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  • Volcanic activity: its risk for solar energy, and possible mitigations

    A forum member was concerned about two ways volcanic eruptions could reduce output from solar panels: ash settling directly on them, and haze high in the atmosphere.
    So I dug around for some science on the topic. Here's what I came up with; corrections welcome.

    1. Is volcanic activity increasing in general?
    The Smithsonian Institution's Global Volcanism Program says probably not, see http://volcano.si.edu/faq.cfm#q6
    That doesn't mean there's no risk, though, so we shouldn't let that stop us from dealing with what risk there is.
    And there is some evidence that volcanos under glaciers can increase their activity after the glaciers melt, so there might in fact be some increase; see
    https://scholar.google.com/scholar?s...,5&as_ylo=2012

    2. What size eruptions should we worry about?
    http://ete.cet.edu/gcc/style/docs/VEI_information.pdf describes how eruption sizes are classified. There are several VEI 6 eruptions per century, so that seems like a good size to plan for, for starters. (There are several VEI 7 eruptions per millennium; let's worry about them after we get ready for the VEI 6's.)

    3. What is the risk of volcanic eruption belching long-lived haze into the sky, blocking out the sun even without any ashfall?
    The paper "Effects of the Mount Pinatubo eruption on solar insolation: Four case studies",
    http://www.osti.gov/scitech/servlets...176846-n0t9sc/
    said it caused a decrease of insolation in the studied locations in North America of about 5% to 12% for about six months.
    That was a largish VEI 6 eruption, and is probably as good a guess as any at what a typical VEI 6 eruption might do.
    However, on the bright side, figure 2 of http://climate.envsci.rutgers.edu/pdf/ROG2000.pdf shows that with that loss of *direct* insolation comes a corresponding increase in *indirect* insolation; the light is scattered, not absorbed. So it's possible that systems that are good at accepting ambient light would
    experience a lower loss of ouptut.

    4. How much ash needs to settle on a panel before the sun is blocked out?
    The paper "Influence of volcanic tephra on photovoltaic (PV)-modules: an experimental study with application to the 2010 Eyjafjallajökull eruption, Iceland"
    https://appliedvolc.springeropen.com...617-015-0041-y
    states:
    - 1mm of ash decreases output to zero on horizontally oriented panels
    - 1/25th of a mm of fine ash is enough to decrease power output by 30% on horizontally oriented panels
    - vertically oriented panels don't gather much ash at all, so that's the best orientation for panels likely to get lots of ash

    5. How much ash needs to settle on powerlines before they start failing?
    The publication "Advice for Power Transmission and Distribution System Operators in volcanic ash events" at http://www.aelg.org.nz/document-libr...c-ash-impacts/ says power lines are vulnerable to flashover after as little as 3mm of ash,
    if it gets wet.

    6. What is the risk of that much ash falling on any given area?
    Page 200 of "Global Volcanic Hazards and Risk",
    http://globalvolcanomodel.org/wp-con...ok-low-res.pdf
    has a draft map of the world, showing how often each part of the world is at risk of >= 1mm of ashfall.
    That seems like a good place to start in the absense of more local data.

    So, putting it all together, here are some ways to reduce the risk:
    - power companies could plan to be able to handle something like 12% lower output than normal from solar energy for periods of several months several times per century (possibly by installing 12% more panels)
    - solar farms in areas that get a 1mm of ash eruption more than about once per century could adopt some sort of ash mitigation (e.g. using
    bifacial panels, and orienting them vertically, either as their fixed orientation, or dynamically upon warning of ashfall).

    I *think* those together would make our solar power resources a lot more resilient to disruption from volcanic activity. I'd love to hear
    what other think, and whether any states or power companies are thinking along these lines.

    One should also remember that fossil fuel power plants also have to worry about volcanic ashfall (see "Advice for Power Plant Operators in volcanic ash events" at http://www.aelg.org.nz/document-libr...ic-ash-impacts ); it's not just solar's worry.
    Last edited by DanKegel; 06-21-2016, 06:27 PM.
    17kw. I like science, but I'm no expert.

  • #2
    Who gives a crap?
    MSEE, PE

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    • #3
      Originally posted by Sunking View Post
      Who gives a crap?
      Why do you equivocate so much ?

      Comment


      • #4
        Dan, how would bi-facial panels in a vertical orientation, be useful ?
        Adjustable racking, in a utility scale, would be a huge increase of expense. Having a blower truck to clean the panels would be more efficient I think.
        Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
        || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
        || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister

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        • #5
          Originally posted by Mike90250 View Post
          Dan, how would bi-facial panels in a vertical orientation, be useful ?
          Adjustable racking, in a utility scale, would be a huge increase of expense. Having a blower truck to clean the panels would be more efficient I think.
          On blowing the arrays clean: I thought so too, particularly in a desert climate where H2O is scarce. Two things have made me reconsider. One is, what happens to all the dust/debris that gets blown off, as in where does it get blown to ? Adjacent panels ? that might require a second/third pass = more cost. a rolling dust collection system w/bags like a giant vacuum cleaner ? More $$/maint.

          The second one is talking to the folks who take care of the 1 MW array in Death Valley. Since 2008, they've figured out that washing the array every 2 years or so seems to be the most cost effective for them. They do not seem to be concerned about dust a much as guano buildup. Their opinion that dust is not a big concern may add some information to my sort of findings that the fouling rate of my array may exhibit some asymptotic behavior - sort of leveling off at after about 6-8 weeks of no rain/cleaning.

          The data gathering continues.

          Comment


          • #6
            Originally posted by Mike90250 View Post
            Dan, how would bi-facial panels in a vertical orientation, be useful ?
            Adjustable racking, in a utility scale, would be a huge increase of expense. Having a blower truck to clean the panels would be more efficient I think.
            Thanks for asking.

            I don't think I proposed adding adjustable racking, or anything that would significantly increase expenses.

            Regarding *tracking* systems, I suggested that if you're going to have a tracking system anyway, you may as well make it more ash-resistant by designing it so it can swivel to a near-vertical position if ash starts falling.

            Vertical or near-vertical panels are helpful because ash doesn't have a chance to settle on the active surface and directly block the light.

            Bi-facial panels might be helpful in two situations:
            1. when a distant volcano has pumped a lot of sulfur haze into the stratosphere, it scatters sunlight so there's an increase in diffuse light, so more light hits the back of the panel in those conditions -- even if there's no local ash.
            2. if a panel is vertical or near vertical and can't track the sun, it's going to have direct sunlight hitting its back.

            Beyond those mitigations, of course if there is ashfall, there's going to be cleaning involved, and a truck with compressed air or a vacuum cleaner driving by the panels will be part of that.

            Those observations are just illustrations that designing in volcano mitigations might be possible and not cost much if anything. If SunEagle is serious about wanting to address the risk of lower utility scale solar output due to volcanic activity, this gives him a way to do something about it: advocate for regulators to require utility scale solar installations to a) calculate their risk over lower output due to likely volcanic activity, and b) design in cost-effective mitigations.
            Last edited by DanKegel; 06-28-2016, 10:55 AM.
            17kw. I like science, but I'm no expert.

            Comment


            • #7
              Originally posted by J.P.M. View Post
              what happens to all the dust/debris that gets blown off, as in where does it get blown to ?
              Good point. With volcanic ash, you probably want to do something to keep it from blowing back up on the panels later. That could mean vaccuming it and taking it away to a dump. (Also, you don't want to get it wet, as that can make it stick; wet cleaning systems shouldn't be used until all the ash is gone.)

              Thanks for that Death Valley data point!
              17kw. I like science, but I'm no expert.

              Comment


              • #8
                Originally posted by DanKegel View Post

                Good point. With volcanic ash, you probably want to do something to keep it from blowing back up on the panels later. That could mean vaccuming it and taking it away to a dump. (Also, you don't want to get it wet, as that can make it stick; wet cleaning systems shouldn't be used until all the ash is gone.)

                Thanks for that Death Valley data point!
                I was in Yakama, WA about 4-6 months after Mt. St. Helen's blew, checking out some equipment in a juice plant for repair/refurbish/restart. The whole Yakama Valley area still looked like the moon, at least when compared to lunar surface photos. I don't think sucking the ash off a surface at that location/time would have done much more than make more room for the next batch of wind blown dust/ash which would come by in the next few min. If there is a lot of ash, aside from pretty much constant blowing/sucking, I'm not sure that acknowledging that we can't control everything and simply shutting a solar facility down until the area dust/ash level is mitigated wouldn't be the necessary approach, at least for a while.

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                • #9
                  Originally posted by J.P.M. View Post
                  If there is a lot of ash, aside from pretty much constant blowing/sucking, I'm not sure that acknowledging that we can't control everything and simply shutting a solar facility down until the area dust/ash level is mitigated wouldn't be the necessary approach, at least for a while.
                  Vertical panels would still be able to generate power under those conditions.
                  17kw. I like science, but I'm no expert.

                  Comment


                  • #10
                    Originally posted by DanKegel View Post

                    Vertical panels would still be able to generate power under those conditions.
                    No kidding, really ?? Of course they would, or at least with a rather large probability. DUH !

                    I thought the matter up for discussion was more about the consequences of an ash event and some talk of how to prepare for /mitigate the consequences, rather than how performance alone would be impacted. Maybe I'm too presumptive. but that output would be reduced seems a distinct no brainer.

                    To prepare and perhaps design for such an event usually takes some thought about how the consequences may occur in order to from a plan.

                    As for vertical panels, considering the rather broad subject of surface fouling alone for now, I'd think a vertical surface facing downwind might just collect more dust than one facing upwind, and I'd guess probably about as much or perhaps more than a horizontal surface if in a windy, dry climate, if gross material loading is considered. That gross loading however, is probably different than changes in a surface's transmittance*absorbance product for solar irradiance in terms of mass loading vs. distributed loading - dirt in the corners or sides vs. evenly distributed or some combination of deposition.

                    One small, but I'd suggest possible example: It may be that an east-west aligned vertical flat plate exposed to a wind with a north vector component might have a lot of fouling on it's south face, and perhaps less on its north face.

                    As for the north face if its a PV panel, since surfaces facing away from the equator don't get much more than 10-20% of the south face, and variable as being more highly influenced by albedo, probably a minor or not much of a consideration for solar applications.

                    How surfaces attract, keep, shed and otherwise interact with fluid borne particulate matter, and what happens after initial deposition is much more than simply gravity controlled. Your thinking seems stuck in the gravity box. NOMB, but if you learn something about particulate fouling and put 2 + 2 together you might have an expanded view of the situation. Without some additional considerations, and perhaps in the same vein as SK's seminal and concise comment, most of this is mental masturbation.

                    Comment


                    • #11
                      Whatever form of ash mitigation is taken, the owners of a large or small solar pv array need to realize that a single small volcanic event could reduce all of their electrical production to 0 for many days.

                      Of course that would not necessarily be a problem if there are other power sources available that are not affected by ash fall.

                      I would hate to see the Diablo Canyon nuclear plants shut down only to be needed later should the West Coast get an event. But then again that CA's problem to deal with.

                      Comment


                      • #12
                        Originally posted by J.P.M. View Post
                        To prepare and perhaps design for such an event usually takes some thought about how the consequences may occur in order to from a plan.... mental masturbation.
                        Thank you as always for your helpful and respectful comments.

                        I'd be happy to respond to your points if you'd rephrase them without the abuse.
                        Last edited by DanKegel; 06-28-2016, 04:01 PM.
                        17kw. I like science, but I'm no expert.

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                        • #13
                          Originally posted by SunEagle View Post
                          Whatever form of ash mitigation is taken, the owners of a large or small solar pv array need to realize that a single small volcanic event could reduce all of their electrical production to 0 for many days.
                          A really cloudy month could do the same. I think they're on top of that problem.
                          17kw. I like science, but I'm no expert.

                          Comment


                          • #14
                            Originally posted by DanKegel View Post
                            Thank you as always for your helpful and respectful comments.

                            I'd be happy to respond to your points if you'd rephrase them without the abuse.
                            You're most welcome. Perhaps you'd find them even more respectful and helpful if you took them seriously and gave them some consideration.

                            In spite of what you seem to expect as some sort of entitled birthright, I have no intention of changing what I wrote to suit your wishes. Nor do I see anything abusive in what I wrote. We seem to have different views of what's abusive, what's straight talk and what's reality.

                            Besides, people are abused, and while not for a hot second believing my post to be the least abusive, I believe my comments were directed at your opinions and writings - not you. Kind of hard to be abusive of an opinion or a comment, unless you consider disagreement to be abusive.

                            I see no need to conform to your notions of political correctness.

                            As usual, take what you want of the above. Scrap the rest.

                            Comment


                            • #15
                              Sigh. I had hoped you'd be interested in a civil conversation. I guess that's not your forte.
                              17kw. I like science, but I'm no expert.

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