Strategies for recycling of solar panels

Date:
July 16, 2020
Source:
DOE/National Renewable Energy Laboratory
Summary:
Researchers have conducted the first global assessment into the
most promising approaches to end-of-life management for solar
photovoltaic (PV) modules.



FULL STORY ========================================================================== Researchers at the National Renewable Energy Laboratory (NREL) have
conducted the first global assessment into the most promising approaches
to end-of-life management for solar photovoltaic (PV) modules.


==========================================================================
PV modules have a 30-year lifespan. There is currently no plan for
how to manage this at end of their lifespan. The volume of modules no
longer needed could total 80 million metric tons by 2050. In addition
to quantity, the nature of the waste also poses challenges. PV modules
are made of valuable, precious, critical, and toxic materials. There is currently no standard for how to recycle the valuable ones and mitigate
the toxic ones.

Numerous articles review individual options for PV recycling but, until
now, no one has done a global assessment of all PV recycling efforts to identify the most promising approaches.

"PV is a major part of the energy transition," said Garvin Heath, a senior scientist at NREL who specializes in sustainability science. "We must
be good stewards of these materials and develop a circular economy for
PV modules." Heath is lead author of "Research and development priorities
for silicon photovoltaic module recycling supporting a circular economy,"
which appears in the journal Nature Energy. His co-authors from NREL are Timothy Silverman, Michael Kempe, Michael Deceglie, and Teresa Barnes; and former NREL colleagues Tim Remo and Hao Cui. The team also collaborated
with outside experts, particularly in solar manufacturing.

"It provides a succinct, in-depth synthesis of where we should and
should not steer our focus as researchers, investors, and policymakers,"
Heath said.



==========================================================================
The authors focused on the recycling of crystalline silicon, a material
used in more than 90% of installed PV systems in a very pure form. It
accounts for about half of the energy, carbon footprint, and cost to
produce PV modules, but only a small portion of their mass. Silicon's
value is determined by its purity.

"It takes a lot of investment to make silicon pure," said Silverman,
PV hardware expert. "For a PV module, you take these silicon cells,
seal them up in a weatherproof package where they're touching other
materials, and wait 20 to 30 years -- all the while, PV technology is improving. How can we get back that energy and material investment in the
best way for the environment?" The authors found some countries have
PV recycling regulations in place, while others are just beginning to
consider solutions. Currently, only one crystalline silicon PV-dedicated recycling facility exists in the world due to the limited amount of
waste being produced today.

Based on their findings, the authors recommend research and development
to reduce recycling costs and environmental impacts, while maximizing
material recovery. They suggest focusing on high-value silicon versus
intact silicon wafers. The latter has been touted as achievable, but
silicon wafers often crack and would not likely meet today's exacting
standards to enable direct reuse. To recover high-value silicon, the
authors highlight the need for research and development of silicon
purification processes.

The authors also emphasize that the environmental and economic impacts
of recycling practices should be explored using techno-economic analyses
and life- cycle assessments.

Finally, the authors note that finding ways to avoid waste to begin with
is an important part of the equation, including how to make solar panels
last longer, use materials more effectively, and produce electricity
more efficiently.

"We need research and development because the accumulation of waste will
sneak up on us," Silverman said. "Much like the exponential growth of PV installations, it will seem to move slowly and then rapidly accelerate. By
the time there's enough waste to open a PV-dedicated facility, we need to
have already studied the proper process." If successful, these findings
could contribute one piece of a PV circular economy.

The U.S. Department of Energy's Solar Energy Technologies Office funded
the analysis.


========================================================================== Story Source: Materials provided by
DOE/National_Renewable_Energy_Laboratory. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Garvin A. Heath, Timothy J. Silverman, Michael Kempe, Michael
Deceglie,
Dwarakanath Ravikumar, Timothy Remo, Hao Cui, Parikhit Sinha,
Cara Libby, Stephanie Shaw, Keiichi Komoto, Karsten Wambach,
Evelyn Butler, Teresa Barnes, Andreas Wade. Research and
development priorities for silicon photovoltaic module recycling
to support a circular economy. Nature Energy, 2020; DOI:
10.1038/s41560-020-0645-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200716144738.htm

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