Is It Time for DC Power?

In the 1880s, the War of Currents was raging between the two main factions - direct current (DC) which was heavily promoted by none other than Thomas Edison and alternating current (AC) advocated by George Westinghouse. The DC system was developed first and worked well for lighting which was the primary use of electricity in its early days. The AC system, however, has proven to be more efficient for powering motors and for carrying energy across long distances. In the end, AC won and the rest is a history. Today, our electricity grid is AC based.

Thomas A. Edison

When I look around my house today, I see a number of motor-based appliances including the washer, dryer, refrigerator, heater, air conditioner, etc. Those appliances use AC and that is the more efficient source of power for them. Yet increasingly, more and more of my electrical devices use a power adapter because they run on DC power: computer, printer, iPhone, iPad, PC speakers, cordless phone, Apple TV, TV set, alarm clock, radio, not to mention the many devices that use batteries: camera, keyboard, mouse, flashlight, fire alarm, etc.

Using all the power adapters to generate DC power is a hassle because of the lack of standardization. We practically have a different adapter for each device which is hugely inconvenient. Traveling with a bag full of power supplies is a major pain as I have written about in my post Environment and the Power Charger. In addition, power supplies are only about 70-80% efficient which means that about a quarter of the energy we produce (and pay for) is wasted on the AC to DC conversion.

This situation is particularly absurd for the increasing number of households that use solar panels to augment their power supply, often making them entirely independent from the AC power grid. The power produced by the solar panels is DC power. All the solar systems today require expensive inverters to invert the DC current into AC current. These inverters are expensive, often representing a significant portion of the entire cost for the solar power system. They are also inefficient, with efficiencies ranging from 50-90% - this is where we lose up to 50% of the energy produced by the solar panels!

So we are inverting DC solar power into AC current to power the house while losing up to 50% of the energy. At the same time, our devices increasingly use the DC power which requires an adapter that loses another 25% of the energy. So we are losing a significant percentage of the energy that we pay for. That sounds pretty inefficient, doesn’t it?

LED light bulbs may be the trigger

The story becomes even more interesting with the advent of LED-based light-bulbs. Lighting represents about 20% of household’s energy consumption today and switching to the LED light bulbs offers great opportunity to save on the monthly energy bill while doing something good for the environment at the same time. The LED lights are still pricey but those prices will surely go down, just like they did for the fluorescent light bulbs a decade ago. The problem with the LED light bulbs is LEDs work on DC and so each LED bulb has to contain a power converter which converts the house AC into the DC that the LED lights need. More AC/DC craziness, not to offend any rock fans...

All of this begs the question - is it time to wire our houses for DC power? We have standardized DC power in our cars with a slew of gadgets and appliances using the "cigarette lighter outlets" - from phone chargers and GPS to air pumps and mini-refrigerators. Many airlines provide a DC outlet in every seat to power our laptops and other gadgets. Why not have such DC outlets in every room of the house? Why not have the lights wired on a DC circuit?

USB outlets exist today

Sure, we will still need to transport power across long distances and we’ll need an AC circuit to power the big appliances with motors. But most houses have a separate 220V circuit for big appliances in addition to the standardized 110V wiring. In Europe, most house have 220V (well, 240V really) and they also have a 380V circuit for their washer, dryer, water heater and other big appliances. Why not have a separate DC circuit for all the devices? AC would come to the house like it does today but one single converter would replace all of those individual power adapters. On top of that, DC power is easier to store and a couple of batteries could provide an effective backup power supply.

Re-standardizing something as essential as the power system is a major undertaking. But we live in the times of major undertakings. If Google can take pictures of every street in the world and Tesla can build a network of charging stations throughout the entire country and SpaceX can fly to space, we might be also capable of switching to a more efficient power circuitry. We even have a standard - USB - which may not be meeting all the needs, but could be a starting point. Of course, we would first have to convince Apple to add USB interface to all their devices...

PS: Thank you, Brett, for an inspiring dinner conversation!

Environment and the Power Charger

My post today is a step away from my usual topics. I am packing for vacation and being a connected wannabe-hip geek, and so I am packing a bagful of gadgets. There is the SLR camera, the pocket camera, the video recorder, the Flip recorder, the GPS, the DVD player for the kids, my shaver, my blackberry, my wife’s iPhone, my iPod, the iPad, and I am still debating the laptop. That’s not a particularly impressive list, just what a man needs to barely scrape by.

The problem is that every one of these gadgets requires a power supply, a battery charger, a car outlet charger – or sometimes all of them. That’s creates some problems. First, I can’t find many of the adapters since I only use them on vacation trips which are not frequent enough. I have multiple gadgets that have been retired only because I can’t find the charger and getting a new one is either impossible or unreasonably expensive. Second, many of the power supplies require a separate cable which may also be difficult to locate; not to mention an additional cable for data connectivity. Then finally, there is all the added weight and bulk that easily doubles what was originally a reasonably sized bag. That’s just not right.

Why, I have to ask, don’t we have a standardized universal power supply? All gadgets could probably be powered by the same DC voltage. Apple uses the same power supply for my iPod, iPad, and iPhone. And if the gadgets do need a different voltage, the supply should have a switch between 3, 6, 9, and 12 Volt, preferably automatic. The gadgets should have the same type receptacle – or different sizes according to the different voltage requirements. I hate RIM for introducing a new size receptacle in my BlackBerry Bold 2 that requires a separate cable than my cameras. Sorry my RIM neighbors, that alone is an incentive to buy an iPhone!

The cable needs to be detachable from the power supply and it needs to use the USB adapter to connect to it the way that Apple does. That way, the same cable would work for data connectivity with computers and other devices. Basically, I want one power supply and one cable that can act as both power cable and data cable for all my gadgets. Is that too much to ask? No! Oh wait, and of course the whole thing needs to be small and work in any country. Yes, that’s doable – just ask Apple.

I believe that it is absolutely unacceptable that companies such as Sony, JVC, Panasonic, RIM, LG, Olympus, Canon, Nikon, and Kodak are not only NOT working together but they are even using different power supplies and cables for their own devices. That’s crazy! As consumers, we should demand better. We want the vendors to work together and agree on a standard. The USB standard is a good example and proof that it is possible for vendors to agree. The results would not only be a huge convenience but also some major economic benefits for the vendors. They could ship devices without power supplies. There could be an aftermarket for fancy power supplies in different colors, with battery back-up, solar charger, hand crank, etc.

The elimination of power supplies would also represent a major environmental benefit. Imagine all those power supplies that wouldn’t have to end up in the landfill. In fact, the government should step up and drive such standard in the name of the environment. If the vendors are not capable to work together, the government could come up with a useful regulation for once.