Abstract
This paper describes the life cycle assessment (LCA) for photovoltaic
(PV) power plants in the new ecoinvent database. Twelve different,
grid-connected photovoltaic systems were studied for the situation
in Switzerland in the year 2000. They are manufactured as panels
or laminates, from monocrystalline or polycrystalline silicon, installed
on facades, slanted or flat roofs, and have 3 kWp capacity. The process
data include quartz reduction, silicon purification, wafer, panel
and laminate production, mounting structure, 30 years operation and
dismantling. In contrast to existing LCA studies, country-specific
electricity mixes have been considered in the life cycle inventory
(LCI) in order to reflect the present market situation. The new approach
for the allocation procedure in the inventory of silicon purification,
as a critical issue of former studies, is discussed in detail. The
LCI for photovoltaic electricity shows that each production stage
is important for certain elementary flows. A life cycle impact assessment
(LCIA) shows that there are important environmental impacts not directly
related to the energy use (e.g., process emissions of NOx from wafer
etching). The assumption for the used supply energy mixes is important
for the overall LCIA results of different production stages. The
presented life cycle inventories for photovoltaic power plants are
representative for newly constructed plants and for the average photovoltaic
mix in Switzerland in the year 2000. A scenario for a future technology
(until 2010) helps to assess the relative influence of technology
improvements for some processes. The very detailed ecoinvent database
forms a good basis for similar studies in other European countries
or for other types of solar cells.
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