Rethinking household/office power, beyond 60hz
I've written before about the desire for a new universal dc power standard. Now I want to rethink our systems of household and office power.
These systems range from 100v to 240v, typically at 50 or 60hz. But very little that we plug in these days inherently wants that sort of power. Most of them quickly convert it to something else. DC devices use linear and switched mode power supplies to generate lower voltage DC. Flourescent lights convert to high voltage AC. Incandescent bulbs and heating elements use the voltage directly, but can be designed for any voltage and care little about the frequency. There are a dwindling number of direct 60hz AC motors in use in the home. In the old days clocks counted the cycles but that's very rare now.
On top of that, most of what we plug in uses only modest power. The most commonly plugged in things in my house are small power supplies using a few watts. Most consumer electronics are using in the 50-200w range. A few items, such as power tools, major appliances, cooking appliances, heatters, vacuum cleaners and hairdryers use the full 1000 to 1800 watts a plug can provide.
So with this in mind, how might we redesign household and office power...
The first assumption I would make is that we would like smart power. With smart power, a data protocol would exist between the power supply equipment and the power using equipment (or "load") and/or the recepticle in the wall. The supply would talk to the load to learn what sort of power it wants or can use, and only provide full power when the load is properly connected. (There would always be some basic very low level power available to run the devices that do this data protocol.)
In the quantities of which we are speaking, these devices would be very cheap -- pennies -- the way USB chips have become. Default chips for legacy devices (which would just say, "I need 120v at 60 hz 15 amps" or similar) would cost just a few pennies, and adapters to plug old devices into new, smart recepticles, would be made very cheaply." Adapters to plug "new" devices into old sockets would also be cheap, though perhaps just a couple of dollars.
The base power transmitted would possibly be high-frequency AC. That's because most devices these days, with switched mode power supplies, immediately convert the incoming power to high-frequency AC. (This may not be able to make universal. Many power supply designs regulate the output voltage by controlling the frequency of the intermediate AC.)
The main supply, down in the basement, might know things about the wiring (be it old or new) including gauge, resistence, length and voltage rating. Some of those things it could measure with the aid of a smart endpoint.
There are trade-offs over what voltage you use. Low voltages are safer, and of course are what most modern electronics actually use. Low voltages require high current (and thus thicker wire) to deliver any real power. High voltages can deliver lots of power over thinner wires, but can also do damage to people and property. They need more insulation and larger spark gaps.
Smart power allows higher voltages for several reasons. First, we can have ground fault circuit interrupters, which are already not that expensive, to assure that power is shut off if it ever leaks out or could cause other trouble. With smart recepticles, it is possible to determine how much power is being lost in the internal lines to spot arcing or overheating. In addition, with smart power, high voltage is never applied until the load is properly connected. Your kid can stick a knife into the wall socket at no risk.
This might allow the wires to the oven, clothers dryer or dishwasher to run at 600 volts or even more depending on the rating of the wire. That means several times more power over the same guage of wire. Or lower current for the same power with less loss and risk of melting wires. The special lines to your electric car might like even more voltage and would be wired for it.
DC devices would often not have power supplies, or just have minimal rectifiers and a low-drop voltage regulator. They would just plug into the wall and ask for the voltage or voltages they need. Or at the worst, plug into a universal supply that plugs into the wall.
With low voltage it might also be possible to construct walls with power "strips" that allow the placement of recepticles anywhere on the wall. To do this, two horizontal metal strips would be laid like a "bus" along the entire wall at socket height. These would, on demand, provide something like 12v at 100hkz AC (just an example frequency, the right universal frequency would be carefully chosen for best utility and minimal interference.) Later, after the wall is constructed, one could cut a hole just above the strips for a smart power box, and punch lines to the strips, then plaster and paint over.
It's also possible to imagine a power wall. In this case, there would be two planes (live and ground) sandwiched over an insulating layer. All low voltage, and of course protected against shorts or ground faults. Possibly with extra layers to reduce interference. Then one could place devices (clocks, flat panel screens, efficient lights) anywhere on the wall and punch through and clamp to get power for them -- no wires. Of course such a wall would block radio signals, which is a downside. You would still need to wire some sockets for high power devices like vacuum cleaners, independent of this power wall.
Power wall material might also make sense to build into desks and equipment cabinets. The material could come with pre-drilled holes that can be found with a sensor and punched into by anybody, or one could drill a hole (with power off) and then insert a standard plug which clamps onto the two planes to securely connect to the power. Of course all devices on the power wall must use the same base power, so some will need converting power supplies.
It would also be possible install these strips or planes in floors and ceilings. If the metal for a plane is too expensive, strips (which again can easily be located with a metal detector or AC sensor) could be laid on studs. You could not put devices literally anywhere, but you could come close.
And of course, you would never have to carry power supplies for your portable devices once this caught on. There would be power for them everywhere. Before the wall sockets get smart, smart universal power supplies would be bought which plug into regular household voltage and deliver the power needed, as I described in the earlier post.
How to get there
Here's the path I see to take us to a smarter power world.
- People start creating more universal DC power supplies, the type you can already buy with smart-tips that tell the supply what voltage to provide. A protocol is defined for the tips to be active.
- These supplies get cheaper, and we start seeing "multiple" units that will power many devices at once with different tips, just to replace the nest of power supplies we have now.
- People start making devices with a smart power plug on them. Universal power supplies are provided or sold as an accessory with them.
- Eventually, devices stop coming with a power supply. You're expected to have one of your own.
- A universal switching supply for DC devices is available to be installed at the power distribution center. People doing new home construction start using it. Others use it for power-over-ethernet based power. This gets cheaper.
- Larger units capable of providing high power become available, and are installed in new construction. Cheap adapters are put in place to have wall sockets generate 110v as desired for old devices.
- More and more devices become able to connect to the smart jacks, no need for adapters.