One of the criticisms that's been leveled at the photovoltaic panel industry is that it can take more energy to make the panels than the panels produce over their usable lifespan. But a new study indicates that that may no longer be true, and that the PV panel industry may "pay back" the energy invested in all previous years of panel production as early as 2020.
As recently as 2010, according to a study by Michael Dale and Sally M. Benson at Stanford University's Global Climate and Energy Project, the amount of energy it took to fabricate and install photovoltaic panels may well still have outstripped the energy end-users gained by using them -- a classic example of a negative Energy Return on Energy Invested (EROEI).
But according to that study, recently published in the journal Environmental Science and Technology, a combination of more efficient manufacturing processes and greater energy productivity at the "user-end" mean that PV manufacturing was probably already energy positive by 2012, using less energy in manufacture than is created when the panels are used. And by 2020, say Dale and Benson, the surplus EROEI from photovoltaic power will likely be large enough to "pay back" the energy deficit accrued in all those earlier years of PV manufacturing.
Dale and Stanford University produced a video to explain the results of the study in laypersons' terms (hat tip to Francie Diep at PopSci for the link):
Which means that at some point soon, the energy investment our global society has put into PV will start to pay off. If it hasn't already.
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sheila says :
argh. what a scary, disingenuous measurement basis! industrywide worldwide "net energy balance?" at this stage? are you kidding me?
NREL calculated the "embedded energy payback" of actual installed rooftop PV systems years ago and determined that on a per-panel basis, it averaged less than 2 years. that is where we should focus. ~38 years of energy "free" in exchange for ~2 years of energy "cost." sure, killing wilderness to site panels and string SF6-spewing transmission uses a ton more energy, which is one more reason not to do it, but rooftop installation, especially with locally-produced panels is a HUGE net energy producer already.
to try and include all the R&D energy, and energy used building manufacturing facilities that have 40 more years of useful life, etc. in that payback, and then to include all the energy used in manufacturing and shipping panels that are not yet in service (especially since it is well known that there is a glut of panels already manufactured) and then to only count the first ~10% of the energy production that installed panels have in them and draw a line under the "industry" there is arbitrary, misleading and, frankly, ridiculous.