CO2 emissions inevitably occur in ORW because of the poor efficiency of the injection sys­tem and because of the natural outgassing from the growth medium. Only four publications

(Kadam, 2002; Stephenson et al., 2010; Campbell et al., 2011; Collet et al., 2011) take into account these losses, with respective emissions of CO2 equal to 0.07%, 30%, 10%, and 10%. A few studies only consider emissions of other gases. Campbell et al. (2011) consider that 0.11% of the nitrogen is volatilized without specifying the forms of the emissions. According to Hou et al. (2011), 0.5% is volatilized as NH3. Finally, Batan et al. (2010) mention NH3 volatilization without quantification.