Source: Frost & Sullivan Technical Insights

Technologies such as photovoltaics have the potential to dramatically change the energy market worldwide, decreasing dependence on fossil fuels for electricity generation. However, there has been concern in some circles that the manufacturing and fabrication of solar cells could potentially be environmentally damaging as well.

Photovoltaic systems benefit rural communitiesFrost & Sullivan has therefore taken interest in an analysis published in the journal Environmental Science & Technology by an international team of researchers examining the greenhouse gas emissions, heavy metal emissions, and emissions of pollutants such as sulfur oxides and nitrogen oxides involved in the life cycle of four different types of solar cells.

"Life cycle emissions result from using fossil-fuel based energy to produce the materials for solar cells, modules, and systems, as well as directly from smelting, production, and manufacturing facilities," said Vasilis Fthenakis, one of the authors of the report. "All anthropogenic means of generating electricity, including solar electric, create pollutants when their entire life cycle is taken into account."

However, the researchers found through their analysis that the emissions from the life cycle of multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride photovoltaics "are insignificant in comparison to the emissions that they replace" when the cells are introduced into normal European and US power grids.

Of the four different types of cells studied, the researchers found that thin-film cadmium telluride (CdTe) photovoltaics had the least amount of associated emissions, mainly due to the significantly lower energy needs to produce thin-film cadmium telluride systems than those requiring large amounts of high-purity silicon. Interestingly, the CdTe systems were associated with lower heavy metal emissions than the silicon systems, once heavy metal emissions produced via coal-fired power plants were included in the analysis.

The exact emissions profile of each system depends in large part on the fuel sources used in the electricity supply used during the manufacturing process. "Emissions differ in different countries, depending on that country’s mixture in the electricity grid, and the various methods of material/fuel processing," said Fthenakis.

Using photovoltaics in ‘breeder’ scenarios, in which a portion of solar cell production is used to replace the energy sources required to power later rounds of additional solar cell production, could be a good way of dramatically shifting the emissions profiles of the photovoltaic life cycle, the researchers believe.