Although the current batteries are "durable and reliable, " Hartline said lithium ion batteries pack more energy into a smaller space.

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Hitting the earth at 28, 000 mph an asteroid the size and mass of Apophis would pack the energy of 58, 000 Hiroshima nuclear bombs.

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Researchers at the Washington State University said Wednesday they have figured out how pack more energy into a lithium-ion battery and boost the rate of charging it.

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Boeing convinced regulators to allow the use of lithium-ion batteries on its 787, which are lighter and pack more energy than traditional nickel-cadmium batteries, but are prone to catching on fire.

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Who leads the pack in energy efficiency?

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But it does pack some energy.

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The Tesla Roadster, which indeed uses Li-ion batteries, stores 56 kWh of electric energy and delivers up to 215 kW of electric power (a NiMH battery pack with the same electric energy would weigh over twice as much).

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He notes that many species of algae pack a far denser punch energy-wise than the plants now used as energy crops.

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The combustion engine slowly recharges the battery pack when it is not using energy to move the vehicle.

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"These cutting-edge Panasonic batteries will combine with Tesla's battery pack technology to produce the highest-energy density EV battery packs in the world, " said Straubel.

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