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EVs Are Essential Grid-Scale Storage

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Re: EVs Are Essential Grid-Scale Storage

#111

Post by thehappypm »

raxxorraxor wrote: post #87
vbezhenar wrote: post #73

Earlier quoted context omitted.

Phone battery is something like 4V. Watts depend on voltage. I guess home batteries use other voltage so their watt actually provides more electricity.

No, Watts should be independent of voltage, it is the product of voltage and ampere (don't know the exact English terms here). You perhaps mean ampere hours, I think that is often used for phones. But it is only ever meaningful if you have the respective fixed voltage and it often make sense for a batteries to quickly calculate how long they should last if you know how much ampere a device draws. It could also become…

I think what they’re talking about is the amp-hour measure of battery capacity, which is common in electronics, but converting to actual energy requires knowing the voltage.

Re: EVs Are Essential Grid-Scale Storage

#112

Post by pjc50 »

londons_explore wrote: post #25
Yizahi wrote: post #10

Aren't people wary about using their very expensive car batteries for the grid? E.g. imagine you plug in your phone for the night, but instead of a single top up change it is now constantly discharging and charging again. Lifetime of pocket sized batteries is not too great even now, and in such scenario they will go bust 2-3 times faster, in year instead of 3 or so. Also discharge swings would be probably much bigger…

Luckily, any degradation can all be predicted ahead of time. A 60kwh car battery might cost $10k, and allow 2000 charge cycles. So each kwh cycled into and out of the battery costs 8 cents. So a smart algorithm can decide it's worth draining the battery back into the grid if the profit to be made is more than 8 cents. Buuuut ... Delaying charging till later is free. So another car owner's car might see on the futures…

> Delaying charging till later is free. So another car owner's car might see on the futures market that delaying charging starting from 6pm till 11pm might save a few cents.

Yeah, I think that's far more likely. I can also see the possibility of a grid-mandated signal for "please, stop charging for five minutes, we're at capacity".

Re: EVs Are Essential Grid-Scale Storage

#113

Post by schiffern »

dahfizz wrote: post #69
schiffern wrote: post #40

Earlier quoted context omitted.

> instead of a single top up change it is now constantly discharging and charging This is where V1G beats V2G. V1G (AKA grid-adaptive charging) just chooses when to charge the car, to efficiently spread out the grid load overnight and spatially across the network. No extra charge cycles, in fact it's probably more mild than just charging at full speed. The key is that you need a UI setting for "Immediately charge to…

> Or better yet, owners set their car to only "bid" for a grid storage job when the cost-per-kWh is greater than the cost of degradation. It would have to be substantially greater. I'm not going to deal with reduced battery capacity and the hassle of replacing it early for a couple of cents here and there. Considering the extra cost of equipment to allow the EV to send power to the grid, I don't think the economics w…

That's the great thing about choice: you can choose your price! But it sounds like V1G might be a better choice for you instead of V2G.

The economics don't work out at the monthly average rate. That's why storage only kicks in when spot prices are well above average.

Re: EVs Are Essential Grid-Scale Storage

#114

Post by ajross »

raxxorraxor wrote: post #2

I don't understand the discrepancy between EV kWh and house battery kWh. Some cars have > 100 kWh capacity. Why do I pay > 1000$ per kWh for a house battery? At some point it is cheaper to just buy a car, even if you would never drive it. A Tesla Powerwall has 13 or so kWh? Why don't they use the car battery with nearly 10 times as much capacity? It is just unit prices that are far better for cars? Is the charge/disc…

House batteries are never purchased in isolation. They're what amounts to a luxury add-on to a much bigger solar system, so you'd expect to see a "markup". That may change with the recent rollback of net metering in CA, which is making a battery system a requirement to reach break even on cost.

Re: EVs Are Essential Grid-Scale Storage

#116

Post by dahfizz »

ffmpegy wrote: post #106
dahfizz wrote: post #82

Earlier quoted context omitted.

> most cars aren't used every day Huge citation needed. > most cars are parked during the day Yes, parked somewhere where there is no V2G infrastructure. By the time we pay millions of V2G charging stalls, we would be better off just buying actual grid scale storage.

https://www.reinventingparking.org/2013/02/cars-are-parked-9...

From your source:

> this suggests an average of just under 18 trips per car every week.

So cars on average are used multiple times a day. OP's claim that most cars aren't used is ludicrous.

Re: EVs Are Essential Grid-Scale Storage

#117

Post by sokoloff »

Yizahi wrote: post #10

Aren't people wary about using their very expensive car batteries for the grid? E.g. imagine you plug in your phone for the night, but instead of a single top up change it is now constantly discharging and charging again. Lifetime of pocket sized batteries is not too great even now, and in such scenario they will go bust 2-3 times faster, in year instead of 3 or so. Also discharge swings would be probably much bigger…

If V2G is economically unattractive for car owners to participate, they won't. That's fine but everyone involved knows that. Peak power costs the utilities a substantial factor over base load power generation. There's no reason to think that the market will settle on "a retail kWh plus 20%" rather than on "2-4x a retail kWh".

For $0.04/kWh, I'm not the least bit interested. For $0.40/kWh, I'm probably indifferent. For $1/kWh, I'll buy another car (or fixed battery) just to participate in this scheme.

Re: EVs Are Essential Grid-Scale Storage

#119

Post by gwbas1c »

This really only makes sense for short-term, emergency storage: IE, if a major power plant suddenly goes offline, calling on EVs to push power back into the grid for 10-60 seconds. This is enough time for things like pumped storage and quick start generators to come online. (It also wouldn't cause noticeable wear.)

Likewise, even disabling charging for a short-term, emergency 10-60 second period might be more practical. Feeding back into the grid requires additional complexity / hardware that could add cost to the consumer.

For day-to-day storage: As soon as someone goes to use their EV in the morning, and they find out that the battery isn't full, they're going to turn it off.

Re: EVs Are Essential Grid-Scale Storage

#120

Post by noptd »

greenthrow wrote: post #62
Yizahi wrote: post #10

Aren't people wary about using their very expensive car batteries for the grid? E.g. imagine you plug in your phone for the night, but instead of a single top up change it is now constantly discharging and charging again. Lifetime of pocket sized batteries is not too great even now, and in such scenario they will go bust 2-3 times faster, in year instead of 3 or so. Also discharge swings would be probably much bigger…

We are not talking about multiple 0-100% cycles daily. The places where pilot programs have been run always left the car with some amount of charge so it can be driven, and you don't normally charge NMC car batteries to 100%. Vehicle batteries have 8 year 100k mile warranties today, and those manufacturers who have spoken on this topic have said that utilizing your battery as grid storage will not violate the warrant…

Excluding Tesla: https://news.ycombinator.com/item?id=34518608

Perhaps you should do more research before ending a comment on such a condescending remark next time.

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