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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

#71

Post by the8472 »

wongarsu wrote: post #6
jameskilton wrote: post #3

> The wind and solar farms simulated in the study would cover more than 9 million square kilometers and generate, on average, about 3 terawatts and 79 terawatts of electrical power, respectively. This study is looking at a combined farm size that's almost as large as all the land mass in the US. https://en.wikipedia.org/wiki/List_of_U.S._states_and_territ...

That seems a bit excessive, considering that the world energy consumption is only about 18 terawatts (and only about 3 terawatts of that are electrical right now).

Civilisation is to a large extent constrained by available energy, which is why new energy sources have lead to industrial revolutions. As long as you're not spending other resources on it excessively any massive amount of energy surplus can be put to good, previously uneconomical and fantastical-seeming uses.

Given enough energy you could regulate the entire biosphere by brute force.

And if you ever want to get serious about colonizing space a stupendous amount of energy has to be spent just lifting people and materials into orbit.

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

#72

Post by saltcured »

sampo wrote: post #59
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.

Here is a study from 2013 in Environmental Research Letters. Comparing Minneapolis and Miami, the coldest and the warmest metropolitan areas in the US. Minneapolis uses (per capita) 3.5 times more energy for heating and AC (mainly heating) than Miami (mainly AC). "This finding suggests that, in the US, living in cold climates is more energy demanding than living in hot climates." http://iopscience.iop.org/article/10.…

Miami can only be considered "hottest" because it never gets cold and you consider the average. It actually spends a long time near room temperature. Somewhere like Las Vegas or Phoenix gets both hotter and colder.

If we arbitrarily pick 70F as room temperature, Miami has a typical annual high/low spread of approximately 60F-90F or -10 to +20 degrees relative to room temperature. Meanwhile, Minneapolis has a typical annual spread of approximately 10F-85F or -80 to +15 degrees relative to room temperature.

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

#73

Post by sampo »

saltcured wrote: post #72
sampo wrote: post #59

Earlier quoted context omitted.

Here is a study from 2013 in Environmental Research Letters. Comparing Minneapolis and Miami, the coldest and the warmest metropolitan areas in the US. Minneapolis uses (per capita) 3.5 times more energy for heating and AC (mainly heating) than Miami (mainly AC). "This finding suggests that, in the US, living in cold climates is more energy demanding than living in hot climates." http://iopscience.iop.org/article/10.…

Miami can only be considered "hottest" because it never gets cold and you consider the average. It actually spends a long time near room temperature. Somewhere like Las Vegas or Phoenix gets both hotter and colder. If we arbitrarily pick 70F as room temperature, Miami has a typical annual high/low spread of approximately 60F-90F or -10 to +20 degrees relative to room temperature. Meanwhile, Minneapolis has a typical…

You should look at section 2.2 in the article. Miami has more cooling degree days (2423) per year than Phoenix (2327) or Las Vegas (1786).

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

#74

Post by sunstone »

jameskilton wrote: post #3

> The wind and solar farms simulated in the study would cover more than 9 million square kilometers and generate, on average, about 3 terawatts and 79 terawatts of electrical power, respectively. This study is looking at a combined farm size that's almost as large as all the land mass in the US. https://en.wikipedia.org/wiki/List_of_U.S._states_and_territ...

So in the Sahara that would probably mean all solar and a few batteries. Wind turbines would have maintenance issues from the sand storms.

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

#75

Post by CapitalistCartr »

nine_k wrote: post #16
jameskilton wrote: post #3

> The wind and solar farms simulated in the study would cover more than 9 million square kilometers and generate, on average, about 3 terawatts and 79 terawatts of electrical power, respectively. This study is looking at a combined farm size that's almost as large as all the land mass in the US. https://en.wikipedia.org/wiki/List_of_U.S._states_and_territ...

Generating terawatts is not unreasonable. But transportation of it out of North Africa would be almost as big an effort as building the solar farms in question.

At least 600kv HVDC lines for moving gigawatts. Several billion US dollars to build. Might be worth it to tie into Europe's grid.

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

#76

Post by spangry »

peterashford wrote: post #68
pmwhite wrote: post #53

Earlier quoted context omitted.

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.

It was the CSIRO converting hydrogen to ammonia for transport, and then back to hydrogen again: http://www.abc.net.au/news/2018-08-08/hydrogen-fuel-breakthr...

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

#77

Post by whatshisface »

bobthepanda wrote: post #64
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.

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...

>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.

That's definitely not a significant contributor to American energy usage, given that not everyone in America is a millionaire.

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

#78

Post by peterashford »

kryogen1c wrote: post #67
clairity wrote: post #51

Earlier quoted context omitted.

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.

You're worried that we haven't discussed the results of something that you admit is not effectively modelable?

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

#79

Post by selectodude »

whatshisface wrote: post #77
bobthepanda wrote: post #64

Earlier quoted context omitted.

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...

> 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. That's definitely not a significant contributor to American energy usage, given that not everyone in America is a millionaire.

There are 139 homes for sale in the Dallas Metroplex that have 6 or more bedrooms for $600,000 or less.

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

#80

Post by narag »

nine_k wrote: post #16
jameskilton wrote: post #3

> The wind and solar farms simulated in the study would cover more than 9 million square kilometers and generate, on average, about 3 terawatts and 79 terawatts of electrical power, respectively. This study is looking at a combined farm size that's almost as large as all the land mass in the US. https://en.wikipedia.org/wiki/List_of_U.S._states_and_territ...

Generating terawatts is not unreasonable. But transportation of it out of North Africa would be almost as big an effort as building the solar farms in question.

Why should it be transported out of North Africa? That huge power availability would be a much needed incentive to attract factories there. With so much energy, water can be desalinized and transported near the generation sites so in the long term the energy would transform the desert in a very desirable location.
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