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0 pointsgwbas1c3y ago0 comments

> and your domestic usage is mostly in appliances which convert back down to DC immediately behind the plug socket (most of us have this) then at some point we're going to start wanting to power our homes like houseboats or camper vans.

Most of these appliances use low voltage which travels poorly over long distances. Your car, camper van, and boat all use ultra-thick cables to move 12 volts. This is quite uneconomical for anything larger than a small studio apartment. (Copper isn't cheap.)

Furthermore, note that I said "12 volts," which is what cars and capers use. (Not sure about boats.) Some DC appliances need 5 volts, some need 20... They'll all need converters.

So how are both of those problems solved? You'll probably send 100-200 volts, DC, though the wall! The big question is, does this really simplify anything? The big advantage with AC is that it's super-easy to change voltage with a simple transformer. What do we gain by going DC in the walls? Are there any real advantages in simplifying voltage conversion at appliances? Is it worth the added complexity of a whole-house AC-DC converter; or the complexity of a DC grid?

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freedomben3y ago

My thoughts exactly. A/C has some important electromagnetic characteristics that make it a lot easier to transport. Particularly for long distance lines, high voltage is critical and transformers make it trivial to modify voltage levels, such as to get to 120V for the house. it's also a lot easier to convert AC to DC than the other way around. If we start transporting with DC, we take on a number of problems/challenges that we don't deal with now.

I could see a point in time where there are AC outlets and DC outlets in a house depending on where the power comes from (power lines vs. solar panels/battery), but unless we radically decentralize (which I don't see happening) it seems unlikely to me that we switch to DC for long-distance power transmission.

euroderf3y ago

Would it make sense to think about upping the line frequency ? IIRC Engineering 101 said that 50~60 Hz are frequencies most dangerous to humans; choosing a higher line frequency would be safer to work with and would (natch!) permit the use of thinner conductors.

gwbas1cOP3y ago

> it's also a lot easier to convert AC to DC than the other way around. If we start transporting with DC, we take on a number of problems/challenges that we don't deal with now.

Which brings up a very good point: What happens when grid-scale battery storage is common? Does a DC grid make a lot more sense then?

ornornor3y ago

Isn’t there also a marginal safety advantage for AC in that because it’s an alternating current, you can let go of whatever is live you’ve grabbed and is shocking you? Whereas with DC, your muscles stay contracted and you can’t let go.

caleblloyd3y ago

Yes, I have heard that higher voltage DC plugs would be designed differently to break arc in a safer manner too, example research: https://ieeexplore.ieee.org/document/8566878

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