The Honorable Miranda A. Ballentine, assistant secretary of the Air Force for Installations, Environment, and Energy, and U.S. Senator Brian Schatz are shown the hydrogen refueling process by Gene Hughes, Service and Operations Manager for U.S. Hybrid Corporation during a tour of the Hawaii Center for Advanced Transportation Technologies, Aug. 26, 2015, Joint Base Pearl Harbor-Hickam. The Air Force in partnership with the state of Hawaii established a National Demonstration Center to facilitate demonstration and validation of the latest fuel efficient and environmentally compliant technologies for use in Air Force ground vehicles, support equipment, base infrastructure, and basic expeditionary airfield resources. (U.S. Air National Guard photo by Senior Master Sgt. Kristen Stanley /released)