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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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« Enterprise to Grid in Atlanta | Flying home from yet another meeting »
Thursday
Oct302008

DC, Service, and Bacteria

Regular readers know I am intrigued by DC (Direct Current) power systems in buildings. This fascination was born while examining a data center UPS system several years ago. The potential efficiencies shouted out to me. This week, I found something new that fueled my interest.

Most consumer devices are DC powered. That brick outside your laptop is to convert AC (Alternating Current) power to DC. Your television has a similar brick built inside it. That annoyingly large plug on your cell phone charger is another AC/DC converter. The digital world is a DC world. The exceptions in your homes are the incandescent lights, and the motors in your appliances: refrigerator, dishwasher, and washing machine.

In commercial buildings, the designers and maintenance staff often refer to building systems and their controls collectively as the low voltage systems. The low voltage systems are powered by DC The controls that manage the air conditioning system and all their sensors are powered by an isolated low voltage DC system. The security system with its window sensors is DC. The video cameras and their network are powered by DC. We live in a DC world.

Several years ago, an APC salesman generated an epiphany as he proudly demonstrated his new data center racks. The racks has built in power conditioning and batteries, and seemed sturdy and well designed. The servers were fed from the batteries at all times, protected from power dips, sags, and spikes by the constant power source. All power coming into the racks was converted into DC and fed into these batteries, keeping them fully charged. The power coming out of the batteries was converted in AC power, and routed into plugs for the servers. Each server, as they usually do, had a plug in the back into a little removable brick, just as in your laptop, converting that power back to DC.

It was the proximity, I guess. I have the same set up supporting the server room at work, but the refrigerator-sized battery is down the hall, invisible during normal operations. Seeing the batteries and the servers so close, I could no longer ignore their absurdity. I was converting power to AC to go a yard to convert it back, losing 10-30% of the power each way, only because it was the way things always were.

Since then, I have paid more attention to DC systems. Since then, I have often wondered how many "almost there" technologies are held back by infrastructure assumptions. How many solar projects, for example, that don't quite make economic sense, are held back by the double tax of DC to AC and back again....

So why this week? Why do I bring this up again?

For the last two mornings I have had the pleasure of breakfast at the B&B with a quiet electrical engineer, unassumingly working on a project I am calling bacteria-powered low-voltage distribution. Much of metabolism can be envisioned as getting rid of electrons to the most available receptor; his company is offering bacteria wires as the as the most available receptor.

He sees his system being used as a third world power source He only needs enough power to light LEDs at night. In many areas wood is burned for light in the evening, contributing to deforestation and reducing the fuel available for other purposes. His company has recently received stage one funding, and is looking for short term revenue in other areas. One potential project is yard lights that are powered by the soil they are pushed into, and that work better than solar for northern latitudes in moist climates.

I got a call from the folks at FreeLight yesterday, to discuss their progress with in-place hybrid installation of DC in existing buildings, and the availability of low power DC lighting. Such lights are programmable to display any color, or even pictures and text. Such lights are very light, with high efficiency, and no local power conversion.

Can such systems work together, moving the power for emergency lighting off the grid and away from batteries? Would labor cost avoidance (maintenance for batteries) be the factor that drives adoption?

Future buildings and local generation are coming. There is no need for future building systems to be powered like those of today. Challenging our power distribution assumptions will be as important as changing our power generation assumptions.

At FIATECH, I spoke on specifying buildings by services, not by technology or process. The engineers at FIATECH agreed that service and performance specifications would free up their creativity and innovation. Energy distribution strategies might be part of that innovation.

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