Metals costs may constrain some solar energy goals
Government agencies, academics, and many firms have proposed scenarios for a future in which photovoltaic technologies grow rapidly. For some PV technologies, the production of the required input materials would need to grow at a rate never before seen in the metals industry.
That's the conclusion of a new analysis by MIT researchers Goksin Kavlak, James McNerney, Robert Jaffe, and Jessika Trancik in a paper recently published in Proceedings of the 40th IEEE Photovoltaic Specialists Conference.
Silicon-based PVs look promising from a material point of view, but the researchers say the outlook is complex for newer PV technologies made from CdTe and CIGS (copper indium gallium diselinide).
Trancik summarised the paper's findings concerning CIGS and CdTe production: "To meet even relatively small percentages of electricity demand by the year 2030, these technologies would require historically unprecedented [metals production] growth rates."
The reasoning? In mining, CIGS and CdTe are not mined for their own sake, but only accessible as byproducts of the mining processes for other metals, such as copper. Upping their production, therefore, is a cost-intensive process.
"It is quite possible that the cost and availability of these critical elements will constrain deployment of otherwise game-changing technologies," said Jaffe.
"We provide a new perspective by putting the projected PV metal requirements into an historical context," says Trancik, who is the Atlantic Richfield Career Development Assistant Professor in Energy Studies at MIT and the team lead. "We focus on the changes in metals production over time rather than the absolute amounts."
This approach allows for an assessment of how quickly metals production would need to be scaled up to meet the rapidly increasing PV deployment levels required by aggressive low-carbon energy scenarios.
To calculate the metals production growth rates required under those scenarios, the researchers first estimated the required production in 2030 for each metal of interest, and then calculated the annual growth rate needed to reach that level. They took into account the projected demand for each metal by both the PV sector and other industrial sectors. In addition, they looked at the effect of potential improvements in PV technology that would reduce the amount of each metal required in production.
The researchers then compared these projected growth rates to historical metals production growth rates in order to "understand the extent of production growth that happened in the past and whether the projected growth rates have historical precedent," says Trancik.
The research was sponsored by the US Department of Energy.
