179 points by rbanffy
6 days ago
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. Instead of using say 30% of the battery per day in normal use cycle, maybe not even every day, you will now see multiple 0%-100% charge cycles daily.
New battery for small car costs 13-20k$, so if its lifetime will be shortened from I don't know, say 10 years, to 3 years, then electric company need to compensate owners accordingly and I highly doubt they will pay even 10% of that sum over 3 years.
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 market that delaying charging starting from 6pm till 11pm might save a few cents.
Obviously that means it's most economically efficient for every owner to do grid balancing merely by smartly delaying charges - and in turn price fluctuations will rarely exceed 8 cents.
The component that is missing to make this happen is cars which have code to automate this process, and markets in place that have API's to let the car buy and sell energy, and futures in energy, by the kwh. Users need not understand how it works - they just tick the tickbox which says 'charge and discharge smartly to minimize electricity costs'.
Today, those markets are typically only open to big players, cars don't have a tickbox, and wall chargers typically won't let a car put power into the grid.
> Buuuut... Delaying charging till later is free.
This functionality is already there.
> So each kwh cycled into and out of the battery costs 8 cents.
This is quite much. If you add other infra overhead, feeding power back into the grid is not going to produce much revenue for the individual unless the selling price is maybe 20 cents above the price when charging.
On the other hand, something that MAY make more sense, is if the car battery can be used to provide power to the owner's own house during short price peaks. This might allow some savings even in stable grids, but the killer app would be in grids that have rolling blackouts during high demand periods.
And even for grids where blackouts are infrequent, if your car can serve as large UPS for your house (combined with a large capacitor to keep the power stable), such functionality in the charger may be worth the cost of the hardware for many people. (Bringing the number of units up and hence the cost per unit down over time.)
Still, though, for grid stability it is probably much better to use dedicated batteries as part of the grid itself than to use car batteries.
For a blackout situation your car won't be of much help: any inverter that is grid tied will refuse to come on as long as there isn't a low impedance functioning grid connection present. Typically they'll measure the conditions for a minute or two, then make the connection (you'll hear a relay trip) and then bit by bit the inverter starts pushing power by advancing its on phase relative to the grid. If that doesn't stay within very precise parameters it will switch off, wait for a bit and try again.
So you can forget about your car (or even most solar inverters) to work during blackouts unless a couple of things are present:
- a automatic grid disconnection switch (aka a transfer switch)
- special firmware to allow the inverter to operate in 'off grid' mode
Both Xantrex and Victron have inverters that can do this but they are not normally deployed for such installations and they wouldn't know what to do with your car battery (voltage much higher than the ones that they require, typically 48V max).
Growatt has some off-grid units too, but those still won't satisfy the impedance requirements of your cars inverter (the grid is 'too small' so it will fluctuate too much due to high impedance).
Fronius have hybrid inverter for 400V lithium batteries, witch are essentially the same used in cars, the missing part is the integration p.v. inverter-car's BMS.
Personally having an EV and a Victron inverter with batteries and same vendor car charger I HATE the fact I can't even adapt charging amps depending on p.v. available power in AC charging.
Yes, this lack of standardization and ability to communicate is infuriating. I don't have an EV but even without that adding a battery to an existing setup is not that simple, besides being in theory a massive fire hazard, so it can't be in the house.
With HA and a bunch of scripts you can actually get quite far in automating all this, but when the grid fails everything will shut down.
I'd love to see these babies become more easily (and cheaper!) to source:
The energy density isn't super but for stationary applications that's fine. 6K+ cycles, fast charging, what's not to like?
Actually I have a LIMITED automation with the free inverter GPIO pins who allow a simple open/closed contact depending on how much power is available from p.v., with a bit of scripting to avoid oscillations due to a cloud passing by etc but the issues is still that almost NO APPLIANCE is designed to be piloted like that.
Beside modern water heater nothing else is available on sale and even to simply "trigger switches by software" means pay not marginal prices for IoT devices like Shelly ones, who have simply too much stuff, starting from a webui, to justify their costs.
Even the simple, decades old modbus, is BADLY spoken just by few devices, MQTT even less...
Yes, I know what you're up against. It is quite frustrating. I have a habit now of testing new appliances by pulling the plug on them mid-cycle and then to plug them back in again to see if they will continue where they left off, do some graceful recovery (for instance: if the washer will re-heat the water or continue to work with cold water instead). Found a couple of positive surprises and an endless list of disappointments but you only really need one of each to get to a workable solution and this sort of brute force allows you to retrofit remote control into anything by virtue of a powersocket with a local internet hookup.
I can definitely recommend the 'Shelly' stuff, it's been absolutely problem free and super reliable, they have a nice range of sensors and controllers.
Essentially what I want is moderately simple: appliance vendors should offer an optional remote control of the machine, a simple ModBUS, like "hey, if you want, pay this and get a small card allow to replicate/bypass the physical knobs/controls of the appliance, so you can automate it/control it from remote, WITHOUT adding crappy cloud-based services, of course.
Some actually have happened, like minisplit with optional remote control module to be installed easily lifting the front top and some hot water heater, but such controls are still very rare and damn limiting...
A small example, I cite it because it's not on sale anymore (there is a slightly updated version, with a different name) my home hot water is made with a Daikin/Rotex M2O EKHHP it feature a "renewable integration" witch consist in two dry contacts who allow just to tell the machine:
- do not run
- run as you want
- run full power (heat pump, if possible PLUS classic resistive stick)
- run for an hour with heat pump only, then full power.
Those who design such logic have NO IDEA about domestic p.v. self consumption. Why the hell such logic instead of:
- do not run, except antifreeze
- do run full power (heat pump and resistance)
- do run ONLY in heat pump mode if possible
- do run ONLY with resistance
My actual "solution" is:
- knowing the outside temperature in HA, so being able to decide if I can run the heat pump or not
- decide to trigger the "run for an hour with heat pump only, then full power", switching to "do not run", switch again to "run for an hour with heat pump only, then full power"
just to limit the load to ~600-800W of the heat pump, BUT for instance sometimes I can use more, like the 2kW resistive stick BUT NOT 2kW+600-800W and for that I have no option. Sure it does not change my life, but it's absurd. Why not give such simple controls?
My VMC is even nicer: it have a range of ModBUS controls, with some registers badly enough documented I can't understand what they mean, some not documented but understandable through observation manually command the machine via it's own keyboard/display.
I've decided to buy an absurdly expensive EV domestic charger from the same vendor of my main home inverter, a Victron EVC. It claim formally to be integrated. Actually in p.v. mode all it do is staring a charge at 6A if there is at least them available from p.v. of course if there is room to more amps no way to change them, it seems to be hardcoded. Only option use the manual mode driven via ModBUS from Home Assistant. At that point I do not even understand the dams logic, the only thing better than a far cheaper charger is that it's three-phase, I have a 3-phase 36kVA domestic contract so if I need a quicker charge I can run around 7*3kW from grid. But that's all. Other domestic chargers for EVs are not better and still with absurdly high price for a simple metered socket with some extras on a mini-board computer, something who can cost around 30€...
> And even for grids where blackouts are infrequent, if your car can serve as large UPS for your house (combined with a large capacitor to keep the power stable), such functionality in the charger may be worth the cost of the hardware for many people. (Bringing the number of units up and hence the cost per unit down over time.)
> Warranty Limitations
> This New Vehicle Limited Warranty does not cover any vehicle damage or malfunction directly or indirectly caused by, due to or resulting from normal wear or deterioration, abuse, misuse, negligence, accident, improper maintenance, operation, storage or transport, including, but not limited to, any of the following:
> Using the vehicle as a stationary power source
> All model year 2013 and newer Nissan Leafs are approved for use with the FE-15 bidirectional charger, and the automaker states that battery warranties will not be affected.
> Ideal for companies with fleet vehicles, the Fermata Energy Demand Charge Management application, along with the FE-15 charger, continuously monitors a building’s electrical loads, and may draw on the Nissan LEAF’s energy to provide power to the building during more expensive high-demand periods. In states with utility demand response programs, bi-directional-enabled Nissan LEAF vehicles (MY2013 and later) are able to safely send energy stored in the battery to the grid during peak energy demand times, such as in summer months.”
> The downsides to V2G tech are that it must degrade your battery (to some extent or another) to be discharging and charging more frequently, and it leaves your battery with less charge at times when you may wish you hadn’t discharged at all. Some people will always take that tradeoff, though, and it is great to simply have an option on the table for consumers who really want V2G tech. Stay tuned and watch this space.
> The article on the Fermata Energy/Nissan announcement is not quite correct. It’s for commercial use only – not residential. The Nissan-approved FE-15 bidirectional charger is available for commercial and government fleet owners. https://www.fermataenergy.com/fe15-sales
The other part is that this is grid supplemental charging where there is already a steady main current to be matched. If you are using it to power an island (home or similar disconnected from the grid), it is a different situation and would require completely disconnecting from the grid with safety cutouts to make sure that when the grid comes back on that the systems are not out of phase and damage equipment.
Grid storage is a different (and arguably easier) problem than home backup in the case of a blackout.
V2H system with grid power outage support is available in Japan for a decade. I don't know what's the blocker in the US.
The cars need to be designed in a way that facilitates that rate of discharge. Not all electric cars have been.
There needs to be a specialized charging (and discharging) setup in the garage. People who charge using a regular extension cord without installing additional hardware will not be able to do V2H or V2G.
The charging setup needs to be able to cut off power from the grid to the home. This involves a more extensive modification to the home's electrical setup. Note that there's a different culture with housing in Japan.
> An unusual feature of Japanese housing is that houses are presumed to have a limited lifespan, and are generally torn down and rebuilt after a few decades, generally twenty years for wooden buildings and thirty years for concrete buildings – see regulations for details. Refurbishing properties, rather than rebuilding them, is a relatively uncommon practice in Japan, though its prevalence is increasing, indicating that attitudes towards older houses may be changing.
> The taxable value of a house is controlled by its building material. Wooden houses are considered to have a lifespan of twenty years, and concrete ones to have a lifespan of thirty years, and the assessed price depreciates each year contrary to housing markets in other nations.
This means that basically every 20 years the house is rebuilt and you've got more recent electrical setup. If you're building/buying a new house in Japan and had an EV, the incremental addition to the cost of building the house isn't significant.
The house I am living in was built before electricity was available, had gas pipes to each room for lighting (though not in use), and had functioning knob and tube wiring as recently as 2010.
I do look at a home generator (and the corresponding changes to the electrical wiring needed) - but that's not a small change. If I was getting an EV, and considering V2H as an add on, it would likely not be something I'd do.
V2X (vehicle to grid, home, or load) is pretty new, but there are some vehicles out there with it. Tesla is not one of them. They seem to be more focused on solving storage with powerwall. I don't know where that's good or bad, but I do wish I could use my Tesla to jump another dead EV.
>This functionality is already there.
Simple delayed charging with a timer is common, yes. The grid interactivity part? Much less so.
The few V1G pilot programs out there have been very encouraging.
>better to use dedicated batteries as part of the grid itself than to use car batteries
Fortunately, it's not an either/or. We can better optimize the total system cost by doing both.
We really just need a standard. The j1772 includes data lines. V2G is would literally be just controlling when the cars battery is connected to the charge circuit.
> Still, though, for grid stability it is probably much better to use dedicated batteries as part of the grid itself than to use car batteries.
Why? Every kwh we can store using car batteries is a kwh of dedicated grid storage we don't need to purchase. It can increase the speed we add new storage on the grid. It is a more efficient use of lithium and other precious metals. This "smart charge" or "flex EV" is the type of incentive utility companies can push, and something that would decrease the amount of capital investments they need to make.
I can imagine a few counter arguments for why dedicated batteries are better, but nothing that convinces me. This claim that dedicated batteries are better than car batteries has little support in your comment and I would like to understand why you believe this claim.
Mainly because the main long term cost for batteries is wear due to use. Expected lifetimes for cars match their expected lifetimes relatively well, so if car batteries are used at scale to feed power back to the grid, the probability increases that the battery will need to be replaced. (And sooner).
Then there are the efficiency downsides. Storage "at the edge" means more transmission infrastructure is needed, on average, compared to more centralized storage. Also, grid batteries can be optimized for number of charge cycles, not for charge amount per unit weight. Finally, servicing individual cars is probably more expensive than replacing batteries in a storage facility.
And this is before going into inconvenience aspects, such as risking that your car doesn't have a near-full charge when you need to go on an unexpected trip, or the hazzle of handling the payment agreements, etc, just for a couple of dollars per day in potential revenue.
In computer terms, it's kind of running mining software on your computer GPU at night. For those especially interested, it may be fun, but for the average consumer, probably not worth bothering with.
This can be done by using a smart AC charger.
In europe (At least) the company Easee makes AC chargeres that are WiFi / 4G enabled. In Sweden (And Norway) you can connect them to a service like Tibber, which allows you to automatically enable/disable charging with the electricity price, assuming you have a spot price electricity contract.
Easee chargers also have a pretty bitching API, so you can also make your own automations using e.g. home assistant or what have you.
> 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 owners, because they will have economies of scale and battery banks designed for this use. 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. Or alternatively if getting 8c now is better than getting 1 charge in several years time (plausible if interest rates, energy futures prices etc are right).
However, this could be wrong. The same logic says rooftop solar can't exist without special subsidies, and a lot of people disagree with me there.
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.
This reminds me of how in Germany, before there has been a value added tax, there'd been a revenue tax. It was lower, but you had to pay it on every $ of revenue, even if your profit margin was very small. So a lot of businesses started to vertically integrate. Once the system switched to one where you get back the tax for the things your business buys, businesses got broken up or grew in only one of the steps of their supply chain.
> 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.
If you completely neglect the installation part, sure. Utility-scale solar farms have massive efficiencies of scale on purchasing panels and on labor-related overhead.
It's not that clear cut, basically.
I think what the EV model allows is for private car owners to essentially sell a part of their car back in increments, if for some reason their driving behavior changes and they don't need to drive as much as they used to.
> Rooftop solar outcompetes solar farms because energy from a solar farm pays taxes and distribution costs before it is delivered to a user.
This depends where you live and the size/efficiency of your rooftop setup, right?
Power has two big costs: generation and distribution. Once rooftop solar power is below the cost of distribution it doesn't matter how much it costs to generate power; rooftop solar is always going to be cheaper.
That milestone has been hit in some places Australia already.
I don’t quite buy your argument.
If the system still depends on distribution, someone has to pay for it.
It may be that rooftop solar users will be asked to pay more for that distribution than they think is reasonable.
I’m sure not excited about my grid operator proposing a $50/month minimum for electricity, it makes my panels seem worthless. But there is logic; I was being subsidized by net metering. And in future I may have to pay a cost closer to the true cost of access to the stability of the grid.
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
I think you may have missed the point here.
Rooftop solar is heavily subsidized almost everywhere it’s popular. Rooftop solar isn’t a good deal for utilities or their non-rooftop-solar customers.
I say this as someone who lived off the grid on solar for years; encouraging rooftop solar may have kickstarted the learning curve for the solar panel industry, and as such may have been pretty good social policy.
But it definitely owes its existence to subsidies.
These days grid scale solar makes lots of sense, rooftop solar still doesn’t (and the subsidies are now harder to defend).
There are special subsidies for rooftop solar here in the US (Solar Investment Tax Credit). Are there not subsidies for solar where you live?
> The solar Investment Tax Credit (ITC) is one of the most important federal policy mechanisms to support the growth of solar energy in the United States. Since the ITC was enacted in 2006, the U.S. solar industry has grown by more than 200x - creating hundreds of thousands of jobs and investing billions of dollars in the U.S. economy in the process.
The same link says:
The Section 48 commercial credit can be applied to both customer-sited commercial solar systems and large-scale utility solar farms. The rate is effectively at 30% until Treasury issues guidance on new wage and apprenticeship standards. Two months later, the rate will be at 6%, with an additional 24% (for a total of 30%) available for meeting these new labor standards.
So utility-scale solar farms can get the same 30% credit as rooftop solar. They're both tax-advantaged compared to (e.g.) building a new gas plant, but the rooftop credit isn't any higher, at least not on the federal level. Self-consumption from rooftop solar may avoid other taxes, like sales tax, but in many states there is no sales tax on residential electricity to begin with.
The interesting question of there being a subsidy for rooftop solar is the difference in subsidy to me between my roof having solar panels or my roof not having solar panels, not between my subsidy for my roof having solar panels or someone else's for their field having solar panels on it.
Subsidies are a terrible way to run energy policy because they can change quickly with politics. Big players stay away from big commitments to subsidy based markets.
Subsidies of “do this this year and we’ll pay you $X” work and are relied upon. Subsidies like the CF that was the SREC market are indeed highly suspect and should not be relied upon, as generators of SRECs can attest.
Not any more, other than no sales tax on the panels.
It's part of the "Inflation Reduction Act of 2022" (and at a higher rate than before): https://www.solar.com/learn/inflation-reduction-act/
That's a foreign law applying to a foreign country
>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.
"X cents per charge cycle" is a bit simpler than the reality. The actual wear cost of charging/discharging a big EV battery is cheaper in the middle and more expensive at the extremes.
I already have to own a car for short trips most days and an occasional long trip. And when I'm not going on a long trip I have a lot of extra battery capacity that I can rent to the grid at extremely low (additional) cost to me.
A dedicated battery storage facility on the other hand has to justify the entire price of the battery.
I took their numbers only as a simplified illustrative example to teach the idea.
A real deployed algorithm would estimate the "degradation cost curve" over the entire DoD, and stop charging when total (fully-considered) costs exceed revenue.
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.
This is “let a large entity suck up much of the arbitrage value, with a small fraction going to you”, and already exists in most countries.
Seems quite different from “your household is an autonomous actor and you get almost all of the arbitrage value of reducing peak consumption”, which would be a radically different system (but ignores who’s going to pay for distribution, which is getting closer and closer to being the dominant cost of the grid).
People value things differently. You'd have to pay me way more than the 8 cents/kwh it cost me to use my battery. I'd want to be heavily compensated for the inconvenience of replacing the battery or car prematurely.
If I had a LiFePo4 battery that's good for 750,000 km I'd be willing to accept less than 8c because there's no way the rest of the car is going to last 750,000 km.
You'd be willing to take around a penny per km of battery lifespan? I accept your decision at face-value, but it hardly seems worth it to me.
That might just inevitably conclude in "OK, I guess others are willing to ask a lower price than I am, so I won't be in a position to participate in a V2G scheme."
From GPs post its actually $5 plus 8c per KW.
That seems more reasonable for the owner, but no utility co would pay it.
Plus the reduced range between new and replacement.
Plus my time and inconvenience of not having full range transport at all times. The time of someone who can currently afford an EV is more expensive than the time of someone who cannot.
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.
Most cars use NCA or NMC chemistry which has 500ish cycles. Grid storage will soon use LFP which is cheaper to begin with and has 5000+ cycles. It has a lower density than other chemistries and very poor cold weather performance, making it less ideal for vehicles (though Tesla is using it in the standard range model 3 now). Those downsides don't matter for grid storage and really change the economics of charge/discharge.
> has 500ish cycles
That's on the low end, like if you're fully charging/discharging the battery frequently.
For grid scale storage Li-Ion is a transitional technology at best. It sees interest right now because it's quick to deploy (unlike the much cheaper pumped hydro), and because so much money had been pumped into Li-Ion research and production that other battery technologies have a hard time competing.
If it turns out people don't need all the cycles out their car battery then there's value in capturing that, but new large scale installations will move to other technologies over the next decade or two.
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.
> 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
The problem is that capacitors (assuming you mean super and ultra capacitors) don't have much capacity compared to batteries, so their cost per MWH of storage is high even if their cost per MW is low.
The idea of super-capacitors in cars is positively horrifying, knowing how explosive just the small ones can be. At grid level though, is there anything that speaks against them?
Edit: to answer my own question, they look pretty good . Significantly lower storage density than batteries (roughly 50Wh/L versus 420Wh/L for Li-ion), but still dense enough for this to be workable at grid level. The linked presentation proposes converting decommissioned power plants into grid-level capacitor storage facilities, since the transmission switchyards are often intact. Furthermore, all the technology is available today, and when built, capacitors require almost zero maintenance.
Todays grids don't have much need for energy storage on the sub-10 second timeframe. Ie. there is rarely any money to be made by taking power from the grid now and returning it in 10 seconds.
For technical reasons, thats because the 'spinning reserve' - which is momentum of every synchronous motor and generator across the nation - already adequately handles this.
Also, large generation stations are required to have a 'load line' which damps high frequency oscillations. The load line can best be described as 'whenever the grid frequency starts slowing down, generators must put more energy in automatically'. Things like wind and solar typically don't have the ability to do that.
For human reasons, it's because electricity markets tend to be minute by minute at most.
For all those reasons, I don't think you'll make any money with capacitor energy storage banks (not to be confused with capacitors for grid scale power factor correction, which can be profitable).
Isn't it expected that 'spinning reserve' will be decreasing because we shutting down dirty power plants? Possibly it is needed in the future.
capacitors are very low energy density and very high cost per joule of storage so they are never used this way
There are various niches in grid storage.
Li-ion are good for frequency stabilisation: initial response times of the order of ten milliseconds, run times up to several tens of minutes maybe.
For longer durations, flow batteries and other chemistries are probably better. They win because of very good cycle life and calendar life (20_000 cycles, 50 years) but tend to take longer to start up.
Flow batteries include vanadium redox, zinc-bromine, iron-saltwater (being piloted). Other chemistries: sodium-sulfur (NaS, developed by NGK and sold by BASF in Europe/NA), carbon polymer based (PolyJoule), and a great number of experimental types.
There are also thermal batteries and compressed air energy storage, and pumped hydro.
Pumped hydro is by far the biggest form of grid storage today and is not as limited by geography or cost as one might think. It can be used in the "hours to months" range of energy delivery durations.
These up and coming battery types look fantastic, but everyone seems to forget that lead-acid batteries are already way better than Li-ion or LiFePo for non-mobile energy storage, in terms of price per kWh stored.
Let's hope you don't need to go anywhere urgently in the middle of the night... oops not enough battery to make it!
This is why you have an "always charge immediately to X%" option in the UI. You set this to whatever range an unexpected trip might require.
If your life is so chaotic that this doesn't work for some reason, don't turn on V1G
The spread between wholesale energy prices between high and low renewable times (with low-compared-to-future renewable penetration) is around $20/MW (it’s not $2 and it’s not usually $200), or about $0.02/kwh, so this isn’t a viable return. I doubt selling into the grid will ever get you retail prices in return (someone had to maintain load power lines).
I think people worry a lot about market access when it doesn’t make sense. The market operators cannot handle the settlement and operations overhead of microscale power generators. They are not offering reliable commitments, and the metering just doesn’t exist at the small scale. Your local PG&E equivalent isn’t equipped to operate an efficient power market, I don’t think.
For context - a “small” scale solar power plant is in the 10s of MWs, which >1000x bigger then a car battery at full output. Utility-scale storage is also in the same ballpark.
> A 60kwh car battery might cost $10k, and allow 2000 charge cycles
After those 2000 cycles is the battery completely dead, or does it still work but at a reduced capacity?
If it does still work at a reduced capacity, does continued use reduce the capacity to 0 after a while, or does is plateau at some fixed reduced capacity and stop further degrading?
It may be calculable, but is it economical? That 8 cents isn't free. If the power company pays, that means customers pay. If customers don't pay, society has to pay. There are other power storage solutions like pumped hydro that don't have to deal with battery chemistry degradation, for example, but they have higher investment costs.
This study is great but a energy storage comparison study that calculates total cost would tell us much more. Wouldn't be surprised if the Department of Energy already has or is 
 They do a lot of these studies already. i.e. https://iea.blob.core.windows.net/assets/ae17da3d-e8a5-4163-...
Here in EU, day ahead prices that are available to me as consumer are now ranging from €0.18/kWh to €0.34/kWh in the same day (winter). So that is 16 cents per kWh diff to profit from. I guess there is some energy loss with charging and de-charging.
Since prices a per day, announced the day before, the algorithm is not that complicated.
Also, if I install solar panels, the electricity just goes back into the grid, and I would get money for it. For the car it would be the same, just reverse the electricity into the grid. So it is mostly just the connecting the day-ahead prices, plus the cars and wall chargers returning electricity of-course.
> 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".
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.
The number of cycles a battery can sustain strongly depends on its state of charge and depth of discharge. A cars battery can cycle between 30 and 70% charge for 20000 cycles or 0.8 cents/kWh according to your calculation.
Now that's an interesting idea. Let's see how it will unfold globally. Maybe it will indeed be painless feature.
The way I read it, the paper is more interested in what happens to EV batteries when they drop to 80% of the maximum storage capacity. If I understood them, they're saying that at this level, the battery is no longer suitable for transportation purposes. So what do you do with the old battery when you replace it?
They're suggesting using these extremely expensive but no-long brand-new batteries for additional grid storage. Take the battery you don't use anymore, and instead of paying someone to dispose of it, plug it into the grid and get paid for its use.
Modern fluid cooled batteries (Basically anyone but Nissan I believe?), the battery should last the life of the car. You would only really have a spare if
1) The battery gets damaged or the car is totaled (in which case, you might not want it)
2) The car is 20 years old and done with life
The reason they use the 80% mark is that Li-ion batteries tend to rapidly degrade after they reach that point, so once they get there it's best to replace them.
> Aren't people wary about using their very expensive car batteries for the grid?
As an EV owner, no.
We need to own a car due to having kids, we happen to have gotten one with a pretty large battery so we can easily use it for road trips too. Also because there was only one choice for battery size with the model that suited us (Ioniq 5)
But I live close to work. I fully cycle the battery maybe 2-4 times a month. I could easly double that and still not wear out the battery in the lifetime of the car. If not more.
This is in Norway, so I get that others wouldn't buy an EV with a large battery in that situation. But as EVs/batteries become cheaper in general, this will be the norm elsewhere.
And then you can flip the question on its head: if you expect to only use half of the life cycles of the battery within the lifetime of the car itself, isn't it incredibly stupid and waste of valuable batteries to NOT use it for V2G?
I suspect the cost equation will be benifical for car rental companies too, since they can get economies of scale when replacing the batteries.
> so if its lifetime will be shortened from I don't know, say 10 years, to 3 years
Uh, 3 years? Even my previous EV, a 2015 Kia Soul EV, with a pretty bad battery chemistry, only air cooling, and high cycling rate since the battery was small, is still in very good condition after 7 years. Even Leaf batteries without cooling have lasted 10 years.
First gen Nissan Leafs and Kia Souls are borderline unusable once their battery degrades to 75%, but new EVs with large batteries should still have useful range with 75% degradation, so using up the rated battery cycles (generally specified at the point where degradation reaches 80%) doesn't mean the car is dead.
Do the newer batteries even degrade past 50%? The first 10% happens pretty fast, but then the curve seriously flattens. I am not sure I could get to 75% degradation before the battery just gives up and dies of old age.
> 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 X%" and "Charge to Y% by Z:00." This avoids the problem where you find yourself without enough charge to get to work (or the local hospital).
> you will now see multiple 0%-100% charge cycles daily.
Even for V2G, why wouldn't there be a depth of discharge slider?
> if its lifetime will be shortened... then electric company need to compensate owners
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.
This should be the default after enabling V2G.
> The key is that you need a UI setting for "Immediately charge to X%" and "Charge to Y% by Z:00." This avoids the problem where you find yourself without enough charge to get to work (or the local hospital).
I would be happy to let the grid operator decide when to charge my EV, especially if I could inform them when I wanted charge by and have an override button to be ready for road trip departures.
I wonder how long it will be before the grid operators are subsidizing parking lot operators and businesses to install tons of smart L2 chargers so commuter vehicles are absorbing all the excess solar power available mid-day that would otherwise go to waste.
> 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 will ever work out.
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.
Thank you for posting this. This focus on V2G is nuts.
We move huge volumes of our residential portfolio every day just setting EV schedules - enough that our total residential profile peaks at market bottom price hour nearly every day, even in winter with lots of ”dumb” heating load.
Very much not likely.
You have to realize how big the batteries are on EVs. It isn't uncommon to have 80 or 100kWh batteries on EVs (and that number is likely to go up.). Even small batteries are around 40kWh.
Average home energy consumption is 30kWh per day in the US. Meaning even for a small battery you are looking at a single extra cycle per day at most. However, if you are pairing your car charging with home solar then you are looking at a more ideal charge/discharge (Possibly keeping the car between 40 and 80%)
You're making very aggressive assumptions about amount of use the EV battery would be subject to, to the point of this being a straw man. You're right that people wouldn't agree to have their expensive EV battery trashed by multiple 0-100% discharge cycles daily. You wouldn't get any takers if that was your offer.
A more reasonable expectation is that people would lease a portion of their capacity. Say 20% for argument sake. You could even place other limits on it "never below 50% and above 90% on weekdays". In this example the power company gets to use between 50% and 90% state of charge in your battery on weekdays and pays you a small fee or other compensation in return.
You are missing something: lifetime depends on how much you cycle the battery. If you take the battery from 80% to 50% 5 times feeding the grid you do a lot less damage to the lifetime than just one 100% to 0% cycle, even though the first supplied more power overall to the grid. Smart management of batteries can ensure that this happens.
For some really complex lithium battery theory, if you have no long trips planned, the battery will have less wear sitting at 80% than it will sitting at 100%.
Tesla UI in fact warns you if you set the charge level to more than 90% for more than 1 day in a row. 90% is the value they suggest.
I have so far "babied" my battery and max charge at 70% outside of road trips. So far, my degradation is right on track as average, which I assume is people doing the 90% charge trick - so trying to outsmart the battery hasn't worked for me yet.
Car batteries are not really comparable to cellphone batteries. Even among "lithium" batteries in cars there are multiple chemistries with different longevity and trade-offs (e.g. LFP can be kept charged at 100%, while NMC would rather not).
1. Cars have advanced battery management system with heating and cooling, which noticeably improves the battery life (e.g old Teslas have lost 1%-2% capacity per year over a decade, while Leaf about 3% per year, most likely due to lacking liquid cooling).
2. Cars won't let the battery discharge to 0%. Modern EVs even have an inaccessible reserve, so that when the car shows 0%, it's actually ~5%. Cars with vehicle-to-load/vehicle-to-grid typically stop giving power at 20% state of charge. Slowly cycling around 50% is quite gentle for the battery.
3. The grid just has to pay more for the storage than the cost of battery wear. The "duck curve" means they'll want to pay you to take electricity off of them at noon, and pay you a premium to get it back in the evening peak time.
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.
Well the ones with li-ion batteries ought to last at least 2000 cycles, or about 6 years with a cycle each day, but there are lots of mid tier models being made with lifepo4s now, and those last like 6000 cycles, so there is far more breathing room. They're also cheaper so you may be able to more easily break even.
That just means people will buy daily drivers with small batteries and charge them nightly. 15 years out of a cheap compact car with near zero operating costs sounds like a good deal, still does not make sense to waste a cycle for $1 = 20kWh fed into the grid.
The important part is that it isn’t necessary for people to use their cars for the _public_ good for this idea to work.
If there's an economic incentive for EV owners to use V2H to reduce their _own_ load during the time of low generation (and thus high prices), then the setup would already do a great job at balancing the grid.
People aren’t dumb and will be able to figure out where the break-even point is and at what price point it makes sense for them to discharge. Today the only problem is the availability of the V2H tech. My belief is that the _only_ important change that needs to happen is a govt. mandate for V2H support in vehicles and home chargers. Supporting this is quite cheap, and today’s implementations of V2L/H are just price gouging on the novelty basis.
Aren't people wary about using their very expensive car batteries for the grid?
In short, no. I have a 10 year old Leaf that has been on a V2G trial for the last 3 years. (I also work for the company that built the charger.) The battery is not being deep cycled; it goes between roughly 30% and 90% state of charge. The trial has found no clear evidence that it ages the battery at all. In fact, it appears that this is better for the battery than regularly fully charging it and letting it sit. Calendar age appears to be the biggest cause of battery degradation along with deep discharging and rapid charging (which this isn't doing).
In California, recently approved NEM3 makes people involved in the energt market - paying or earning rounded rate for that specific hour.
Few hours during summer months can earn you $1-2 per kW, so single discharge of EV at that time would earn you $100-200, easily outweighing the cost of degradation.
New rule has been strongly criticized about being more costly and disentivizing solar, but the one thing it does right, is insentivizing end users to do a propertine shifting of their usage.
>Aren't people wary about using their very expensive car batteries for the grid?
EVs have mostly not yet filtered down to the socioeconomic rungs that have reason to be skeptical of things by default.
Based on what we know about EV battery lifetimes so far and how graceful their failure is I think your concerns are unfounded though.
The problem is that the battery is not the only expense on the car. You have to depreciate the vehicle's value too, because there is a good chance a BEV will be disposed of rather than have a battery replacement.
Say the lifespan of a battery is 10 years. If you lose 10% of the charges for grid storage you're looking at replacement at the 9 year mark. Until we know that the vehicle itself will be reusable at that point you need to depreciate the battery usage against the cost of the entire vehicle, and be compensated for it.
depends on how much the demand is. If all they have want is (collectively) a small drain (less than 1-2%) once or twice a day then why not? Especially if there are some incentives provided for the same.
I admit I don't know much about power grids, but I heard that they are structured in a lot of smaller zones, so if there is a local drop in the generation due to accident then probably only close EVs will be discharged, but by a lot, to compensate.
I would never voluntarily use my vehicle to charge the grid.
I might use my vehicle to power my house, if the grid is down. But there I would prefer to have batteries inside the house that are used for that purpose, and backed up by a generator.
The power that I would have in the vehicle is my last resort of getting out of the house, if things have gotten bad enough that the household batteries are drained and the generator is down.
I have a 6 year old EV with very minimal degradation doing all sorts of stuff that is frowned on: charging up to 100% all the time, using fast chargers regularly, and even letting the car sit outside on hot days (it does warn me if it's >100F to get it into the garage).
So no, I'm not really worried as I don't drive a Leaf and my car has industry-standard cooling system for the battery pack.
Well they're paying you. In the recent tesla powerwall virtual grid experiment people were printing like $60/day
We are not talking about multiple 0-100% cycles daily. The places where pilot programs have been run always left the car with some amount of charge so it can be driven, and you don't normally charge NMC car batteries to 100%.
Vehicle batteries have 8 year 100k mile warranties today, and those manufacturers who have spoken on this topic have said that utilizing your battery as grid storage will not violate the warranty (Ford said this about the Lightning, which can do V2G today.)
Please stop spreading misinformation and go do some research before you spout FUD like this.
Posting a question in an internet forum counts as doing research, surely?
It’s much more persuasive to allow reasonable-sounding questions to arise and receive polite, well-thought-out answers, as happened here, than to have everyone chanting in unison. The latter looks like a lie even when it’s actually the truth.
Starting paragraphs of misinformation with a vague question is not a get out of jail free card. That comment was full of misinformed nonsense.
Excluding Tesla: https://news.ycombinator.com/item?id=34518608
Perhaps you should do more research before ending a comment on such a condescending remark next time.
V1G to the rescue!
Existing Tesla cars can do V1G (grid-adaptive charging), but not V2G.
How far down do they discharge the battery, then? Like, how much range would you expect to have at the deepest part of the discharge cycle?
This is something pilot programs are helping to figure out. The ideal case is the driver can set minimum discharge as they can set a maximum charge (that's how it works on the Ford Lightning.) on top of that many EVs have the ability to set a departure time and the vehicle will ensure it is charged to your maximum level at the departure time.
I don't understand the discrepancy between EV kWh and house battery kWh.
Some cars have > 100 kWh capacity. Why do I pay > 1000$ 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/discharge speed relevant? Is the technology different? Are the capacities for cars just fake? Preferably I would want 200kWh or more capacity for my home.
$300/kWh for home storage is readily available.
Deep cycle lead-acid batteries are available around £100/kWh, and they'll last pretty-much as long as a LiFePo if managed sensibly.
> they'll last pretty-much as long as a LiFePo if managed sensibly
Typically lead acid lifespan is around 10x less than lifepo4, even if kept within spec.
But in practice it's hard to keep them in spec too, shit sulphates immediately when you look at it wrong.
LiFePo is maybe 10x the lifespan of a normal Lead-Acid battery, if you're cycling it several times a day. A car battery for instance will not do very well in this test. But I'm talking about deep cycle Lead-Acid batteries, cycled every day or couple of days down to 70% capacity (so using 30%). This is a fairly typical workload if you're (for instance) using it as a backup for solar panels. Under those circumstances, the LiFePo battery will die from time elapsed probably about the same time as or maybe even earlier than the Lead-Acid battery dies from cycle count.
Well that was interesting, I wasn't aware that flooded lead acid was that much better and that AGM just plain sucks in general, which was also my observation dealing with UPS batteries.
Still, I would've expected that ever increasing self discharge would've made them far worse in comparison since it gets worse as the batteries age and you can end up losing major amounts of charge to it. Not sure if that's not as much of a problem for flooded as it is for AGM but I haven't heard it mentioned in the rundown.
> so using 30%
In that case, they cost about $413/effective kWh.
Kind of. Consider solar panels. A lot of the time, you'll be using around 30% of the discharge capacity to keep you overnight. However, some days will be cloudy, so you might have to use more of the capacity.
In this situation, a Lead-Acid will have the full capacity that you bought, but will age like you're using 30% of the capacity most of the time.
Managing lead-acid sensibly in my experience means never letting levels go below 40%. Temperature too I suppose.
I didn't know they could last as long as LiFePo though. Is this really true?
If this is true, why don't we just use more lead-acid batteries then?
LiFePo can last longer than Lead-Acid. It depends on the usage.
LiFePo has a very high maximum cycle count. But after ten years, they'll die anyway. The only way that you can actually achieve a cycle count as high as the specification says is if you're cycling the battery two or three times a day, which I can believe if you're doing grid-levelling, but not if you're providing backup for your solar panels.
For lead-acid batteries, be aware of the difference between normal lead-acid, which are optimised for standby operation, and deep-cycle lead-acid, which are optimised for long life under regular cycling. Normal lead-acid batteries will die very quickly if cycled - they're designed to be charged all the time, and drawn on for very short period, like a car battery or a UPS.
Deep-cycle lead-acid batteries age by cycling, in contrast to LiFePo, which age by elapsed time. Their maximum cycle count is much lower than LiFePo, but if you're cycling them every couple of days, like in an off-grid solar project, and you're avoiding draining them below around 40%, then they can last 10 years.
So, if you want to cycle your batteries two or three times a day, then LiFePo is going to last a lot longer than Lead-Acid. But if you're cycling every couple of days and limiting the drain, then they can last about the same amount of time. It depends on the usage.
What helps with Lead-Acid is because it is that much cheaper than LiFePo, you can buy a larger capacity Lead-Acid battery for the same or less money, and then for the same performance requirements that larger battery will be drained less and at a lower rate, and therefore be less stressed and even last longer.
I think we don't use Lead-Acid as much as we do for several reasons:
1. Lead-Acid batteries have a reputation of flaking on us after a depressingly short amount of time. But that reputation has been earned from normal Lead-Acid batteries, not deep cycle ones.
2. People get scared by the lead in them, and how lead is toxic and we should be stopping using lead in everything. But really, lead in these batteries is not a danger to us, and Lead-Acid batteries are one of the best recycling success stories in the world. That lead isn't generally getting out into the environment. LiFePo batteries are much harder to recycle.
3. Electricians recommend installing expensive stuff, because then they get a bigger commission.
4. Lead-Acid batteries are commodities, but LiFePo batteries are new and exciting, and have aggressive marketing.
5. Lead-Acid are bigger and heavier for the same capacity than LiFePo. So, a LiFePo installation is going to look prettier in a nice consumer unit and be easier to install. They're heavy enough as it is.
This is very insightful, thank you. I guess for price per kWh, lead-acid is also still unbeatable. And as you mention, deep cycle can give good lifetime as long as you don't go below 40%. I see deep cycle batteries come in all kinds of voltages though - is there a preference? I've seen huge 1000Ah batteries with 4V or 6V.
> they'll last pretty-much as long as a LiFePo
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 basically give that away for free. There are reasons for that, but the most efficient way would be to use the energy yourself as much as possible.
Sure, 5kWH is enough to soften peaks and there could already be huge benefit to this. But a bit more capacity would be really nice to really safe the energy of sunny days. Reminds me if disappointing USPs that let me play Tetris for an additional 7-8 minutes before I feel like civilization has broken down completely until power comes back.
Phones are more like 10-15 watt-hours, not kWh.
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.
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.
Voltage isn't fixed across a discharge cycle.
As a chemical battery discharges, the voltage drops, so at the same load in amps you get less watts later.
edit: Wh is independent of voltage I mean... of course a product is dependent on its factors...
You're right, I mangled Ah and Wh in my head, sorry. 4V 1Wh battery and 24V 1Wh batteries are equally useful.
Your numbers are a little bit off though. I just googled some power bank (which is supposedly better than smartphone). It claims to provide 20 000 mAh at 5V. So it's 20 Ah at 5V or 100 Wh. I think most smartphones are around 10-20 Wh. Far from 5 kWh. But this discrepancy was already noted in other comments.
Those 5kwh "server" batteries are overpriced compared to prismatic cells and a bms.
They aren't when you factor in labor and the other components involved (wiring, breakers, terminals, steel box, etc). I've built my own system in my RV but will be going with racked batteries for my house due to how much time and effort they will save.
Part of it is cars get a bunch of free tax money, but most of it is that cars were at the front of the queue and locked prices in ahead of time (before the self same orders pushed prices up) and they have actual pressure to compete.
There are cheaper products, but reliability and trustworthyness is an issue. A good budget offering may decide to sell out their rep or start charging premium prices.
Budget offerings are about $250/kWh right now, or there are some for about $350 with cold weather protection.
In a few more years markets will mature a little and the price gap will be smaller.
They had better, with 230 wh/kg LFP and 150 wh/kg lithium-free sodium ion coming to mass production, and those chemistries are far safer than nickel/cobalt chemistries because they don't catch on fire, the "OEM" cost of a large battery pack will certainly drop under 100$/kWh, if it already hasn't.
With sodium ion the cost should drop to 50$/kWh.
I guess what might happen in a decade or so with EVs with "obsolete" batteries in the used market is that you just get a used EV and you have a powerwall and a secondary/tertiary city car.
What a wild and ironic twist if we actually get some increase in transit use because leaving the car at home pays for the ticket.
Either Chinese companies are reaping huge profits on batteries, or the American companies that repackage them into their bespoke platforms (EGo batteries don't work with greenworks or ryobi AFAIK because they put different plastic shapes around the battery cells so you're locked into their ecosystem for example) are reaping the profits.
Hopefully, 200-230 wh/kg LFP and 150 wh/kg sodium ion batteries should be a revelation in all use cases of batteries in the next year or so.
Tesla gets to operate at the extremes of volume, so they get to demand the best prices I would imagine, but the markup still seems astronomical in other things (like tools, home powerwalls, etc).
IMO there needs to be some governmental nudge. Battery prices (in theory) should be dropping in price such that many ICE-based tools will be fundamentally cheaper as batteries. An electric lawnmower shouldn't be more expensive than a very very dirty two stroke ICE lawnmower with the LFP/Sodium Ion that is coming to market.
But a lot of electric tool makers are using the reduced sound and superior torque abilities of electric tools as a price premium product. Things like lawnmowers and leaf blowers and snow blowers being high performance electric tools is like a "starter EV" for millions of Americans: it teaches them about recharging batteries, how EVs are better than ICEs in many ways (quieter, better torque, less smelly, no gasoline to spoil over winter) and how to deal with the annoyances (recharging).
The explanation is quite simple. Electricity from the grid is still very cheap. It therefore makes no economical sense to buy huge batteries for buffering your home solar panels. Since there is no demand, there are no products.
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.
> 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.
NEM3.0 doesn't make a battery a requirement to break even on costs, it just extends the payback time of solar without batteries by 3-5 years. It reduces the still absurdly long payback time of home battery storage somewhat, though. Only when you can sell power back to the grid with batteries at peak wholesale rates will batteries have anything like solar's payback time.
I've seen a lot of different numbers thrown around (and to be clear: I'm in Oregon and not part of the fight). Let it suffice that NEM3.0 makes the relative benefits of a battery for time shifting (and thus the costs of a solar system without a battery, as was typical for early installations) much, much higher.
I guess it depends on the rate structure you have. Higher rate variance between off and on peak periods definitely helps with the economic case for batteries, since it offers an arbitrage opportunity.
I haven't done the math yet to figure out how that variance relates to payback time for batteries, but would be a fun exercise.
Car manufacturers are buying every battery they can.
If we reach a point where there is an actual secondary market for used EV batteries, the house battery market will start to boom. But 10+ year old batteries are still 85-90% healthy mostly, so it might take a while...
My guess is supply constraints. Tesla would rather sell cars than Powerwalls; other suppliers can't make a dent in the market because EVs are slurping up all the capacity at every level of the supply chain. This really is only a guess though.
Tesla is supply limited, so they can put prices high. That's probably about it.
State level regulations around installation driving up prices?
Nope, not that. See my sibling response above.
As someone who recently self-installed home batteries (LiFePo), I learned quite a bit about what drives up prices. It's not regulation. If anything state incentives in California can drive down the prices (if you qualify for them), and federal incentives drop the price by 30%, thanks to the Inflation Reduction Act.
In my experience, the big cost with home batteries are the same things that make artisinal custom designed and built homes expensive: the labor cost of the complex system design, installation and integration, and the premium charged because they are still marketed as a luxury product, not as a basic home appliance.
Why the complexity? It should be easy to install batteries on a house, right? In reality, every house has an idiosyncratic set of challenges and decisions that need to be made when integrating battery storage: What loads do you want to back up, and for how long? Where will the backup sub-panel be installed, and how can the backup circuits be routed to it? Where is a safe location for the battery and the automatic transfer switch to be installed? They are all answerable, but there is no general solution and each one is on a case-by-case basis.
And yes, this all does have to meet electrical codes (which exist for a reason), and needs sign-off by local building authorities, but they are not the main cost obstacle any more than they are for any major electrical upgrade to a house.
Take away the "luxury premium" part, and this also explains why home rooftop solar will always be much more expensive on a per-watt basis than utility scale solar (and yes, utility scale solar doesn't include the cost of transmission, as with any grid scale generation source).
Compare that to an EV, where thousands are assembled with predefined requirements, a known set of inputs, all in a purpose built environment (a factory).
And even better, they come with a standard plug interface that we can use to send power back to the house or the grid! But hold on: if you want power when the grid goes down, you're going to need an islanding transfer switch and perhaps decide which loads to back up. I mean, do you really want to run your 40A jacuzzi heater or your 50A air conditioner off you car battery?
In an ideal future, every house would be built with a standard connector (analogous to USB for phones or EV charger standards) that you could just plug a stationary storage system into. The houses would also be built to include an automatic transfer switch that islands the house during a power outage, and a smart load panel that dynamically decides what loads to back up based on battery capacity and user preferences. But right now, no such standards exist, and no house is built from the start that way, so everything is an expensive retrofit.
House batteries are a much smaller market than batteries for EVs (at least right now). They also have other supporting components, safety features, etc. that add to the price. Since they’re normally installed as part of a solar install, they also usually qualify for a tax credit (between federal and state this can be over 50%) which further drives up the price because the vendor is able to capture a large chunk of the tax credit as profit.
Actually they require less safety features (they don't need to be crash-safe) and can use heavier batteries and components. Which should make them cheaper than EV's batteries in theory.
But that market is in early stages with all associated downsides of early adoption, I agree with that.
There are other features for a home battery. There are shutoffs. Each job is a bit custom on the install + electrician work. Retail markup.
You can use your car battery - though you will degrade that car battery much faster which is probably the battery you want to have better performance.
That's a failure of government with home solar.
Home solar + storage adds community-level resiliency in disasters and will reduce the grid load needed for home EV charging and industrial level charging used by electric tractor trailers. It should be a major complimentary effort of governmental policy along with grid scale solar/wind, grid scale storage, and whatever load leveling we can effectively decarbonize.
Good luck getting that through our deadlocked government.
Unless the $/kwh or lifecycle count of EV batteries change significantly, using them as a grid-scale storage is just not financially feasible.
E.g. a NMC battery has a lifespan of around ~2000 cycles, a model S 90 D has a 90 kWh battery. That's around 180 MWh of total energy that can be moved through the battery before it is dead.
On Reddit, a tesla user reports (https://www.reddit.com/r/teslamotors/comments/v4dqkp/19000_n...) it costing him 19 000 USD to replace a 90kWh battery in his model s.
This means that the replacement cost of the battery for the owner costs ~ 106 USD per MWh hour, which is more than most generation sources (https://en.wikipedia.org/wiki/Cost_of_electricity_by_source#...). In other words, it's cheaper to build and run a natural gas power plant than to pay EV owners for the grid-scale storage capacity from the NMC batteries in their cars.
Battery lifespan in 'cycles' is kinda simplifying things too much.
Most batteries, if charged and discharged slowly, in the right temperature range, and while keeping the charge between 40 and 60% capacity, get far higher lifetime than the advertised 'cycles' number.
The damage and degradation happens mostly near 0%, near 100%, when charging/discharging fast, and when excessively cold or hot.
Cell balancing becomes less important when you're not nearly full or empty, and balancing wastes quite a lot of energy - making the battery more efficient when used between 40-60% too.
During most of last year prices in Europe were routinely over 300, 400 even occasionally over 1000 per MWh because there was an energy shortage. At the same time the prices can easily go negative if the conditions are favorable for renewables. It's not crazy to think that you would be paid to charge your car when there is an excess and then get paid a lot when there is a shortage. I don't know who would say no to this deal.
My point is mainly that there are plenty of options available to stabilize grid prices that are way cheaper than using EV's. Europes energy crisis is temporary, over time the price fluctuations will go down.
That's actually not true. Let's say your calculation of ~100 per MWh for batteries is correct, we've seen that the wholesale prices were a multiple of that basically this whole year. Nuclear is above that price. I don't think anybody is seriously planning to use car batteries as the backbone of the grid, but as one of the last resorts yes. It makes sense for everybody.
which other options are feasible today outside hydro pumping?
Isn't that the big question? Whoever is confident that they have correct answer to that question should invest any coin they can get their hand on right this second.
Purely from a theoretical perspective, anything that can generate power at lower prices than the current market rate will be financially viable. With this past winters prices in Europe, it means literally anything. Even at times a diesel generator from your local hardware store would be a good idea (~.60 EUR per kWh).
But these prices won't last, in a few years we will be already back down to manageable price fluctuations.
It's pretty easy to see though that if battery based grid storage is going to be a big thing, it is not going to be EV batteries. The chemistry used in them is not optimized for life cycles (at least currently). LFP chemistry batteris that are in some Teslas has bettery cycle duration. Sodium Ion batteries will most likely be the choice for grid-scale deployment if they can be commercialized.
Of course at some point in the future if a lot of people with EVs say yes to this deal, the price range will narrow significantly, and eventually stabilize to the point where it's only just profitable given battery degradation costs. But it may take a long time to get to that stage.
- Read up on LFP. their cycle counts are far higher. and newer high density stuff is coming to market that competes with NMC chemistries from just a few years ago, and they are safer and more stable chemically, so less safety systems, so any density difference gets made up at the pack level
- replacement battery costs will probably drop a LOT in the next ten years. that quoted cost is $200/kWh, but Tesla is at $100/kWh (possibly less). That is a hell of a markup, probably reflects battery supply prioritization to new cars (Tesla gets more money if you buy a new Tesla rather than keep an old one running). So lets not treat this as some permanent condition. Sodium Ion batteries should stabilize at somewhere around $50/kWh I would guess, especially if they can get them close to 200 wh/kg, which is on the roadmap. And in 5-10 years there will be some solid state, sodium-sulfur, or lithium-sulfur battery that is even cheaper.
- Gas turbines still externalize their carbon emissions aka they don't pay for them. When will that madness change? Who knows. Another example of false economics. The only way I see gas turbines as a good thing is if it keeps the oil wells from burning off their excess methane for absolutely no benefit.
Maybe you are some astroturfer or not, but it is really frustrating talking about energy policy over the next 5-10 years and counterarguments are:
- this guy for this car got charged this price this one time anecdote that you know perfectly well is not representative of future costs and availability
- dude, lets burn more fossil fuels, it's "cheaper", which you know it really isn't
- let's talk about essentially outmoded chemistries and their problems, and ignore both current ones and ones that are scaling up production
1. A battery isn't completely dead when it reaches its cycle life. It's often defined as the point where the capacity degrades to 80% of its initial rated capaity. For an EV with a large battery, most of them will be able to continue to use the battery for a good while after that. A Model S 90D is still a very usable car for many people with even 50% range.
2. You assume that every EV owner will use many cycles. That's generally not the case. I use at most 2-3 gentle cycles (charging to 80%, never discharging below 20%) in a month on our EV. I have plenty of spare cycles in the lifetime of the car.
3. Time degrades batteries as well. For EVs with low mileage, you could be throwing away useful battery cycles by not using it for V2G.
4. Most batteries, by far, will not have to be replaced until the vehicle is over 10 years old. In 10 years, it might be far cheaper to replace EV batteries. Batteries will be cheaper and you'll have better economies of scale for replacements. You might get a better battery with longer range than when the car was new too.
I seriously doubt that V2G will cause a lot of people to have to replace their EV battery in the lifetime of the car. People who drive their cars the most will not use V2G because they won't have spare battery capacity. It might trigger one battery change, but then an EV might need a battery change at one point in its lifetime anyway.. and so it doesn't mattery unless V2G triggers the need for a third replacement. (In 10 years batteries might have longer cycle life too).
It's not cheaper to run a natural gas power plant if you want to be carbon neutral. Then you have to run it with hydrogen, which is quite expensive to make. It also gets more expensive if you only want to run the gas plant a couple of hours per month because at all other times renewable power is sufficient.
It is cheaper to run a nuclear power plant though. Like a lot.
Also uses about 50x less material per MWh
It's not cheaper if you only want to run the nuclear power plant occasionally.
> 106 USD per MWh hour, which is more than most generation sources
Minute by minute electricity prices vary really widely. It isn't unusual for prices to spike up 10x briefly at peak times.
Most power stations have too high a capital cost to only run 2% of the time... whereas your tesla battery has no capital cost, so using it to power the grid 2% of the time when the prices are sky-high is very attractive.
So people being asked to discharge their Tesla into the grid should be paid a significant premium, right?
Since they are providing power on demand in a way that doesn't have upfront costs, that should mean that car-based power demands a cloud-like premium (10-50x over traditional servers) over traditional power plants.
They are getting a little premium today, but likely won't once this practice becomes normal.
It's a market - so whoever is willing to do the task for the smallest premium gets the business...
$0.11/KwH is super doable. Keep in mind that discharging is only necessary and profitable during peak demand, when prices are much higher than that. $0.50/KwH is far from uncommon. E.g. today energy peaks at €0.28/KwH in my area. It dipped at €0.17 so it would've already broke even.
Does the cost of the natural gas power plant include the green house gas costs it is emitting?
There are many estimates for the generation cost on wikipedia, at least the IPCC one does not try to estimate what the costs of the emissions would be.
And the price of the battery does obviously not include the generation costs of the energy needed to charge it, any charging/discharging losses, nor the infrastructure costs of a V2G setup.
So it's a very simplistic and incomplete comparison that gives a rosier picture of V2G MWh price than reality would.
Even if you completely do away with concerns of battery wear, I'd only be willing to participate in this as long as my household still had an ICE vehicle to fall back on. When I get home and plug the car in I don't want to have to think about whether I might want or need to leave the house at a particular time with a particular charge; I just want the charge to be as high as possible as soon as possible.
That is going to be an expensive habit in the future once time-variable pricing is the standard, which I think is inevitable. Charging your car at 6PM is going to be super expensive compared to 3 AM or 1 PM.
Also note you'll still have fast-chargers, you don't always need to charge immediately at full capacity at home, just as you wouldn't always top up on gas after every drive.
Just a note for any UK readers that this is coming in sooner than you think. There are already proposals on the Ofgem site to force mandatory half-hourly meter reads that mean energy companies can offer pricing that more closely matches demand.
don't want to be part of that? run your house off your EV and charge it back up at night. my house takes about 6KWh a day, so I could run it for almost a week from my car even if I didn't charge it.
All you need is a ‘no selling electricity today please’ button.
I use an app for my home heating that lets me define a schedule every day. If I'm going out I can turn it down or off, and if I have guests over I can boost the hot water.
It already has an EV charger plugin, so I'm in complete control of my selling energy back to the grid if I want to use it.
Some of the comments on this post feel like the "government is coming for your guns" level of foaming-at-the-mouth.
Remember the ultimate aim is to use energy more efficiently and reduce our dependency on fossil fuels, not make it pointless or difficult to live life.
Or "always leave me 150 miles of range".
At that point it's cheaper to buy a car with a smaller battery and use a stationary battery for grid storage.
I might want a car with 300 miles charge for vacations, but most of the time be making trips to the grocery store. The grid might only dip into my car's battery for a 15-30 minutes at a time to prevent brown-outs while power plants spin up.
There are plenty of scenarios where the EV makes more sense than a dedicated battery for it.
You might be at work (away with car) while the midday sun is filling your home battery.
Sure, if you have solar, by all means get a home battery and enroll it in the same grid backup program. Makes plenty of sense.
In my case, I live on a very shaded property; no solar for me. I also live next to an electrical substation, so extended outages from storms is highly unlikely; I'm first on the fixed list every time. In my case, the home battery doesn't make sense, but the EV might still.
EVs as grid storage is an option that may be compelling in some areas and for some people. I think that's worth exploring.
No. You are going to charge up for longer trips e.g. on holidays.
How do you know when it is safe to activate?
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 other, more sustainable overall, mobility modes become available and/or popular.
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.
> 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
Having chargers at the office is a thing. You could imagine grid operators subsidizing setting up EV chargers at office parking lots on the condition that they're V2G capable.
I wouldn't mind letting my EV charge at home at night and discharge down to, say 50%, at work.
Also, there's generally a big peak just as people come home from work. I could charge at night, discharge the first couple of hourse right after I come home, and then charge again.
I don't always drive to work either, I hope to take the bus or train more when kids are done with kindergarten (they can walk to school on their own). But this is Europe, I get that this is less realistic in USA.
You have some good points, but I think the next 10-20 years will be so critical for the switch to renewables that we can't afford to wait. If we can get some help from V2G until more permanent solutions are in place, why not?
Peak electricity demand occurs in the evening when people come home from work and start cooking and watching TV and giving the kids and bath and so on. Bring your car home, plug it in, and it supplies the grid at this peak time. Then it charges up again overnight when demand is otherwise low, and it is ready for you to go to work in the morning. As long as you have some charge left in your battery at the end of the day, it can work out fine.
Also, some of us work from home, or commute by public transit, or whatever, and only use the car on weekends.
Here's some data for your claim: https://www.eia.gov/electricity/gridmonitor/dashboard/electr... . Interestingly it does look like there's two peaks a day, 6-8pm when people get home and 8-10am as people are waking up. Weekend morning peaks are noticeably lower than weekdays too.
Yeah, the utility of smoothing grid demand overnight seems limited. Nighttime is when demand is least peaky. And if you commit to having the EV charged in the morning, you can't get net energy out which means it can't be used to compensate for lack of sun either. It doesn't seem to solve any problems that we actually have.
Peak grid load is not during the day when people are at work. It is right after they get home when their EVs would be plugged in. EVs can be used to soften this demand's load on the grid.
Doesn't the average US household have 2 cars? And probably higher in the households that can afford a new Tesla?
Battery swapping allows you to have both EVs and the benefits of decentralized stationary installations.
The "gas station" model of battery swapping has a number of features: lower sticker price on cars, key for mass-market adoption; expert battery pack charge and diagnosis, maintenance and repair; extension of pack lifetimes by offering cheaper rates to drivers who only want to go short distances and therefore can use old battery packs with only 65% of original capacity; easier power planning and control for distribution grid operators with smoothed electricty consumption and abillity to return energy to the grid in peak demand/low supply hours; easy revenue collection for local governments.
Battery swapping has a number of disadvantages: forcing all the cars to use a specific size and shape battery, which may not be great for packaging efficiency. Battery has to be physically more robust to be able to withstand regular handling. It has to be designed to be quickly detachable, because if the battery takes 20 minutes to take out, it's definitely not faster than just charging the thing.
I made this argument a few years ago when my wife asked me if it was a good idea for us to get solar panels for the house. My reply was that solar farms get economy of scale and would out-compete us, plus our roof views East/West, not South. Now that electricity prices have trebled, I have changed my mind.
The simple fact is that these static larger installations should be better, but they're not happening at nearly high enough rate, and so there is still benefit to be had by individuals installing smaller less efficient systems.
> This feels gimmicky and fragile
If anything is very much anti-fragile. Decentralized batteries would only make the grid more resilient both to outages and overloads.
my comparison is between EV batteries and stationary batteries, not a system without batteries (which is in any case unworkable if input is solely based on renewables).
a stationary distributed system seems superior in many ways to the mobile version (more capacity, more predictable in both charging and discharging schedules, potentially less costly battery technologies etc). if such a system happens anyway, I'd see the issue of linking the EV fleet as secondary
It is gimmicky but the batteries in EVs are really big and especially in the US everyone has a car. I don’t see a large amount of houses getting a 30-70kWh battery unless they install rooftop solar. So what are the realistic options ? Other than large infrastructure spend to get grid batteries which is probably what will happen in the end
> So what are the realistic options?
Maybe the utility companies could do their job and provide a reliable electricity source, instead of outsourcing it to customers.
> Companies could do their job
This is quite a naive view of how the world works.
Their actual “job” is to make the most amount of money possible.
A realistic option has to be one that is both technically superior and something a company is incentivised to do.
> Their actual “job” is to make the most amount of money possible.
That is generally true, but not of quasi-public utility companies. The government controls the price utilities charge, and could force them to invest in storage.
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 to load shift charging of EVs and use it as "storage" in that way. Its an easy load to shed when needed, and an easy load to ramp up when renewables are plenty.
> So EVs are still going to be a net energy consumer during the night, when you need the storage the most (no solar production)
Solar isn't the only green energy source, there's also wind, hydro, nuclear...
Historically, electricity consumption is low at night. With the conventional grid, nighttime charging is a net boom because it brings load when the grid has excess capacity.
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.
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.
When the Ford F-150 Lightning came out I was interested to learn that the battery was powerful enough to power a standard American house for over two days.
This made me wonder why new houses don't come with a battery built in, thereby making power outages obsolete. A battery that could withstand a 48-hour power outage without the occupants even realizing anything had happened seems like it would give the power grid a lot more flexibility and could be a real lifesaver in the case of natural disasters and other emergency situations.
Adding a battery would probably add $10k to the cost of a house, but for a home that costs $400,000, that is only 2.5% of the price. A smaller battery that just provided 12 hours of power might only cost $3k.
I'd be interested to hear from knowledgeable people what the downsides to this idea are. I suppose the battery might degrade over time, and it is likely it would go for several years at a time without being called upon.
I'm curious to see what comes of V2G tech and other home battery systems. I know that Panasonic & Enphase have their own systems rolling out. Adding these systems to new home builds makes a lot of sense to me in the interest of future-proofing.
Here's an interesting example where a new housing development in Las Vegas built all the houses with battery storage as well as solar generation for the entire neighborhood
Soon enough (2030+) someone's going to solve NIB batteries (mainly sodium refining, I guess) and a bit heavier, but dirt cheap sodium ion batteries are going to be everywhere.
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.
Cool, but will the energy company pay for the wear and tear? Do you get paid extra if you promise to not use your car between hours X and Y?
The way most energy companies work, they do indeed 'pay for readiness' - ie. they'll give you money simply to be available to deliver power, even if you are never asked to deliver power.
That is also usually a market - ie. power stations can bid to provide that service, and the lowest bids are selected.
The only thing missing is that little residential guys usually aren't welcome to bid... Usually there is something like a 5MW minimum to play the game.
an energy company paying customers extra? lolllllll. if anything they're gonna find a way to charge you for the privilege of giving them power
This is completely accurate. Often done by shifting the reported cost structure to claim transmission is vastly more expensive than generation. You are not doing transmission, they are so you pay them more.
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.
Exactly. This is just offloading of expensive energy storage to consumers, so energy company can show bigger profits.
"Quick, don't make the world more efficient! The wrong people might also benefit..."
This strikes me as the opposite of "planting trees whose shade you'll never sit under." If the latter makes civilizations great, where does the former attitude lead?
There is no reason to subsidize energy companies. They are operating renewable power plants, which have intermittency issues, they should be solving this problem. I don't see any reason why I should be part of their problem of their own making.
They solve their problem by paying me money. I'm fine with that. You don't have to get paid if you don't want to.
If you're a consumer in the UK, and thinking about an EV, consider Octopus Energy's Go tariff: https://octopus.energy/go/. They also offer a salary sacrifice scheme to buy EVs: https://octopusev.com/, because this grid-supplementing storage is part of their offering, I think.
Concerns such as, "will my car be charged in the morning -- or for that emergency hospital run?" are considered, I believe, and you can set things like a "minimum charge" with smart chargers.
So not only do the batteries lose 2.3% capacity each year, and lose up to 40% of their range in cold weather, but now the power company wants to drain your car battery at night to power other people's homes. What a comedy of errors!
Au contrarie, it’s a solution to bring grid storage online to offset some wind and PV intermittency.
That's just saying what I said in a different way.
I’d guess that vehicle-to-grid will get not get past small-scale trials. Not because of wear-out, but because the vehicles are probably not located at the most ideal locations for the grid operator.
> Before long, there will be more EV battery capacity than the grid can use
yes, but because nobody is deploying V2G at high density housing, and also because the grid doesn't have the capacity
Decentralized energy storage does seem like one solution to the mismatch between renewable energy inflow, and energy usage. EV batteries certainly have the capacity (har har) to support a household during the low-generation times or to "cut the tops" off peak demand.
This approach though presupposes that everyone lives in suburban dwellings with garages/driveways, which is at odds with the more sustainable, higher density living scenarios (eg, urban centers) where public transit / alternate transportation usage is higher, and there is less space for personal cars. Eg someone on the 5th floor of a walkup is not going to run a cable from their window to their car parked at the other end of the block.
I think solutions like the Powerwall (or other brands' equivalents) might be a better way to go.
Someone else's EV is going to charge mine at night
Yup. They’ll be getting paid a nice markup to charge their batteries cheaply during the day and sell it to you at night.
This would require quite a bit of hardware on both cars and houses to work. And in many ways doing both backup to the house and being able to feed into the grid is pretty damn hard.
So I will be surprised if this happens on large scale. This is an idea that sound great on paper but there are really a lot of practical issue between where we are now and in this ideal future.
What's hard about being both a house backup and a grid feeder? Seems like all that's needed is a smart transfer switch
Counter point, getting the resources for those batteries and building them has no small environmental impact - including carbon impact: https://www.theguardian.com/us-news/2023/jan/24/us-electric-...
> The US’s transition to electric vehicles could require three times as much lithium as is currently produced for the entire global market, causing needless water shortages, Indigenous land grabs, and ecosystem destruction inside and outside its borders, new research finds.
> It warns that unless the US’s dependence on cars in towns and cities falls drastically, the transition to lithium battery-powered electric vehicles by 2050 will deepen global environmental and social inequalities linked to mining – and may even jeopardize the 1.5C global heating target.
We definitely need to figure out grid scale storage. But I'm not convinced Lithium Ion batteries are the answer. And I strongly disagree with the idea that electric car batteries are the solution.
Arguing for car batteries to be a primary means of grid storage basically presupposes we fail to make the transition away from cars, which means we're committing to a much more difficult and expensive path to the carbon cuts we need to make.
It’s not just cars. How would homes store energy overnight without lithium? The current best available home storage is still lithium based (lithium iron phosphate).
Why do houses need storage? Why can't the grid operators do their job?
Pumped hydro is a practical grid-scale storage solution that doesn't need lithium.
 cost $4B for 24Gwh of storage. That's about the same as the cost of an equivalent amount of batteries. But it has run for 37 years. A battery installment would have had to be replaced at least twice.
This is never going to happen at scale. Energy is fungible: one cannot compete on "quality" of energy, just on price, a kWh is a kWh and the provider with the cheapest energy will always win in the marketplace. So this means any EV owner looking to make a profit is competing against large scale industrial storage entities that:
- have large mass and purchasing power, optimizing their battery purchasing and operational costs;
- have grid-scale storage oriented solutions tuned for maximum charging cycles and lifetime-storage
- use stationary batteries with no mass penalties, affording them the use of low density exotic chemistries (Na-ion) or non-battery storage systems.
Meanwhile, the EV owner has a mobility-optimized battery that is tuned for maximum density that still results in a cycle count comparable with the lifetime of the car. At market equilibrium, any revenue he extracts while serving the grid will reduce the useful life time of the battery and therefore depreciate his capital, and make his battery a "spare parts consumable" which is a major profit driver for most auto-manufacturers, especially a custom form factor battery for a 5 year old vehicle that is no longer sold.
Never mind that the whole operational cost, changing the meter to a bidirectional one, making sure the vehicle is connected for extended periods of time etc. is probably not going to be worth the pennies you will earn.
Grid storage is EVs is a decade old pipe dream, it will never make sense economically, it has been attempted multiple times and always failed, just let it die.
My electricity cost currently is split around 1/3 generation (~10¢/kWh) and 2/3 distribution (~20¢/kWh). If the power from this scheme can avoid most of the costly distribution, eg. I use it directly in my house and neighborhood, then it’s an economic win. This would be true even if the centralized generation was free.
It can't, because the distribution fee is an amortized cost of having distribution infrastructure built. Since that infrastructure still needs to exist regardless of where you get your energy (and in fact needs to be upgraded to handle bidirectional consumer/producers), EV storage won't bypass it regardless of where the EV and the consumer is physically located.
If you consume what you store, then you will charge up at low (production prices + distribution fees) for the times when (production prices + distribution fees) are high. The second term is constant so you are arbitraging on production prices.
> Energy is fungible: one cannot compete on "quality" of energy, just on price
It is fungible, but prices can vary according to limitations on supply. If the big company's capacity is maxed out and demand continues to increase, energy already acquired at lower cost and stored in the car can be sold for profit.
But if that limitation is repetitive to the point of investing in infrastructure to use EVs, then some other large-scale investor will close that arbitrage opportunity.
Basically, the next-day / week energy markets, where EV owners can compete, will be saturated by grid-scale battery operators. Renewables will leave large gaps for seasonal energy needs - for example two weeks of winter with no sun and no wind - but EVs cannot help there. So some spin on-demand non-renewables will need to cover that (i.e., the current main providers, after becoming too expensive to run due to carbon pricing).
It'll always be some marginal utility - the main purpose of the EV will always to be a car. You can use it to store energy purchased at non-peak hours so you can avoid using the grid at those times, something that'll probably raise peak prices, because if you need the energy right then, you really need it.
So, EV owners may use their cars to help reducing their energy costs and supplementing their PVs and fixed batteries (if any), but shouldn't expect a car to pay for itself like that.
But you will not use it if the depreciation on your car vastly exceeds what you could earn from the scheme.
I see, renewables will only leave gaps that fit your argument. You don't see any scenario where there could be brownouts during the day, say in the summer when AC usage is high?
And no, using cars for grid-scale storage has not been tried multiple times. The technology has never been available/feasible at a large scale before.
There is an economic case being made above that explains why, you might want to try and follow that and respond on point instead of mindlessly nitpicking.
There exist large scale trials for this idea, you never heard of them because (aside from the fact you are arguing on a subject you know little about) they failed or are barely limping along.
Let's get ISO15118 working at scale before we declare it essential. I'm not aware of any EV for sale today that uses it for V2G.
You might want to take a look at this - several production vehicles that are available near me have V2L (similar to V2G) support already.
This sounds like a great way to destroy the longevity of my battery.
If they want to use my car as grid storage, then the power company better pay to replace my battery, plus compensate me for the added inconvenience of having to perform that maintenance far more frequently.
It's a well known fact that cars stay parked for over 90% of the time, so this idea has been floating around for a while. The wear and tear issue is only a concern if nothing changes in the way we currently charge for electricity, e.g. a fixed price that gets adjusted from time to time. But I don't think we will -- even today we have more and more providers that charge with prices fluctuating hourly to reflect wholesale market prices. Thus if you can charge dirt cheap and sell it later for a large multiple more, you have a big incentive to do that. With the rise of renewables that basically looks unstoppable this will become a reality a lot quicker than I think a lot of people anticipate.
What a joke. Renewables intermittency is not a problem of a user, but problem of the operator of renewable power plant. Government should mandate that any renewable power plant must provide installed power (i.e. 100MW) for at least 24 hours without interruption, independently on weather and if it can't because operator cheapen out on power plant's energy storage, sanction them until bankruptcy.
What a joke. Every candy store should provide insulin free of charge for 1% of customers.
We already have that, like when store have obligation to take old electrical appliance for recycling when you buy new one.
Another olive branch extended to the auto industry
This seems like a massive waste of energy, why not just produce the amount of energy we need?
The demand for energy is highly variable. Without storage, the production capacity has to be overbuilt to match the peak demand, and then sit underutilized for the rest of the day.
Even with just fossil fuels, it's preferable to build a smaller power plant that runs 24/7 than invest bigger money in a bigger power plant and then operate it only some of the time.
See "duck curve".
No you don't have to overbuild? Just build enough load following.
Storage will waste massive amounts of energy through conversion