A new joint study by the U.S. Department of Energy's Argonne National Laboratory and Northwestern University has discovered that solar panels made in China have a carbon footprint that is twice the size as those panels made in Europe.
A correspondent from Northwestern University said last week that after exhaustive research, they found that panels produced in China are "likely" to use substantially more energy during the manufacturing process when compared to panels produced in Europe.
"We estimated that a solar panel's carbon footprint is about twice as high when made in China and used in Europe, compared to those locally made and used in Europe," said Northwestern corresponding author of the paper (titled: Domestic and overseas manufacturing scenarios of silicon-based photovoltaics: Life cycle energy and environmental comparative analysis) and assistant professor of chemical and biological engineering, Fengqi You. "While it might be an economically attractive option to move solar panel manufacturing from Europe to China, it is actually less sustainable from the life cycle energy and environmental perspective especially under the motivation of using solar panels for a more sustainable future."
A systematic life cycle analysis was employed by the research team in order to draw up hard data, analyzing the entire energy used in the production of a solar panel including the energy consumed in mining the raw materials required; the fuel burned in transporting the materials and products; the electricity required to power the manufacturing plant, and so on.
The study looked at silicon panels installed in southern Europe, an area with high levels of solar irradiation. Once evaluated under the life cycle analysis, researchers concluded that a panel made in China but installed in southern Europe would take up to 30% longer to generate the electricity required in order to balance out the energy used to make it. The carbon footprint, meanwhile, was double that of a solar panel produced domestically in Europe (the study did not, however, take into account utility-scale savings, of which Chinese manufacturers may benefit, both economically and environmentally).
Lack of regulations
Despite solar PV's undoubted green credentials, environmental concerns do not often appear as high up the agenda as one might expect for solar companies. In China, too, environmental governance standards are poor or often non-existent, and manufacturing efficiencies lag behind those imposed in the EU. In short, producing any product in China is invariably a more energy-intensive undertaking, with coal and other non-renewable sources involved more readily in the mix, wrote the authors.
"It takes a lot of energy to extract and process solar-grade silicon, and in China that energy tends to come from dirtier and less efficient energy sources than it does in Europe," said co-author of the report and Argonne scientist, Seth Darling. "This gap will likely close over time as China strengthens environmental regulations."
Darling added that although this particularly study did not factor in transportation of the finished module, had it done so then the disparity between Chinese- and European-made would have (for a panel installed in Europe) been even greater, perhaps by as much as 60%.
Further research carried out by the team included an analysis of different types of silicon panels. The study found that monocrystalline solar panels delivered the best efficiencies in harvesting solar energy but, due to their energy-intensive manufacturing process, the ‘pay back' on energy used overall was longer. Multicrystalline panel products were the second-best in terms of efficiency, followed by ribbon silicon panels, which, although the least efficient in harvesting energy, were also the least energy-intensive to make, meaning their ‘energy pay back' period is the shortest.
The report's conclusion on making the production of solar panels more sustainable arrived at the proposed introduction of a break-even carbon tariff, calculated in the range of 105-129 ($143-$176) per ton of carbon dioxide used.
"This tariff would be based on the carbon footprint and energy efficiency difference between manufacturing regions, and would be a better market- and science-based solution than a solar panel tariff," said the papers lead author, Dajun Yue.
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