One of the largest challenges facing the alternative energy industry has been coming up with a cost-efficient, long-term storage of electricity generated by wind and solar power.

However, that obstacle hasn't diminished growing international interest in alternative energy. Since 2009, the worldwide solar power installations have reportedly increased annually by 40 percent, while wind turbine generating capacity has doubled.

Energy storage technology has become a municipal and political issue as well.

Last year, California became the first state to adopt an energy storage mandate. That mandate requires California's three major, investor-owned utilities to start increasing electric storage capacity by the end of this year. By the end of 2020 the capacity must reach the amount of energy needed to run around one million homes.

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"Storage really is the game changer in the electric industry,” California Public Utilities Commissioner Mike Florio said at the time in an interview with the San Jose Mercury News. “And while this new policy is not without risk, the potential rewards are enormous.”

Among the companies looking to reap those potential rewards is Pennsylvania-based Axion Power International (OTC: AXPW), which has developed an advanced lead-carbon (PbC) battery as an alternative to standard lead-acid batteries.

More than eight years of R & D on these PbC batteries, according to Axion, has determined they have faster recharge rates, longer lives and greater charge acceptance than lead-acid batteries. They also compare well against lithium-ion batteries.

Axion CEO Tom Granville told Benzinga the PbC batteries are more of an evolution, rather than a revolution, in energy storage technology. “It's not going to change (energy storage) as much as many people would like,” he said, “but it can do it more quickly. And in doing it more quickly you can take advantage of being able to store more wind power, for example.”

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Granville said his company is gearing up for the micro-hybrid battery market – supplying the ancillary electrical functions needed for hybrid vehicles, such as starting and stopping the engine, powering the brakes, lights, air conditioning and other electrical needs. “We're a solution for that stop-start market,” he says.

Axion is now ready to “fully commercialize” its energy storage technology, although Granville noted the industries they deal with – utilities, rail and automotive – take time to retool to new technologies. “They're slowest to adapt to a change,” he said, “and demand thorough testing.”