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Modeled impact of large-scale wind and solar farms in the Sahara

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Re: Modeled impact of large-scale wind and solar farms in the Sahara

#61

Post by sampo »

0xCMP wrote: post #30
weberc2 wrote: post #28

Earlier quoted context omitted.

I’m doubtful about both of these claims (Europe has more heating than the US and that heating is more energy-intensive than AC). The latter seems particularly hard to believe given how efficient heating is compared to A.C.

It may have to do with where the heat comes from? I live in southern most areas of US, but from what I understand it's common for heating to use Gas/etc. instead of electricity. Therefore they use less "energy" (i.e. Electrical energy) All just a theory

The most efficient way to heat would still be generating electricity from gas. You lose 50% of the energy (well, you can still use part of the residual heat for heating, too), but with the electricity, you can run a heat pump that heats with about 400% efficiency. 50% × 400% is still 200%, so twice as good as burning gas for heat.

Re: Modeled impact of large-scale wind and solar farms in the Sahara

#62

Post by ebikelaw »

mikeyouse wrote: post #31
ebikelaw wrote: post #26

Earlier quoted context omitted.

Like any utility, you don't need a guy just hanging around waiting for the transformers to explode. You truck him in every 50 years when that actually happens. It's time domain multiplexing, essentially.

The cleaning is largely a solved problem too.. You don't need 50 $10k/year people with squeegees, you just need one person in a $50k truck. https://www.alibaba.com/product-detail/China-Road-tunnel-wal...

If there’s one job that robots are certainly going to take, it is solar panel squeegee guy.

Re: Modeled impact of large-scale wind and solar farms in the Sahara

#63

Post by roenxi »

jopsen wrote: post #48
spacenick88 wrote: post #13

Earlier quoted context omitted.

Almost no one in Europe has per-capita energy use anywhere close to the US, so why would China? And I don't think it's just that we have less AC, though that's surely the strongest contributor.

Exactly, As we see efficiency increase as well.. things are not as bad. Sure energy consumption will increase, but not to US levels.

We should expect increases in efficiency vs the US to /increase/ energy use relative to US levels.

https://en.wikipedia.org/wiki/Jevons_paradox

Re: Modeled impact of large-scale wind and solar farms in the Sahara

#64

Post by bobthepanda »

spacenick88 wrote: post #13
Analemma_ wrote: post #9

Earlier quoted context omitted.

If countries like China, India, Malaysia, Nigeria etc. start to have per-capita energy use close to that of the United States, global energy consumption could easily double or triple even without any increase in population. I said "if", but I really should say "when", because this is what's expected to happen as these countries modernize and start getting things like air conditioning on the same scale as US household…

Almost no one in Europe has per-capita energy use anywhere close to the US, so why would China? And I don't think it's just that we have less AC, though that's surely the strongest contributor.

The main issue is that Americans have much more house than Europeans do. The three-car garage McMansion with double-height ceilings and a double-height foyer is a ridiculous amount of space to cool down and heat up for a single household.

Nice visualization of that kind of data: https://www.reddit.com/r/dataisbeautiful/comments/7ei5f4/com...

Re: Modeled impact of large-scale wind and solar farms in the Sahara

#65

Post by skybrian »

xyzzyz wrote: post #39
weberc2 wrote: post #28

Earlier quoted context omitted.

I’m doubtful about both of these claims (Europe has more heating than the US and that heating is more energy-intensive than AC). The latter seems particularly hard to believe given how efficient heating is compared to A.C.

Sure thing. Heating (space + water) represents nearly 80% of EU household energy use[1], compared to 60% in the US[2]. I have no clue what you mean by "heating is efficient compared to AC". In fact, opposite is true -- unless you use some kind of heat pump, which are very uncommon in Europe, you only get exactly one unit of heating per unit of energy consumed. On the other hand, with AC (which _is_ a heat pump), you…

This way of thinking about efficiency doesn't take into account gains from insulation and/or reducing unnecessary heating. An electric blanket is more efficient than heating a room, which in turn is more efficient than heating a house.

Re: Modeled impact of large-scale wind and solar farms in the Sahara

#66

Post by philipkglass »

sandworm101 wrote: post #24
ebikelaw wrote: post #19

Earlier quoted context omitted.

Solar utility installations in California that I’m familiar with employ fewer than 1 person per square km.

And how do they keep all those panels clean? Who maintains the transformers when they break? Who swaps out the panels as they reach their life expectancy? It isn't just the night watchman, but the entire community of people involved in any large outdoor installation.

And how do they keep all those panels clean?

Robots, like these from Ecoppia:

https://www.ecoppia.com/wp-content/uploads/2016/08/Product_D...

https://www.youtube.com/watch?v=VIH-C29N82o

Re: Modeled impact of large-scale wind and solar farms in the Sahara

#67

Post by kryogen1c »

clairity wrote: post #51
kryogen1c wrote: post #46

I have always been alarmed that I've never seen the weather effects of solar and wind power discussed - they are by definition removing energy (randomly) from the global climate system. As one of the least understood and most complex systems that _drastically_ impact our lives, this should be cause for concern.

that energy loss to solar and wind power is a miniscule percentage of the energy available, which is provided by the sun and most of which gets radiated away anyways. no need to worry about it for another 5 billion years or so.

The concern is not the output of the sun, but energy moving in an unplanned (and unplannable fashion).

In other words, solar panels shade ground that would have been sunned. Windmills change atmospheric differential pressure by removing windspeed.

The best case scenario is these changes are negligible, but that is a luck-based result. We have no idea because global climate is not effectively modelable.

Re: Modeled impact of large-scale wind and solar farms in the Sahara

#68

Post by peterashford »

pmwhite wrote: post #53
state_less wrote: post #29

Earlier quoted context omitted.

Distributed generation seems like it would make sense (with current tech). Italy and Spain could help here. Maybe you could go from Tunisia to Europe, but supplying African countries seems more attainable. It'd be nice if you could turn the energy into a gas like methane, pull CO2 out of the atmosphere in the process. Good for the atmosphere and you could transport gas over long distances. https://en.wikipedia.org/wi…

I wonder if hydrogen is practical to transport in large quantities. My guess is no. Your idea of methane, if it could be done efficiently, seems more likely.

I saw that very recently an Australian company had worked out a way of transporting hydrogen in large quantities by converting it into something else which I conveniently can't remember.

Re: Modeled impact of large-scale wind and solar farms in the Sahara

#70

Post by strainer »

I would not have guessed that the solar arrays beneficial effect on precipitation is dependent on them not being too efficient and so releasing more heat than bare desert (which is very reflective).

From the article - "The precipitation increase in our solar farm experiments is due to the relatively low conversion efficiency of the panels (15%, typical current conversion efficiency for photovoltaic panels), which results in albedo decrease. However, if solar panel efficiency and the associated effective albedo are high enough to lead to an albedo increase relative to the background environment (as, for example, a 45% efficiency would), the climate impact would be surface cooling with precipitation suppression, similar to the impact of overgrazing in the desert. Assuming an intermediate conversion efficiency higher than 15% for solar panels (e.g., 30% efficiency) results in negligible albedo change and, thus, insignificant climate impacts."

[^] http://science.sciencemag.org/content/361/6406/1019

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