title: Comparison of Land, Water, and Energy Requirements of Lettuce Grown Using Hydroponic vs. Conventional Agricultural Methods.
abstract: The land, water, and energy requirements of hydroponics were compared to those of conventional agriculture by example of lettuce production in Yuma, Arizona, USA. Data were obtained from crop budgets and governmental agricultural statistics, and contrasted with theoretical data for hydroponic lettuce production derived by using engineering equations populated with literature values. Yields of lettuce per greenhouse unit (815 m2) of 41 ± 6.1 kg/m2/y had water and energy demands of 20 ± 3.8 L/kg/y and 90,000 ± 11,000 kJ/kg/y (±standard deviation), respectively. In comparison, conventional production yielded 3.9 ± 0.21 kg/m2/y of produce, with water and energy demands of 250 ± 25 L/kg/y and 1100 ± 75 kJ/kg/y, respectively. Hydroponics offered 11 ± 1.7 times higher yields but required 82 ± 11 times more energy compared to conventionally produced lettuce. To the authors' knowledge, this is the first quantitative comparison of conventional and hydroponic produce production by example of lettuce grown in the southwestern United States. It identified energy availability as a major factor in assessing the sustainability of hydroponics, and it points to water-scarce settings offering an abundance of renewable energy (e.g., from solar, geothermal, or wind power) as particularly attractive regions for hydroponic agriculture.
authors.affiliation: School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-5904, USA. glagesba@asu.edu.
authors.forename: Guilherme Lages
authors.initials: GL
authors.lastname: Barbosa
authors.affiliation: School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-5904, USA. falmeida@asu.edu.
authors.forename: Francisca Daiane Almeida
authors.initials: FD
authors.lastname: Gadelha
authors.affiliation: School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-5904, USA. Natalyaemmanuely.Mohrkublik@asu.edu.
authors.forename: Natalya
authors.initials: N
authors.lastname: Kublik
authors.affiliation: School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-5904, USA. ajprocto@asu.edu.
authors.forename: Alan
authors.initials: A
authors.lastname: Proctor
authors.affiliation: School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-5904, USA. lreichel@asu.edu.
authors.forename: Lucas
authors.initials: L
authors.lastname: Reichelm
authors.affiliation: School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-5904, USA. eweissin@asu.edu.
authors.forename: Emily
authors.initials: E
authors.lastname: Weissinger
authors.affiliation: School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-5904, USA. gwohlleb@asu.edu.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Wohlleb
authors.affiliation: School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-5904, USA. halden@asu.edu.|Center for Environmental Security, The Biodesign Institute, Global Security Initiative, Arizona State University, 781 E. Terrace Mall, Tempe, AZ 85287-5904, USA. halden@asu.edu.
authors.forename: Rolf U
authors.initials: RU
authors.lastname: Halden
mesh_terms: D000383:Agriculture / Q000379:methods*; D001130:Arizona; D018527:Hydroponics; D018545:Lactuca / Q000254:growth & development*
keywords: Arizona; agriculture; energy; hydroponics; land use; lettuce; sustainability; water