An electric aircraft is on the horizon. In fact, it has already been built and flown.

Last summer, NASA sponsored the “Green Flight Challenge,” in which teams of aeronautical engineers competed for a grand prize of more than $1.25 million. The winning group, Team Pipistrel-USA.com, built a four-seat, electric-powered aircraft that flew nearly 200 miles non-stop.

“It is a really exciting time for aerospace engineers,” said Dr. Tom Edwards, director of aeronautics at NASA’s Ames Research Center. “Just when people are saying that aircraft [technology] has been the same for the past 50 years … there is a fusion of information technology and traditional aerospace engineering that is making the field evolve very rapidly.”

Edwards will be the keynote speaker at the Boeing Future of Flight Foundation’s Earth Day Celebration this month. He will talk about the work being done with environmentally progressive aircraft.

According to Edwards, it’s all about the battery. Electric car manufacturers have a lot to teach the team at NASA. “They are so much further invested in it than we are. But we can cherry pick the technology, and particularly the advances that they are making in batteries — those are really important to us.”

So far, batteries weigh too much and don’t store enough energy for serious aviation.

“Right now, we understand how to make an electric aircraft — we have done it, lots of people have. We need batteries that have much higher energy and power density. If we could get the perfect battery today, we would be able to address a number of other challenges.”

In addition to the battery dilemma, NASA is working on many issues to create environmentally friendly aircraft, including decreasing noise around airports and carbon and other chemical emissions from engines, addressing wing, engine and passenger compartment designs, and focusing on the flight routes of aircraft. They are also working on lighter-weight structures and materials to reduce fuel consumption, which Boeing implemented in its newest aircraft, the 787 Dreamliner.

Edwards hinted that he may give visitors at the Earth Day Celebration a peek “very far into the future ... [at aircraft] that looks radically different from today’s aircraft.”

The Earth Day celebration will be held from noon to 5 p.m. on Sunday, April 22. The Future of Flight Foundation, located at 8415 Paine Field Blvd. in Mukilteo, will be open to the public. All exhibits, including grand openings for the wind power, solar power and Wikispeed electric car exhibits, will be free of charge.