Google has a truly sky-high idea for connecting billions of people to the Internet — 12 miles in the air to be exact — through giant helium balloons circling the globe that are equipped to beam WiFi signals below.

Google will announce Saturday it has 30 balloons floating over New Zealand to provide free Internet access to disaster-stricken, rural or poor areas. Eventually, as the balloons move across the stratosphere, consumers in participating countries along the 40th parallel in the Southern Hemisphere could tap into the service.

Called Project Loon, the experimental program was hatched by engineers at the company’s top-secret Google X laboratory in California’s Silicon Valley that invented driverless cars and eyeglasses equipped with voice-activated computers. Some of those technologies won’t immediately — or ever — make money for the firm. Google said it pursues these “moon shot” ideas with the aim of solving big problems and creating breakthrough technologies that ultimately will bring more users to its services.

These projects also help Google extend its sprawling reach into the lives of global Internet users, amid an intensifying debate over Internet privacy. Already, the company has the leading Web search, e-mail service and Internet video site, while its Android mobile software has become the most popular in the world.

These tools have enabled Google to track a wide range of consumer behaviors, which the company sells to advertisers. In recent weeks, privacy advocates have raised concerns over how much of this data is being shared with the U.S. government.

The balloons also represent another of Google’s forays into the telecommunications business. The company has been setting up Internet connections in Kansas City, Austin and elsewhere that offer speeds 100 times faster than what most consumers have today. Google also offers free WiFi in the Chelsea neighborhood of Manhattan and a few other U.S. cities. Top executives have long complained of the slow expansion of Web connections as a bottleneck to the growth of its business.

Mike Cassidy, the director of Project Loon, said the aim is to provide much cheaper Internet connections around the world. In many African nations, for example, monthly Internet costs are higher than monthly salaries.

“We are focused on an enormous problem, and we don’t think we have the one solution today,” he said in a phone interview from New Zealand. “But we think we can help and start having a discussion on how to get 5 billion people in remote areas” connected to the Internet.

The thin plastic balloons hovering over New Zealand — measuring a few minivans in diameter and barely visible to Earth-bound spectators — use a mix of highly sophisticated and basic methods to deliver Internet connections of at least 3G cellular speeds.

The high-pressure balloons carry antennas, radios, solar-power panels and navigation equipment that talk to specialized antennas on rooftops below. But they do not have motors, and their travel largely depends on wind patterns.

The cluster of balloons provide a kind of drifting Internet network in the stratosphere, moving at a snail’s pace and lasting more than 100 days in the air. As long as a balloon is within a 24-mile radius, people would be able to tap into the network, Google said. Much cheaper than satellite technology — Google would not reveal specifics — the balloons could provide service in remote regions or perhaps an area that has lost its communications because of a violent storm.

That’s why the firm picked the cities of Christchurch and Canterbury in New Zealand for its first test case. The area is largely rural, and government leaders have embraced the plan.

Google needs permission from local governments to tap public airwaves. But if the balloons drift into the wrong areas, the engineers can use GPS and other telecom technology common among weather balloons to adjust their flight.

That the balloons are aimed at the Southern Hemisphere illustrates the importance of Africa and South America to Google’s future growth, some analysts said.

“There is an enormous problem of affordability of broadband access in much of the developing world,” said Gene Kimmelman, senior associate at Global Partners Digital, a technology policy consulting group. “We have an explosion of wireless devices everywhere, even among the poorest nations, but in most instances there is limited access to the Internet.”

About two-thirds of the world’s population is not connected to the Internet. In developing nations, the portion is larger. About seven out of eight people in emerging market economies have no Internet access, according to the International Telecommunications Union, a multinational organization of communications regulators.

Balloons have been used for hundreds of years for military communications. But to make the inflatable Internet networks work, Google engineers had to overcome significant technical hurdles.

The balloons fly in the stratosphere, twice as high as airplanes, and engineers had to find a way to control their direction. So they came up with navigational controls that move balloons up and down to find altitudes where wind is traveling in desired directions. They also wanted to keep the balloons in clusters to ensure consistent connectivity in a given area.

All of this was done in secret for two years.

“I couldn’t even tell my parents about it, so I’m excited for them to know today,” said Cassidy, the Google project director.

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