General Electric and others continued working on PEM fuel cells in the 1970s. Fuel cell stacks were still limited principally to space applications in the 1980s, including the Space Shuttle. However, the closure of the Apollo Program sent many industry experts to private companies. By the 1990s, automobile manufacturers were interested in fuel cell applications, and demonstration vehicles were readied. In 2001, the first 700 Bar (10000 PSI) hydrogen tanks were demonstrated, reducing the size of the fuel tanks that could be used in vehicles and extending the range.