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Daedalus was the mythical great architect and artificer of the classical world. Today, embedded intelligence is enabling the most profound changes in the way we create and use buildings since his day.

Building Intelligence meets the Intelligent Building. The Intelligent Building negotiates with the Intelligent Grid. How will this transform how we interact with the physical world?

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« No special Demand-Response plan for the data center | Back to Silicon Valley »
Saturday
May242008

Edison was Right – or – Green up with DC

Sustainability initiatives come in four kinds. No harm initiatives accomplish something, but perhaps not as much as their proponents think. Let’s pretend initiatives make people feel good, but with reckless disregard for the actual results. Let’s pretend initiatives, like corn ethanol, may well do more harm than good. Yeah but initiatives would work well, maybe very well, but for some reason, you can’t get there from here. Usable initiatives are the few remaining that are simple, cost effective, and uncontroversial.

DC (Direct Current) in buildings has long been a “yeah but” technology. DC is clearly superior for the home and office. Almost all modern equipment is already DC. We all convert power from AC (Alternating Current) to DC again and again in our homes and offices. Every frustratingly unique power cord, every rectangular wall wart with its glowing green eye is a transformer producing DC power.

Larger appliances, such as televisions and computers, perform the same conversion. The transformers in these devices are hidden inside the cabinet, but the process is the same. There are some exceptions, such as the washer and refrigerator, but certain characteristics of DC motors might push them in to DC in time; already their control consoles are moving to DC. Surely, we already live in DC homes and work in DC offices.

This plethora of AC/DC transformers is a problem. It is easy to get them lost or confused. Each manufacturer selects a transformer as cheap as he can get away with; power, too much power, is lost in every one. That lost power is released in the home and office as heat. In the worst cases, the power used is too much the same whether the device is on, off, or even detached. These transformers have become a significant part of the power use in every building.

If power in buildings was distributed by DC, all these transformers could be eliminated. Better, more efficient, building-scale transformers would convert power from AC to DC more efficiently. Even efficient transformation from DC to AC loses energy, and that energy is lost as heat. In a building-scale transformer, all that heat would be concentrated in one location. In one collection it can be captured and recycled for new use.

Zero net energy buildings come closer fast if we have DC buildings. Solar, wind, and other local power generation technologies produce DC power. Today, that DC power is subject to an AC tax. All DC power must be converted to AC, distributed, and then converted back to DC. This tax may consume as much as 30% of the power available. Even batteries, which store DC power, are subject to this tax. Without the AC tax, every battery that loses just too much energy during storage, is now effectively 30% better without waiting for new technology.

Yeah but...

But buildings are wired for AC. Everything I own today plugs into AC. Even if I could afford to re-wire my building, I cannot afford to replace all the equipment inside. Where would a landlord find someone willing to move into such a building? You can’t get there from here.

I have seen technology that changes all that. Technology that is almost a product enables cost effective installation of a hybrid AC/DC power system in the existing office building. The system uses DC to immediately reduce lighting and networking costs. The solution provides a means to reduce the costs of all building systems that rely on networking. The system can make each room in a building more responsive to the tenant. And the tenant can continue to use his existing equipment as the market matures.

It is time to move DC buildings from the category Yeah But to the category Usable. Migration from AC to DC in commercial space will soon be simple, cost effective, and uncontroversial.

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Reader Comments (4)

Greetings,

This text has been automatically translated from Spanish
thanks to "Google Traslator," Sorry for the inconvenience that may result.

For some time I also thought that distribute "DC" in the buildings might be a good idea. Avoiding double conversion and improving energy efficiency.

But after studying a little more in depth this option, I ruled out.

I think that there is a need for change in the way of distributing electric power, but I believe that since all change is a problem, because they do not adopt a more aggressive strategy. Making distribution in "AC" but in high frequency.

Why in high frequency?

The term you use, "transformer", is somewhat ambiguous, indeed all electronic devices that are used today, including many of the lighting systems and conversion systems for electric motors actuated variable speed, perform a coversión "AC / DC," but this is only the first step, this power immediately "DC" is again in Convertible AC but high frequency.

In the case of SPMS "http://en.wikipedia.org/wiki/Switched-mode_power_supply" in its block diagram "http://en.wikipedia.org/wiki/Image:SMPS_Block_Diagram.png" we see these conversions.

A power distribution in "high frequency" AC would eliminate the first two blocks replaced by a simple triac control,
simpler, more energy efficient and robust.

As we can see in: "http://en.wikipedia.org/wiki/Electronic_ballast # Electronic_ballasts" implementation would be the same.

In the case of controlling electric motors: "http://en.wikipedia.org/wiki/Variable-frequency_drive # VFD_controller" implementation would be similar,
with the added advantage of the higher overall energy efficiency of all motor cargo (eg pumps and fans in HVAC).


All these modern electronic systems are more efficient than their "classic" and they all use high-frequency AC.

The distribution of power in high frequency AC is not an easy task but I believe it is worth investigating in all this.

Thank you.

June 1, 2008 | Unregistered CommenterAngel J. Garcia

Cool.

I will have to read more about high frequency AC.

June 1, 2008 | Registered CommenterToby Considine

Hi Toby

In reading your GREEN enterprise to GREEN buildings I was reminded to discuss with you the GREENING of IT as the heat from the data centers can be used in an absorption chiller to cool the office buildings. Also DATA Centers are primme targets for the Combined Heat and Power systems that were well described in the EATON Energy Vision report from CABA. Let's discuss.

June 3, 2008 | Unregistered CommenterDavid Katz

Tesla invented his magnifying transmitter to send power across ground surface.That was harmless new kind of electricity. Just plug your home wire into ground through a converter device and all power is here... This is more then AC at high frequency.

March 15, 2009 | Unregistered CommenterTesla advocate

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