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EV batteries alone could satisfy short-term grid storage demand as early as 2030

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Re: EV batteries alone could satisfy short-term grid storage demand as early as 2030

#221
post #144

Earlier quoted context omitted.

LFP batteries can do 3k-10k cycles. Assuming a range of 500km per cycle out of an 100 kWh pack, that's 1.5 million km of total range (assuming 3k cycles). Only a small number of people will ever get that much out of a car - maybe 40% that, if maintained very very well. But we're talking Prius/Mercedes level endurance here, most cars won't make it that long. So in most cases, 70+% of the usable cycles in an LFP pack w…

Your range figures seem pretty crazy high. Pretty sure most EV batteries are smaller than 100k--my Model Y is only 75k for instance, and I'm not getting anywhere close to 500km per cycle because (1) my Model Y doesn't actually get 500km on a full charge and more importantly (2) like most EV owners, I don't charge to 100% and run my battery down to 0% but rather something closer to 80%/20%. So for my Model Y scenario,…

There are 100kWh EVs out there, and they will quickly increase in number. For them, 500km is a rather conservative estimate.

> I would expect them to get recycled and put back into cars

In that case, you'd also get something in return for not having used those cycles. It's a matter of choice then - do I rent out my battery during use, or do I sell it after 8 years.

Re: EV batteries alone could satisfy short-term grid storage demand as early as 2030

#222
post #144

Earlier quoted context omitted.

LFP batteries can do 3k-10k cycles. Assuming a range of 500km per cycle out of an 100 kWh pack, that's 1.5 million km of total range (assuming 3k cycles). Only a small number of people will ever get that much out of a car - maybe 40% that, if maintained very very well. But we're talking Prius/Mercedes level endurance here, most cars won't make it that long. So in most cases, 70+% of the usable cycles in an LFP pack w…

Your range figures seem pretty crazy high. Pretty sure most EV batteries are smaller than 100k--my Model Y is only 75k for instance, and I'm not getting anywhere close to 500km per cycle because (1) my Model Y doesn't actually get 500km on a full charge and more importantly (2) like most EV owners, I don't charge to 100% and run my battery down to 0% but rather something closer to 80%/20%. So for my Model Y scenario,…

If you keep the charge between 20 - 80%, your battery will last for far more cycles than when charging 0 - 100%. So you'll only get 60% of the kWh per cycle, but the battery will do 3-6 times as many cycles.

In fact, the battery management system won't even let you fully charge or discharge the battery for exactly this reason. When it shows 100%, there will still be 1-2 kWh empty and the same for a zero percent charge.

For example, a Toyota Yaris use a tiny (0.7 kWh) lithium ion battery and it gets charged/discharged constantly while breaking/accelerating, but it still last a long time because the charge is kept at about 50%.

Re: EV batteries alone could satisfy short-term grid storage demand as early as 2030

#223
post #165

1) This only works when the overlap peak electric demand and peak vehicle demand do not overlap. Night time, when the cars sit idle, is also a low demand time of day, and the afternoon energy demand peak coincides partially with the evening commute. 2) The loss of value to the owner based on cycles used needs to take into account that the failure of the battery in a vehicle can be what causes its final retirement, i.…

Absolutely. As an EV owner who wants to keep his car for at least ten years, it doesn't make sense to me to dull out the high capacity batteries to support the grid. It seems to me that it would be better to use recycled batteries for home PV storage etc. I'm not too obsessed but it was easy enough to look up the data on what charge states result in the least loss of range over time.

What if your car battery had a chemistry that could sustain ~10000 cycles if well handled, and aging in general was a bigger issue than cycle degradation?

We’re approaching this with the recent LFP generations.

Re: EV batteries alone could satisfy short-term grid storage demand as early as 2030

#224

Earlier quoted context omitted.

The Nissan Leaf had no battery management system when it launched. Many similar cars from that era lacked a BMS. E.g. the Renault Zoe and a few others. I'm not sure about the early Teslas. I think they saw the need for a BMS pretty early. I think you are just playing semantics here. Obviously they had some simplistic controls on the electronics. But no smart distribution of load, cooling systems, etc. Calling people…

> Nissan Leaf had no battery management system when it launched. Citation needed? As far as I know even the 2012 Leafs had a per cell thermal management. I think in the earlier Leafs a lot of the intelligence on charging operation and battery cooling/heating was offloaded to the BCM module but it is a bit of a hyperbole to say that there was no battery management. They may not have had a dedicated BMS module in the O…

There is thermal management and then there is thermal management.

Nissan leaf had cell level voltage and temperature monitoring, it also had a rudimentary heating element that would not let the battery freeze solid.

Its battery also was poorly designed so some of the cells had worse conditions than others and the batteries "died" because a few cells went out of limits and the BMS would limit the performance/range of the car. The rest of the cells could go much further. Also you should never charge lithium batteries (other than LTO) below freezing as it forms crystals that are lost to the capacity. Leaf did not to my knowledge compensate for this.

Moreover 24kWh battery doing 1000 cycles is about 100 000 km of driving.

Then there is Tesla batteries that have liquid cooling and heating of the whole pack. Battery is never charged below freezing, also above freezing the charging is adapted to the cell temperatures and for fast charging the battery temp is raised up to 60C, above 65C the cooling kicks in.

The batteries are much larger in Teslas, typically say 80kWh. That combined with better efficiency, better battery management, lower power draw per cell, etc means that they get more than 1k useful cycles out of it. Say 2k (tho they claim more, and there is considerable variability due to use and environment). So 500km * 2k cycles is 1 million km.

The battery may degrade due to age before it reaches its cycles.

Also as mentioned above. Tesla does draw up to 300kW out of the battery. The onboard AC charger is 11kW so if that is bidirectional then the it is really gentle on the battery.

That said, I'm not dissing Nissan, they were truly innovative and we owe them lots of gratitude for popularizing EV's and they have also evolved their tech considerably. Others are doing battery management very well as well nowadays.

Re: EV batteries alone could satisfy short-term grid storage demand as early as 2030

#225

This is already happening today in California, a couple gigawatts of batteries are charged during the day and released in the evening to offset peak demand. https://www.caiso.com/TodaysOutlook/Pages/supply.html

This seems high(?): for comparison, average power of French solar panels is 1.6GW (and a bit more for wind power).

Insolation is higher in California, with the same solar panel surface you can probably get double the energy over a year, compared to France.

Re: EV batteries alone could satisfy short-term grid storage demand as early as 2030

#227

Earlier quoted context omitted.

Absolutely. As an EV owner who wants to keep his car for at least ten years, it doesn't make sense to me to dull out the high capacity batteries to support the grid. It seems to me that it would be better to use recycled batteries for home PV storage etc. I'm not too obsessed but it was easy enough to look up the data on what charge states result in the least loss of range over time.

What if you were reimbursed 5x your meter price for the power you sell back to the grid? With electricity spot market, this sort of money is around and should of course go to the vehicle owners, at least a big share of it. Only a fraction of the total battery capacity would be involved in this scheme and with light load, so the battery degradation would not be that big. And this would not happen daily.

> With electricity spot market, this sort of money is around

This happens precisely because of supply-demand - peak dispatchable bulk generation is more expensive. VtG brings a lot of cheap supply bringing prices down and causes balancing stress on distribution grid, increasing distribution costs. 5x sounds like an absolute pipe dream

Re: EV batteries alone could satisfy short-term grid storage demand as early as 2030

#228

Earlier quoted context omitted.

> The early ones from ten years ago had no battery management systems I think you misunderstand what a battery management system is. If a Li-Ion battery had no BMS -- especially one that is large, high power, and composed of many cells, it would literally be an incendiary bomb if not carefully managed by the user. The BMS is responsible for maintaining the cells -- they must be equalized and cannot go below or above…

The Nissan Leaf had no battery management system when it launched. Many similar cars from that era lacked a BMS. E.g. the Renault Zoe and a few others. I'm not sure about the early Teslas. I think they saw the need for a BMS pretty early. I think you are just playing semantics here. Obviously they had some simplistic controls on the electronics. But no smart distribution of load, cooling systems, etc. Calling people…

I cannot claim that it is impossible to run a lithium ion battery pack in an EV application without a BMS but I can claim that if you do that it will almost certainly catch on fire. Quote below from (https://batteryuniversity.com/article/bu-908-battery-managem...):

"The purpose of a BMS is to:

1. Provide battery safety and longevity, a must-have for Li-ion.

2. Reveal state-of-function in the form of state-of-charge and state-of-health (capacity)

3. Prompt caution and service. This could be high temperature, cell imbalance or calibration.

4. Indicate end-of-life when the capacity falls below the user-set target threshold.

Not all BMS offer all these features. The most basic functions are battery protection and showing state-of-charge (SoC)."

Without battery protection and while running many hundreds of individual cells your battery will catch on fire. I will bet the house on that. No EV maker would ever make an EV without a BMS.

You have gone beyond ignorance at this point by claiming that you are insulted and asking for an apology. I won't ask you for one, but I will ask for a public correction and acknowledgement that you were wrong.

Re: EV batteries alone could satisfy short-term grid storage demand as early as 2030

#229
post #165

1) This only works when the overlap peak electric demand and peak vehicle demand do not overlap. Night time, when the cars sit idle, is also a low demand time of day, and the afternoon energy demand peak coincides partially with the evening commute. 2) The loss of value to the owner based on cycles used needs to take into account that the failure of the battery in a vehicle can be what causes its final retirement, i.…

As other parts of the EV have a longer lifespan, like an electric motor, it may be more common to do a battery exchange mid-life ?

Re: EV batteries alone could satisfy short-term grid storage demand as early as 2030

#230
post #165

1) This only works when the overlap peak electric demand and peak vehicle demand do not overlap. Night time, when the cars sit idle, is also a low demand time of day, and the afternoon energy demand peak coincides partially with the evening commute. 2) The loss of value to the owner based on cycles used needs to take into account that the failure of the battery in a vehicle can be what causes its final retirement, i.…

And keep in mind it's to store energy from renewables (minus hydropower), i.e. mainly solar and wind. Solar is nonexistent at night. And although it varies, wind is generally strongest during the day and delivers less energy at night. But night-time is exactly when the vehicles are charged in people's homes, at least currently that's the situation and it would necessitate a ton of new infrastructure to change that. H…

> But night-time is exactly when the vehicles are charged in people's homes

Average wind production over the last 2 years in the UK is 5.8GW, with the peak (>6GW) between 1400 and 2200, and trough (But that's only a 5% variation between high and low.

Total demand though is lower at night than in the day. It's 25% down on the low at 0300-0400 and 17% up on average from 1800-1900, which more than offsets the daily variation in wind.

Throw in grid solar and sure, more renewables during the day (domestic solar isn't measured aside from a drop in demand) and you get an average 24% of current UK electricity driven by renewables, with a peak of 33% at midday and trough of 18% from 1900-2100.

But if you doubled wind that average peak would be 52% at 1200 for renewables, and a trough of 36%.

Assuming an infinite capacity grid (as the data isn't readily available), doubling wind+solar energy would save 40TWh of gas a year even with current demand. Tripling would save 60TWh, increasing 5-fold would save 76TWh, reducing Gas usage from 88TWh a year to 11TWh a year.

Those savings are based on real world generation and demand data from 2021.

Sure wind and solar can't entirely replace gas on its own, but it can knock usage down by 90% quite easily by putting up more strings between areas of the grid and simply building more.

You don't need to eliminate fossil fuels completely to make a difference.

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