A comparative life cycle assessment (LCA) of lighting technologies for greenhouse crop production

Greenhouse, indoor or vertical horticulture using supplemental lighting have become an important part of specialty crop cultivation. This study reports a comparative life cycle assessment of different lighting systems applied in greenhouse crop production. Two typical cases are considered: (1) 1000 W HPS lighting system vs. 650 W LED lighting system with functional unit defined as 653 kg tomatoes from 8 sq. ft. floor area over 15 year; (2) 150 W incandescent lighting vs. 18 W LED lighting with functional unit defined as 1640 sq. ft. of bedding plants from 8 sq. ft. floor area over 15 year. Impact assessment is done using TRACI methodology and cumulative energy demand (CED) is also considered. The results show that 650 W LED lighting system has smaller environmental impact than the HPS lighting system (38%-47% reduction). The use phase dominates the total environmental impacts (approximately 74%-97% for HPS lighting system, and 78%-100% for LEDs). Benefits of substituting LEDs for incandescent lighting for greenhouse applications are even larger leading to a significant reduction (67%-90%) on most environmental impact categories considered (except carcinogenics where LED is 12% higher)). For this case, the use phase remains the largest contributor, accounting for 28%-100% for incandescent and 47%-100% for LEDs.