With the growing threat of global warming, the search for vehicles with small carbon footprints becomes more hectic every day. And as cars like the Honda Civic Hybrid and the Toyota Prius grow in popularity, automakers strive to market more fuel-efficient, environmentally responsible cars. One of these options is the hydrogen fuel cell car, which may include an on-board hydrogen purifier.

A hydrogen purifier is a device that extracts hydrogen from a fuel source such as gasoline or biodiesel. While in the past, hydrogen purifiers have been too bulky and impractical to fit into modern automobiles, companies like Power+Energy have simplified the process, making a smaller, more efficient hydrogen purifier, which can work alongside a hydrogen fuel cell.

There are several components to the , including a fuel tank and a water tank; a heat exchanger (where excess heat is transferred away from the compounds after they’re separated from the fuel), a fuel cell (not necessary to the purification process; on the contrary, a hydrogen fuel cell can’t work without the ultrapure hydrogen) a hydrogen purifier provides, and the two most important parts: The reformer and the multi-function membrane reactor.

The reformer pulls in fuel from the fuel tank, then, using heat and water from the water tank, breaks the fuel down into its individual components. Usually these are carbon monoxide, carbon dioxide, methane and water. These are all carried through the heat exchanger, which cools them down by transferring their heat back to the fuel as it’s carried to the reformer. The only emissions from this process are water and carbon dioxide.

After leaving the reformer, the broken-down materials – collectively referred to as “reformate” – are taken to the multi-function membrane reactor, where the hydrogen is harvested. This reactor is the core of the Power+Energy technology.

The reformate, which is a mixture of water, hydrogen and molecules of fuels like methane, carbon monoxide, and ethane. Using the water and a specialized catalyst, the hydrogen purifier’s reactor frees some of the hydrogen from these molecules. Inside the reactor is a membrane made of a palladium alloy. (Palladium has the distinction of being able to absorb up to 900 times its own volume in hydrogen at room temperature.) The membrane allows only hydrogen through, keeping the other molecules in place until the water and catalyst can separate the hydrogen from them. After a short time, all of the reformate has been reduced to nothing but carbon dioxide and water, having lost all the hydrogen in the breakdown process. This CO2 and water are emitted as waste, and the ultrapure hydrogen is carried to the fuel cell, where it fuels the vehicle.

Hydrogen purifiers have long been used for a variety of purposes, from creating hydrogen for jet fuel to making semiconductors and light-emitting diodes. As companies like Power+Energy continue to develop more advanced forms of hydrogen purification, the process will only get more efficient.