14,600 X More Powerful Than CO2, HFC-23 Output Hit All-Time High In 2018, Despite Kigali Amendment

[hatrack]

China began enforcing the Kigali Amendment to the Montreal Protocol last week—and the climate implications are huge. The agreement requires China and other signatory nations to slash the production and use of powerful greenhouse gases known as hydrofluorocarbons (HFCs) over the coming decades, and to immediately stop emitting the most potent, HFC-23, a greenhouse gas that is 14,600 times more powerful than carbon dioxide in warming the atmosphere.

HFC-23 is an unwanted byproduct of the production of hydrochlorofluorocarbon-22 (HCFC-22), a chemical used as a refrigerant and a component in Teflon and other products. Unlike carbon dioxide, which can not be easily broken down, HFC-23 can be destroyed at relatively little cost through incineration, offering a rare opportunity to quickly address climate change at a fraction of the cost of other methods aimed at reducing carbon dioxide emissions.

But an estimated 15,900 tons of HFC-23 are still being released into the atmosphere each year, equal to the annual greenhouse gas emissions of 50 million automobiles. Eliminating emissions of HFC-23 and other HFCs could prevent half a degree of additional warming by the end of the century.

Now comes the hard part for China, given its current rank as the world’s largest HFC-23 producer. The task of reducing emissions will be complicated by the fact that some Chinese chemical companies may have failed to comply with the country’s previous requirements for incinerating HFC-23, and by the country’s rapidly growing sector of new HCFC-22 producers, according to a review by Inside Climate News of United Nations documents, Chinese government reports and company records.

EDIT

https://insideclimatenews.org/news/22092021/china-super-pollutants-kigali-amendment-motreal-protocol/

[NNadir]

1. I know how to make HFC-23 (fluoroform, CHF3) "green."

It's easily done.

Just declare that it can be used to etch silicon nanowires for solar cells.

To wit:

A review on plasma-assisted VLS synthesis of silicon nanowires and radial junction solar cells

(Soumyadeep Misra et al 2014 J. Phys. D: Appl. Phys. 47 393001)

From the text:

2. Synthesis of silicon NWs

NWs are elongated one-dimensional (1D) nanostructures with a high aspect ratio (higher than 5 : 1) [34]. Note that even though we adopt the term NWs, quantum size effects are not the purpose of this work. NWs also have a large surface-to-volume ratio, which may lead to enhanced surface recombination. Silicon NWs find their applications in various fields, e.g. transistors [35], chemical or biological sensors [36], energy conversion [37] or storage devices [38], etc. There are many different approaches for fabricating SiNWs, including laser ablation [39], molecular beam epitaxy [40], evaporation of silicon monoxide [41], solution–liquid–solid method [42], different lithographic techniques [43, 44] combined with reactive ion etching (RIE)...

... 2.1. Top-down approaches

In the 'top-down' approach, the initial material is in the form of a bulk sample (c-Si for example) and the fabrication of nanostructures involves removal of some amount of material. The lithographic techniques, used to define the pattern, have to be combined with a standard etching process to remove the materials. RIE and wet chemical etching can produce highly uniform vertical SiNWs on c-Si wafers by substrate selective etching using a mask. Although well-oriented 1D nanostructures can be designed via a number of nano-lithographic techniques, such as the electron-beam [43] or the extreme ultra-violet interference lithography [44], they are limited to the laboratory scale due to their high cost and low throughput. The role of the etching mask is to protect certain areas of the wafer, which can also be easily achieved by patterning using the nanosphere assembly or nano-imprint lithography...

...Hsu et al successfully used SiO2 nanoparticle assemblies deposited by the LB method for Si nanopillar/nanocone formation by RIE, with uniform coverage over an entire 4 inch wafer [45]. First, monodispersed SiO2 particles with diameters ranging from 50 to 800 nm are deposited on a c-Si 〈1 0 0〉 wafer in a close packed monolayer formation. In the next step, an oxygen (O2) and fluoroform (CHF3) gas mixture is used to tune the diameter and spacing of the nanoparticles by selective and isotropic RIE. This is a crucial step to determine the diameter and the pitch of the nanopillars. Afterwards, Si nanopillars are fabricated by chlorine (Cl2)-based selective and anisotropic etching, and finally the SiO2 particles are removed by hydrofluoric acid (HF) etching [45]...

See! Now it's "green."

Any chemistry, no matter how dangerous, no matter how many persistent pollutants it leaves behind, no matter how often it needs to be repeated to maintain the illusion that its goal is to eliminate climate change, even though it hasn't, isn't and won't, can be made "green" by saying it's for the solar miracle that hasn't come, isn't here and won't come.

The sink for fluoroform, HFC-23, is radiolytic decomposition, or alternately, very high temperatures, where upon, in the presence of steam, it degrades to CO2 and the molecules of hydrogen fluoride gas.