Slow Electricity: The Return of DC Power? (2016) • Hacker News Board

Re: Slow Electricity: The Return of DC Power? (2016)

#201

Post by ip26 » Wed, Aug 18, 2021, 2:42 PM UTC

hutzlibu wrote: post #113

function_seven wrote: post #44

Earlier quoted context omitted.

I get unreasonably angry when Victorian cosplayers think they've found the solution to our wasteful modern life. Simply eschew modern conveniences and spend hours each week beating your clothes against a rock! Simple , instead of grocery shopping twice a month, ditch that wasteful freezer and walk to the farmers' market down the block before dinner each night. Was it cloudy yesterday? Simple! , take a whore-bath¹ at…

"Simply eschew modern conveniences and spend hours each week beating your clothes against a rock" My question is, if those people actually tried that by themself before suggesting it, or if they just picture the women doing it somewhere. I mean in this specific instance I can imagine they tried. And I did too, while off grid. It gives you a special connection to your clothes. But suggesting this as a general way of l…

I think if you read lowtechmag much it's fairly clear they are true believers and probably have done a fair amount of washing clothes the hard way. They aren't simply armchair philosophers.

https://solar.lowtechmagazine.com/2019/10/mist-showers-susta...

Re: Slow Electricity: The Return of DC Power? (2016)

#202

Post by bluGill » Wed, Aug 18, 2021, 2:47 PM UTC

dheera wrote: post #40

petschge wrote: post #23

Earlier quoted context omitted.

That is because that package internally steps down that voltage. Any LED that produces light in the visible range will have a bandgap in the 1 to 2 Volt range. Feeding it a higher voltage than that would lead to disastrous current run away. The package that contains the LED and the current limiter and whatever other electronics are in there might of course accept 24V DV, or 110V AC or 230V AC or 17.4V at 4kHz. But th…

LEDs are usually current-controlled, not voltage controlled. You might have several LEDs in series and they might very well have a voltage drop across all of them of 24V or even much higher when maintaining an operational amount of current.

The could, but in general you would prefer to wire them in parallel so that nobody notices when one burns out - it just gets a little dimmer.

Re: Slow Electricity: The Return of DC Power? (2016)

#203

Post by JKCalhoun » Wed, Aug 18, 2021, 2:48 PM UTC

throw0101a wrote: post #137

Robotbeat wrote: post #28

So, I used to be "team DC" as well, but after learning up a bit, I realized there are still a lot of advantages to AC in the 21st Century. One reason DC power is more viable nowadays is (as others here have mentioned) the use of DC-DC converters. They internally actually use AC to do the conversion (usually at much higher frequency to save weight and cost on inductive elements). But they're not super cheap (not cheap…

> Low voltage DC (like 12V) requires MUCH thicker cables for the same power, which means a lot more copper (and copper mining). Typical line voltage can be very lightweight. -48V DC has been a thing with telco equipment for decades: it's what a landline telephone uses for signalling. * https://www.servertech.com/blog/48vdc-power-and-the-backbone... If we'd use anything DC, it would probably be that.

12V has been standard in auto/marine for quite some time. There are plenty of consumer items that already run on 12V.

Power hogs like refrigerators, window-AC units would no doubt still run on 110/220.

But I already have mixed voltage AC in my home: otherwise 110V but purpose-placed 220V for electric stove/oven (in kitchen) and electric clothes dryer (in garage).

In my perfect future only those high-current outlets would remain — the rest of the house would have 12V plugs and lighting.

Re: Slow Electricity: The Return of DC Power? (2016)

#204

Post by ip26 » Wed, Aug 18, 2021, 2:50 PM UTC

citrin_ru wrote: post #125

SilverRed wrote: post #77

Earlier quoted context omitted.

Not always using a clothes dryer is fine and good advice. But not using an electric kettle and replacing it with heating water on a gas stove is so beyond absurd I'm shocked how they even came to this conclusion since gas stoves are less efficient and much worse for the environment than a kettle. And a kettle is so low impact anyway. It uses a high amount of power for a very short time and spends almost all of its li…

> since gas stoves are less efficient and much worse for the environment than a kettle. It is not obvious at all and requires calculations. When you use electric kettle you use energy which was obtained mostly from coal and gas (60% of it in the US) and efficiency of the conversion is less than about 40% on average (limited by efficiency of a steam turbine). Then about 8% of this power is lost during transportation/d…

This has been studied a fair amount, from memory gas is in the low to mid 40% range, induction & immersed coil are in the mid 80% range.

Gas stove is nominally competitive, but as soon as you start adding renewables to the power mix or considering indoor air quality & venting, electric seems like the path forward to me.

Re: Slow Electricity: The Return of DC Power? (2016)

#205

Post by JohnWhigham » Wed, Aug 18, 2021, 2:51 PM UTC

dijit wrote: post #134

JohnWhigham wrote: post #124

Earlier quoted context omitted.

If you're careful about water usage and use cold water, you'll always beat a dishwasher. Another thing people often forget about dishwashers: you're supposed to pre-scrub the hard shit off the dishes. Well, you just did half the mechanical work yourself, why not finish it? I think part of it can also be (at least for me) upbringing. We always handwashed our dishes, and only used the dishwasher a couple times per year…

I grew up handwashing too but I disagree with your assertion. Firstly, you can't wash with cold water because soap doesn't activate with cold water, hot water also kills bacteria and helps cut through grease. Fats themselves are hydrophobic and without activated soap you wont get them off... enjoy your "filmy" dishes. Second, humans expend a lot more energy than you think. The act of standing and using our arms relea…

you can't wash with cold water because soap doesn't activate with cold water

Bunch of pseudoscience. I've never noticed any difference between washing with cold or not.

hot water also kills bacteria

Ultimately doesn't matter because they're all being washed away by the soap molecules anyway.

The act of standing and using our arms releases...

Lol, are you seriously trying to reason that what little energy you burn is more than a dishwasher?

Re: Slow Electricity: The Return of DC Power? (2016)

#206

Post by readflaggedcomm » Wed, Aug 18, 2021, 3:06 PM UTC

dijit wrote: post #134

JohnWhigham wrote: post #124

Earlier quoted context omitted.

If you're careful about water usage and use cold water, you'll always beat a dishwasher. Another thing people often forget about dishwashers: you're supposed to pre-scrub the hard shit off the dishes. Well, you just did half the mechanical work yourself, why not finish it? I think part of it can also be (at least for me) upbringing. We always handwashed our dishes, and only used the dishwasher a couple times per year…

I grew up handwashing too but I disagree with your assertion. Firstly, you can't wash with cold water because soap doesn't activate with cold water, hot water also kills bacteria and helps cut through grease. Fats themselves are hydrophobic and without activated soap you wont get them off... enjoy your "filmy" dishes. Second, humans expend a lot more energy than you think. The act of standing and using our arms relea…

>you can't wash with cold water because soap doesn't activate with cold water

That may be true for most laundry detergents, which have to pull grime out of fabrics, but not simple dish soap. Just look at how well Dawn works to take oil off concrete, for example. Nobody's heating that up.

Re: Slow Electricity: The Return of DC Power? (2016)

#207

Post by skybrian » Wed, Aug 18, 2021, 3:11 PM UTC

awesomeusername wrote: post #76

To all the detractors here. I lived on a boat for many years which was 12v only and didn't have the mod cons. You adapt pretty quick then hardly think about it. So everyone saying how it's fantasy to expect peoples behaviour to change, just remember if you haven't tried it you are likely highly over estimating how much effort it is, and not aware of many of the unexpected advantages.

Sure, the wires won’t be very long in a boat, though?

Re: Slow Electricity: The Return of DC Power? (2016)

#208

Post by dijit » Wed, Aug 18, 2021, 3:18 PM UTC

JohnWhigham wrote: post #205

dijit wrote: post #134

Earlier quoted context omitted.

I grew up handwashing too but I disagree with your assertion. Firstly, you can't wash with cold water because soap doesn't activate with cold water, hot water also kills bacteria and helps cut through grease. Fats themselves are hydrophobic and without activated soap you wont get them off... enjoy your "filmy" dishes. Second, humans expend a lot more energy than you think. The act of standing and using our arms relea…

you can't wash with cold water because soap doesn't activate with cold water Bunch of pseudoscience. I've never noticed any difference between washing with cold or not. hot water also kills bacteria Ultimately doesn't matter because they're all being washed away by the soap molecules anyway. The act of standing and using our arms releases... Lol, are you seriously trying to reason that what little energy you burn is…

> I've never noticed any difference between washing with cold or not.

Soap not activating when cold is not "pseudoscience", it's just a fact. Like grease doesn't become liquid unless heated. It's a similar principle.

> Ultimately doesn't matter because they're all being washed away by the soap molecules anyway.

If they bind, but, I'll give you this one.

> Lol, are you seriously trying to reason that what little energy you burn is more than a dishwasher?

Humans are pretty shitty at expending energy. This is one of the largest arguments against cycling long distances (though those arguments I don't agree with, but we're talking about total Co2 output here).

Re: Slow Electricity: The Return of DC Power? (2016)

#209

Post by throw0101a » Wed, Aug 18, 2021, 3:27 PM UTC

JKCalhoun wrote: post #203

throw0101a wrote: post #137

Earlier quoted context omitted.

> Low voltage DC (like 12V) requires MUCH thicker cables for the same power, which means a lot more copper (and copper mining). Typical line voltage can be very lightweight. -48V DC has been a thing with telco equipment for decades: it's what a landline telephone uses for signalling. * https://www.servertech.com/blog/48vdc-power-and-the-backbone... If we'd use anything DC, it would probably be that.

12V has been standard in auto/marine for quite some time. There are plenty of consumer items that already run on 12V. Power hogs like refrigerators, window-AC units would no doubt still run on 110/220. But I already have mixed voltage AC in my home: otherwise 110V but purpose-placed 220V for electric stove/oven (in kitchen) and electric clothes dryer (in garage). In my perfect future only those high-current outlets w…

There is more and more 24V in marine systems to deal with higher loads in recent years. Your 28' (8m) day sailor may not need much more than a starter battery, but once you're at 40' (12m) and above things start changing. E-motors in the marine world generally use 48V (AFAICT).

48V is also being looked at in the auto world as well, at least for "low voltage" stuff:

* https://www.automotiveworld.com/articles/48-volt-likely-to-b...

The IEEE's 802.3bu PoDL can handle sending 12, 24, and 48V, and automotive is one of its deployment spaces:†

* https://blog.siemon.com/standards/ieee-std-802-3bu-2016-powe...

* https://en.wikipedia.org/wiki/Power_over_Ethernet#Standards_...

† 10BASE-T1, 100BASE-T1, 2.5GBASE-T1, 5GBASE-T1, and 10GBASE-T1; .3cz task force is working on 25/50/100 Gb/s.

Re: Slow Electricity: The Return of DC Power? (2016)

#210

Post by fuoqi » Wed, Aug 18, 2021, 3:39 PM UTC

bombcar wrote: post #26

nikisweeting wrote: post #24

There is a line that’s incorrect in the article: > AC won, mainly because of its higher efficiency when transported over long distances. AC is not actually more efficient at long distance transmission, it’s less efficient due to the skin effect. AC is just easier to convert.

Yeah I seem to recall that many extremely high voltage long distance lines are actually DC

There are two main reasons for using DC for long distance power lines:

1) The line connects two synchronized grids. It's much easier to convert electricity to DC and back to AC on receiving end, than to synchronize grids or to implement something similar with AC.

2) The line runs under sea water for a significant distance. Due to the conductivity losses DC is more efficient in such contexts that AC.