Dogs love to chase cyclists. Turn this into energy.
Attach your dog to a bar jutting perpendicularly from the bicyle, give the bicycle a push and let your dog simultaneously chase and push the cycle around the yard. Optionally attach a manequin which turns its head and mocks your dog with every cycle. Naturally, the turning wheel will generate electricity and/or take you to the park and back.-- 4and20, Apr 01 2024random, halfbakery