June 18, 2009 10:00 AM PDT
How does a hybrid work?
Toyota is the current king of hybrids, selling more than any other automaker. In this episode of CNET's The Green Show, Brian Cooley shows you just how Toyota's Synergy hybrid power train is put together.
The synergy drive is obsolete technology to me. This is a PR campaign of Toyota to dissuade others from making EV like those of Tesla, Aptera, Fisker, and others. Even the EREV like that planned by Aptera 2h and GM-Volt would make more sense. This would be a terrible loss to Toyota in the patent licensing fees of their synergy drive as many other companies are not investing heavily on this obsolete technology. So Toyota is the main one that will be using this and they are shying away from plug-ins, investing heavily on NiMH instead of Li-Ion for their hybrids.
Here's a Newsweek article stating why some people are convinced that the synergy drive is obsolete:
http://www.newsweek.com/id/195662
The video has a big mistake. The Prius doesn't have a belt-driven CVT transmission. There is no transmission. The 2 motors and 3 way gear is used both as a way to eliminate the transmission (that matches engine speed with wheel speed) but also to allow mechanical coupling that allows electric-only or gas+electric drive. This technology allows bigger newer batteries to be used to make a plug-in. (Other hybrids, e.g. Honda, can't run electric only-- they are gas-always with electric boost.) For a Prius plug-in, the gas engine can be used for fast acceleration, and the electric drive can take over to sustain speed or for low acceleration, and a much smaller battery is needed than for a serial hybrid like the Volt.
Until battery prices come way down, I think the synergy drive architecture provides the lowest cost/saved-fuel for gas-only HEV, PHEV, or electric-only. The extra cost for synergy drive is about half the fuel cost-savings (about 1/3 less fuel). For a small car like the Prius with already low fuel cost, there isn't much remaining potential savings available for plug-in batteries, but most any size would be possible from 1kWh (double) to 10kWh, depending on the cost.
Why is that, you ask? It comes down to driving style. With the Prius model, when you start out from a stop you are running on pure electricity. When you get up to a certain speed or load demand, the gas engine kicks in. This assumes you are a feather light touch on the gas pedal and driving in optimal traffic conditions.
The real world scenario of a shuttle service is a lot of rapid starts and stops. When you depress the throttle beyond a certain point, the engine cuts in regardless of the need. You tend to accelerate more quickly and that means more wasted fuel. Also, the battery gets used up faster doing the rapid acceleration which drains the battery and requires the gas engine to run to recharge it. It is not unusual to see a Prius on campus sitting there idling to charge the battery in between runs.
This is all driving style. For a commuter, it may not be as much of an issue. For MSFT, they have started going to more gas efficient diesel commuter / shuttle buses instead.
Assuming you are light on the throttle, then this can very much be the case. If you are lead-footed, then you'll end up with worse mileage than a gas equivalent.
At the end of the day, is the fuel savings enough to make up for the added costs of the higher price of the vehicle? Remember that the Prius no longer qualifies for tax cuts or rebates from the government. It's a very real financial question that has to be addressed.
Overall I think the Chevrolet Volt has the best design to offer to date- a battery that always drives the car, and the engine on board only runs to charge the battery as needed. Fewer moving parts, easier maintenace and design. The Volt is *not* a taxi-like or suitable vehicle though in the current incarnation.
Some cities are requiring the use of a percentage of a taxi company's fleet be hybrids. That isn't the taxi company's choice- if they wish to do business in the city, they are forced to have hybrids. That isn't an economic decision, but is instead one being forced down upon them. New York, for example, is one such city that was well on the way to requiring such all hybrid fleets and the taxi companies bought up the hybrids in advance of the new city requirement before the proposal was shot down and is currently in dispute. In the mean time the taxi companies are forced to buy much higher priced vehicles that aren't meant for use as taxi's.
Taxi use- the use of retired police cars (Ford Crown Victorias) is one of necessity. They are meant to idle for long periods of time, have heavy duty suspensions and drive trains meant to handle the demands put on them. Larger brakes, displacement on demand engines, large trunks and cabin spaces make them ideal. As they are used fleet vehicles, they come at a bargain for both intial price and repair. A new Toyota Prius can cost tens of thousands more at initial purchase and are not meant for the heavy duty use that a taxi endures. This means a lower service life for the vehicle and more frequent / costly repairs. Vehicle replacement costs go up. All that has to be accounted for and the numbers just don't add up currently. It's only the requirements by cities to go to hybrid fleets that are forcing the hand there.
Should be an interesting time though.
Step 1: Add $20,000 to the stick price
Step 2: Promote it as "Green" and will save $$ against expensive gas prices.
Step 3: Engine/Battery does this by ????
Step 4: Profit $$$$$
-
by wfolta
June 21, 2009 5:35 PM PDT
- What a lot of misinformation in these postings.
-
Reply to this comment
-
(9 Comments)1. A pure EV is a pipe dream at this point, except for those who should probably be using public transportation in the first place. (Except for the fact that you need a single-family home to charge your EV in the first place: condo/apartment dwellers need not apply.) Not only that, but the higher-cost, higher-capacity batteries required are not fully recyclable, while a Prius' batteries are 100% recyclable.
2. The MSFT anecdote makes little sense. I regularly accelerate faster than the Prius' gauges would indicate, and my overall average over the last 400 miles is 53 MPG. All it takes is a tiny bit of thinking and planning to get that kind of mileage. The MSFT drivers must've been stomping on it and then slamming on their brakes for stops 200 feet apart. Seriously, when I drive in city traffic or stop-n-go highway traffic, my average goes UP.
3. High cost? We paid $24,000 for a mid-range Prius. In the same ballpark as what we'd have paid for non-hybrid alternatives with similar features and size. Gas-wise, we get 53 MPG overall -- real-world mileage, not a sticker, and not obsessing and hypermiling. (Mileage will increase a bit as the car/tires break in. And if we decide to obsess about MPG, we know people who achieve 60+.)
4. Prius cabs? Every hybrid cab I've ever seen is a Camry hybrid, which is significantly larger. Probably not built like a taxi, but what cars besides Checker Cabs (no longer made) are?