A reality check on plug-n hybrids

<div class='quotetop'>QUOTE(efusco @ Sep 25 2006, 06:46 AM) [snapback]324624[/snapback]</div>

Even with your criteria, you'd have to consider the energy cost of making and disposing of the batteries. The $ cost is a fair surrogate for the energy cost, so if you don't save money over the life of the vehicle, then you'd have to wonder if you're really reducing overall emissions. You may just be transferring emissions from where you are to where the batteries are made. And you'd better hope they're not using a coal-fired plant for their power there.

Having said that, I think that hybrids, even with expensive batteries, do in fact reduce emissions. Mainly because I think that the lifetimes being used for the cost-benefit calculations are too conservative.

As long as the batteries aren't made by Sony.

mark

 

<div class='quotetop'>QUOTE(chogan @ Sep 25 2006, 01:00 PM) [snapback]324761[/snapback]</div>

I must have owned 11 cars over the years, and only one died from ICE failure, even though my usual strategy is to drive 'em 'til they drop. The rest had multiple problems, like rust, transmission woes, terminal accidents, and various system failures.

Most recently, we gave up on a 13-year old car with only 30K miles on it because so many age related (rather than wear related) items were failing: plastic and rubber components are particularly susceptible, and steel corrodes eventually. All the parts of a car are designed around a mean-time-to-failure rationale, and it becomes fiscally punitive to push that envelope: I seriously doubt that a 30-mile PHEV would last all that much longer, unless one were willing to replace all the rest of the 'expired' components.

 

<div class='quotetop'>QUOTE(hobbit @ Sep 25 2006, 03:49 PM) [snapback]324979[/snapback]</div>

Hobit -

I know we've had this discussion before... and since them I've been following the industry a bit closer.

Until there is some sort of industry standard way to measure this, there just isn't a viable way to express this amount. The EPA numbers that we all know and love come from a fixed driving sequence that doesn't relate to our realities very well. But it is at least a consistent measure to compare cars. I'm not saying it is valid, just consistent.

If you take a car that claims "100mpg" range and first fill it with electricity and gasoline, it will likely get far BETTER than 100mpg on any of the EPA tests. And if you take the cost of the electricity into account, and convert that to how much gas it would buy... you're STILL doing better than 100mpg. You're asking for a *serious* reality check - and there it is. None really needed. What sould we call this new unit of energy measure? You suggest MPGGE, and I agree. YOu can safely swap MPG with MPGGE and you're doing just fine. How do we state this number in a way that the average consumer can comprehend it though? The average consumer doesn't want to hear:

No gasline for the first 40 miles
100 Wh/mile for the first 40 miles
60mpg gasoline for all the remaining miles for which you have not plugged in
No electricity cost for the remaining miles for which you have not plugged in.

Would make for a pretty big and confusing sticker! So we switch over to MPGGE, and nothing changes. The answer is still "about 100 MPGGE." If you figure out a driving route that nets you 100mpg of actual gas... and then add in the energy that you've used from the batteries, and calulate the cost for that energy, convert it into how much gas it would buy you... we find that you lower your number to something around 90 MPPGE. But since the average PHEV conversion is actually doing quite a bit better than 100mpg of gas on REAL driving missions, we find that this 10% difference still keeps us happily above 100MPGGE.

By using an average *real* trip cycle, we're finding that a PHEV 40 would allow WAY better than 100mpgge on an average day. Some days would be infinite mileage (all electricity) and the rare long trips would be 60MPGGE. And these numbers INCLUDE the energy from the outlet. We have to find that average - just like the EPA does to put on the sticker. And that average is better than 100mpgge - even when using REAL driving by today's standards. Using the EPA tests would yield results much higher than that - and again - that INCLUDES the energy that comes from the outlet.

The energy CS cars can only manage about 100mpg with the CA emissions requirements (cold start of the ICE even when not needed) but enjoy up to 200mpg on an average driving day when that cold start is not used. For around-town trips (what most cars are used for in America) there is NO gas used.

So many complicated issues to consider, that there's just no easy answer! Nobody is trying to ignore the electricity input. They're just trying to make it easy for the driving public to understand. I see little harm in that, when the differences are so slight anyway.

 

<div class='quotetop'>QUOTE(darelldd @ Sep 30 2006, 08:42 PM) [snapback]326105[/snapback]</div>

Personally, I do consider publishing mpg values for cars that are partially driven by electricity as wrong and misleading. What we need is a new, more complete approach to the calculation of car efficiencies. For example, it should be easy to calculate the amount of CO2 produced per mile by different types of cars, if you take the current state of electricity production into account.

For EV's, I have seen several studies where they estimate that the power plant-to-wheel efficiency is around 66% (including regenerative braking). This includes factors such as losses in the transportation system.

For hydrogen fuel cells, it is as low as 22%

For diesel hybrids using SOFC, the well-to-wheel efficiency could be as high as 33% (a bit of a stretch since no such car exists yet to my knowledge)

So, if you can make all your electricity from renewable energy sources (wind, solar), of course nothing beats an EV. But if you need to make the majority of your electricity from fossile sources (which is the case today), the 66% efficiency multiplies with the sub-40% efficiency of the power plant, to come to values that are lower than what could be achieved by burning diesel directly in a hybrid car (albeit using a fuell cell).

It becomes even more interesting if it would become possible to create bio-diesel efficiently. Then we would have an efficient, renewable source of energy that blends very well into the current approach to mobility and the current infrastructure. Of course I know that bio-diesel is a joke right now. But people have only just started to look at how this whole process can be made efficient.

So, could it be that hybrids with bio-diesel fuell cells are the answer? In a sense, the bio-diesel serves as the so-needed flexible storage medium of energy, to store the solar energy captured by the plants to grow. That would solve the biggest problem with electricity right now: there is no acceptable way to store and buffer it.
It would also have the advantage that you can deliver it to places where electricity can't go: boats, remote locations, etc...

As far as mobility is concerned, fossile fuell and hydrogen has the tremendous advantage over electricity that the distribution of the energy is naturally integrated into the medium itself: a boat or a place carries it's own fuel, for cars all you need are the roads themselves to distribute the energy. The more cars you have, the more roads there will be and the more you can distribute over those roads. The capacity of energy distribution scales naturally with the mobility itself. That is why so many people are stubbornly looking at hydrogen, ignoring all the drawbacks. But maybe one day bio-diesel will fullfill this promise in a better way?

 

New to posting, and trying to determine if a $12,000 conversion kit would be worth my investment after my car hits 100,000 miles (post warranty).

It seems that the return on investment would require that I own and drive my car for at least 300,000 miles.

Here's the math, assuming 25,000 miles driven per year.

at 50mpg = 500 gallons * $3 per gallon = $1500 in gas a year.
at 100mpg = 250 gallons * $3 per gallon = $750 in gas a year.

So that's a $750 a year savings with the plug in conversion kit. If that kit costs $12,000, then at 25,000 miles a year, it would take an additional 8 years of driving to break even on the investment. So will I own my car for 12 years?

Two variables: 1. How will Toyota manage ongoing service on the modified vehicle and 2. Will the cost of a conversion kit come down in 2 years to make it more financially feasible. AND.... will Toyota offer a dealer installed option that resolves both of these questions?!

Anyone care to comment?

Donnie

 

<div class='quotetop'>QUOTE(dgunkman @ Oct 8 2006, 12:06 AM) [snapback]329667[/snapback]</div>

The arithmetic for this is a little more complicated.

First, a lot of the savings depend on the length of your typical round trip from home (or, really, from charge to charge). At 25K/year, you're averaging almost 70 miles a day 365 days a year. Or, if you only drive on work days, more than 100 miles a day. If you can only plug in at home, you'll exhaust the battery pack less than halfway through every day, and your savings might be less than what you think.

(I'm in the opposite situation -- it's a rare day when my car would go over 30 miles between recharge opportunities.)

Second, while you can get 100 miles to a gallon of gas, that doesn't include the cost of the electricity, and that's for "typical" driving, whatever that means. So, the 100 MPG is more of an advertising slogan than a hard dollar calculation. If you net out the (typical) cost of electricty, I've calculated (and Felix Kramer of CalCars has stated) that you get the dollar equivalent of about an 85 MPG Prius. Again, based on how Kramer drives his car. That's literally 100 MPG for the gas, then taking back some for the cost of the electric.

That's kind of a squishy number, in that Kramer gets 100 MPG based on how he drives his PHEV Prius. Clearly, some of the time, he's exhausted the battery pack.

If you want a number for a back-of-the-envelope calculation, you need to figure a weighted average of electric and standard Prius operation, based on how you're going to drive the car. Assume pure electric propulsion is the cost equivalent of about 160 MPG in the Prius (that's ballpark, I think), and that your regular Prius mileage is 50 MPG. Then, for 100 miles a day, with no midday recharge, you'd do 70 miles/50 MPG + 30 miles/160 MPG = 1.6 gallons of gas cost-equivalent. Then 100 miles/1.6 gallons equivalent = 63 MPG cost equivalent. The fuel for the PHEV 30 would cost you the same as a gas car getting 63 MPG.

It's low because a low fraction of your miles are driven by wall-socket electricity. I mean, shoot, if you got infinite mileage on the electric portion of the trip, you'd only get 71 MPG overall. Because only 30% of your driving is powered by wall-socket electric.

Third, over the long haul, it's not clear with the existing conversions that you're going to get 8*365 = 3000 full discharge/recharge cycles out of the batteries they're using right now. My understanding of these conversions is that they use the battery a lot harder than the Prius uses the current traction battery. They'll drain it right down to empty, or at least a whole lot closer to empty than the Prius will allow for the traction battery. I also think that typical mass-production NIHM batteries will go a few thousand (2? 3?) full, complete charge/discharge cycles, before they wear out. So you'd need to worry about whether the mod would last the life of the car or not.

My take on the current state of things is that PHEV and EV are coming soon, that batteries are improving at an almost unbelievably fast pace, with lots and lots of good competition, and that individuals willing to do the $12K PHEV mod right now are doing it, at least in part, for reasons other than straight out-of-pocket cost savings. And that the savings are a LOT higher for a guy like me, with nothing but short trips, than for somebody doing 100 miles a day. I've considered it even at $12K, but I'm not anxious to jump into it, given all the ferment in the marketplace. But I'm surely going to keep my eye on it, see how things develop. I think it's just a matter of a few years before PHEV becomes, if not the norm, then a typical option for full hybrids like the Prius or the Ford Escape.

 

<div class='quotetop'>QUOTE(dgunkman @ Oct 7 2006, 11:06 PM) [snapback]329667[/snapback]</div>

Bingo!

Service concern was a big hold up when Prius was first rolled out in the United States. Many owners take it for granted now that mechanics have built up the required experience. They were quite hesitant at first. Longer labor durations and replacement rather than repair was a common practice originally. Back then, you wondered about the work itself too.

Things have changed. It isn't that big of a deal getting service from the dealer for a hybrid anymore. They are familiar with the system now. Recognizing problems with a modified vehicle is an entirely different matter though. That is a new frontier, one they simply are not willing to accept due to liability. How the aftermarket sellers will overcome that remains a very big mystery... a concern that will hold back sales initially.