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From Slashdot:

A new study by Environmental Progress warns that toxic waste from used solar panels now poses a global environmental threat. The Berkeley-based group found that solar panels create 300 times more toxic waste per unit of energy than nuclear-power plants.

I'm specifically interested in whether:

  • The article accurately summarizes the study
  • The study withstands scrutiny and whether it has valid criticism
  • The study conclusion is supported by other studies
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    Even if so, they're different types of toxic. Industrial byproducts can be treated or otherwise mitigated; nuclear waste is dangerous for tens of thousands of years.
    – Kevin
    Commented Jul 5, 2017 at 16:10
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    "Study" may be a generous term for what looks like a footnoted blog post (environmentalprogress.org/big-news/2017/6/21/…) from an avowedly pro-nuclear organization that "defines as toxic waste the spent fuel assemblies from nuclear plants and the solar panels themselves, which contain similar heavy metals and toxins as other electronics, such as computers and smartphones."
    – jeffronicus
    Commented Jul 5, 2017 at 16:13
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    I have a few gallons of toxic waste in my garage (mostly used motor oil) which doesn't worry me too much. A few gallons of uranium on the other hand would wipe the entire city as it would be well above the critical mass.
    – Dmitry Grigoryev
    Commented Jul 6, 2017 at 8:38
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    @DmitryGrigoryev: The problem with spent nuclear fuel is neither the possibility of criticality excursion nor the uranium in there -- uranium is comparatively tame compared to some of its fission products, and those pose the big problem (looking at you, Cs137). That's why the fuel rods going into a reactor don't require much in the way of special handling, but the fuel rods coming out of a reactor are "hot" indeed.
    – DevSolar
    Commented Jul 6, 2017 at 9:39
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    @Kevin Nuclear waste can also be treated and mitigated, and it is routinely done. And the more radioactive the waste is, the faster it stops being radioactive (which is why nuclear waste is safe enough to handle given a few precautions after a few years in a pool). A lot of the complications come from (reasonable) fears of nuclear proliferation etc. But you're entirely right that comparing "kilograms of waste" is nonsense. Combustion engines produce tons of water as waste, but we usually aren't too concerned about that. Though e.g. uranium is more dangerous as a heavy metal than a radiator.
    – Luaan
    Commented Jul 7, 2017 at 9:51

2 Answers 2

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This study, by a nuclear advocacy group, is based on treating a cubic meter of used solar panels as being equivalent to a cubic meter of spent uranium.

Just digging around the links, I find the following:

  • Yes, slashdot's description is pretty accurate.
  • "Environmental progress" is a pro-nuclear advocacy group. The website initially presents as a general environmentalist and social advocacy group, but looking at their "this is a source of concern that we need to mobilize about" pages makes it clear that pro-nuclear is what they do and are.
  • The "study" was made from relatively small amounts of generally available data with a lot of assumptions. It also equates "solar waste" (ie, discarded solar panels, which contain relatively small quantities of things like lead) with nuclear waste (ie, discarded radioactive materials) and compares them by volume (discarded solar panels being significanly less dense than spent uranium). It's pretty blatantly biased.

the "study":

The study defines as toxic waste the spent fuel assemblies from nuclear plants and the solar panels themselves, which contain similar heavy metals and toxins as other electronics, such as computers and smartphones.

To make these calculations, EP estimated the total number of operational solar panels in 2016 and assumed they would all be retired in 25 years — the average lifespan of a solar panel. EP then estimated the total amount of spent nuclear fuel assemblies that would be generated over a 25 year period. EP then divided both estimates by the quantity of electricity they produced to come up with the waste per unit of energy measure.

While nuclear waste is contained in heavy drums and regularly monitored, solar waste outside of Europe today ends up in the larger global stream of electronic waste.

Solar panels contain toxic metals like lead, which can damage the nervous system, as well as chromium and cadmium, known carcinogens. All three are known to leach out of existing e-waste dumps into drinking water supplies.

This was then seized on and amplified by the National Review - not exactly known for a strong pro-environmental stance.

...and the initial bullet points from the site's "Clean Power In Crisis" US Section

In the 1960s and 70s, the US was the world leader in nuclear technologies.

Half of the US nuclear fleet is now at risk of premature closure by 2030.

Wind and solar receive, respectively, 17 and 140 times more in federal subsidies than nuclear.

Thirty states have mandates to deploy clean energy that exclude nuclear.

It would take 12 years to replace the 120 billion kilowatt-hours of yearly production from the eleven at-risk nuclear plants with wind and solar, and 81 years to replace the entire reactor fleet. Dozens of climate scientists and conservationists urged former president Barack Obama to do everything in his power to protect and expand America's largest source of clean energy. They have also written to President Donald Trump and the leaders of large environmental organizations.

So, yeah. A blatantly biased group is twisting the numbers hard to try to make nuclear look good at the expense of non-nuclear clean energy sources.

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    So the study measures toxic waste not by actual toxicity, but only by weight? And not even by weight of any toxic material, but by weight of the total garbage, including non-toxic? That doesn't seem very reasonable. I would +1, but skeptics.SE discourages completely unsourced answers. Could you add a link to the about page of EP and a link to their "study" (plus relevant excerpts)? If you have, actual numbers about the toxicity of solar and nuclear would also be great, although it seems that the 300 number is clearly unreasonable, and links to EP itself should make this clear.
    – tim ♦
    Commented Jul 5, 2017 at 16:37
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    I added some quotes, for those who don't like having to click a few links. I also noticed... it wasn't even comparing based on mass. It was comparing based on volume. Spent uranium is pretty dense stuff, I suppose, and if you're going to spin it hard enough to equate discarded solar panels with spent fuel cores, why hold back at all?
    – Ben Barden
    Commented Jul 5, 2017 at 17:53
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    In fairness, can you explain why mass is a better measure of toxic waste than volume. If you are talking about filling up a dump, volume is the more relevant measure.
    – kingledion
    Commented Jul 5, 2017 at 18:44
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    @kingledion Mass is better because that's how we define ld50 and how the transport of bad stuff into watersheds and the like is expected to work. But I understand the common concern is about how bad is it to just bury it. Cubic miles of stuff you can later build housing developments over isn't as interesting as a few cubic meters you can't get anyone to agree to throw down a deep hole a hundred miles from where people live.
    – user36688
    Commented Jul 5, 2017 at 19:00
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    @user3067860 And of course if they were serious about comparing landfill size, they'd consider how much of the PV units can be recycled in 25 years. Already in 2017 we have a company claiming to be able to recycle 96% of a used PV module, and that's despite the volume of PV waste not being particularly high yet.
    – user56reinstatemonica8
    Commented Jul 5, 2017 at 21:06
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No. Nuclear energy produces far more toxic waste than solar.

Distribution of the fake news story

The fake news that began circulating at the end of June 2017 stems from a self-described "study" conducted by the nuclear industry advocate, Environmental Progress (EP). James Hansen, a nuclear proponent previously a lead in climate modelling at NASA, has unfortunately been dispersing this disinformation. In February 2018 he said he had been unaware of the method used to produce the graph he displayed. EP published the graph only in their blog, where they described their method: "The study defines as toxic waste the spent fuel assemblies from nuclear plants and the solar panels themselves." They used TrinaSolar module specifications, assumed a 25 year lifetime, and used the module's entire installed volume as the volume of toxic waste. For nuclear, they used only the spent fuel assembly. They arrived at the two numbers displayed in a bar graph and repeated in various articles and Hansen's presentation: 34,000 cubic meters per TWh for solar and 101 cubic meters per TWh for nuclear. (Deasi and Nelson 2017).

The blog was immediately embellished by several conservative news outlets, including SlashDot and the the National Review. Some articles added to the strange logic. One, for example, did a life cycle cost analysis comparing solar to nuclear by using the assumption that this solar panel waste will need to be buried in 2-5 km deep boreholes being considered for spent nuclear fuel. (Middleton 2017). Another article in the Daily Caller explained why solar panel waste should be considered more dangerous than nuclear waste: nuclear waste is radioactive and will therefore go away, while after 30 years on your roof, the solar panel module doesn't radioactively decay and will have to be disposed of permanently. (Follet 2017).

Toxic waste stream of solar PV

The majority of a solar panel module's mass is glass, which can be recycled. The steel housing is also recycled. The panel itself is usually silicon, which is also non-toxic and can be recycled into new semiconductor material. A fraction of solar panels use CdTe as the semiconductor material. Lead and silver are captured in the waste stream for all solar panels, but the cadmium is the most problematic waste generated by manufacture and disposal of solar panels is cadmium. Even for CdTe solar panels, nuclear power generates more cadmium waste on per-unit-energy basis. (Mulvaney, 2014) Manufacturers of CdTe panels monitor for worker safety and environmental emissions and have 0 incidents across ten years of US manufacturing. (Heard, 2014)

Even if you only look at cadmium and make the faulty assumption that solar panels will be disposed of instead of recycled, nuclear power generates more cadmium in waste than solar panels use in the entire manufacturing process. Nuclear power generates a wide variety of toxic waste materials, and one minor constituent is cadmium. Even as a minor constituent of the total nuclear waste, it is still significant compared to cadmium produced by other energy sources (Mulvaney, 2014):

  • Coal: 3.0 g Cd per Gwh
  • CdTe PV: 0.3 g Cd per Gwh
  • Si PV: 0.0 g Cd per Gwh (or 0.9 g Cd per Gwh if manufactured with electricity sourced from coal)
  • Fission: 0.5 g Cd per Gwh

Toxic waste stream of nuclear

While nuclear fission produces more cadmium waste compared to CdTe solar panels, cadmium is hardly the only waste from fission. Nuclear waste includes many categories of radioactive waste, all with different storage requirements. Spent nuclear fuel is a small fraction of total radioactive waste.

Nuclear power waste includes: (IAEA 2018)

  • HLW (high-level waste) includes spent fuel and requires containment for tens of thousands of years
  • ILW (intermediate level waste) radioactive wastes requiring containment for thousands of years
  • LLW (low-level waste) "requires robust isolation and containment for periods of up to a few hundred years" but can be stored in near-surface facilities
  • VLLW (very low-level waste) can be disposed of in special landfills

HLW is only 0.06% of the total radioactive waste, and only 1% of the HLW is solid, the portion of waste that includes spent fuel. So less than 0.0006% of nuclear waste is the spent fuel assembly, the only part of the waste included in the EP blog. Said differently, nuclear power creates 160,000 times more radioactive waste than the spent fuel assemblies alone. (IAEA 2018) Per unit of energy, this means nuclear produces 500 times the waste compared to solar panels, but only if you count the entire solar panel and ignore the waste produced by nuclear plant decommissioning.

Spent nuclear fuel rods must be contained for several thousand years. In the case of breeder reactors such as a thorium reactor, the 0.0006% of the nuclear waste stream that is spent nuclear fuel is recaptured. From the spent fuel, the plutonium is separated, introducing the additional hazard of nuclear weaponization. (Ford and Schuller 1997, p111)

References

Desai, J. and Nelson, M. (2017). Are we headed for a solar waste crisis? Retrieved from http://environmentalprogress.org/big-news/2017/6/21/are-we-headed-for-a-solar-waste-crisis

Follett, A. (2017). Solar panels generate 300 times more toxic waste than nuclear reactors. Retrieved from http://dailycaller.com/2017/07/01/solar-panels-generate-300-times-more-toxic-waste-than-nuclear-reactors/

Ford, JL and Schuller, CR. (1997). Controlling threats to nuclear security: A holistic model. Washington DC: National Defense University Press.

Fthenakisa, V. and Kim HC. (2010). Life-cycle uses of water in U.S. electricity generation. Renewable and Sustainable Energy Reviews, 14. pp2039-2048. Retrieved from https://www.sciencedirect.com/science/article/pii/S1364032110000638/pdfft?md5=e76eb25e7a96a5886503e1aaf0d282d7&pid=1-s2.0-S1364032110000638-main.pdf

Heard, A. (2014). Response to Mulvaney. Retrieved from https://www.sciencedirect.com/science/article/pii/S0016718514001705

IAEA. (2017). Trend in electricty supplied. Retrieved from https://www.iaea.org/PRIS/WorldStatistics/WorldTrendinElectricalProduction.aspx

IAEA. (2018). Status and Trends in Spent Fuel Radioactive Waste Management. Retrieved from https://www-pub.iaea.org/books/iaeabooks/11173/Status-and-Trends-in-Spent-Fuel-and-Radioactive-Waste-Management

Middleton, D. (2017). Waste from solar panels: 300 times that of nuclear power. Retrieved from https://wattsupwiththat.com/2017/06/29/toxic-waste-from-solar-panels-300-times-that-of-nuclear-power/

Mulvaney, D. (2014). Are green jobs just jobs? Cadmium narratives in the life cycle of photovoltaics. Geoforum 54 pp178-186. Retrieved from https://www.sciencedirect.com/science/article/pii/S0016718514000281

World Nuclear Association (2017). Radioactive Waste Management. Retrieved from http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-wastes/radioactive-waste-management.aspx

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    @MichaelK Why do you say that the toxic waste from Solar plants last forever? Do you have any sources for that?
    – T. Sar
    Commented Mar 1, 2018 at 17:34
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    @MichaelK Cadmium is also a regular waste from nuclear power plants, so I don't get where you are comming from. By your logic, then nuclear power plants also have toxic waste that lasts forever!
    – T. Sar
    Commented Mar 1, 2018 at 17:45
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    @MichaelK Not exactly. At the moment, I was show some evidence that nuclear power plants produce more waste than solar panels (as provided by this answer), but I'm open to change my mind if someone pops up with something that shows that this answer is wrong. I'm not sure about the need for the personal attack.
    – T. Sar
    Commented Mar 1, 2018 at 17:57
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    Just considering the cadmium in the fission products alone, and considering only the minority of solar panels which use CdTe semiconductor, fission power produces twice the cadmium per GWh compared to CdTe solar panels.
    – Bennett Brown
    Commented Mar 4, 2018 at 2:36
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    There is no toxic waste from solar panels that must be disposed of; it gets recycled into the material inputs. The vast majority of nuclear waste must be stored and cannot be recycled, even in a scenario in which spent fuel is reprocessed.
    – Bennett Brown
    Commented Mar 4, 2018 at 3:06

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