This reminds me of a watch a friend had. It did not use batteries. It worked off the movement of his wrist/hand. He said the watch somehow converted kinetic energy into power for the watch. The watch was always fast, we suspected he masturbated too much.
But a backpack that will produce enough juice to run electronics. WOW!!
A while back, a friend went to Isle Royale, a primitive island off northern Michigan. He said a boat went there once a day, in the morning, and once it left, you were stuck on the island. No toilets, no running water, no nothing but wild wolves and a thick forrest. There was no doctor, no police, no anything. But people went there to hike and camp. He said in 6 days of deep hiking, he only ran into 2 other hikers.
Now imagine how portable batteries that charge off movement would change things...
He could take his cell phone with him, and know it would not die. So if work needed to call, they could. He could take his laptop, so for those insomniac nights he could catch up on work.
I dunno, when I go hiking, I take food and water. I don't think I would want 80 pounds of batteries on my back.
The usefullness of batteries would be on a truck. Toss a ton of batteries and generators on a truck, because the extra weight won't mean anything. But for a human, 80 pounds is a lot of extra weight if you also want to carry water.