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.
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.
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