Charging cars at home at night is not the way to go: study • Hacker News Board

Re: Charging cars at home at night is not the way to go: study

#331

Post by vanviegen » Sat, Sep 24, 2022, 5:47 AM UTC

wodenokoto wrote: post #326

alexb_ wrote: post #17

>We're doing it wrong, according to a new Stanford study Wrong according to what metric? Cost? Raw efficiency? A lot of people are more than willing to give up efficiency so that they don't have to actually worry about finding a station during the day. To say that something is just outright "wrong" based on their personal preference of priorities comes off as unhelpful to me. The solution is simple. Make electricity…

> Make electricity cheaper when it's more available, and people will use it. It’s _not_ like that in the states? In Denmark people are sharing spreadsheet that can tell you when to run the washing machine to save on electricity since the energy crisis following Russias invasion of Ukraine has pushed prices enough that these optimizations become valuable to regular consumers.

Is hourly pricing the norm in Denmark?

Re: Charging cars at home at night is not the way to go: study

#332

Post by tsimionescu » Sat, Sep 24, 2022, 5:47 AM UTC

parker_mountain wrote: post #269

ars wrote: post #199

Earlier quoted context omitted.

> If all iPhones do this it will matter. No it won't. An phone has around 5 watt hours. So: 5 watt hours / day * 150 million people * 365 days = 273GWh / year / 4,116 billion kilowatthours / year = 0.006651% of electrical usage. Yah, it's virtue signaling, not anything real. And keep in mind 0.006651% is total electrical usage - this time shifting might save 10%, so actual savings are even less than that.

"150 million people" There are over a billion iPhones in use worldwide. This technology is also being brought to MacBooks (100 million+), Watches (100 million+), and iPads (150 million+). Your fundamental numbers are staggeringly inaccurate. And, most crucially, representing it as a whole of the electric usage instead of peak hours intentionally misses the point of reducing peak hour usage. It's called "peak hour" fo…

And the total worldwide use of electricity is 22,848 TWh/year, (according to the IEA [0]). So that would be 5Wh/day * 1 billion phones * 366 days = 1,830 TWh = 0.0008% of world electricity consumption.

Getting data about peak hour usage is much harder, but I would wager it's at most as much of that. So yes, completely insignificant at a large scale.

If anything, the biggest impact will come to individual consumers, if and when electricity prices start varying more widely across times of day.

[0] https://www.iea.org/reports/electricity-information-overview...

Re: Charging cars at home at night is not the way to go: study

#333

Post by tsimionescu » Sat, Sep 24, 2022, 5:51 AM UTC

fsckboy wrote: post #243

SoftTalker wrote: post #217

Earlier quoted context omitted.

The point is that off-peak isn't necessarily the best option anymore. In areas that are going all-in on solar, there is power during the day, but at night it would have to be generated or come from storage batteries. Off-peak traditionally means when demand is low. Now you have to change your thinking to be when supply is high.

> Now you have to change your thinking to be when supply is high teachable moment, all along you should have been using price

The price is the same at all these times, unless someone acts to make it different. The whole discussion is about how to adjust energy price to incentivize the health of the grid (which is a shared resource individual market actors don't care about).

Re: Charging cars at home at night is not the way to go: study

#334

Post by morsch » Sat, Sep 24, 2022, 5:56 AM UTC

parker_mountain wrote: post #265

spoonjim wrote: post #161

Earlier quoted context omitted.

LOL. This is classic “virtue signaling.” Your iPhone battery is not even a rounding error on your electricity consumption.

Very short sighted to think it's about "your" individual power consumption. There are over a billion iPhones in use today. Assuming 10% of them get charged during peak times, each one shaving a watt off of its peak is 100000 kilowatts of load reduced from the energy grid. Considering the number is probably a lot higher, and the load reduction a lot greater, my estimate is probably pretty conservative. And then furthe…

It's still a rounding error, 100MW is 0.003% of the average global electricity generation. It's probably still worthwhile doing, especially if sets a trend for other categories of devices. https://www.wolframalpha.com/input?i=100+megawatt%2F%2828500...

Re: Charging cars at home at night is not the way to go: study

#335

Post by ldrndll » Sat, Sep 24, 2022, 6:05 AM UTC

nicoburns wrote: post #307

Terretta wrote: post #152

Earlier quoted context omitted.

Weirdly, the latest iPhone + iOS pops a dialog box saying it will do this. // Weird given tiny amount of energy for your iPhone. But perhaps reasonable in aggregate.

iPhones do it to help preserve battery health. Slower charging is better for the battery, as is being near the middle of its charging range.

This is different to optimized battery charging. As of iOS 16 (in an as yet unreleased point version) Apple plans to add support for clean energy charging, which will charge your iPhone when the grid has a cleaner mix of energy. I think this is US only to begin with.

Re: Charging cars at home at night is not the way to go: study

#336

Post by tsimionescu » Sat, Sep 24, 2022, 6:07 AM UTC

qqqwerty wrote: post #172

NickM wrote: post #115

Earlier quoted context omitted.

My point isn't that we should actually shrink EV batteries and use the excess for stationary storage, my point is that car batteries as a demand-leveling mechanism is not likely to be an optimal solution. That said, it's not something that's really happening right now anyway, so the "power your home with your car at night" idea seems unlikely to take off unless there is a (possibly misguided) legislative push for it.

Batteries are a bit too expensive to make sense as stationary storage outside of some specialty cases right now. But EVs have been economical for a while. So while we wait for battery prices to drop, two way EV charging absolutely make sense as a transition technology. Most of those EV batteries are sitting unused for large chunks of the day, and the entire capacity of the battery is often only needed by the driver a…

> Most of those EV batteries are sitting unused for large chunks of the day

Yes, that is the point of having a battery, or any fuel storage of any kind. Especially one that degrades with use and that doesn't even change its weight based on being full (which could potentially offset some of the costs).

Re: Charging cars at home at night is not the way to go: study

#337

Post by tsimionescu » Sat, Sep 24, 2022, 6:11 AM UTC

kevinpet wrote: post #222

NickM wrote: post #97

Earlier quoted context omitted.

The problem is, you need a full charge in the morning if you're leaving on a road trip, so then your car will not be powering your house the night before. This would likely lead to big spikes in demand the night before the start of holiday a weekend, for example.

I don't have an electric car, but I can't imagine this is a challenging problem at all. All you need is a target charge level. If you're going on a trip tomorrow, set it to 100%. If your normal commute is 20 minutes, no reason to charge past 75% or even 50%.

They were saying this creates huge problems for the grid. Let's assume people will want to destroy their car battery by draining it to power their house every night, and that this indeed supplements the need for grid storage overnight. However, when holiday seasons comes around, all of a sudden a significant percentage of homes will start demanding much higher power usage from the grid, as people co-ordinate in setting their cars not to drain power into their homes on the night before.

Re: Charging cars at home at night is not the way to go: study

#338

Post by nikau » Sat, Sep 24, 2022, 6:17 AM UTC

morsch wrote: post #329

kodah wrote: post #238

Earlier quoted context omitted.

> This can disincentivize employers from installing chargers, especially once half or more of their employees have EVs. > So yes, there are weird red herrings in this thread from people who want a technology first and a solution second (or never) and/or who don't understand design of incentive structures. Speaking of incentive structures, one of my former employers installed EV chargers in all of the bottom floors of…

Buy a small EV for everyday trips and rent another car for road trips. Nobody in our car culture, where people drive F150s just in case they need them; nobody is going to do that, but environmentally it'd be much preferable to everybody getting a big Tesla weighing several tons. Financially it works out for a couple of road trips a year, not so much if you're doing it a couple of times a month.

Or get a plug in hybrid that results in the convenience of one car but most of the environmental/cost benefits.

Re: Charging cars at home at night is not the way to go: study

#339

Post by nikau » Sat, Sep 24, 2022, 6:20 AM UTC

JohnFen wrote: post #235

spoonjim wrote: post #226

Earlier quoted context omitted.

I think many virtue signalers are earnest and think that Tweeting #BLM or other useless actions are actually useful.

If someone is doing something because they think it makes a real difference, then it's not virtue signaling by definition.

Virtue signalling is typically something easy with no real inconvenience to the person doing it.

So doing a #supportsoupkitchens on a twitter repost vs actually going and volunteering at one.

Re: Charging cars at home at night is not the way to go: study

#340

Post by jjav » Sat, Sep 24, 2022, 6:25 AM UTC

themitigating wrote: post #282

saidajigumi wrote: post #51

Earlier quoted context omitted.

This is precisely what the linked article says. From the section "Charging Incentives": “And it’s not just California and Western states. All states may need to rethink electricity pricing structures as their EV charging needs increase and their grid changes,” added Powell, who recently took a postdoctoral research position at ETH Zurich. The article also includes other interesting and more nuanced policy details tha…

Seems that commercial power costs less than residential. Sometimes the difference is negligible but other times it's significant. I know residential lines cost much more to maintain because of the distances but that doesn't apply to residential apartments buildings in cities and I believe there's a seperate charge for that. Why? https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...

I rent an office very near my house. The PG&E rate for peak time at the office is over 20c cheaper than at my house. Not very fair to residental usage.