This invention is a method, device, and system to provide respiratory assistance to people with Obstructive Sleep Apnea (OSA), or other respiratory conditions, comprising harvesting and storing energy from gas outflow during exhalation and using that stored energy to increase gas inflow during inhalation. In an example, this invention may provide Positive End-Expiratory Pressure (PEEP) or Continuous positive Airway Pressure (CPAP). This invention can be embodied in a self-contained energy-harvesting positive airway pressure mask, nasal inserts, or mouth appliance. This invention offers a combination of the following five benefits for Obstructive Sleep Apnea (OSA) treatment: minimally-invasive energy self-sufficient freedom of movement hypercapnia avoidance and adjustable energy harvesting over multiple respiratory cycles.