A laptop powered by a hydrogen fuel cell, going for weeks without refueling. That vision of the future is described in a pair of patent applications filed by Apple and made public Thursday.

One of the patent applications, entitled Fuel Cell System to Power a Portable Computing Device, describes a fuel cell system with a fuel cell stack that generates electricity, as well as a system controller and a bidirectional communication link between the controller and the device.

'Days or Even Weeks'

The other application, Fuel Cell System Coupled to a Portable Computing Device, describes a fuel cell system that "is capable of both providing power to and receiving power from a rechargeable battery in a portable computing device." The application notes that this would eliminate "the need for a bulky and heavy battery within the fuel cell system," thus significantly reducing the size, weight, and cost of the fuel cell.

Fuel cells, such as hydrogen fuel cells, can pack a lot of electricity-generating power into a small package. As one of the applications noted, "Fuel cells and associated fuels can potentially achieve high volumetric and gravimetric energy densities," which could potentially mean that portable devices could operate for "days or even weeks without refueling." Similarly, the other application's description of linking the fuel cell to the rechargeable battery helps to keep size and weight down, and time between refueling up.

Apple's applications discuss using sodium borohydride powder mixed with water as a fuel, and the hydrogen would be obtained from the sodium borohydride. The hydrogen then mixes with oxygen via a membrane, producing electricity and water vapor.

'Future Proofing'

The integration of the fuel cell system into the device would assumedly be one of the key features for which patent protection is sought. Another patent application by Apple, published in October, described a design for fuel cell plates.

Laura DiDio, an analyst with Information Technology Intelligence Corp., said Apple's patents indicated it was "future proofing and hedging its bets," and that the real question was whether the innovative company "has something cooking like this in the back room?"

She added that it was possible that Apple is not moving forward on this front, but simply looking to protect itself against other companies' ventures into fuel-cell powered mobile computing devices. Even if the Cupertino, Calif.-based company is using some of its large supply of cash to conduct R&D in this area, DiDio said, it was unlikely that mainstream products would emerge in the next decade or so.

As with many large technology companies, patents figure prominently in Apple's strategy. The biggest example of the importance of patents is the ongoing legal war by Apple with Samsung, HTC, and Motorola Mobility, over aspects of those companies' Android-based devices that Apple says violate its patents. Apple recently won a minor victory in its U.S. patent fight with HTC, lost a next step in its war with Samsung in Australia, and both won and lost some battles with Samsung in Europe.