About a decade ago, the United States federal and state governments began experimenting with hydrogen fuel cells, said Stan Osserman, director of the Hawaii center for advanced transportation technologies.
The push was driven by high oil prices at the time. As the prices tapered, however, the development kept going.
"The prices have come down and the weight has come down on [hydrogren fuel] equipment," said Osserman. "Lots of companies are realizing this is a good business case on its own."