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interview > greene > greene 5

Greene 5 (3:06)
Topic(s): Biofuels / Efficiency / Electric & Hybrid / Future Transport
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Greene

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Well, I think in the near term what we can do about making cars more energy efficient has to do with conventional gasoline engines. There are lots of things that can be done to reduce the internal friction of the engines, to improve their thermodynamic efficiency, if you will. There're many sources of energy losses in an engine. It takes energy to pump the air in and out of the engine. There are clever ways to reduce that with valve controls. There are more efficient transmissions available. It used to be that a 3-speed automatic was standard; now more or less a 5-speed automatic is standard, but 6-speed, 7-speed, and 8-speed transmissions are also available. There's such a thing as automated manual transmission that reduces many of the losses associated with a standard automatic transmission. All of these things, which are sort of a tweaking, if you want to think of it that way, of the existing gasoline internal combustion engine, could improve efficiency by 50% over the next 10 or 12 years.

Well, I think—we also have technologies like hybrid vehicles, which I'm not including in that 50%, even, although certainly they would help. We have diesel engines coming to the United States soon, and they're inherently about a third more efficient than gasoline engines. So — and especially diesel engines may be most useful in the large trucks that we seem to like. For towing purposes and those kinds of things, a diesel engine is ideal.

So after we have done this 50% improvement, I think we will need to begin with some novel technologies. Let me back up on that, and say that the—some of the novel technologies, like hybrid vehicles, are just going to increase in their market share over time. The costs will come down, the batteries will improve, and the numbers of makes and models that are available for people to choose from will increase. So hybrid vehicles will make an increasing impact on the market. And so that's a sort of mid-term, if you will, near-term and mid-term technology.

Technologies that are on the horizon but not ready for the marketplace yet, for example, are plug-in hybrid vehicles that can take some electricity from the grid, as well as generate their own electricity while they're driving. These vehicles would not only allow a completely new source of energy for transportation, which is taking electricity from the grid, but also create more price responsiveness, because there would be some ability to take more or less electricity, more or less gasoline, depending on the prices of the two. So that would be very helpful.

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