There's lots of spare capacity in the electrical grid. It's built to handle peak load (late afternoon/early evening). This can be solved with simple economic incentives to charge more for electricity at peak times. The cars are already smart enough to be programmed to charge themselves over night. Plug them in when you get home, and then they start charging once peak is over, with plenty of time to finish topping up by morning (especially considering most people won't drive close to a full battery's worth on the average day).
The car batteries are really only stop-gap measures to allow the utilities to better match their plants with demands. It's for synchronization only.
A coal power plant might take several days to reach a "set point" and to generate a certain amount of power.
A natural gas plant might take as little as 5 minutes or as long as an hour to get operational.
A diesel generator might turn on and make power in as little as 30 seconds.
A hydro plant might be able to go from 0% to 100% in just a few seconds.
Given that the utility companies can't KNOW for sure EXACTLY how much power people will demand in the future they've always got excess capacity ready and waiting. But these idling plants aren't free and that drives the price of electricity up.
The idea behind V2G is that the utility companies can get some of their demand power from the cars whilst they fire up diesel generators or natural gas plants or whatever, thus saving them from having to keep those plants idling until they're definitely needed.
EDIT: The idea isn't that you constantly charge/discharge car batteries it's that you charge them in the morning after the drive to work so they're full by noon. Then as the day heats up you can pull small amounts of power from large amounts of cars until the demand is high enough that you fire up a peaker plant. Use that to charge the cars back up and provide the afternoon A/C electricity and shut it down as everyone starts to go home.
Instead of having the peaker plant be at ~20% capacity from 12-2, ~60% capacity from 2-5 and ~30% capacity from 5-7 you get to run 0% from 12-2, 80-100% from 2-5 and 30% from 5-7. Two hours of runtime saved per day is 600 hours per year. Turbine rebuilds aren't cheap; a buddy of mine is a private jet pilot and they have to put away between $500 and $2500 per hour that engines are running for overhaul at either 1000 or 2000 hour intervals. And that's for the kind of small engines in a 6-12 seater business jet. I'd wager that 20MW (~20,000 HP) natural gas turbines are substantially more.
That's why electrification of transport will be good for the grid.
Cars can charge at night, or any other time when energy supply is abundant and/or demand is low, and export back into the grid at peak times with V2G. Storage batteries on wheels!
You can drive your car empty faster than your home battery might charge (due to supply/demand), and it is possible to give back to grid if there is a peak in your area.
That works in a car because a car's energy demands are bursty. The power to accelerate the car from a stop comes from the battery and then the car's energy requirements drop by 95% and the tiny engine can eek out a little more than the 5% needed to maintain cruising speed and use the rest to slowly recharge the battery.
The power grid doesn't work like that. The base load is around half of the peak load. It never drops to 5%.
That doesn't mean the batteries can't be useful. If the average load is 150GW but that's because it's 100GW at night and 200GW during the day, the batteries let you get away with having only 150GW of average generating capacity instead of 200GW, because during the times when the generation exceeds the demand you can put the surplus in the batteries.
But you still need to maintain an average of 150GW of generating capacity or the batteries will get empty and the power goes out.
I think the electric car as dispatchable load holds the most promise. I don't know the physics of the batteries but I imagine that reducing the rate of charge of many car batteries would temporarily reduce demand without causing a charge / discharge cycle of the battery and would benefit the stability of the system in the short term if required
Edit:
Also using car batteries as dispatchable load and not dispatchable generation simplifies the problem for utilities. They still have to deal with increased load but not drastic changes in power flows.
That makes more sense as it can be better planned based on projected demand. They also have more batteries than customers. With individual car owners, they often can't charge when it's convenient for the grid because they drive their car and need it when they need it.
Yep that makes sense. That's one of the situations I was referring to when I said:
> let me be clear that I think using car batteries to time-shift load on the power grid makes some sense
Note of course that you could probably achieve something similar by just having teslas be smart enough to stop charging during peak times if the owner OKs it instead of actually discharging full ones.
I don't think using cars for grid storage makes sense since you do want to limit cycles. Giving those batteries a second live as grid storage when they're down to X% of capacity might be worth it though. Also yes shifting charging to low demand times will be a thing.
The idea is not to charge the e-cars overnight at home, but during the day at the company parkhouse or parking lots, so that the energy companies can unload energy during the peak hours from those batteries. That's the most expensive energy, and car batteries are perfect for that. Win-win.
Fully charged recently did a video on the city of Utrecht in the Netherlands where I used to live: https://www.youtube.com/watch?v=L_BYDKz3_Jg. They are implementing a plan there with vehicle to grid that basically boils down to having enough plugged in capacity at any time to be able to run the entire region for a while. The city of Utrecht has a few hundred thousand people and the wider region has closer to a million people.
Many people have the wrong ideas about the intentions of batteries on the grid. They are mostly used to deal with short term dips and peaks in demand and supply of power. A few thousand cars can provide a lot of power. Long term, we are talking millions of cars.
For reference, the Netherlands has about 8M cars on the road and a production capacity of about 35GW. If millions of those cars were plugged in they could easily keep the Netherlands powered for a few days even if all that production capacity was wiped out. That is of course not the goal and it would not be a good plan. But it's interesting that it could work.
A more likely scenario would be that those millions of cars would be used to deal with dips and peaks to the extent of a few hundred MW. Instead of switching on a gas peaker plant of e.g. 1GW for an hour or so, you'd instead end up draining less than a KWH per car over the course of an hour. The point of having that much capacity is not using all of it but being able to spread the load such that the load on each car is minimal. That minimizes the wear and tear on the battery and makes it easier for power companies to deal with even substantial demand peaks.
Additionally you can match local demand with local supply and not deal with efficiency losses associated with getting power from elsewhere; or worse importing it from abroad over long distance cables.
One thing to add: Electric cars. They come with energy storage in-built.
By rough calculation, if 10% of cars in my city (Perth, Australia) were electric, their batteries could supply the entire city's demand for duration of about 2 hours (or 10% of demand for 20 hours etc). This could work really well for demand balancing and peak shaving - overcapacity (which in Perth is massive, since the policy is to maintain supply even on extremely hot days, when demand shoots up and generation capacity goes down) and spinning reserve could be tremendously reduced.
I suspect some good software and a little hardware will be needed to account for the owners' needs optimally.
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