On Monday, 25 November 2019 19:26:15 UTC, Bill Wright wrote:
Or-- (Lightbulb moment) If I mounted a loudspeaker near the gate and put
a microphone on the gate, and played really loud music with a lot of low
bass, the mike output should be enough to charge a battery. Simples.

Or paint the gate up as a shrine and get all the local devotees to come and light candles (for a small donation).

Owain