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