In May, findings were published addressing the potential health impacts of putting PV modules in landfills when they reach the end of life. What was the result?
What we found was that through different exposure routes and taking many conservative, or health protective, assumptions, PV modules put into unlined landfills likely do not present risk of cancer or non-cancer outcomes greater than health protective risk thresholds set by different health agencies –the U.S. Environmental Protection Agency and also the World Health Organization.
Is that saying that according to norms and standards today that PV modules in landfill present an acceptable level of risk to health?
That’s right. The threshold is set at a level that is in accordance with a health-protective model above which calls for additional scrutiny. If results come in above that level, it says to the evaluators, to the health officials, ‘we might have a circumstance here that we should examine further.’
The approach we use is pretty detailed, looking at generic risk exposure scenarios – not a particular landfill with a specific water table or meteorology. We do what’s called a screening-level assessment. It layers health protective assumptions through a National Academies of Sciences-developed approach using available data on the potential chemical release and human exposure scenario and compares the risk calculated to a threshold. If the risk isn’t above that threshold, then you can say that risk is below this publicly-deemed acceptable level of risk and therefore we don’t need to study this further.
This landfill study is a part of a broader program looking at potential health impacts of PV. What else did you examine?
We completed a series of three publications from an international group that I lead, of the PVPS – on PV sustainability. I should note that Parikhit Sinha of First Solar is the lead author of this series.
The first publication addressed PV exposed to fire. When exposed to fire, there will be things that burn, and those things that burn do emit air pollutants, and people can be exposed to them. So, we analyzed the potential risks from that scenario. The second was PV modules that have cracks in them that are left in the field. Through these cracks, water can get into the module and down to the semiconductor layer and other places, and there metals can leach out – and we examined that. In both the fire and field breakage studies, the risk assessment methods did not indicate significant health risks.
And the third, and it has been the one that has been of greatest public interest, has been about putting PV modules into a landfill.
The human health risk assessment approach that we’ve taken in all three analyzes, but in landfill analysis was the most extreme, follows U.S. EPA and international guidelines for doing risk assessment. It takes a health-protective perspective. That means that at every step along the way, in doing these calculations about potential risk, you take a risk-conservative assumption. And when you add up all the different steps in a risk assessment, from the initial potential for release of a pollutant, to its transport, to what’s called its fate – which means transformations in the environment to turn it into something else, or transport across a media or at the interface of different media (air, water, soil) – you take conservative assumptions, you assume the high end of potential risk. As this is meant for regulators, who are supposed to protect the health of humans; in the end, you have gotten something that is the worst case.
Looking at the landfill specifically, what kind of form were you assuming the modules to be in?
We didn’t assume that the PV sandwich is intact when it goes into the ground – the metal, glass, and polymers that are built to last 20-30 years in warrantied performance. We assume that they are crushed and broken up, like everything is, in the dump-trucks, the loading, the unloading, and the front-end loaders that push material around in the landfill. That means that the modules have lots of cracks, a much greater surface area, and exposed surfaces where the metals can be released.
You said that this third phase of the IEA research project, the landfill phase, has garnered the most amount of public interest. Why do you think that is?
Like your magazine, through the UP Initiative, many people have started to think about the environmental implications of a continually, rapidly, exponentially growing PV industry on the management of materials and of the risks and end of life. Especially also with the concept of the circular economy taking hold in the public sphere, but certainly also with industry and regulators. [PV] is one of the major growth industries globally, and certainly, our energy sector does get a lot of attention, and we are trying to clean it up. It is one area that deserves more attention for photovoltaics.
There is another important contextualization of the human health risk assessment that we have performed, and that is that the result that PV modules don’t present risk above thresholds should not suggest that it is ok to landfill them. It should not give anyone the impression that it [landfill] is a preferable solution. It will likely be, and it is, in places outside of Europe, the case that landfilling is chosen. So, we want to address those circumstances because they are real, and they could happen. But as a group, and we say this very clearly everywhere we can, that it is much preferable to try to recover materials in an environmentally friendly manner from these modules through recycling, lifetime extension, reuse, or other circular economy pathways.
So, just because you can doesn’t mean you should.
Right, there you go.