Predicting potential climate change impacts of bioenergy from perennial grasses in 2050

•The energy availability and mitigation effects were assessed for perennial grasses in 2050.•The bioenergy production can up to 24.33 EJ and satisfy 34.15% of the global bioenergy supply.•A newly developed framework was implemented to assess the climate change impacts of bioenergy.•The highest mitigation effect can be 5800.06–6716.64 mt CO2 eq by substituting coal-fired power.