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Catastrophic Greenhouse Gas Emissions from mass production of solar panels

Discussion in 'BBS Hangout: Debate & Discussion' started by ChievousFTFace, Jun 15, 2015.

  1. ChievousFTFace

    ChievousFTFace Contributing Member

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    "Solar energy" and "Catastrophic Greenhouse Gas Emissions" are not supposed to be synonymous with one another.

    I'm back again, with less politics and more science. Hopefully this will create better discourse as to how we should be stopping the advancement of global warming with regards to our energy policy/priorities. This is an argument only looking at the energy sector and doesn't focus on other things that we need to do to reduce human-caused GHGs. We can definitely identify other huge causes of GHGs (tech), but this is not the point of this thread. Discussion of other factors and solutions are absolutely welcome.

    I have tried to provide as many unbiased links as possible to show that the data and research are trustworthy. Any red comments can be considered my arguments.

    Just so my words or intentions aren't distorted, I am making the following claim:

    The push to speed up the phasing out of all fossil fuel energy production (it's mostly natural gas today) by using solar as one of the main drivers will cause significantly more damage to the atmosphere if we mass produce solar panels using current manufacturing technologies.

    People should not equate "reduction of greenhouse gas emissions" with "reduction of global warming potential." This can be further explained by looking at how each greenhouse gas breaks down in the atmosphere.


    Four Types of Greenhouse Gasses
    The EPA breaks down all GHGs into 4 major groups. Each group has its own atmospheric life and Global Warming Potential multiplier ("GWP". This number was developed to allow comparisons of the global warming impacts of different gases). Each type of GHG breaks down differently in the atmosphere, but we won't go into that much detail now. The following groups are:

    1. Carbon Dioxide (CO2): Makes up for 82% of all man-made GHGs. They have a varying atmospheric life and a GWP multiplier of 1.

    2. Methane (CH4): Makes up for 10% of all man-made GHGs. They have a 12 year life and a GWP multiplier of 28 to 34.

    3. Nitrous Oxide (NO2): Makes up for 5% of all man-made GHGs. They have a 114 year life and a GWP multiplier of 298.

    4. F-Gases: These make up for 3% of all man-made GHGs. There are no natural sources of F-Gases. These are broken into 4 subgroups:
    Hydrofluorocarbons (HFC): Up to 270 year life and a GWP multiplier of 12,000 to 14,800.
    Perfluorocarbons (PFC): Up to 50,000 year life and a GWP multiplier of 7,390 to 12,200.
    Nitrogen Trifluoride (NF3): 740 year life and a GWP of 17,200.
    Sulfur Hexafluoride (SF6): 3200 year life and a GWP of 22,800.

    We can see that even though the combination of CO2 and CH4 (the main emissions from fossil based energy production) account for 92% of the quantity of GHG emissions, F-Gases have a significantly larger Global Warming Potential.
    So what are these F-Gases used for?
    Taken directly from the EU climate action page
    Hydrofluorocarbons (HFCs) are used in various sectors and applications, such as refrigerants in refrigeration, air-conditioning and heat pump equipment; as blowing agents for foams; as solvents; and in fire extinguishers and aerosols.

    Perfluorocarbons (PFCs) are typically used in the electronics sector (for example for plasma cleaning of silicon wafers) as well as in the cosmetic and pharmaceutical industry. In the past PFCs were also used in fire extinguishers and can still be found in older fire protection systems.

    Sulphur hexafluoride (SF6) is used mainly as an insulating gas, in high voltage switchgear and in the production of magnesium and aluminium.

    This is why the Kyoto protocol made sense in that it attacked F-Gas emissions. Pretty much everything is geared towards eliminated as much HFC, PFC and SF6 emissions as possible. The EU just revised its F-Gas regulations this year, which "replaces the first and applies from 1 January 2015, strengthens the existing measures and introduces a number of far-reaching changes. By 2030 it will cut the EU’s F-gas emissions by two-thirds compared with 2014 levels."

    Alright! Now we're talking about using cleaner substitutes for these F-Gases...
    Wait a second... They forgot about NF3!
    The EPA showed 4 major types of F-Gases but didn't give any examples or breakdowns of Nitrogen Trifluoride (NF3). The EU protocol only talked about HFC, PFC and SF6. So what the heck is NF3?

    Wikipedia summarizes NF3 as a colorless, nontoxic, odourless, nonflammable gas. It finds increasing use as an etchant in microelectronics. It was originally promoted in 2004 as a clean chemical!!!

    A silicon wafer or flat-panel screen sits in a sealed chamber. Different gases are pumped in to create patterns or build up layers on the material. Then, the wafer or screen is removed, leaving leftover gas in the chamber. When NF3 is pumped in, the highly reactive fluorine in the gas combines with what's left over in the chamber, cleaning it out for the next use. The process is faster, cheaper and cleaner with NF3 than it is with other products.

    Here is a pdf from a manufacturer of it stating that it was designed as a replacement to PFCs, which may reduce equivalent global warming emissions by 6-7x due to it's lower emission rate.

    Even if the emission rate during manufacturing is lower, 6-7x lower is still too damn high!!! While it doesn't have the atmospheric life of tens of thousands of years like the chemicals it replaced does, it still is up there for 740 years!
    So what does this have to do with Solar Energy?
    In 2011, China accounted for 63 percent of solar panel production worldwide. They were able to make each panel 23 percent cheaper than US companies. The competitive gap has closed in recent years. To compete against one another, most manufacturers use a silicon-based thin-film solar cell. From the linked silicon-based wiki: The main advantage of a-Si in large scale production is not efficiency, but cost. a-Si cells use approximately 1% of the silicon needed for typical c-Si cells, and the cost of the silicon is by far the largest factor in cell cost.

    In summary, the largest factor of cost in producing a solar cell is silicon. This type of thin film literally costs companies a penny on the dollar to use. Companies are using NF3 to manufacture this cell.

    Back to the science from the NF3 wikipedia:
    Nitrogen trifluoride is used in the plasma etching of silicon wafers. Today nitrogen trifluoride is predominantly employed in the cleaning of the PECVD chambers in the high-volume production of liquid-crystal displays and silicon-based thin-film solar cells. In these applications NF3 is initially broken down in situ by a plasma. The resulting fluorine atoms are the active cleaning agents that attack the polysilicon, silicon nitride and silicon oxide. Nitrogen trifluoride can be used as well with tungsten silicide, and tungsten produced by CVD. NF3 has been considered as an environmentally preferable substitute for sulfur hexafluoride or perfluorocarbons such as hexafluoroethane.

    The process utilization of the chemicals applied in plasma processes is typically below 20%. Therefore some of the PFCs and also some of the NF3 always escape into the atmosphere. Modern gas abatement systems can decrease such emissions.

    So basically, a certain amount of NF3 escapes into the atmosphere any time a silicon-based thin-film solar cell is manufactured. This is definitely not the time to go into mass production based on policy driven demand increases.
    What are the trends of NF3 emissions and who is the world's #1 producer of it?
    We only became aware of the GHG effects of NF3 in 2008. It was being pushed as the clean alternative to other options. Because of this, the production of NF3 has sped up exponentially.

    Since 1992, when less than 100 tons were produced, production has grown to an estimated 4000 tons in 2007 and is projected to increase significantly. World production of NF3 is expected to reach 8000 tons a year by 2010. By far the world's largest producer of NF3 is the US industrial gas and chemical company Air Products & Chemicals.

    From the NF3 wiki:
    An estimated 2% of produced NF3 is released into the atmosphere. Robson projected that the maximum atmospheric concentration is less than 0.16 parts per trillion (ppt) by volume, which will provide less than 0.001 Wm−2 of IR forcing. The mean global tropospheric concentration of NF3 has risen from about 0.02 ppt (parts per trillion, dry air mole fraction) in 1980, to 0.86 ppt in 2011, with a rate of increase of 0.095 ppt yr−1, or about 11% per year, and an interhemispheric gradient that is consistent with emissions occurring overwhelmingly in the Northern Hemisphere, as expected. This rise rate in 2011 corresponds to about 1200 metric tons/y NF3 emissions globally, or about 10% of the NF3 global production estimates.
    Possible Clean Alternative?
    A German company was able to use fluorine (F2) instead of NF3, which has no GHG effect. According to the CDC , the issue with fluorine is that it is extremely hazardous and reactive which leads to handling and transportation issues. F2 is already in wide use and it's demand is directly tied in with NF3.
    Conclusion
    To conclude, I focused on NF3 because it has widely been ignored with regards to regulating F-Gases. These F-Gases are 100% manmade and are the largest contributor to GHGs. They are used for all sorts of applications ranging from pharmaceuticals to flat screen TVs. If we want to promote more solar panels in our near future, we need to make sure that they are being made with an alternative method that doesn't use NF3.


    One political follow-up to my other thread:
    In 2013, the US added almost 24,000 jobs for solar, with only 100 jobs being for manufacturing. Most solar panels are made in China and Taiwan. The Chinese have been effectively subsidizing renewable energy in the United States through its support for Chinese photovoltaic (PV) manufacturers. This is why the US recently imposed a tariff on Chinese and Taiwan solar imports for illegally subsidizing solar. This could bring new manufacturing jobs back to the US.

    Ok... so maybe I got a little political, but the company I referred to in the Tom Steyer thread, Sungevity, buys its panels from a specific Chinese company. Steyer’s investment firm holds stock in the leading photovoltaic solar panel supplier in California, Yingli Green Energy Holding Company of China.

    Are we letting China drive our energy policy or are we ignoring NF3 because of other tech/economic implications?
     
  2. rocketsjudoka

    rocketsjudoka Contributing Member

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    It looks like you basically counter the central premise of your own thread by pointing out there are alternatives. Anyway just reading through the Wikipedia link the possibilities that NF3 from solar panel production could lead to catastrophic warming seems overblown.

    [rquoter]One study co-authored by industry representatives suggests that the contribution of the NF3 emissions to the overall greenhouse gas budget of thin-film Si-solar cell manufacturing is overestimated. Instead, the contribution of the nitrogen trifluoride to the CO2-budget of thin film solar cell production is compensated already within a few months by the CO2 saving potential of the PV technology.[20][/rquoter]

    While yes more production of solar panels will likely lead to greater concentrations of NF3 in the atmosphere I think if that would have to be weighed in regard to how much other GHG are possibly not emitted from solar power replacing carbon based energy sources. Consider that while NF3 is used in the production of a solar panel over the lifetime of the solar panel is used it is no longer emitting GHG while an internal combustion engine or carbon burning powerplant is continually releasing GHG over its lifetime.
     
  3. ChievousFTFace

    ChievousFTFace Contributing Member

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    Thanks for taking the time to respond.

    I pointed out alternatives because nobody should be against the cleaner choice if it's technologically and economically feasible. Fluoride gas (F2) can be used and emits no GHG. You just have to trade the emissions for higher costs and more safety hazards. The Chinese/Taiwanese have created a solar panel market that has seen the majority of global competitors go out of business. Here's a Forbes.com article from 2012 talking about this. If we're gonna start pushing for solar using subsidies, we should give it to those who use panels from manufacturers that use F2 and not NF3. Basically... screw the Chinese and their cheap panels!

    Again, I'm just trying to keep this debate about apples to apples. This would be comparing existing power plants to solar panel energy generation on the residential and utility scales. There are multiple options for combustion engines and we have been progressing towards much higher emission efficiency standards.

    There's really no way to concretely say that a mass production of solar panels today is safer. The Kyoto protocols didn't require companies to inventory NF3 until 2013, so there are no reliable sources at this time.

    According to most engineers and experts, utility scale solar farms would take 11,000 square miles of solar panels to power the entire US.The largest solar farm today is 9.5 sq miles. As of 2014, the Topaz farm only generates roughly 110,000 MwH per sq. mile.

    Most utility size panels are about 17.6 square feet. This would mean that for every square mile you could fit 1,584,000 solar panels. At a minimum you would need 17,424,000,000 solar panels to fit into 11,000 square miles. For reference, the top 10 manufacturers of solar panels combined to produce 75M panels in 2013.

    We will get a better feel on NF3 inventories at some point soon. Until then, I'm comfortable saying that using the current cheap manufacturing techniques by the Chinese, the overall greenhouse gas impacts of manufacturing 17.5 billion panels are much greater than the lifetime equivalent of the current electric power portfolio. Also, if we did decide to build the electric grid using more expensive, but cleaner means, how much would it cost to build 17.5B panels?
     
    #3 ChievousFTFace, Jun 16, 2015
    Last edited: Jun 16, 2015
  4. ChievousFTFace

    ChievousFTFace Contributing Member

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    Major clarification: After further research, the numbers listed by the EPA are already in a CO2equivalent format. Therefore, I will have to retract a lot of my statements. Many sites do not make it clear that they are using CO2equivalence. They just use "percentage of greenhouse gas emissions" or "percentage of emissions."

    With that being said, it is still important to monitor the new inventories coming in on F-gases.
     

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