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Comment by wyldfire | Hacker News Reader

Maybe this is a stupid question but I wonder if there are any ecological concerns about redirecting terawatts of power from the photons hitting Earth into electricity. Of course, it's bound to be a big net win over burning hydrocarbons. But is there any drawback?

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At 100TW, solar power would use a whooping 0.06% of total solar radiation the Earth receives. The Sun is truly immense.

The biggest environmental concern is the disposing of the batteries when they die, and that should seen solutions soon as solar gets more and more popular.

The overwhelming majority of solar energy storage will likely be in batteries with little need for disposal: giant spinning flywheels, pumping water up high, storing energy in millions of smart thermostat homes by overheating/cooling them during peak hours to reduce demand at other hours, etc.

Finally, I see mention of the HVAC "battery" idea I've been flogging for years. Progress!

I hope this progresses to using the pile-of-rocks "battery" to store heat/cold in cheap hours and draw on it in expensive hours.

You might be interested to read about a seasonal thermal storage project in Vojens, Denmark:

https://deepresource.wordpress.com/2020/12/16/district-heati...

Looks like the Danes are very smart!

It was popular in the 1950s. Deployed near where you live, even.

I know Seattle has an old steam plant to supply the downtown with heat. Never heard of rock storage in the US. I'm interested in a reference.

If so, Americans have forgotten all about it, replaced with a desire to do it all with electric batteries.

"storing energy in millions of smart thermostat homes by overheating/cooling them during peak hours to reduce demand at other hours"

Who's going to go along with this? I suspect millions in the US alone would flip their lids if such an idea were even considered and rightfully so. IMO this would be a great idea if your ultimate goal was to cause smart thermostats to be banished from the home.

I think GP meant overheating/overcooling during off-peak hours? In which case plenty of people in well-insulated buildings go along with this, motivated by lower electricity prices during off-peak hours.

I took it as over-heating/cooling during peak electric production time (daylight probably) when power is more available in order to reduce usage during off-peak times. I think it would require compulsion or a large amount of voluntary adoption on the part of the customers to really make much of a difference though, and I doubt that the latter is likely on a meaningful scale (though I could be wrong of course).

It already happens today with little complaint.. many utilities are offering discounted rates if you agree to let them reduce your consumption on a handful of days per year. One such example;

https://consumersenergy-faqs.tendrilinc.com/faqs/what-is-the...

Everything's fine as long as it's voluntary. And by voluntary I mean both not compulsory (mandated by some level of government) as well as not normalized to such a degree that virtually every electric provider independently offers no other option. These types of things have a way of worming their way into our everyday lives; I imagine I'm not the only one who is wary of loss of agency from this as well as other similar things as the Overton window is dragged farther and farther away over time.

The fraction of storage in the form of batteries will diminish to near zero, except in cars and garages. That will be a large absolute amount of batteries, but will not grow at anything like the rate generating capacity will.

Consider that 40% of American corn crop (created, as you say, by redirecting the suns energy) is turned into Ethanol, to be burned for energy.

Solar panels are "roughly 200 times more energy per acre than corn" according to https://pv-magazine-usa.com/2022/03/10/solarfood-in-ethanol-...

There are ecological concerns but the alternatives have them too.

There's an albedo change where previously the light would have reflected back out.

The melting ice is likely a bigger change, considering some of the solar is going on dark rooftops that already bake in the sun

Yes, whatever is under the solar panels gets less sunlight. There are even some companies starting to lay solar panels directly on the ground, which means it gets none at all.

I don't think it's all that hard to take that into account, though; it's a land use concern. What was the land being used for before?

Also, the terawatts of power generated will get converted to heat in developed areas where it's used, but that's true of any electricity use.

But if the sunlight that produced that power had hit something else instead, it also would have been turned into heat. There's no net heating of the planet from solar power. (Of course, the distribution of heating can change.)

Recall that PV panels are black. They get quite hot, almost certainly hotter than plain dirt would if uncovered. Plenty hot enough that you can't touch them for more than a moment.

For reference, that's somewhere just above 50°C

I am not sure that is correct. It is possible that solar panels absorb more total energy and keep it locally than would otherwise be reflected back into space via radiative cooling.

Possibly, although it would behoove solar panels to have a high albedo along the non-electrically producing wavelengths. Lower panel temperatures mean higher efficiency, but the effort might not be worth the marginal improvement.

Yes, and when electricity is used to do work, the vast, overwhelming majority of the energy used is turned into heat.

So solar panels are moving heat, not sending it into a black hole somewhere.

That was my point.

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