Automakers are teaming up all over the world to prepare for the next big game in clean transportation, fuel cells.

The latest partnership is between Audi and Hyundai, which announced yesterday that they will share resources to develop fuel-cell vehicles.

The two said that the first fruit of this partnership will be a full-size Audi crossover SUV planned to go into production in small numbers "in the beginning of the next decade," perhaps as early as two years from now. Reading between the lines, it could be a fuel-cell version of the upcoming electric Audi e-tron SUV.

2019 Audi e-tron electric SUV

2019 Audi e-tron electric SUV

Hyundai has been an early adopter of fuel-cell technology, releasing the Tucson fuel-cell vehicle in California in 2013, and it plans to release its next-generation Nexo fuel-cell SUV next year. Neither Audi nor its parent Volkswagen has yet produced a fuel-cell car for public consumption.

Audi board member for Technical Development Peter Mertens called fuel cells "the most systematic form of electric driving," and "emission-free premium mobility of the future."

The announcement follows another last month in which Honda and GM, two of the historic leaders in fuel-cell development (alongside Toyota), announced that they would partner in developing fuel cell vehicles. 

First 2015 Hyundai Tucson Fuel Cell delivered to lessee at Tustin Hyundai, June 2014

First 2015 Hyundai Tucson Fuel Cell delivered to lessee at Tustin Hyundai, June 2014

Two fuel-cell vehicles are currently on sale in California, the Toyota Mirai, and the Honda Clarity Fuel Cell. (The Hyundai Tucson fuel cell is on hiatus for 2018.)

California is working to encourage the construction of hydrogen filling stations and has about 35 stations operating around the state. No other state currently has any hydrogen filling stations open to the public.

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The potential advantage fuel-cell cars have over battery electric cars is their ability to refuel quickly for more than 300 miles of range on a fill-up. Merten's statement may indicate that at least some automakers are planning to market fuel-cell vehicles as a premium upgrade to battery electric cars based on their fast refueling and their ability to make spur-of-the-moment long trips.

Building out a network of hydrogen filling stations, however, is still a massive challenge, especially in light of longer-range battery electric cars and 350-kw fast chargers coming online.