The X PRIZE Foundation is a fantastic organization. They launched the $10m Ansari X PRIZE, which was won in 2004. This prize rewarded the first private team to fly to 100km (twice in two weeks).
Now they are working on a prize for energy and the environment. I'm helping get this kicked off and it's a really interesting project. There are literally dozens of potential areas that might be appropriate for an X PRIZE. However, it has to be an area which $10m will move the needle, and so asking teams to compete for something there were going to do already is a waste of time.
If you have any thoughts as to what might be interesting for the X PRIZE Foundation to focus on for an energy prize, please drop me a line (at my aaronfyke email address at yahoo.com - my Turing test for spam bots). I'd love to get input! Also, providing input would not disqualify you from any future prize competition.
