The hybrid would run on a gas-fueled internal-combustion engine, but would use a highly efficient battery to raise mileage to about 80 miles a gallon.

Nuclear reactors could also power stations where motorists charge highly efficient batteries.

Barack Obama has also made investments to manufacture efficient batteries for hybrid and electric vehicles.

The G.M. car, the first to market, uses lead-acid batteries, but will get more efficient nickel-metal-hydride batteries this year.

Develop efficient and cheap batteries so that solar energy (and wind power) can be stored.

Nickel metal hydride is easier to dispose of, but it does not always make an efficient battery.

The teammates have designed an efficient battery to power the robot.

As a researcher, Sadoway has focused on environmental ways to extract metals from their ores, as well as producing more efficient batteries.

In addition, there may be useful spin-offs for the energy sector, in the form of fuel cells or nano-porous hydrogen absorbers and efficient solar batteries.

These highly efficient batteries were originally developed for space applications where reliability is essential.