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Electric Car

Electric cars are battery powered automobiles that run on electric motors instead of internal combustion engines. Battery electric vehicles, or BEVs, are powered by rechargeable batteries that can be plugged in to recharge when the car is not in use. Electric vehicles have been around for over 100 years, but are becoming more popular today due to advancements in technology, such as batteries that allow them to travel greater distances between charging. Many major car manufacturers are producing electric models in 2011 such as Mitsubishi, Nissan, and Tesla Motors, which produces solely electric vehicles such as the Tesla Roadster.

History

Range

One of the main concerns with the use of electric cars is the limited range they have compared to cars with internal combustion engines. Recharging the car’s battery is also a much longer process than simply filling up a tank with gas, with batteries taking hours to recharge. This limits the aim of electric vehicles to people driving in cities or who don’t drive great distances over the course of their day. The Tesla Roadster has a range of 245 miles and a 3.5 hour charge time to charge the battery from empty to full (1). The Tesla Model S has three battery options, a 160, 230 or 300 mile range, with the price of the car becoming greater accordingly. The Model S also has a 45 minute quick charge, making recharging quicker than other electric models (1). The Nissan Leaf has a range of only 100 miles per charge and has a charging time of 8 hours to fully charge the battery (2). The Th!nk city can travel 160 kilometers on one charge and its lithium battery takes 8 hours to charge. Its Zebra battery, which is a sodium based battery, takes 7 hours to charge to 80 percent and another 4 hours to charge from 80 to 100 percent (3). In comparison an average car with an internal combustion engine can travel around 300 to 400 miles on one tank of gas and it takes only minutes to refill an empty tank. The limited range of electric cars is why they are mainly marketed at drivers in cities or drivers who only travel a short distance on a daily basis. Battery There are many different options in batteries to power electric cars. Using a battery with the right combination of battery weight and efficiency is very important. Using a battery that is too heavy will limit the range of the car, but using one that is too light will not give the car a great amount of power. Lead-acid, nickel-metal hydride, and sodium-nickel-chloride batteries are all used in electric cars (4). Lithium ion batteries have become the main choice to power electric cars today (4). Lithium ion batteries are used and favored because lithium is the lightest metal and also has the greatest electrochemical potential, giving the battery greater power and energy density (4). Lithium ion batteries are also 90 percent efficient charging, meaning 90 percent of the electricity used in the charging process actually goes to charging the battery (5). There are downsides to the use of lithium ion batteries too. For one, lithium ion batteries lose their ability to hold charge and start degrading as soon as they are produced and leave the factory (6). Also, lithium ion batteries are sensitive to high temperatures. Exposure to high temperatures causes them to degrade and lose their ability to hold charge more rapidly (6). As battery technology advances and electric cars can be made with a greater range they will become more practical. Environmental Impact Since electric cars run on only battery power they do not produce any tailpipe emissions. The lack of carbon dioxide emissions makes electric vehicles environmentally friendly. Some countries such as New Zealand are currently looking at the use of electric cars as a means to cut back on their carbon emissions (8). While driving electric cars does not produce any carbon emissions, the increased production of electricity needed to power a fleet of electric cars would produce carbon. To measure the level of indirect emissions that the use of electric vehicles would cause the well to wheel emissions are measured (7). These emissions are significantly less than the current emissions from cars with internal combustion engines (7). A case study for Milan found that if a quarter of the cars driven in the world are electric by 2030, there could be a 20 percent reduction in carbon dioxide emissions (5). Another study found that if there was a shift to a completely electric fleet globally there could be a 90 percent reduction in carbon dioxide emissions (7).

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