Driving hybrid cars and burning biofuels are two ways people in the United States are trying to reduce the country's dependence on foreign oil and reduce emissions of carbon dioxide, a greenhouse gas. Hybrid cars help reduce foreign oil dependence and carbon dioxide emissions by getting superior fuel economy. Biofuels offer a possible partial or total substitute for gasoline.
How Hybrid Cars Work
Hybrid cars have two motors: a gasoline engine that powers the car when it is operating at normal speeds and an electric motor that provides additional power when it is needed--for accelerating or climbing hills--and powers the car entirely when it is operating at low speeds.
Why Hybrids Get Better Gas Mileage
Hybrid cars get better gas mileage for three reasons: because the electric motor provides additional power when it's needed, the gasoline engine is smaller than would otherwise be required; because a hybrid operates on electric power only at low speeds, when gasoline engines are least efficient; and because the engines in many hybrids shut off entirely when the car is sitting still, as at a red light.
Why Do Biofuels Help Reduce Carbon Dioxide Emissions?
Living organisms, such as plants and algae, and waste products, such as food waste products, are used to produce biofuels, which can be solids, liquids or gases. According to Alternative Energy News, a fuel must contain more than 80 percent renewable materials to be considered a biofuel. Because plants absorb carbon dioxide during photosynthesis, burning these plant-derived products should not increase carbon dioxide concentrations in the atmosphere. The amount released should equal the amount taken up during plant growth.
Ethanol Industry
Congress, through the 2007 Energy Security and Independence Act, which mandates the use of 36 billion gallons of biofuels on an annual basis by 2022, encouraged the development of biofuels. As of 2010, ethanol is the primary biofuel being produced in the United States. Ethanol is primarily made from corn, although it can be produced from sugar cane and other plants.
Problems with Corn-Based Ethanol
According to the "The New York Times": "There has been heated debate about whether carbon emissions from ethanol production and use are lower than those from oil and whether the 33 percent of the U.S. corn crop diverted to ethanol drives up the price of food." In addition, production of corn requires substantial quantities of fertilizers and pesticides, and runoff from corn farms is a major source of ocean "dead zones." In addition, the production of ethanol requires substantial quantities of water: 3 gallons of water are consumed for every gallon of ethanol produced.
Other Potential Biofuel Crops
Saplings and grasses, which contain more cellulose, the material from which the cell walls of plants are made, are considered to be potential alternatives to corn. According to "National Geographic" magazine, cellulose-based biofuels "could be more efficient than current biofuels, and emit less carbon dioxide."
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