Looking for a Green Alternative To an Electric Powered Weed Trimmer (string Trimmer)?

I am looking for a green alternative to my current gas-powered weed trimmer, a green substitution comparable to my rotary push mower rather than my old gas mower. It seems crazy to mow the lawn with the push mower then get out the gas-powered string trimmer to do all the edging!
What did people use before gas- and electric-powered weed whackers?