So, lets say your car has been parked for two weeks and you have to go city driving -where Prius excels- and the batteries are low, wouldn't it be wise to recharge them before going out so that you drive mostly on the electric motors?

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So, lets say your car has been parked for two weeks and you have to go city driving -where Prius excels- and the batteries are low, wouldn't it be wise to recharge them before going out so that you drive mostly on the electric motors?

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Manolo,

The point he was making is that if you have to recharge your car, you're drawing electricity from the power grid that has to be generated somewhere, possibly from burning coal (and hence creating pollution). He's sorta saying it balances out with driving on the cars engine since you're also polluting to some degree.

Now as to whether or not the pollution levels are the same and how much fossil fuels are used in each case, etc..., well, I can't answer that.

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I can tell you from almost two years of heavy duty study of the Prius and Toyota's stance, that while some people may pick flaws in their logic, I do not. The Prius pollutes far, far less than virtually any power station while burning gasoline - apparently it is so clean, than accidentally spilling a kitchen cup of gasoline on your driveway while refuelling your lawn mower, pollutes as much as 25,000 miles in a Prius (Toyota New Zealand info). So, the obvious solution is to clean up the power station emissions worldwide, improve the hybrid batteries, after which I'm betting Toyota might say "we'll offer one."

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"Now as to whether or not the pollution levels are the same and how much fossil fuels are used in each case, etc..., well, I can't answer that."

Drawing from a representative grid mix (50 coal, 20 nuke, 18 natural gas, 7 hydro, 3, oil, 0.7 solar/wind/geothermal, 1.3 other), using electricity to move a Prius produces less CO2, more NOx, extra pollutants like SOx, mercury, etc. Concentrated mobile emissions of NOx and hydrocarbons leads to ground-level ozone (especially with higher surface temps), whereas distant power plants would have less of an effect on air quality in population centers.

The bottom line is that it's a tradeoff, and of course there are regional variations in the mix that powers the grid (eg, lots of hydro in the Pac NW).

Most proponents of plug-in hybrids envision them wedded to home renewable energy systems (like photovoltaics or microwind), or at the very least paying for "green" power from the utility itself (like Xcel's Windsource program).

Toyota's probably right in their assessment about the impact on the environment, since it's likely if they mass-marketed plug-ins, most people would source their power directly from their electric utility. Of course, they could also set up a supplementary business (or partner with someone) to help their customers do renewable energy conversions for their home as part of an option package when buying a plug-in.

I doubt they're going to offer factory manufactured plug-ins, mostly because they've made an effort to educate people that the Prius is not an electric car and it doesn't need to be plugged in.

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That is true.
However, in my selfish way of thinking, my priority will be:
what is cheaper for me?
to charge the batteries at home paying electricity at grid prices?
or using the engine and paying gas at today's pump prices?

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Joseph, if any car company would be willing to get into the "solar plug-in" business it would be Toyota or Honda, just as a guess. I see your point - and Toyota and Honda could collaborate on an easily plugged in system using voltage not seen in household wiring and specific plugs (please, Toyota, Honda, SAE - standardize the voltage and plug shape) so that only the solar power could charge the car while it sits in the parking lot waiting on its owner or in its garage I was rather hoping I could buy a small solar panel (less than $50) and plug it into the 12 volt power outlet to help keep the car charged but this will not work - not least because the 12 volt power outlet (aka "cigarette lighter" hole) is "off line" when the Prius is off. How about that as a minor change for the 2007 Prius, Toyota? Make it possible to keep the 12 volt battery charged with a solar panel and offer the panel through Toyota dealerships? I understand that if I leave the Prius for an extended (long) period of time, it may run down the 12 volt battery - though I believe this problem was far worse on the first generation Prius.

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This demand for a plug-in option--certainly from what I've heard from people asking about this elsewhere--would seem to just be part-and-parcel of the confusion that consumers have that hybrids are "electric" cars, or are some sort of step along the path towards the demise of the evil internal combustion engine. Of course that's mistaken, if these systems actually work in wringing better efficiency out of the combustion engine then that just makes it that much harder for 'alternatives' to compete.

Barring quantum leaps in battery technology--and nothing of the sort is within sight--the electric car is going nowhere. And given the state of the electrical grid('round here anyway) advocating transportation that's dependent upon that system seems just a tad bonkers. I wouldn't be suprise if in 10 years we see more people powering their homes WITH their cars than driving electric cars.

The batteries in the Prius do not have enough capacity to run long enough electric-only for a useful distance relative to the time it would take to charge. And household solar? It would take days to charge it up enough to go a few miles. The only utility in a plug-in option is poseur value.

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"However, in my selfish way of thinking, my priority will be:
what is cheaper for me?
to charge the batteries at home paying electricity at grid prices?
or using the engine and paying gas at today's pump prices?"

Good question. Here's the answer.

A new Prius can go 3.82 miles with 1 kWh of electricity in all-electric mode (acc'd to the Calcars folks who've developed some plug-in Priuses).

The Prius has an EPA rating of 55 MPG.

The national average gas price is $2.59 right now.

So, to go 55 miles using gasoline will cost $2.59. Since it takes 14.4 kWh of electricity to go 55 miles, the electricity would need to cost 18.0 cents per kWh to be as expensive as the gasoline. The average residential price right now for electricity is 9.53 cents per kWh.

The question then comes to the amortized cost of the additional batteries and associated additional hardware per mile. I'm not that familiar with those costs, but I did see one electric vehicle that had 25 lead acid batteries claiming a per mile cost of about 7 cents for those batteries. My limited understanding of the plug-in Priuses that have been developed is that they use far fewer batteries than that, but they're still experimenting with how many and what type. So I don't know what those battery costs would be per mile.

Again, I think their thinking on this is that extending the all-electric range of the Prius would allow it to be a "zero emission" vehicle for those days when one doesn't rack up too many miles. The scenario being a home renewable energy system which would provide the electricity for the extra battery capacity, which would reduce the amount of gasoline needed on average per mile -- thus their claims of extraordinarily high MPG figures.

But to get back to cost comparisons, gas is going to be 4.7 cents per mile and average electricity is 2.5 cents per mile. The question then is are the extra batteries more or less than 2.2 cents per mile. Of course, one could live in a place like Seattle and have super cheap electricity, which would change the cost equation.

Hope that helps a bit.

In any case, it's all garage hack stage type of work at this point, but it's an interesting angle to watch. Personally, I'm content with a normal Prius which gets 55 MPG -- far better than the 20 MPG average of any given personal vehicle on the road in the US today.

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Ah. The old "distraction" ploy like a magician's trick. Point out that plug-in's cause more enviromental damage than a Prius that's not pluggable.

Uh,huh. Not buying it. If the issue was true, there would have been massive public outcries for power plants to become more efficient.

But that's not a vehicle issue. Sorry, Toyota, Americans are not buying it (but we'll buy your vehicles and enthusiasts will continue to modify them.)

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"Barring quantum leaps in battery technology--and nothing of the sort is within sight"

Actually, there have been some pretty amazing developments in battery technology. For example, Toshiba will put out a lithium-ion battery next year which improves recharge times 60-fold -- recharging to 80% capacity in just one minute. So, the recharge time problem of electrics will probably be solved in the near future. Approaches like zinc air also radically increase the energy density of batteries. So, I would say that there's quite a number of large leaps in technology happening.

"The batteries in the Prius do not have enough capacity to run long enough electric-only for a useful distance relative to the time it would take to charge."

Seeing as the recharge would probably take place while people are sleeping, the absolute amount of time for recharging relative to "useful distance" (under a short daily commute usage scenario) wouldn't really be a problem. Again, I think the point of plug-ins is simply to extend the all-electric mode range of the Prius to lower the average amount of gasoline consumed over all miles driven.

"And household solar? It would take days to charge it up enough to go a few miles."

That's not really a logical statement -- it's all going to depend on the size of the home solar array and the insolation values for the location.

Say you have a 4 x 4 meter space (roughly 12 x 12 feet) on your roof covered in photovoltaics and the efficiency of the panels is 12%. 1 m^2 will produce 120 watts, so 16 m^2 will produce 1.92 kW.

A place like Los Angeles has an average insolation value of 5.62 (ie, average daily direct sunlight equivalent of 5.62 hours), so that 4 x 4 meter PV array would put out 10.79 kWh on average throughout one year.

It takes 0.262 kWh to move a Prius in all-electric mode, so that 10.79 kWh could move it a little over 41 miles (which, coincidentally, is the average daily miles driven if one drives 15,000 miles per year).

So, someone with a 20 mile one-way commute could theoretically do it without using gasoline. The only problem is that the stock Prius can only be in all-electric mode up to 20 MPH or so, so that limit would probably need to be modded. I also don't know what the energy consumption is in all-electric at any given speed - the Calcars people (and their advocates) just provide the average.

In terms of cost, Real Goods sells a 123 watt panel that's about 1 m^2 for $600, so a 16 panel array would cost a little under $10,000, but a lot of states are providing large tax breaks and other subsidies to offset the costs of installing those kinds of systems. There's also system costs like inverters, intertie meters, etc.

But even if there weren't cost offsets, assuming a 30 year lifespan for the panels, the panels would be $10,000 for 450,000 miles of driving, or 2.2 cents per mile -- equivalent to $1.22/gallon of gasoline.

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Excellent comment by the Toyota spokesman. Tells me that behind the scenes they are doing exactly what they need to do to get a good greener and/or non-fossil fuel car. It was my understanding too that the battery technology is a real baffler to get around.

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Many locales now allow for competitive supply of electricity.

Here in Massachusetts, I buy my electricity from a wind farm/small Hydro provider called New Wind Energy. Buying renewable electricity costs me about $10 a month over what I would normally pay MassElectric.

If our Prius could be plugged in, we would do so and charge it with low-carbon renewable electricity.

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OK, Joseph, just a minor correction to blog #10 - I have seen my Prius go 45 miles per hour on electric-only for short distances, I think I've seen others say 42 miles per hour. Not 20 miles per hour max. I've seen 59 miles per hour (this morning) on electric only - down a long hill, though..... More batteries and solar-only or wind-only home rechargers would work out for hybrids. Maybe employers could put help out and get green credits on taxation or something, by providing solar panels to plug employee hybrids into to charge while people are at work... this would double as a sun-shade to keep the interiors of the cars cooler (I notice a lot of power is used getting the Prius's inside temp down from the high-90's to mid-70's when I first get out of work on hot day - yeah, we do occasionally have hot days in Michigan, okay???)

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People tend to forget other costs associated with "dirty" power generation. You can calculate the pollution released to generate 1 kWh at the plant, but the story does not end there. After transmission losses and conversion losses, you have significantly less than 1 kWh of juice in your battery per kWh produced at the plant.

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You're right, Glenn - I was using the 20 MPH figure from what I had heard. Apparently Toyota's cut-off is about 35 MPH.

http://www.greencarcongress.com/2004/12/turning_the_pri.html

That makes sense, considering the recent hypermiler test of a Prius that ended up getting 110 MPG. During the test, the drivers tried to keep the speed between 30 and 40 MPH, which would indicate they were trying to work near that electric-only mode limit.

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"People tend to forget other costs associated with "dirty" power generation. You can calculate the pollution released to generate 1 kWh at the plant, but the story does not end there. After transmission losses and conversion losses, you have significantly less than 1 kWh of juice in your battery per kWh produced at the plant."

True. Conversion and transmission losses chop off about 2/3 of the primary fuel's energy at the end-use. However, the emissions comparison I used upthread accounts for that by using macro emissions data from power plants and dividing it by end-use electricity consumption to get emissions/kWh numbers.

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Considering the state of the power grid here in California, this is a sensible stance for Toyota to take. The grid here is antiquated and stressed. Even ignoring the hidden environmental costs, which are significant, I'm not sure the grid here could absorb the impact of 100% electric cars if they became popular.

Plug-in cars are appealing much in the same way a fully cooked steak is. A lot of people don't stop and think about what it takes to get it in their hands.

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lol

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Hey Rip,

You hit the nail on the head, from what I've heard about the power grid in California.

There is hope yet for California, tho. Back in 1980 when I was newlywed, we moved to this area (my home town) and lived in a rural area, had Cherryland Rural Cooperative Electric. It was totally unreliable - all the time. It was expensive - all the time.

Moved back to my hometown about 12 years ago - had to go with Cherryland again. They were not so expensive any more, and quite improved - in fact in 12 years, they've made many many improvements.

Beats the hell out of the 32 volt direct current Delco system my grandpa's farm had when my father was a boy, too. (Remember Green Acres on TV in the 1960's, and they could only use one or two appliances or lights at the same time?)

I work at a classic auto insurance company and one of my customers with a Model A said to me one time "there is no reason for modern cars to get any less than 60 miles to a gallon, my Model A can do 20". It was one of those "shazam" moments for me and then when Toyota announced the Prius II, I started studying exactly HOW modern cars should be built.

Happy to say I'm lovin' my Prius. I actually miss it when I carpool with my friend/neighbor/co-worker and we taks his Saturn or Ford. But I don't want to drive all the time, just like any carpooler. Sometimes my wife takes the Prius when I carpool (may as well take the car which uses 1/2 the gas of the 2nd car).

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