Pyrolysis Kinetic Modeling of a Polyethylene/Vinyl Acetate Encapsulant Found in Waste Photovoltaics

[NNadir]

The paper I'll briefly discuss in this post is this one: Pyrolysis Kinetic Modeling of a Poly(ethylene-co-vinyl acetate) Encapsulant Found in Waste Photovoltaic Modules (Charlie Farrell, Ahmed I. Osman, John Harrison, Ashlene Vennard, Adrian Murphy, Rory Doherty, Mark Russell, Vignesh Kumaravel, Ala’a H. Al-Muhtaseb, Xiaolei Zhang, Jehad K. Abu-Dahrieh, and David W. Rooney Industrial & Engineering Chemistry Research 2021 60 (37), 13492-13504)

I'm not going to spend a lot of time on this paper, but just excerpt some statistical portions from the text - some of which are covered in the abstract - and point to aspects that may be misleading or omit some relevant considerations.

From the introduction:

Owing to the ever-growing population and increased energy demand, the world is transitioning away from fossil fuels toward renewable energy technologies in order to decarbonize and meet Paris Agreement climate targets.(1−3) Of these renewable technologies, the solar photovoltaic (PV) devices has gained considerable interest because of their ability to produce electricity without any subsequent noise or air pollution in the form of emissions.(4−6) As of 2018, solar has taken the lead for renewable capacity additions at 55%, surpassing that of its competitive counterparts such as hydropower and wind.(7)

One of the most common misrepresentations about the so called "renewable energy" fantasy is the deliberate lie that putative peak capacity - which in practice is never realized for solar cells - is the same as energy.

I detailed the capacity utilization of solar energy, as reported by the California Energy Commission - capacity utilization is the actual energy produced as compared to the theoretical peak capacity if a generation system (any generation system) functioned at full peak capacity for a given period of time as a percentage - in another post on this site: The Growth of Solar Capacity In California, Capacity Utilization, and Solar Energy Production.

For convenience I reproduce the table from that post:



In general, depending on the geographical area in which it is located as well as the weather, the capacity of utilization of solar energy is lower than the already abysmal capacity utilization of wind. Even in California, known for its sunny weather, the capacity utilization has never, not once, in any year, approached 30%. In fact, in only three years in this century did it exceed 25%, and for five years it was below 20%. Thus to talk about capacity in comparing solar to wind and or hydroelectricity is rather absurd.

Also it is outrageous to claim that "the world is transitioning away from fossil fuels." This is nonsense. According to the World Energy Outlook (2019 edition) in the year 2000, the world was consuming 420.19 Exajoules of energy, 80.0% of which was produced by the combustion of dangerous fossil fuels. By 2018, the world was using 599.34 Exajoules of energy, 81% of which was produced by the combustion of dangerous fossil fuels. The use of dangerous fossil fuels is rising, rapidly, and no real "energy transition" has been observed. It's a lie, a very big lie, we tell ourselves routinely while the world literally burns.

The paper continues:

The solar energy industry is helping to meet the ever-growing global energy demand that is estimated to reach 778 EJ by 2035.(8) At the end of 2019, the global installed capacity of solar PV passed the threshold of 600 GW.(9,10) PV modules have a limited lifespan of 25–30 years, and this is also reflected in the manufacturer’s guarantee.(11−13) However, it is worth noting that the lifespan can vary based on the type of the failure mode or degradation experienced by the module. For example, the recent work of Tracy et al. outlines encapsulant adhesion as a function of environmental stressors (UV exposure, temperature, and humidity) with lab and field data in various climates.(14) As annual installations increase exponentially, so does the waste that will arise. Of the two commercially available generations of PV modules, the first-generation, also known as crystalline silicon (c-Si) PV modules, equates to a market share of 80–90% over the last 40 years.(15,16) In 2012, PV modules were added to the EU’s WEEE directive, making it a law as of February 14, 2014, that PV manufacturers and suppliers are now responsible for their end-of-life (EoL) management.(17−19) Despite this legislative driver, approximately only 10% of PV modules are recycled globally.(20) To date, there are limited studies available on EoL PV modules considering the effect that it will have in the near future.(21,22)

The first sentence is delusional. The world is now consuming about 600 EJ of energy per year. After 50 years of mindless cheering, and the expenditure of trillions of dollars the solar industry doesn't produce 5 EJ of energy per year. It never has.

But solar waste - which is a form of electronic waste - is accumulating. No one apparently bothers to think too much about this issue, because solar energy is said to be "green," but it is very real. How much waste?

Well the paper continues:

PV modules consist of numerous material types, such as glass, metals, and polymers. For reference, please refer to Figure S1 in the Supplementary Information for an exploded diagram of a c-Si PV module. This mixture of material types makes the recycling of PV modules difficult. However, as the decomposition temperatures of the constituent types are vastly spread, thermal treatment such as pyrolysis can be used to selectively remove individual components. The first material to decompose is the polymeric fraction (EVA and PV Backsheet) of the module at approximately 500 °C.(23)
Already, there are approximately 25.8 million tonnes of plastic waste generated in Europe every year.(24) In 2018, 12.4 million tonnes of post-consumer plastic waste were sent for energy recovery,(25) growing at an average of 4.9% every year and a 77% rise from figures reported in 2006.(26)

It is estimated that between 60 and 78 million tonnes of EoL PV modules will be in circulation by 2050.(27,28) Of these 60–78 million tonnes, 6.09–7.92 tonnes equate to the waste polymers found in PV modules when considering the 10.15 wt % that they contribute to the mass of the module. Furthermore, 3.93–5.11 tonnes equate to the waste polymer poly(ethylene-co-vinyl acetate) (also known as EVA), when considering its dominant 6.55 wt % contribution to the mass of the polymeric fraction of the c-Si PV module.(29) EVA acts as an encapsulant protecting the solar cells and metal contacts from mechanical shock and moisture and has excellent adhesion properties to the glass and backsheet layers. EVA is also widely used in a plethora of applications, such as cable sheaths, packaging films, hot melt adhesives, and some drug delivery devices.(30)

In addition to this, EVA has been the industry standard for PV module encapsulation since the 1980s, and according to the current ITRPV report, it is expected to continue to be the industry standard until at least 2029, as there is no available data beyond this point.(31−33)

Note that so called "renewable energy" depends on lots and lots and lots and lots of interconnects because of its poor reliability, this means more wires, more transmission lines and in that "renewable energy" paradise of California, more fires.

Polyethylene is made from dangerous natural gas, as is vinyl acetate. This is yet another way - besides the need for back up power - that the so called "renewable energy" industry is dependent on access to dangerous natural gas.

Note that none of this waste includes the chemical waste, notably aliphatic fluorides, acids, that go into making solar junk, nor does it address the fact that silicon is reduced with carbon using heat generated by the combustion of dangerous natural gas, nor does it account for the trucking of transport to solar plants or McMansion rooves, and the hauling of this distributed waste away.

The paper continues:

hroughout a PV module lifespan, EVA is prone to degradation (sometimes referred to as yellowing) over time. As EVA yellows, the transmittance of light reaching the solar cells lowers and this subsequently has a detrimental effect on the power output of the module. Although not fully understood, it is believed this degradation is related and linked to UV light exposure and moisture ingress.(32,34,35) A mechanism has been outlined recently by Tracy et al. which focuses on the underlying degradation processes that are active at a molecular level and which accounts for the competition of chemical reactions such as cross-linking and chain scission in the bulk encapsulant and bond dissociation because of hydrolytic depolymerization at the cell and glass interfaces.(14) When the power produced by the module is less than 80% of the wattage quoted at the time of manufacture, the PV module can be considered as EoL.(36) However, it is worth noting that there are many failure modes of PV modules that can also deem them as EoL. For example, broken solder connections, failure in lamination, or environmental catastrophes such as storms can also affect how a module can be classified as EoL.

The EVA encapsulant found in first-generation c-Si PV modules poses the most significant challenge in the delamination of PV modules and subsequently in the recycling of the other constituents. Some methods that have been previously utilized to remove the EVA fraction are pyrolysis,(37−39) combustion,(40) organic solvents,(41−43) dissolution in acidic media,(39) high-voltage pulse crushing,(44−46) and shockwave.(47,48) To date, pyrolysis has been reported to be one, if not the most effective, method for the removal of waste polymers found in PV modules, removing a significant fraction with little residual material left post-pyrolysis.

Pyrolysis is of course, causing the plastic to decompose by heating it.

At what temperature you may ask. From the paper:

Pyrolysis of polymers usually involves the heating of waste polymer materials under an inert atmosphere in the temperature range of 300–900 °C.(49) Parameters such as temperature, pressure, residence time, and the employment of a catalyst used in conventional pyrolysis can be altered to optimize product yields of the pyrolysis process.(50,51) From the previous work, conventional pyrolysis is ideal for treating waste EVA as there is approximately 1 wt % residual remaining.(52) A significant drawback in the developmental transition of thermochemical conversion processes from lab to industrial scale is that more quantitative information regarding the chemical reactions in question is needed. An important part of this information is the development of a kinetic model of the given reaction system.

There you have it, 300–900 °C.

Lie to yourself as much as you'd like to do, but let me tell you something. That heat isn't going to come from solar ovens operating for a few hours a day in a vast trashed area of desert covered with bird frying ovens near the summer solstice.

It's coming from combustion.

OK?

The planet is literally on fire. It's not getting better. It's getting worse, and its getting worse faster and faster and faster. I know. I keep track.

Might it not be time to think clearly?

Have a nice day tomorrow.

[wyn borkins]

1. Thank You

Most kindly indeed, for this interesting and essential material.

I appreciate your attentions in this area.

[NNadir]

2. ...and I thank you for not responding with hand waving, denial and wishful thinking. .

The types of responses listed fully characterize the general responses to questioning the "solar will save us" dogma. It hasn't saved us; it isn't saving us; and it won't save us. The solar industry is entirely dependent on the continued use of dangerous fossil fuels.

[wyn borkins]

3. Your Intelligent and Truthful Words Are Worthy Of Repetition:

Solar Dogma:

"It hasn't saved us; it isn't saving us; and it won't save us. The solar industry is entirely dependent on the continued use of dangerous fossil fuels."