Life cycle assessment and cost of a seawater reverse osmosis plant operated with different energy sources

Seawater desalination plants consume significant amounts of energy sourced primarily from fossil fuels, leading to significant environmental impact. Life Cycle Assessment has been applied to desalination systems powered by a single renewable energy source with the underlying assumption of sufficiency of power supply. However, in several locations in the world the intermittent nature of these renewable sources prevents a full reliance on a single source and necessitates a combined fossil fuel-renewable energy mix. This study addresses this issue by performing life cycle assessment and preliminary costing analysis for different renewable-energy-grid combinations (photovoltaic-grid, wind-grid and anaerobic digestion-grid). Whilst the grid-anaerobic digestion and grid-photovoltaic scenarios provided significant improvements in all environmental impact categories, the grid-wind energy option resulted in the highest reduction whereby a 60% decrease in carbon footprint was observed. The unit product cost for the environmentally optimum grid-anaerobic digestion scheme was the lowest at 0.94 $/m(3), while the unit product cost for the grid-photovoltaic scheme was the most expensive at 1.47 $/m(3). An integrated photovoltaic-wind-anaerobic digestion scheme may offer further reduction in environmental impact and a potentially lower unit product cost.