An excerpt from a post that originally appeared on www.mnn.com January 6, 2015
In fact, the home of today primarily runs on DC. We just have all this AC stuff running between it.
By: Lloyd Alter
Tue, Jan 06, 2015 at 05:44 PM
Topsy the elephant just before the execution. (Photo: Wikimedia Commons)
Poor Topsy. Thomas Edison killed the circus elephant, electrocuting the animal to demonstrate how dangerous alternating current was. Edison even described electrocution as being “Westinghoused,” after the company promoting AC. It was the apex of the War of the Currents
, where the evil Edison was pitted against the brilliant Nikola Tesla
. It’s a battle that Edison lost, and all because of transformers, simple coils of wire that could change the voltage of AC and made long-distance transmission of electricity possible, unleashing the power of Niagara Falls. However in the longer term, it looks like Edison’s direct current is winning the war.
An IKEA wall-wart (Photo: Lloyd Alter)
Look around your house. If you have, like me, banished incandescent bulbs
, what is running on alternating current as it comes out of your walls? Outside of your kitchen or laundry, you might have a vacuum cleaner or a hair dryer. Otherwise, every thing you own — from your computer to your light bulbs to your sound system — is running on direct current. There is a wall-wart or a brick or a rectifier in the light bulb base that converts the AC to DC, wasting energy and money in the process. IKEA was kind enough to put its device in a transparent package. How much of the cost of the $20 lamp covers the yellow transformer and capacitors and diodes in this little thing?
Alternating current made sense once; that’s why Edison lost to Westinghouse in the current wars. Alternating current was easy to transform to different voltages, and higher voltages mean you can carry more power longer distances through smaller wires. And we needed a lot of power to run those incandescent bulbs, which are really little electric furnaces that gave out about 4 percent of the energy used as visible light. The new labor-saving appliances had little AC motors. Even the old television set took a lot of power, firing up those vacuum tubes and big electron guns in the picture tube. All that power can be dangerous, so we have licensed electricians running dozens of lines back to circuit breakers, all with an extra conductor just as a ground wire. Oh, and we need outlets every 12 feet along the walls so that dangerous extension cords aren’t needed. Total it all up, and you have 400 pounds of copper in the average house. Back at the mine, it takes a ton of copper ore to make 10 pounds of copper, so it takes 40 tons of ore (coincidentally the weight of an average house) to make the copper for one house. About 40 percent of the copper used in America goes into our buildings and houses. There is also the worry that we are approaching peak copper,
with production peaking about 2030.
For what? To be turned into direct current and fed through thin little wires in milliampere quantities to run our computers and clock radios and LED bulbs. Your electric drill is probably cordless and DC, and if you have a Roomba, AC isn’t even running your vacuum. There is no good reason to have expensive and dangerous AC wiring in a house or office anymore.
The typical office (Photo: EMerge Alliance)
In fact, in the office environment, there are a lot of people working to get rid of AC. The EMerge Alliance
promotes a 24-volt DC standard that is designed to “reduce energy consumption through state of the art device controls and solid state lighting.” Because solar panels produce DC and batteries store DC, it will “facilitate the direct connection and use of energy from solar, wind or other alternative energy sources.” The alliance is going after the residential market too. Chairman Brian Patterson says in a press release:
“DC power distribution would not only maximize the efficiency and ROI of rooftop solar panels by enabling them to directly power consumer electronics, appliances, LEDs and electric vehicles (EVs) without conversion losses, it could also give homeowners a choice to either store excess DC power or continue selling it back to power companies.”
Will USB be your new home wiring?
Then there is the new high-power USB Power Delivery standard
4.0, which can pump out 100 watts. All those bricks and power cables disappear as you plug in your devices and get power and data. You could build a smart home of interconnected devices that talk to each other without less dependable and secure WiFi, and your wiring becomes the backbone of the Internet of Things.
Wiring wouldn’t have to be installed by electricians inside the walls; it could be stuck on the wall like tape and just painted over. It wouldn’t have to be childproofed; it could be anywhere you wanted it. And everything that you plugged into it would be cheaper and more dependable because there is no transformer or rectifier turning AC into low voltage DC — it runs on it native.
The digital home. (Photo: Epri)
Back in the kitchen and laundry, there would have to be some bigger wires to carry the loads needed to run a fridge or an air conditioner. But even they can be more efficient running on DC, thanks to Variable Frequency Drives or VFDs. According to the Electric Power Research Institute,
Use of VFDs is on the rise, since controlling the speed of the motor to match demand can not only save energy but also optimize function. For example, being able to fine tune the motor speed of an air conditioner, and thus functions such as fan speed and air flow, can make room temperatures and conditions more comfortable. As motor-operated loads become increasingly controlled through VFDs — very little will remain in a house that really needs AC power.
The Emerge Alliance claims that running DC can cut electricity use by 20 percent, simply because everything is running native, without those energy-sucking wall-warts and rectifiers. Add the up-front savings of cheaper LED bulbs and the cost of wiring the home, and the savings get much bigger.
None of this is new to people who live off-grid, in RVs or on boats. They have been living in a DC world for years. However the advances in LEDs and the drop in the price of solar is making this lifestyle as comfortable as living in an on-grid home.
Photo: National Park Service
Just toss the solar panels on your roof and the electric car in the garage into the mix, then you’re living in a DC world without any reason to use AC at all — living on your own little micro-grid where you generate your own electricity and store it in your car. The net-zero energy home of the future will run on DC, and we might all be driving Edisons instead of Teslas.
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