Life cycle assessment of the use of biomass heat for the treatment of brackish water in isolated areas.

Access to freshwater is further restricted in dry regions of South America due to the high levels of arsenic and boron. To overcome this, desalination through multi effect distillation (MED) is a potential solution. However, the significant amount of heat needed in MED treatments can have significant environmental burdens. The use of biomass to produce heat is seen as a potential climate-change-friendly alternative to the use of fossil fuels. However, isolated communities may not have direct access to biomass and potential environmental trade-offs can occur associated to the transport. This study has analysed with life cycle assessment (LCA) the environmental sustainability of using biomass for the generation of heat with real data of a MED plant in Northern Chile treating brackish water with high levels of arsenic and boron. The functional unit considered is the production of 1 m3 of distillate water and 13 impacts categories were estimated for two heat generation scenarios: i) by diesel generator and biomass (current operating situation) or ii) its combination with solar thermal fields (alternative scenario). Results show that the alternative scenario is the best option for all impact categories and for the use of biomass, the boiler and the distance of transport are the main environmental hotspots for the current situation.