NASA has selected five green technology concepts that have the potential to transform the aviation industry in the next decade by reducing aircraft fuel use and emissions. The concepts were selected under NASA’s Transformative Aeronautics Concepts Program for a two-year study. The topics, including three specifically targeted at electrically-propelled aircraft are: alternative fuel cells; 3-D printing to increase electric motor output; the use of lithium-air batteries for energy storage; new mechanisms for changing the shape of an aircraft wing in flight; the use of a lightweight material called aerogel in the design and development of aircraft antenna.
http://www.nasa.gov/press-release/nasa-charges-toward-greener-aviation-with-novel-concepts