

The hospital I work for has spent a LOT of money on HVAC for their server rooms. I am talking a LOT of moola.

JT

http://www.FireMe.to/udi
Kevin

Uh, heat sinks, fans, liquid cooling, etc., don’t make things more efficient. They simply provide a way to move heat from one place to another. Once the heat is given up, it is lost with respect to being useful computationally. I think you’re not understanding this important fact.
Kevin

Uh, heat sinks, fans, liquid cooling, etc., don’t make things more efficient. They simply provide a way to move heat from one place to another. Once the heat is given up, it is lost with respect to being useful computationally. I think you’re not understanding this important fact.
Ov3rTheHill

…oh and tansformers don’t work on DC. So the inside of your server, which needs oh I dunno maybe +5VDC at 100 Amps, +12VDC at 5 Amps, +1.blah VDC at a few Amps all out of one power supply is NOT going to get that magically from ONE DC power bus in the data center. It’s going to get it the way it has for the last 30 years, whith an efficient switching power supply. These rectify the AC line, make high freq AC with an oscillator, use a toroidal transformer with multiple secondary windings to supply raw low volt AC, and having rectifiers, filters and regulation after each winding to supply the different regulated DC voltages needed inside the box. Now… the DC power bus proposal would ONLY eliminate the front-side diodes and caps rectifying the input AC input power, i.e. converting it to DC. So every switching power supply takes lo freq hi volt lo current AC in, rectifies it to hi volt lo current DC, uses an oscillator to convert that to low current high volt AC, uses a transformer to step that down to various lo volt AC high current outputs, each of which is independently rectified (very efficiently with synchronous rectifiers) to the various lo volt high current DC power levels needed inside the server box. So the proposed HV DC power bus would only eliminate the front side AC to DC rectification in the switch mode power supply, but not the rest of it. No…. an idle CPU is still burning watt-hours, and I agree that virtualization will yield far more efficiency gains than going to a non-standard-for-the-next-10-years power distribution bus. We will pay thru the nose for that, until economies of scale bring its cost down, and its… oh i dunno… ?5%? power savings might take 30 years to recoup? Show us what THIS bright idea will cost and what real percentage power savings it will bring. Show us some real numbers, and we will compare that to unplugging 2 or 3 servers because virtualization might let us do that, depending on the application loads.
Ov3rTheHill

…oh and tansformers don’t work on DC. So the inside of your server, which needs oh I dunno maybe +5VDC at 100 Amps, +12VDC at 5 Amps, +1.blah VDC at a few Amps all out of one power supply is NOT going to get that magically from ONE DC power bus in the data center. It’s going to get it the way it has for the last 30 years, whith an efficient switching power supply. These rectify the AC line, make high freq AC with an oscillator, use a toroidal transformer with multiple secondary windings to supply raw low volt AC, and having rectifiers, filters and regulation after each winding to supply the different regulated DC voltages needed inside the box. Now… the DC power bus proposal would ONLY eliminate the front-side diodes and caps rectifying the input AC input power, i.e. converting it to DC. So every switching power supply takes lo freq hi volt lo current AC in, rectifies it to hi volt lo current DC, uses an oscillator to convert that to low current high volt AC, uses a transformer to step that down to various lo volt AC high current outputs, each of which is independently rectified (very efficiently with synchronous rectifiers) to the various lo volt high current DC power levels needed inside the server box. So the proposed HV DC power bus would only eliminate the front side AC to DC rectification in the switch mode power supply, but not the rest of it. No…. an idle CPU is still burning watt-hours, and I agree that virtualization will yield far more efficiency gains than going to a non-standard-for-the-next-10-years power distribution bus. We will pay thru the nose for that, until economies of scale bring its cost down, and its… oh i dunno… ?5%? power savings might take 30 years to recoup? Show us what THIS bright idea will cost and what real percentage power savings it will bring. Show us some real numbers, and we will compare that to unplugging 2 or 3 servers because virtualization might let us do that, depending on the application loads.
Ov3rTheHill

Seems to me a WHOLE LOT of context is missing from this article. Going to a DC power bus for distribution to servers and networking gear means the data center’s UPS doesn’t need an inverter on its backside. And the individual pieces of gear (servers, switches) don’t need a rectifier on their front side of their switching power supplies. That’s all. And if it were a relatively high voltage bus, say 350 VDC, the busses and power cables would need 1/3 the copper of standard 115 VAC, again not a biggie in efficienty. A new industry standard, with its own style power connectors and with a whole lot more careful attention to polarity. Plug in your server to this power bus backwards and it’s toast, not so with an AC power bus. When it comes to heat production in data centers, rectification (AC to DC, in each power supply) and inversion (DC to AC, in the continuously online UPS) aren’t the first things that come to mind… unless one makes power distribution equipment for a living and does not make servers or networking gear. The telcos have used 48 VDC for years, but that’s because the original exchanges really did run on batteries, 24 lead-acid cells in series. When it comes to wasted energy, a lost Watt-hour is a lost Watt-hour, whether it originally came from DC or AC.
Ov3rTheHill

Seems to me a WHOLE LOT of context is missing from this article. Going to a DC power bus for distribution to servers and networking gear means the data center’s UPS doesn’t need an inverter on its backside. And the individual pieces of gear (servers, switches) don’t need a rectifier on their front side of their switching power supplies. That’s all. And if it were a relatively high voltage bus, say 350 VDC, the busses and power cables would need 1/3 the copper of standard 115 VAC, again not a biggie in efficienty. A new industry standard, with its own style power connectors and with a whole lot more careful attention to polarity. Plug in your server to this power bus backwards and it’s toast, not so with an AC power bus. When it comes to heat production in data centers, rectification (AC to DC, in each power supply) and inversion (DC to AC, in the continuously online UPS) aren’t the first things that come to mind… unless one makes power distribution equipment for a living and does not make servers or networking gear. The telcos have used 48 VDC for years, but that’s because the original exchanges really did run on batteries, 24 lead-acid cells in series. When it comes to wasted energy, a lost Watt-hour is a lost Watt-hour, whether it originally came from DC or AC.
JP

Mr. Sinister and Jweezy — I think you doods missed the point about AC/DC. The author points out that the components run on DC already. Why have redundant power supplies in each server when the data center could theoretically switch the power for all devices centrally? Consider one big power supply (and of course a backup) for all devices instead of hundreds or thousands of small power supplies in each chassis.

http://en.wikipedia.org/wiki/Economies_of_scale
JP

Mr. Sinister and Jweezy — I think you doods missed the point about AC/DC. The author points out that the components run on DC already. Why have redundant power supplies in each server when the data center could theoretically switch the power for all devices centrally? Consider one big power supply (and of course a backup) for all devices instead of hundreds or thousands of small power supplies in each chassis.

http://en.wikipedia.org/wiki/Economies_of_scale
Armando

Many data centers are DC supplied by replacing the 120volt power supplies with 48 volt models that connect to a DC bus bar in the system’s rack. This is considerably more efficient and also allows for the heat generated by the power supply to be contained separately from the rest of the hardware.

You are probably connecting for the internet through hardware running on 48 volt DC power. Phone and cable companies almost exclusively use these types of systems and have you looked into Cisco equipment lately? You can order almost any router from them with a DC power supply instead of AC. So please, don’t post your stupidity unless you have some idea of what you are talking about.
Armando

Many data centers are DC supplied by replacing the 120volt power supplies with 48 volt models that connect to a DC bus bar in the system’s rack. This is considerably more efficient and also allows for the heat generated by the power supply to be contained separately from the rest of the hardware.

You are probably connecting for the internet through hardware running on 48 volt DC power. Phone and cable companies almost exclusively use these types of systems and have you looked into Cisco equipment lately? You can order almost any router from them with a DC power supply instead of AC. So please, don’t post your stupidity unless you have some idea of what you are talking about.
Mr. McElwain

Telco operations had been all DC for quite a while.

Essentially telephone switching centers running at 48V DC were the original computer data centers.

With the switch to cheaper generic components Telcos have relaxed their requirement for DC systems and have migrated over the years to AC.

It would be interesting to see the world switch back to the Telco 48V standard!
Mr. McElwain

Telco operations had been all DC for quite a while.

Essentially telephone switching centers running at 48V DC were the original computer data centers.

With the switch to cheaper generic components Telcos have relaxed their requirement for DC systems and have migrated over the years to AC.

It would be interesting to see the world switch back to the Telco 48V standard!
http://www.sharkspace.com Scott

“The energy used by the nation’s servers and data centers is growing at an unsustainable rate. Not only that, but web servers are notoriously inefficient. For example, computer servers are used at only 6 percent of their capacity on average”

I believe in the future data centers will deploy more of a virtual private system approach on large scale servers. It would greatly improve efficiency.
http://www.sharkspace.com Scott

“The energy used by the nation’s servers and data centers is growing at an unsustainable rate. Not only that, but web servers are notoriously inefficient. For example, computer servers are used at only 6 percent of their capacity on average”

I believe in the future data centers will deploy more of a virtual private system approach on large scale servers. It would greatly improve efficiency.
Ken Rice

DC Power…. Ok People… what 99% of you dont realize is that the components INSIDE Your computers (desktops, laptops, servers, whatever ARE DC… thats the whole point of the power supply.. Take 110/220 VAC in and convert it to a coupleof different DC voltages…

Now, having used DC power for years in Telecom and Telecom related environments I dont see how people can say there is not expertise out there for this stuff in the DataCenter… one just has to visit a place Like Level3′s Courtland St Data Center in Atlanta to see that it is possible…

Not only is DC possible but it reduces the complexities of Redundant Power via elimination of costly and inefficient DC to AC Inverters…
Ken Rice

DC Power…. Ok People… what 99% of you dont realize is that the components INSIDE Your computers (desktops, laptops, servers, whatever ARE DC… thats the whole point of the power supply.. Take 110/220 VAC in and convert it to a coupleof different DC voltages…

Now, having used DC power for years in Telecom and Telecom related environments I dont see how people can say there is not expertise out there for this stuff in the DataCenter… one just has to visit a place Like Level3′s Courtland St Data Center in Atlanta to see that it is possible…

Not only is DC possible but it reduces the complexities of Redundant Power via elimination of costly and inefficient DC to AC Inverters…
Moltar

There are already many servers available with DC power. You can set up today an enterprise-class datacenter with all DC powered components, from servers to switches to routers to storage networks. IBM, Sun, and I’m sure many others have commodity servers with DC options. See IBM X3650 T for an example.
Moltar

There are already many servers available with DC power. You can set up today an enterprise-class datacenter with all DC powered components, from servers to switches to routers to storage networks. IBM, Sun, and I’m sure many others have commodity servers with DC options. See IBM X3650 T for an example.
Mr. Sinister

It’s important to realize that data centers aren’t composed of top-secret, specialized supercomputers. They’re built from the same servers, routers, disk drives, etc. that are used by businesses and individuals every day…just a whole lot more of them. These components are mass produced for the marketplace. It would be impractical to build components that operate solely on DC power when there is no customer base, and impractical to convert a data center to DC power distribution when there is no equipment available to take advantage of it…simple chicken-and-egg situation.

Yes, there is a lot of room for improvement in efficiency of computing equipment. However, it’s not fair to single-out data centers as wasteful power hogs. Don’t forget about the millions of personal computers in homes and offices around the world. Every one of them has a little box inside that converts AC to DC (quite inefficiently, if you believe the article) dumping waste heat in the process. And every one of them has a processor chipset inside which also wastes energy. Time and effort are better spent in improving the efficiency of the components which make up the data centers than figuring out more elaborate ways to cool an inefficient design. Incidentally, equipment manufacturers are already doing this…multi-core processors that operate at lower speeds, for instance.

Average server utilization is also an irrelevent statistic. Yes, on average, a server may use only 6-percent of it’s capacity. However, these systems must be over-designed to handle peak load for the simple reason that Mr. Websurfer won’t tolerate having to wait more than five seconds for his MySpace page to load. For certain, these servers operate near full utilization at peak times of the day, even if they are lightly loaded at other times. Data centers are designed as they are because of the demands we place on our IT infra-structure. We want it cheap, fast, and reliable…it’s hard to get all that and high-efficiency too.
Mr. Sinister

It’s important to realize that data centers aren’t composed of top-secret, specialized supercomputers. They’re built from the same servers, routers, disk drives, etc. that are used by businesses and individuals every day…just a whole lot more of them. These components are mass produced for the marketplace. It would be impractical to build components that operate solely on DC power when there is no customer base, and impractical to convert a data center to DC power distribution when there is no equipment available to take advantage of it…simple chicken-and-egg situation.

Yes, there is a lot of room for improvement in efficiency of computing equipment. However, it’s not fair to single-out data centers as wasteful power hogs. Don’t forget about the millions of personal computers in homes and offices around the world. Every one of them has a little box inside that converts AC to DC (quite inefficiently, if you believe the article) dumping waste heat in the process. And every one of them has a processor chipset inside which also wastes energy. Time and effort are better spent in improving the efficiency of the components which make up the data centers than figuring out more elaborate ways to cool an inefficient design. Incidentally, equipment manufacturers are already doing this…multi-core processors that operate at lower speeds, for instance.

Average server utilization is also an irrelevent statistic. Yes, on average, a server may use only 6-percent of it’s capacity. However, these systems must be over-designed to handle peak load for the simple reason that Mr. Websurfer won’t tolerate having to wait more than five seconds for his MySpace page to load. For certain, these servers operate near full utilization at peak times of the day, even if they are lightly loaded at other times. Data centers are designed as they are because of the demands we place on our IT infra-structure. We want it cheap, fast, and reliable…it’s hard to get all that and high-efficiency too.
http://ecopolitology.org Timothy B. Hurst

jweezy-

Really? Retarded? Ouch.

I strongly suggest you re-read the post. I would especially urge you to find the portion of the text where I propose the idea of “ALL DC POWER” [your quotes]. If you are able to find that, let me know and I will buy you a beer.

At no point in the post do I suggest we convert to all DC power and replace every electronic device in every commercial and residential building.

I mean no disrespect, but I honestly have no idea what you are talking about.
http://ecopolitology.org Timothy B. Hurst

jweezy-

Really? Retarded? Ouch.

I strongly suggest you re-read the post. I would especially urge you to find the portion of the text where I propose the idea of “ALL DC POWER” [your quotes]. If you are able to find that, let me know and I will buy you a beer.

At no point in the post do I suggest we convert to all DC power and replace every electronic device in every commercial and residential building.

I mean no disrespect, but I honestly have no idea what you are talking about.
jweezy

timmy – you’re retarded!!! do some research man!?

YOU’RE IDEA OF “ALL DC POWER” IS COMPLETELY IMAGINARY… DO YOU EXPECT TO REPLACE EVERY ELECTRONIC DEVICE IN EVERY COMMERCIAL AND RESIDENTIAL BUILDING!? DC POWER IS ONLY USEFUL (ECONOMICAL) IN HVDC TRANSMISSION LINES, NOT DISTRIBUTION LINES. “AC OR DC?” WAS DECIDED AND PROVEN HUNDREDS OF YEARS AGO BETWEEN EDISON AND TESLA!
jweezy

timmy – you’re retarded!!! do some research man!?

YOU’RE IDEA OF “ALL DC POWER” IS COMPLETELY IMAGINARY… DO YOU EXPECT TO REPLACE EVERY ELECTRONIC DEVICE IN EVERY COMMERCIAL AND RESIDENTIAL BUILDING!? DC POWER IS ONLY USEFUL (ECONOMICAL) IN HVDC TRANSMISSION LINES, NOT DISTRIBUTION LINES. “AC OR DC?” WAS DECIDED AND PROVEN HUNDREDS OF YEARS AGO BETWEEN EDISON AND TESLA!