How Vehicles Affect Energy Efficiency

Published On March 19, 2013 | Green Tech

The debate over fossil and alternative fuels often centers on the issue of the automobile and the negative environmental impacts of the internal combustion engine (ICE). Instead of an emotional response of the “all cars are bad” perspective, the issue is significant enough to warrant a close examination of the reality of the ICE and its growing presence in automobiles.

There are two initial issues that help to shape the debate. First, the continued and increasing growth of the number of vehicles on the road, and, secondly, the energy efficiency of the existing ICE.

The Other Population Explosion

According to Wards Auto, the world vehicle population reached 500 million in 1986. That number more than doubled within 24 years. There were 1.015 billion vehicles in use worldwide in 2010. Pointing to China’s 27.5 percent increase in vehicle growth in one year, along with other factors, this rate of increase shows no sign of slowing.

Daniel Sperling, of the UC Davis’ Institute of Transportation, points out that the first 90 years of the combustion engine consumed more than half of all known oil reserves. With the population of cars showing a trend of doubling every decade, 2 billion autos and trucks would be used by 2020. At that level of population, an additional daily production of 33 million barrels of oil would have to augment the current 87 million. It’s unclear if the world is capable of producing that amount of oil.

The Energy Efficiency of Today’s Vehicles

Today’s vehicles have certain inefficiencies that are essentially inherent to their structure. While science and industry allocate billions to achieve even micro-level improvements to energy efficiency, there are finite limits to the potential for such reductions.

It is important to note that while the ICE technology represents the biggest loss in efficiency in converting fuel to power, alternative sources have their own inherent inefficiencies, and, furthermore, do little to deal with the remaining drags on operational efficiency.

According to, the primary losses in energy efficiency in vehicles include:

Engine – 62.4 Percent

ICE engines are undeniably inefficient when converting the chemical energy in fossil fuels to the mechanical energy needed for motivation. Heat and friction are the main culprits and where much research focuses. Diesels can improve this percentage by 25 to 40 percent and will become the preferred ICE in the future.

Idling – 17.2 Percent

Driving in urban areas represents a surprising level of energy loss. New start and generate technologies will lower this specific loss over the coming decade.

Braking Losses – 5.8 Percent

The laws of inertia mean that vehicles use energy to move forward and to slow down. Individual drivers can actually decrease this loss by as much as 30 percent with better driving skills.

Driveline – 5.6 Percent

Physics dictate the loss of energy in transferring power from the engine to the tires. This, again, is an area of intense research in hope of carving out a degree or two of improvement in the loss.

Rolling Resistance – 4.2 Percent

Overcoming this natural source of loss focuses on tire technology and roadway construction techniques.

Aerodynamic – 2.6 Percent

This source of loss already heavily influences the design of modern vehicles. Scientists see the potential for an additional 25 to 35 percent increase in future materials and designs.

Accessories – 2.2 Percent

From air conditioning to windshield wipers and fuel pumps, these devices consume portions of the generated energy.

The issue of vehicles and the environment is not solvable solely by adopting proposed alternatives to the current technology of the ICE. A global focus on the vehicle population is the next unpopular areas of attention for the environmentalists.

— By Editor



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