Automotive Energy Consumption
In the United States, the automobile has come to be more than simply a means of transportation, but also a status symbol and a symbol of autonomy. As a status symbol, automobiles have gotten larger and more expensive, with little or no regard for efficiency or environmental impact. With the proliferation of the Sport Utility Vehicle (SUV), the average fuel efficiency of cars in the United States has begun to fall from a peak over a decade ago. With technological and material advances made in the last decade, it seems counterintuitive that average fuel economy had begun to decline. In order to understand the advances made in internal combustion engine technology, one must have a basic understanding of engines and the fuels they burn.
Four Stroke Internal Combustion Engines
The 4-stroke, internal combustion engine at the heart of most automobiles on the road today is relatively inefficient and produces high levels of pollutants. Even the most efficient gasoline burning internal combustion engines convert only 30-40% of the energy available in the fuel in to work. The rest of the energy is lost to heat, and is thrown away into the environment through a heat exchanger (radiator) or through exhaust gases. Exhaust gases account for much of the pollution generated by internal combustion engines. Gasoline, for example produces Greenhouse gases such as Carbon Monoxide (CO), Carbon Dioxide (CO2), Nitrogen Oxides (NOx’s) and releases unburned hydrocarbons (fuel) into the atmosphere. Greenhouse Gases are responsible for much of the depletion of the ozone layer, lead to global warming and pose health threats to humans. In addition to these drawbacks, fossil fuels are not in endless supply and consequently are not a long-term energy source.
Fossil fuels are formed from decaying plant and animal matter within the earth’s crust over thousands of years. As plant and animal matter decays, fossil fuels are formed from the intense pressure placed on them and from the earth’s geothermal energy. As a result, fossil fuels are a resource that can’t be replenished at the same rate they are consumed. Petroleum products are derived from one group of fossil fuels known as hydrocarbons. There is no definitive quantity of hydrocarbon resources left in the world today, but most estimates are not very optimistic. Given the current rate of fossil fuel consumption and the current rate of increase of consumption, some estimates place the usable life of fossil fuel resources between 15 and 30 years. This leaves little doubt that changes must be made in transportation technology.
Improvements to Fuel Efficiency
Much technology has been developed in recent years to increase the fuel efficiency of automobiles. The integration of lightweight components into automobiles continues to increase efficiency. For example, the use of plastics, aluminum, magnesium, titanium, and carbon fiber, to name a few materials, has...