Thursday, February 07, 2008

And the Winning Photovoltaic Is...

In an effort to quantify the efficiency, related emissions, and the hidden energy costs of the leading photovoltaic technologies, the Brookhaven National Laboratory and Columbia University recently conducted an extensive life-cycle assessment. Comparing data from companies that make single-crystal, multicrystal, ribbon silicon solar cells, as well as the thin-film CdTe photovoltaic systems just introduced to the market, the study, described in an Environmental Science and Technology article, produced a clear winner.

The analysis took into account frames, cables, and other necessary support materials, as well as the energy required for manufacturing under three scenarios, each with a different proportion of electricity coming from coal, natural gas, or other sources. The team based their assumptions on ground-mounted systems under southern European light conditions, over 30-year lifetimes.

In the end, the CdTe photovoltaics came out on top. With more efficient energy conversion and the lowest cost, the technology used less energy and had fewer emissions overall, despite some Cd emissions during the manufacturing process. However, emissions from fossil-fuel-powered electricity dwarfed those Cd emissions by orders of magnitude.

For access to the complete manuscript, Emissions from Photovoltaic Life Cycles, click here.