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Comment by jschwartzi | Hacker News Reader

It's far more dangerous than that. If we had an ash cloud significant enough to dim the sun then plants would receive less sunlight, which means a poorer growing season, which means worldwide famine. If that thing erupts, renewable electrical supply will be the least of our worries. I would say we'll spend most of our time trying to grow enough food.

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But given enough electricity, we could easily grow enough food to feed the entire planet in a relatively small amount of space. Plants don't care if they're growing under the sun or under a UV bulb, if they're growing in earth or hydroponic, if they're growing on land or vertical. At that point it's merely a distribution issue. Existing distribution channels wouldn't necessarily be interrupted, with the possible exception of air travel (and of course, all of the area that is now a crater from the super volcano). The problem really starts if all of our electricity is generated by the sun, and then the sun goes away for a bit.

It's not actually an "alternative power" problem, it's just a solar problem. Wind, nuclear, and hydro power wouldn't be affected.

I'm not convinced wind farms wouldn't be affected as well.

With an ash cloud large and dense enough to restrict that much sunlight, wouldn't we also get a different distribution of warmed land and therefore different wind patterns?

Don't forget the abrasive qualities of volcanic ash. The blade surfaces would be eroded, and the internal bearings supporting the blade, the multiplier gears, and generator inside would quickly become trashed.

Wind and hydro power are solar power in a sense. The energy to move the air and evaporate the oceans comes in large measure from the sun. So a global solar disruption could also change wind and precipitation patterns

With less sun, you get less evaporation; not sure that wouldn't affect hydropower, not to mention other uses of water.

> But given enough electricity, we could easily grow enough food to feed the entire planet in a relatively small amount of space.

Sure, in a hypothetical world. But in the real world, what percentage of our crops are currently being grown under UV bulbs? It's a vanishingly tiny percentage. The problem is not that it's impossible to grow without sunlight. The problem is that it's impossible to transition to a low-sunlight world without a few years of global famine and a massive human die-off.

This was my thought exactly regarding growing crops. The other alternative powers are unpredictable, so we would have to go back to nuclear or similar. My thought is that today we could actually accomplish quite a lot in a short time if we where organized. If we where successful in removing the majority of the current power infrastructure, I'm unsure how much time it would take to get the system running.

Just to replace the wheat crop would require 11x our current total electrical production. We would need All Teh Powerz!

I'm sure in such an emergency we could find a way to switch to a crop that is more calorie dense for the amount of energy it takes to grow it. Wheat is in a lot of products we eat, but not as the main ingredient with just a few exceptions. Just like corn, it's not a terribly efficient crop to grow so we probably wouldn't grow it anymore.

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