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About this Article
Written by: Paul Moldovan
Written on: November 1st, 2010
Tags: chemical engineering, energy & sustainability, transportation
Thumbnail by: Matthias93/Wikimedia Commons
About the Author
Paul Moldovan was a junior at the University of Southern California in Falll 2010. He majored in Electrical Engineering with an emphasis in Power Engineering.
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Volume XI Issue III > Diesel Engines: Is Old Technology Actually Green Technology?

Idle Reduction Technology

Another new implementation that makes diesel engines more efficient is related to not to technical engine function, but to the operation of the engine. Idle reduction technology, as the name implies, has been introduced to reduce the time engines are left idling. An idling engine burns fuel and raises emissions [5]. For example, in the United States, most goods are transported by diesel powered trucks. The trucks are allowed to be on the road for a certain number of hours after which they are required to stop and the driver must rest. During this rest period the driver allows the engine to idle in order to have electrical power, heating, and cooling. This idling of the engine is not only wasteful, but also harmful to the environment. As a result, new electrified parking spaces, which are an example of idling reduction technology, have been introduced where trucks can be parked and truck drivers can receive the same amenities an idling truck provides from an outside system. This not only reduces emissions but also increases the distance a truck can travel on one tank of gas, resulting in less fuel consumption [7].

Diesel versus Hybrid

A few years ago, when buying a new car, most people were concerned about the amenities, the horsepower, and the price. Now, with the new green movement and high gas prices that likely will continue to rise, fuel efficiency has become consumers’ number one priority. Hybrid cars have become the most popular option and are touted as the greenest automobiles available on the market today. A hybrid vehicle’s most alluring characteristics are the ultra-low emissions and high gas mileage. The most popular hybrid is the Toyota Prius, which gets an EPA estimated 55 miles-per-gallon, though it is important to note that this value was determined in ideal conditions. Ideal conditions are described as flat, smooth, paved roads which a driver would rarely encounter on their daily commute. A recent Consumer Reports article finds fault in the testing standards set by the EPA and claims that the actually miles-per-gallon rating for the Prius is 32, a reduction of 42% [8]. On the other hand a Volkswagen Polo, a small turbo diesel car currently only available in Europe, can achieve a claimed 70 miles-per-gallon. Even if this number was reduced by 42% percent to 41 miles-per-gallon, it is still more fuel-efficient than the Prius.
Matthias93/Wikimedia​ Commons
Figure 2: Like diesel-powered vehicles, the hybrid Toyota Prius is known for its green technology.
With the new clean diesel technology, emissions from hybrid and diesel powered cars are also comparable (see Fig. 2). A combination of catalytic converters as well as new filter technology captures nearly all of the particulates and allows for virtually zero emissions. There are new cars using the clean diesel technology, which are branded as Ultra Low Emissions Vehicles by the United States government. It is important to note that both are more fuel efficient and have lower emissions than most gasoline powered cars. Power output is also important when comparing diesel and hybrid engines. The Prius, with its gas-electric engine, produces 134 horsepower and 105 pounds-feet of torque [9]. The new 2009 Volkswagen Jetta, on the other hand, produces 140 horsepower and 236 pounds-feet of torque [7]. This power difference is very noticeable by the driver and in fact makes the Jetta much quicker than the Prius, which has 131 less pounds-feet of torque to work with.