Photo Credit: NASA

It takes a lot of power to fly a passenger plane.That's why aviation fuel is more potent than the blends used by trucks and passengers cars.

But a couple of start-up firms say recent advances in battery technology are close to making electric-powered airliners a possibility.

Zunum Aero says it will build a flock of small electric airplanes capable of carrying 10 to 50 passengers up to 700 miles.

The company hopes to set up terminals at smaller regional airports to establish a sort of flying bus service.

The company says it hopes to start flying by the early 2020s.

The plan is ambitious but it has attracted the attention of Boeing and JetBlue, both of which have invested in the start-up.

Zunum isn't alone.Also planning to launch an electric plane business is Wright Electric, an entrepreneurial initiative from Y Combinator.

Wright says its planes will carry as many as 150 passengers on trips of up to 300 miles.

The company points out that short-haul flights are a lucrative part of the market.Its new planes could carry passengers between London and Paris, for instance.

Wright says it hopes to start flying within a decade.

The small companies will compete with electric-plane projects from established aircraft companies.Boeing has tested battery-powered light aircraft in the past, and Airbus is currently putting the E-Fan, an experimental electric two-seater, through its paces.

Advocates of electric planes point out that aviation is a major source of the greenhouse gases responsible for climate change.

Switching shorter flights to electric planes could put a dent in emissions.Plus, electric planes are quieter than conventional aircraft, which reduces noise pollution at the smaller suburban airports Zunum envisions serving.

Neither Zunum nor Wright can achieve battery-powered flight without improvements in battery technology.

Current electrical storage cells are too heavy and not efficient enough.Test cases with electricity-augmented gliders have been impressive, but they have little in common with the demands the fledgling companies will face when they start carrying full loads of passengers.

Battery technology is improving rapidly.

However, the explosive growth of mobile technology and international research into large-scale alternatives to carbon-emitting electrical power plants have attracted substantial attention and resources to the field of battery development.

Advocates of electric flights are crossing their fingers.