Mobile computing has relied on rechargeable batteries for decades. Like non-rechargeable batteries, these rechargeable cells produce electricity through an electrochemical reaction inside the battery. The fuel cells within the batteries store the energy from an AC power source while they're plugged in by reversing that electrochemical reaction inside the battery. You can read more about what's going on inside the average battery in our article How Batteries Work.
As of this writing, Apple's portable devices products rely on lithium polymer batteries. These batteries use chemicals that rely on lithium ions moving within a polymer electrolyte to produce electricity. Unlike their lithium-ion predecessors, this polymer is an inorganic, nonflammable material. These batteries are notorious for not holding their charge very long and for using materials that require a lot of energy and chemical material to produce [source: EcoGeek.org].
Today, the electronics industry is looking to replace lithium polymer batteries with technology that has historically powered another well-known portable device: the automobile. For decades, scientists and engineers have researched hydrogen as an alternative fuel for cars [source: Wise].
For automobiles, hydrogen fuel cells are flat and thin so that they can be stacked together inside a single battery. Apple's patent applications reveal an effort to use that same fuel cell technology in a smaller package. Besides being scaled to fit within a computer, the hydrogen fuel cell would be lighter and more efficient than lithium polymer batteries.
More importantly, it would last much longer and produce no harmful waste that could pollute the environment.
What Apple isn't saying is what kind of hydrogen fuel cell we can expect. One of the barriers that the automobile industry has had with regards to hydrogen fuel cells is finding a reliable source of hydrogen. Most hydrogen gas produced today is obtained by processing fossil fuels, and the rest uses electrolysis which also requires existing energy. This creates a paradox: The hydrogen fuel cell is cleaner and more efficient, but it still relies on the non-renewable sources it's aiming to replace [source: Wise].
In its patent application, Apple offers some ideas for a rechargeable design that could perform a hydrolysis reaction to produce hydrogen during recharging. It proposes various chemicals to assist this process, though, which calls to question just how environmentally friendly these batteries could be. It's too early to tell whether Apple will run into the same hydrogen fuel cell paradox that the automotive industry did.
Supposing Apple jumps over the hurdle, what are the benefits and risks of having fuel cells in your MacBook or iPhone? Let's look at that next.