Life cycle assessment and life cycle costing of a building-scale, solar-driven water purification system *

Water purification systems require material resources and energy to build and operate, thus leading to environmental burdens. Mature water treatment technologies such as reverse osmosis and multi-effect distillation have been extensively studied for their environmental impacts. There is still a lack of such studies in one of the promising technologies, namely, air gap membrane distillation (AGMD). This study performs a cradle-to-grave life cycle assessment (LCA) and a life cycle costing of a solar-driven AGMD water purification system. This research also assesses the cost competitiveness of the system compared to local bottled water using a levelized cost of water (LCOW) approach. The study shows that the environmental impacts of the water purification systems (using a functional unit of 590 m 3 of drinking water produced over a time period of 15 years) are: 27,224 kg CO 2eq (climate change), 2,408 kg 1.4-DCB (human carcinogenic toxicity), 3,100 kg 1.4-DCB (marine ecotoxicity), and 2,286 kg 1.4-DCB (freshwater ecotoxicity). The solar PV sub-system and solar thermal sub-system have a much higher impact than the water purification sub-system. The LCOW calculations show that the system, with its current runtime of six hours using solar energy, has a levelized cost of 0.46 USD/L. Alternative scenarios, such as the use of grid electricity and end-of-life treatment of generated wastes, are also evaluated. A sensitivity analysis is performed on four parameters, i.e., component lifetime, maintenance frequency, discount rate, and AGMD module production cost. This study could be useful to local governments, investors, and potential customers interested in the water purification system's environmental footprint and cost competitiveness.