Battery Development for Electric Cars
The steep rise in oil prices in recent years, the pessimistic outlook for the future of the world's oil supply and the contribution of greenhouse gases to the atmosphere by the gasoline-powered internal combustion engine have brought home the need for alternatives. Hybrid electric and all-electric cars offer one alternative to oil, but for this alternative to be feasible, improvements in battery technology will be necessary.
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Nickel-Metal Hydride (NiMH) Batteries
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NiMH batteries are similar to Nickel Cadmium (NiCad) batteries, but use a hydrogen-absorbing alloy for an anode instead of cadmium. They are widely used in hybrid electric cars, but have several shortcomings. In his 2007 testimony before the U.S. Senate's Energy Committee, the president of Advanced Automotive Batteries, Menachem Anderman, pointed out that the batteries used in hybrid electric cars account for 25 to 75 percent of the increase in weight, volume and cost over conventional automobiles. In addition to their size and cost, their reliability, longevity and toughness are critical factors in determining the success or failure of electric vehicles.
Anderman also said that practically all vehicles with moderate to significant hybridization use nickel-metal hydride (NiMH) batteries. They have proven to be a reliable power source, but have significant limitations: moderate energy conversion efficiency, shortened life with high depth of discharge cycling and performance degradation at high and low temperatures. They are also expensive, with the battery pack for the 2007 hybrids costing from $600 to $3,000 each.
Lithium-ion Batteries
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According to Isidor Buchmann, CEO of Cadex Electronics, lithium-ion batteries are the most promising and fastest-growing battery technology of the moment. They charge more efficiently than NiMH batteries and can deliver more energy per unit weight. There remain problems in using them for electric vehicles, however. Mr. Anderman cites "unfriendly failure modes" and higher costs, while Mr. Buchmann points out the immaturity of the technology.
The U.S. Advanced Battery Consortium, a joint effort of the U.S. Department of Energy, the auto industry and battery developers has overseen progress toward overcoming lithium-ion limitations. Mr. Anderman believes that in the future lithium-ion may become the battery of choice for electric vehicles.
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Vanadium Bromide Redox Flow Battery
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According to the Centre for Energy and Greenhouse Technologies, a private investment and service provider, the invention of the vanadium bromide redox flow battery by Australian professor Maria Skyllas-Kazacos at the University of New South Wales is one of the biggest renewable energy breakthroughs of the new century. The new battery can be recharged thousands of times without any degradation in performance, and its efficiency for storing and releasing electricity is expected to reach 80 percent. The inventors believe that this battery will be viable for electric vehicles in the future.
Investments in Battery Technology
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In 2009, the U.S. government's stimulus package tabbed $2 billion for battery research and manufacturing. In April, 2010, General Motors spent $8 million to double the size of its U.S. advanced automotive battery laboratory.
Considerations
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America's energy future is unclear, but batteries will play a role. While fuel cell vehicle technology is promising, electric vehicles have the advantage of an existing delivery infrastructure. It would take years to establish a network of fueling stations for hydrogen fuel cells, but the electric power grid is already there.
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References
- Photo Credit futuristic electric car image by Michael Shake from Fotolia.com solar energy image by Catabu from Fotolia.com
