The challenge / opportunity:
Getting a source of clean power anywhere in the world through regular usage in life.
In the past I have seen projects designed to gather energy from fixed locations.... for example pressure tiles in a subway designed to reclaim energy of human movement.
Fixed tiles are great... but it is about getting them where the most people travel... and the power still does not travel with the people. In particular in more isolated areas... backpacking in the woods... you would not take tiles with you and put on the trail :-) Or better yet in areas where you just cannot get power... or in times of power outages... this gives you power as you move about your day.
Shoes or more likely a sole attachement is always where you need it to be, to generate the energy you want. Water, the gift of life can be carried with us... and theoretically could be updated with a filtration system... and maybe even full water reclamation systems with filtering eventually added... but that could be a down the road option. Even right now the water could theoretically be still drinkable in the supply you bring with you in the reservoir...
A light weight battery back like a cell phone recharger style could be a great place to store the energy... to be able to provide light or even cellphone / camera power....