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  • Brief Report
  • Open Access

FREO2: An electricity free oxygen concentrator


  • Received: 23 October 2014
  • Accepted: 11 November 2014
  • Published:


The World Health Organization recommends oxygen therapy for children with severe pneumonia, but this essential medicine is unavailable in many health centres in limited-resource settings. To address this need, an appropriate means of oxygen provision will need to be low-cost and robust, require little maintenance and not compete for fuel with other vital functions, and be environmentally sustainable. This report presents the preliminary results of the Fully Renewable Energy Oxygen (FREO2) system, confirming the viability of a novel means of producing medical grade oxygen without any electricity. The approach relies on exploiting the reduction in pressure of water flowing through a raised siphon to create a source of vacuum. This is used to power a customised vacuum-pressure-swing-adsorption system and produce medical grade oxygen. The FREO2 system has been designed to meet the criteria for successful oxygen delivery in small health facilities. It is ideally suited for deployment in tropical or mountainous regions with proximity to flowing water. Importantly, the oxygen generating capacity of FREO2 rises with the increased demand commonly observed during the rainy season in such climates.


  • oxygen concentrator
  • sub-district health centre
  • pneumonia
  • developing country
  • children