That would probably be legal, however would be difficult to do as stated in the other posts.
Another way which might be easier but probably illegal is to make a microwave transmitter to beam microwave frequencies to a reciever. The reciever is usually a rectenna, which converts microwave to electricity. It could be relativley efficient also.
However, that could be extremley dangerous and illegal in the competion. Other methods that would be safer are also availiable like laser beaming.
One may actually be able to replicate experiments such as this one
http://youtube.com/watch?v=4BxV_48Sjj4
Anyway, I hope that helped.
Amir M.