Hi fm, I think 94-95% is going to be the best converter efficiency and an ICE is around 40-50% if its a diesel, but otherwise I agree a PHEV is a user not a storage supplier and until we have PHEV's that have such large batteries that 75% charge gets you anywhere you want to go AND BACK I don't think they are viable. It's the power companies that want a way to make renewables work without investing in significant grid infrastructure themselves that are pushing this.
We need a viable working renewable energy grid and a similarly working renewable vehicle propulsion system but this will just sick millions out of the public purse without returning any real benefit.
If renewables and storage in batteries isn't going to work then we need to use renewables to converts power plant waste (ie. CO2) back into carbon so that the carbon fuel itself becomes a renewable.
The only other alternative (in the short term only) is to use Thorium reactors for base load and renewables up to 15-25% while improving user efficiency.
@naperlou, absolutely, and consider that a battery is only good for a limited No. of cycles, does that mean that because they wore your car battery out in 12 months instead of the the usual 6 years that they would pay 5/6 of the price of your new battery and fitting? I think that along with your reservations make this really a pipedream. A grid battery needs to have a really long life that includes 1000,s of cycles and/or be very cheap per kW and doesn't need to be light. None of these criteria are a match for on-board batteries. Telecoms companies used to have banks of lead acid batteries so that phones would work during a blackout, I don't know whether that is universally the case now but they were permanently on low float to extend their life. Grid batteries will be going through deep cycle almost daily.
The problem that is ignored with the idea of borrowing power is that battery packs wear out. Every charge and discharge cycle uses up some of that lifetime. Improper use uses it up much faster, but even following the very best practice, each cycle uses up some of the lifetime.
Would the utility be willing to pay extra for that portion of the lifetime that their borrowing power used up? I rather doubt that. Would they really be willing to only have a 3% drawdown on a charge? I doubt that even more. And what happens if I need to make a 2AM emergency run to the hospital with a sick kid? Woulkd the utility suddenly and instantly return the energy that they borrowed? They could not do it even if they wanted to.
Letting the utility take power from your battery does not make as much sense as letting a stranger siphon gas from your tank, except that I I am feeling really generous I may choose to gift some stranger with a gallon or two. But that would be my call to save a stranger in need, instead of a utility unwilling to cut off service to areas that have been drawing excess power. Let folks set the AC at 76 degrees instead of 67 degrees and the power shortage might be a lot less critical.
So the whole concept of the vehicle batery serving as a utility source is a bad idea.
It appears that some of the posts on here are a too little narrowly focused. Adoption of PEV's is still immature and infrastructure changes/modernization take time to implement. If one lives in a sparsely populated area, in the great frozen North, it would probably be wise to consider some alternate energy sources besides super long electrical transmission lines from a central power station.
The power grid has to under go some pretty dramatic changes to make it more robust and to increase capacity. PEV's, either sourcing to the grid or simply not sinking from the grid during peak demand, will play a role in this modernization.
These types of microgrids are the future of the power grid. Utilization of such systems will mitigate the need for rapid responses from large power generation plants enabling the overall effect of a much more stable grid.
In fact, power companies can (and do) encourage these investments on the consumption side by providing cost savings or other incentives directly to consumers. Natural gas peaking plants are a lot more expense to build, operate and maintain than providing cash incentives to consumers.
The owner of the car has an option as to what % of their battery charge may be used. 3% is the number I have seen. I agree 65% is too much for most people. In fact the batteries are generally replaced when they have less than 75% of their capacity, at which point they should be used for stationary grid stabilization, then recycled.
It's biggest value is in frequency/spinning reserve replacement, where the electronics can respond in micro seconds, better than any existing mechanical generator, long enough for the gas turbine peaking units to come online. I have read that some 30% of our electrical energy fuels are spent on spinning reserve and frequency control. That's wasted standby power, not the power actually delivered. Vehicle to grid and vehicle batteries to grid would eliminate that with better performance.
Rosek said "On-demand vehicle operation would still be possible, since the battery pack would maintain a minimum state of charge (probably no less than 65%)."
On-demand would be possible but even more limited than before so now your meager 80mile range is pushed down to 52, but wait their more many pack warentees only garentee 80% power of new battery (LEAF) so now that 80 mile range is 38.4. But wait their is more what if it is a hot day and you want AC or a cold day and need heat now you have even less.
just a bad IDEA.
I am not an EV fan but hey if you like EV's great but let the EV be an EV. The only time you should be using your vechile for power is when the CA electric grid starts to fail again and you have no power.
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