Orlando also tests cleaner hydrogen - powered internal combustion engines . Smoother , quieter engines require million - dollar fueling stations . ` It 's quiet , it does n't shake like diesel , it does n't have that diesel smell , '' said Rafael Sanchez , who has been driving the vans for a year . Testers hope to achieve more by gathering data from nonstop shuttle flights . Hydrogen engines cheaper than hydrogen fuel cells , but they use more hydrogen .
Orlando also tests cleaner hydrogen - powered internal combustion engines . Smoother , quieter engines require million - dollar fueling stations . Testers hope to achieve more by gathering data from nonstop shuttle flights . Hydrogen engines cheaper than hydrogen fuel cells , but they use more hydrogen .