Hybrid vehicles are in season. The two most famous examples at the moment are the Toyota Prius (with large sales and popularity), and the Chevy Volt (with cutting edge technology). The Prius uses a drivetrain that places the electric motor in parallel with the gasoline engine to drive the transmission with the either or both. The Volt drivetrain places the electric motor in series with the gasoline engine, with an electric generator in between. Overall, I much prefer the configuration on the Volt. However, it0s large battery and inefficient gasoline engine are major drawbacks.
The problem I have with the Prius is that the electric motor can't be charged by the gasoline engine, and therefore contributes much less to the overall propulsion of the vehicle. All the energy powering the electric motor must come from recycling energy used to slow the vehicle (i.e. regenerative braking). This gives the vehicle decent gas mileage in stop and go driving, but the electric motor becomes worthless on the highway. Furthermore, the gasoline engine on the Prius is essentially a standard small car engine. It delivers decent mileage at highway speeds but is relatively inefficient in stop and go traffic (as are all small engines since they have to rev so high during acceleration). Despite this, the Prius posts some very good MPG numbers (51/48) overall using the electric motor in city driving and the gasoline engine on the highway, but we can do better.
The Volt drivetrain would be a superior solution to the Prius, but the huge battery and inefficient engine ruin the day. For starters, the battery costs in the neighborhood of $10,000 just to manufacture, and weighs close to 400 pounds with a lifespan of 8 years. The purpose of this massive battery is to give the car a range of up to 40 miles without using any gas at all. Apparently the unspoken assumption here is that people don't want to use gasoline anymore. Doing some math, if I were to drive 40 miles a day in a car that gets 30 MPG, I would be spending $5.33 on gas (at $4 a gallon). Multiply that by 365 days a year and 8 years, and that comes out to $15,500 in gas. GM estimates it will cost $1.50 a day in electricity to power the Volt. Doing the same math as before, that works out to $4,380 in electricity over the same period of time. Add that to the cost of the battery and you discover it that it costs almost the same amount of money to drive the Volt using nothing but electricity as it does to drive a normal car on gas. Sure, if you drive it every day and the cost of gas stays high, you may save a few thousand dollars over the course of 8 years, but it's hardly revolutionary. Admittedly, there are other reasons and factors at play for reducing dependency on oil, and a more detailed environmental impact can be found here. However, if the whole bio fuel from cyanobacteria technology pans out, this might be a moot point.
The other problem with the Volt is GM's choice of gasoline engine. Since the gasoline engine is only used to power a generator for charging the battery, it can be highly optimized to just that task. But, to save time and money, GE decided to throw in a regular 4-cylinder engine from one of its other cars. The result is a feeble 35/40 MPG under gasoline power. The original projection when they first started development on the Volt was 50 MPG under gasoline power. The good news is that GM recognizes this problem and work is underway to replace the engine in the next generation Volt with something far more efficient (References for this paragraph here).
The ideal hybrid vehicle would use the Volt style powertrain, with the electric motor and gasoline engine in series, but do away with the large battery and just run a highly optimized gasoline engine all the time. I can envision a vehicle getting at least 60 MPG without an expensive battery and with all the low-end torque of an electric motor. Without the battery costs and size of the larger engine, the price tag ought to be in the mid-$20k's. You might say, "jeez the Prius does all that now". True, but the Prius is reaching the limits of what its drivetrain architecture can accomplish. The Volt architecture has much more potential for future, especially when coupled with a next generation engine designed specifically for powering electric motors, such as this one. One day we could be looking at over 100 MPG, with no large batteries needed.
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