United States, Nov. 21 -- NASA has selected Plug Power, Inc., of Slingerlands, New York, and Air Products and Chemicals, Inc., of Allentown, Pennsylvania, to supply up to approximately 36,952,000 pounds of liquid hydrogen for use at facilities across the agency.The NASA Agency-wide Supply of Liquid Hydrogen awards are firm-fixed-price requirements contracts that include multiple firm-fixed-price delivery orders critical for the agency's centers as they use liquid hydrogen, combined with liquid oxygen, as fuel in cryogenic rocket engines, and the commodity's unique properties support the development of aeronautics. The total value for the combined awards is about $147.2 million.The contracts begin Monday, Dec. 1, and each consists of a two-y...