Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

EVs Are Essential Grid-Scale Storage

spectrum.ieee.org

Post reply on HN
Print view View original

81–90 of 260 posts

Re: EVs Are Essential Grid-Scale Storage

#81

Post by iso1210 »

dmurray wrote: post #74
londons_explore wrote: post #25

Earlier quoted context omitted.

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…

> 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. If you can really treat the whole cost of the battery as X cents per charge cycle, disregarding the lifetime of the car/battery, this won't work at grid scale. Someone else will build a storage facility that just charges and discharges batteries, and they will outcompete rational EV owner…

This does work today at grid scale, people use their home batteries (either on wheels or not) to charge/discharge to the grid in the UK all the time.

If someone builds that storage facility to do it commercially then great.

> rooftop solar can't exist without special subsidies

Yet it does

Re: EVs Are Essential Grid-Scale Storage

#82

Post by dahfizz »

dtech wrote: post #67
dahfizz wrote: post #57

This boils down to "There are lots of EV batteries, we can use them as storage!". It seems to ignore practical issues: People drive during the day, and charge at night. So you could use EVs as a buffer during the night, but they still need to be charged. So EVs are still going to be a net energy consumer during the night, when you need the storage the most (no solar production). I think the best course of action is t…

Every ignoring that most cars aren't used every day, most cars are parked during the day and peak solar generation time.

> 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.

Re: EVs Are Essential Grid-Scale Storage

#83

Post by lambdasquirrel »

college_physics wrote: post #60

This feels gimmicky and fragile. If distributed / decentralized storage is required (sounds like a good idea overall) it is surely better to have stationary installations, with larger batteries and connectivity optimized for that purpose, not using the EV batteries currently developed for moving these two-ton exosceletons to random places... In fact you want to have the option to significantly reduce EV usage as othe…

I came on here to comment that if you do this, it requires that the EVs be connected to the grid. How is that going to happen during the day when a lot of folks are at work, or out and about, and there aren't that many public chargers?

I don't think this whole EVs-as-grid-storage really makes sense. When the EVs go into the scrap market, the batteries will likely still have 80% of their range left (if not more, based on what folks have been reporting). If it's as low as 80%, it would be a huge detriment in the used market, but that much is still fine and dandy for grid storage. Just wait 10-15 years and use them then, if this is supposed to be a strategy.

Or better yet, keep investing in other non-lithium chemistries, like those involving sodium, and then cost per kwh will go down significantly.

Re: EVs Are Essential Grid-Scale Storage

#84

Post by EGreg »

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…

People measure stuff in terms of $ when they should be looking at the global resources on the planet, the garbage and the externalized costs. Until we move to a resource-based economy that takes these into account, we’ll be destroying the planet while on paper the carbon credit accounting looks perfect.

Re: EVs Are Essential Grid-Scale Storage

#85

Post by devmor »

danuker wrote: post #44
londons_explore wrote: post #25

Earlier quoted context omitted.

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…

It worries me that if industrial-purpose batteries cost the same and have similar degradation, grid services will also decide not to charge/discharge if the profit is less than 8 cents. This tells me that Li-Ion batteries are far from the ideal medium for grid storage.

Batteries are extremely inefficient. Capacitors are much more resilient in terms of charge cycles (by orders of magnitude).

If one were to build a "facility" to hold short term load, that's likely what they'd use. They just can't be used in cars because they're incredibly volatile and don't hold a charge for a long period of time.

Re: EVs Are Essential Grid-Scale Storage

#86

Post by londons_explore »

dmurray wrote: post #74
londons_explore wrote: post #25

Earlier quoted context omitted.

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…

> 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. If you can really treat the whole cost of the battery as X cents per charge cycle, disregarding the lifetime of the car/battery, this won't work at grid scale. Someone else will build a storage facility that just charges and discharges batteries, and they will outcompete rational EV owner…

Rooftop solar outcompetes solar farms because energy from a solar farm pays taxes and distribution costs before it is delivered to a user. Whereas rooftop solar energy is untaxed when it powers your laptop.

> It only makes sense if the EV owner can somehow get charge capacity "for free"

The EV owner has the power electronics 'for free' - ie. they have almost infinite lifespan, and just a capital cost.

Additionally, the variations of energy prices on the grid are really wide. There might be $100k/MWh for 5 minutes per year. It isn't worth a static operator paying the capital cost for the batteries (which also degrade with time) to setup for 5 minutes use per year. But it does make sense for the EV owner to do so, because his marginal cost is tiny.

Re: EVs Are Essential Grid-Scale Storage

#87

Post by raxxorraxor »

vbezhenar wrote: post #73
raxxorraxor wrote: post #35

Earlier quoted context omitted.

True, there are better prices by now. But 5kWh? I thought my smartphone would have that by now... Perhaps 200kWh is a bit exaggerated. And yes you also need a good quality inverter for your home that synchronizes with the net, but I actually don't believe this to be expensive high tech... Ideally I wouldn't want to put the energy I generate with solar, wind or differently back into the power net. In my country you ba…

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 a sensible metric if we always talk about 120V/240V for general household appliances of course.

Re: EVs Are Essential Grid-Scale Storage

#88

Post by scythe »

dmurray wrote: post #74
londons_explore wrote: post #25

Earlier quoted context omitted.

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…

> 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. If you can really treat the whole cost of the battery as X cents per charge cycle, disregarding the lifetime of the car/battery, this won't work at grid scale. Someone else will build a storage facility that just charges and discharges batteries, and they will outcompete rational EV owner…

>It only makes sense if the EV owner can somehow get charge capacity "for free" - eg the car will be EOL after 1000 charges but the battery lasts 2000 - he should sell the extra 1000.

Plug in the numbers. A charge cycle is probably around 200 miles (not even optimistic). That means that 1000 charge cycles is 200000 miles. That's roughly the lifetime of a car. However, I have heard anecdotes that EVs should last longer, due to a simpler transmission, so this may be a little up in the air.

Re: EVs Are Essential Grid-Scale Storage

#89

Post by punnerud »

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…

This already exist in Norway with the company Tibber, that have more than 400.000 users. They do just that, let you connect your EV so they adjust the charging and guarantee a lower price.

The market they can buy and sell this capacity is called an “aggregator”, and they can earn more money on this then selling just power.

Re: EVs Are Essential Grid-Scale Storage

#90

Post by ZeroGravitas »

The original report is more like "we're going to have grid scale storage as a side-benefit of EV rollout", which this headline kind of twists.

More importantly, they'll be grid scale responsive demand. They're basically internet connected batteries so they can charge whenever suits the grid best.

The UK has been explicitly planning for this as a way to enable the further roll out of renewebales for about a decade so it's hardly news. The new bit is someone doing some sums and putting numbers on it with recent estimates.

Post reply on HN