batteries

Pencil graphite and aluminum foil https://www.youtube.com/watch?v=ITzAZFYFo_0

3-penny battery https://www.youtube.com/watch?v=rIdPfDHeROI (newer than 1982 pennies)

Generator to charge cell phone https://www.youtube.com/watch?v=hCxmn1ERbXc

Giant solar lens https://www.youtube.com/watch?v=XFw7U7V1Hok