Orlando airport tests cleaner hydrogen-powered internal combustion engines . Smoother , quieter engines require million-dollar fueling stations . Score: 6 Hydrogen engines cheaper than hydrogen fuel cells , but they use more hydrogen .
Orlando airport tests cleaner hydrogen-powered internal combustion engines . Smoother , quieter engines require million-dollar fueling stations . Testers hope to learn more by gathering data from nonstop shuttle usage . Hydrogen engines cheaper than hydrogen fuel cells , but they use more hydrogen .