title: Dynamic hybrid life cycle assessment of energy and carbon of multicrystalline silicon photovoltaic systems.
abstract: This paper advances the life cycle assessment (LCA) of photovoltaic systems by expanding the boundary of the included processes using hybrid LCA and accounting for the technology-driven dynamics of embodied energy and carbon emissions. Hybrid LCA is an extended method that combines bottom-up process-sum and top-down economic input-output (EIO) methods. In 2007, the embodied energy was 4354 MJ/m(2) and the energy payback time (EPBT) was 2.2 years for a multicrystalline silicon PV system under 1700 kWh/m(2)/yr of solar radiation. These results are higher than those of process-sum LCA by approximately 60%, indicating that processes excluded in process-sum LCA, such as transportation, are significant. Even though PV is a low-carbon technology, the difference between hybrid and process-sum results for 10% penetration of PV in the U.S. electrical grid is 0.13% of total current grid emissions. Extending LCA from the process-sum to hybrid analysis makes a significant difference. Dynamics are characterized through a retrospective analysis and future outlook for PV manufacturing from 2001 to 2011. During this decade, the embodied carbon fell substantially, from 60 g CO(2)/kWh in 2001 to 21 g/kWh in 2011, indicating that technological progress is realizing reductions in embodied environmental impacts as well as lower module price.
authors.affiliation: School of Sustainability, Arizona State University, Tempe, Arizona 85287, USA. clarezhai@gmail.com
authors.forename: Pei
authors.initials: P
authors.lastname: Zhai
authors.forename: Eric D
authors.initials: ED
authors.lastname: Williams
mesh_terms: D002244:Carbon / Q000737:chemistry*; D003460:Crystallization; D012825:Silicon / Q000737:chemistry*; D012993:Solar Energy
chemical_list: D002244:Carbon; D012825:Silicon