But even after green hydrogen is available, the industry must still get it to vehicles. That requires an exponential and nationwide increase in the number of filling stations.
Auto executives have lobbied state and federal governments to do more to boost the nation's hydrogen network.
The North American CEOs of Toyota and Hyundai were among the executives to sign an August letter to California Gov. Gavin Newsom urging the state to allocate $300 million in the state budget to fund the construction of 1,000 hydrogen stations over the decade.
"At this still very early stage in market development, the signal California sends on hydrogen will impact private investment decisions," they wrote.
For now, suppliers can move hydrogen long distances using existing steel pipeline systems, said Conrad Layson, an alternative propulsion analyst at AutoForecast Solutions.
As the smallest of elements, hydrogen molecules can escape through the latticework of steel pipes and bind with the metal, he said. That makes the pipes brittle over time.
"The long-term answer will be to replace the existing right-of-ways with hydrogen-friendly pipes with some substance that resists penetration," Layson said.
Once hydrogen is at a filling station, it offers a key advantage over BEVs: It fills at the same rate as gasoline. Customers, however, are learning that there are other complications, as the stations are frequently down.
On a good day in California, hydrogen refilling stations work about 80 percent of the time, though that number has sometimes been as low as 50 percent, Scott said.
"When it doesn't work, people understandably kind of lose their minds," he said.
Scott said "more robust" compressor and precooling systems are needed. Both are crucial to a refueling station's reliability.
The industry is working to improve its equipment and create a better supply chain for the fuel, he said.
"We put people on the moon," he said. "I promise you this is less challenging than landing a rover on Mars."