Many believe hydrogen to have the greatest potential of all alternative fuels, not only for vehicles but as a primary energy source for all aspects of life. Used in fuel cells to electrochemically create electricity for powering a vehicle’s electric motors, hydrogen produces no emissions other than water vapor and heat. There are no CO₂ or other greenhouse gases.

While hydrogen is largely extracted from methane today, there are bigger things on the horizon. Hydrogen is a virtually unlimited resource when electrolyzing water using solar- or wind-generated electricity, a process that splits H2O (water) into hydrogen (H) and oxygen (O) molecules. Water covers much of the Earth’s surface and is the most abundant compound on the planet.

This has been on the mind of auto manufacturers for years. In fact, editors have experienced many test drives of prototypes and concepts running on hydrogen power for years, like our time behind the wheel of a Mazda MX-5 Miata concept more than two decades ago, along with others from BMW, Ford, GM, Honda, Hyundai, Mercedes-Benz and more.

Along with their own independent hydrogen vehicle development programs, some automakers like GM and Honda are working cooperatively to develop next-generation fuel cell systems and hydrogen storage. Others are working with hydrogen fuel suppliers and state governments to develop an expanded hydrogen fueling network.

In recent years, Honda has been leasing its FCX Clarity fuel cell sedan to limited numbers of consumers in California and Hyundai has recently followed suit with its Tucson Fuel Cell crossover vehicle, also available to limited numbers of consumers in California where hydrogen refueling is more readily available. Both Honda and Toyota have announced plans to introduce next-generation production fuel cell vehicles for consumers shortly.

As with any game-changing technology, hydrogen vehicles come with their challenges. Hydrogen vehicles are presently quite costly to produce, although their cost to consumers who lease them will surely be subsidized by manufacturers until this field matures. The production of ‘green’ hydrogen through electrolysis and other means is also presently limited and costly, plus the nation’s hydrogen refueling infrastructure is extremely sparse, although growing.

The hydrogen vehicle field continues to evolve. A recent study by Sandia National focused on 70 gas stations in California – the state with the largest number of existing hydrogen stations – to determine if any could add hydrogen fueling based on requirements of the 2011 NFPA 2 hydrogen technologies code. The conclusion is that 14 of the 70 stations explored could readily accept hydrogen fuel, with an additional 17 potentially able to integrate hydrogen with property expansions. In this light, expanding the network of hydrogen stations may be more straightforward than previously thought.

Even amid these challenges, with major commitments from automakers like Honda, Toyota, GM, and others in Europe and Asia, hydrogen vehicles are a very real and exciting possibility for the road ahead.

Hydrogen fuel cell buses and cars can now fill up with this zero-emission fuel at AC Transit’s municipal bus facility in Emeryville, California. The hydrogen fueling systems provided by Linde North America are capable of fueling up to 12 buses and 20 passenger cars per day. A second AC Transit hydrogen fueling station in Oakland is expected to begin operating in 2013. Part of AC Transit’s HyRoad project, the stations aim to demonstrate the commercial viability of hydrogen fuel cell technology for public transit.

The transit agency operates buses in 13 cities in the East Bay Area of Northern California, including Emeryville, Oakland, and Berkeley. AC Transit additionally operates trans-bay service to San Francisco.

The California Air Resources Board estimates that fuel cell buses will deliver a net reduction of 2.7 pounds of carbon dioxide per mile using hydrogen reformed from methane, and 6.3 pounds per mile using hydrogen derived from solar, wind, or other renewable sources. With each AC Transit bus projected to travel 36,000 miles annually, this could potentially reduce carbon emissions by 44 metric tons per year when using methane as a source of fuel, or 103 metric tons using renewables.

Importantly, these are tailpipe and carbon emissions reductions that can be duplicated by transit agencies across the country. To do so, however, requires significant public and private investment to enable the effort.