[brc]

>So if everyone had the cheapest Model S, kept it plugged in with the ability to send power back into the grid, and didn't mind that their car was sometimes down to 20% charge, you could power the entire grid on solar alone.

The OP said cost effective, not pie-in-the-sky.

Even if you took out the battery packs and sold them separately, the cost would exceed 10 years worth of electricity supply.

>Owners can be heavily compensated for pushing energy back into the grid.

You're asking people who cannot afford the expensive technology to subsidise those who can. This is the exact reverse logic of most progressive taxation regimes.

>The question is; would 5% of the driving population buy a $50k car if they no longer had to pay for fuel or battery packs? Financially that would probably put it closer to a BMW.

So you want to subsidise the purchase of expensive cars to the point where it is financially a good deal. This magic money no doubt comes from other taxpayers.

And for what end? Just so you can have some type of boutique distributed power generation system?

>What's needed is the will to make it happen.

No, what's needed it pots of other peoples money.

I've spent the best part of 5 years trying to hose down the jetsons fantasies of people pushing ridiculous schemes like this as not only unworkable, but inequitable for forcing up a basic cost input of life - energy - for effectively vanity purposes of a small subset of the population. I usually cop a pile of flamebait and downvotes each time, but I do so because there seems to be a mass delusion going on, and this has become one of those things you can't say.

[caf]

So you want to subsidise the purchase of expensive cars to the point where it is financially a good deal. This magic money no doubt comes from other taxpayers.

The proposal isn't a subsidy. It's a straight market payment for an economic benefit - the difference in cost between off-peak and peak electricity is real, and this means that storing off-peak electricity and releasing it at peak is an activity that's worth money.

I'm not sure I agree that the economics work out exactly as described, though - if it would be worth paying for everyone's lithium car battery packs to do this, then it would be even more profitable to build a giant lithium storage battery in a central location.

[reitzensteinm]

Well, the benefit is that it combines the capital costs of owning a vehicle and storing energy. Many people will be purchasing a 160+ mile range car, but day to day use only 20-30 miles of that - an unused capacity large enough to power an average house for over 24 hours.

This is in contrast to dedicated lithium ion batteries, which just don't work out economically. Otherwise you're right - the utilities would do it themselves at scale.

[caf]

I can see how that's true if the car owner's continue to pay the capital costs of the battery - the part I'm taking issue with is where you say that it would likely that the car owners would have the capital cost of their battery packs paid for by taking part.

[reitzensteinm]

My back of the envelope calculations elsewhere in the thread were $1571/yr savings per car (10% overall reduction in grid cost); the Model S battery replacement insurance is $12k per car, which is a ~7.5 year payback (by which time, they claim the pack will be at 70% effectiveness).

Elsewhere someone corrected me that the peak grid usage in a year is actually significantly higher - the figures I was looking at were average daily figures - which may make grid savings quite a bit higher than 10%.

I don't think it necessarily is a clear financial win now; I'm just saying, if you squint just right it kind of makes sense now, and with the march of battery technology and PV, not to mention the inevitable adoption of EVs whether or not this scheme exists, it's going to look better and better from here on in.

[caf]

No matter how you slice the numbers though, the fact remains that if it's economical to pay for someone's car-optimised battery pack, then it must be even more economical to build a giant fixed battery.

(Since we know that the latter isn't economical, then that also indicates a problem with your numbers - I suspect that for one thing, insurance couldn't be economically provided at $12k/pack if all of those packs were being used for daily peaking storage).

[reitzensteinm]

I suspect you're right, and it may well mean it doesn't make outright financial sense today.

The key is probably that the $12k replacement program is an investment in Tesla; they're cash starved, and are willing to sell the batteries at a loss in return for the cash advance. Also, they're betting on the batteries being ~half price in 10 years.

From further reading, they'd be $30k - 2.5 times the price - to buy upfront today.

But that doesn't mean that the subsidy doesn't exist - if 1% of consumers would buy a Model S due to its other advantages, maybe 2-3% would if that purchase returned $1500 a year back to them.

So while you're right that it's not outright going to pay for itself in 2012, it probably halves the gap between a Model S and a BMW in the same class, and it's only going to get better as battery/PV technology improves.

[Travis]

Wouldn't the increased cycling of the batteries significantly decrease their lifespan?

[reitzensteinm]

First off, I specifically said that the first lot of calculations was based on unreasonable assumptions, to gauge the size of the problem.

Attacking them because they're "pie in the sky" frankly sounds like you're deliberately misinterpreting me, or at least you didn't bother reading the post.

Secondly, the scheme I'm proposing does not require any government subsidies. The money comes from selling the power back to the grid.

With my proposed figures - 5% EV ownership (63,752 cars), 40% battery usage sold back to the grid, you could reduce peak power usage by 15%. South Australia spent ~$990 million on electric power last year (not exact figures; based on 619k households from the census with an average spend of $1600).

Assuming 15% reduction in peak power is a 10% reduction in cost (which is reasonable, because capital costs and fixed running costs dominate electric spending expenses), that yields $99 million a year in savings.

The cost of 63,752 Model S cars is $3.1 billion. However, you have to look at the marginal cost of purchasing a Model S, vs whatever car the high end of the market is buying anyway, AND subtract the spending on fuel.

We're saving $1571 per car per year. Tesla's prepaid replacement program is $12,000 (over ten years), which eats a big chunk of it, however we're also charging with cheap peak solar (the abundance of which is causing this issue to begin with), plus maintenance is cheaper.

BMW 5 series MSRPs are from $38k-68k. Taking the lower end of that, we're paying a $12k premium for a car with significantly lower maintenance costs and little to no fuel costs.

Could you get 5% of cars on the road taking that deal? I don't know. Today? Maybe, maybe not. But I do know that as the price of peak solar and battery technology falls, it will go from being a 'maybe' to a 'no brainer' over the next ten or fifteen years.

In any case, I may be wrong in my analysis. I'm merely presenting an argument for the way I see it. If you disagree on a specific point, I'd be happy to talk more about it, but nothing I wrote deserved your response.

[MikeCapone]

Power plants aren't free, people pay for the service they provide. If you can replace them with less expensive batteries (especially since people will be ready to buy electric cars for their main benefit, which is transportation -- getting paid to lease you battery is a side benefit) to store cheap solar power, that's a good deal, not a subsidy.

[brc]

>If you can replace them with less expensive batteries

Agreed. And when that is the case, then this behaviour will appear at large and be taken up enthusiastically.

At the moment this manifestly isn't the case (stored solar by batter cheaper than large-scale power), so any calls for it to happen is usually a disguised call to force it to happen by producing regulatory benefits to a small subset by driving up the cost for others.

I have zero problem with people electing to spend their own money on solar + battery storage. I find the tech interesting. I am simply determined to point out whenever I see this type of call that usually this means taxing poorer people to pay for richer peoples desires.

[MikeCapone]

Maybe I misread, but I think the OP pointed out that it could be done with today's technology, not that it could necessarily be done cost-effectively today. But batteries are improving and their costs are coming down, so it's certainly possible to predict that it'll be possible at some point in the not-too-distant future. When that happens, people will be compensated because it makes economic sense, not because they are subsidized into an un-economic activity (though that could happen too, but I don't think that's what was argued here).