Environmental assessment of sustainable energy options for multi-effect distillation of brackish water in isolated communities

Access to sufficient quantities of fresh water is becoming increasingly difficult, especially in dry regions. Moreover, high levels of salinity, arsenic and boron are further limiting the access to quality fresh water in many isolated communities worldwide. This paper evaluates the life cycle environmental impacts of a small multi-effect distillation (MED) plant, treating brackish water with high levels of these metalloids in an isolated location in Northern Chile. The facility currently operates solely with electricity from a diesel generator and heat from a biomass boiler. In order to evaluate the environmental impacts of more sustainable energy options, the implications of the use of solar fields and grid electricity as potential alternatives have been analysed. The results demonstrate that coupling solar fields and grid electricity is the best option, sharply decreasing impact in most categories in comparison to the current operating mode of the plant. This was attributed to the impact savings from reducing/eliminating onsite diesel and biomass combustion, and their associated transportation to the plant. For MED desalination in off-the-grid areas, the use of solar energy is highly recommended as an alternative to complement the use of diesel and biomass, especially if the latter is not nearby the unit. The concentration of arsenic and boron was reduced to below the required standards for irrigation and livestock consumption. The article concludes that the use of solar energy and grid electricity are environmentally beneficial for the production of quality fresh water from brackish water using MED at isolated communities.