Harnessing wind power to charge your batteries.  I came across this very interesting concept on Treehugger website.

Febot Wind Powered Battery charger

Seems an idea with potential but would it work here in Shetland?  I quote  “stick it to a surface like a window where the wind whips by”  But what happens if a ‘Shetland wind’ whips by???  I think my batteries may start to disappear along with their charger!!