this post was submitted on 16 Nov 2024
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Anon questions our energy sector (slrpnk.net)
submitted 23 hours ago by MataVatnik@lemmy.world to c/science_memes@mander.xyz
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[–] Tar_alcaran@sh.itjust.works 2 points 18 hours ago* (last edited 18 hours ago) (1 children)

There is simply no excuse other than corruption for the fact that we don't just run a couple trains up a hill when we need to store massive amounts of solar energy.

How about basic maths? I

Scale is a huge fucking issue. The little country of the Netherlands, where I happen to live, uses 2600 petajoule per day. So let's store 1 day of power, at 100% efficiency, using the tallest Alp (the Mont Blanc).

Let's round up to 5000 meters of elevation. We need to store 2.6e18 joules, and 1 joule is 100 grams going up 1 meter. So to power a tiny little country, we need to lift roughly 5e13 kilos up the Mont Blanc. To visualize, that's 1.7 billion 40ft shipping containers, or roughly 100 per inhabitant.

Using 555m blocks of granite, you'd need 166 million of them (9 for every person in the country). Assuming a 2% slope, you'd need to build a 250.000m long railway line. And if you lined all those blocks up, with no space in between, you'd need 3328 of those lines (which then couldn't move, because they fill the entire space between the summit and sea level).

And that's just 1 small country.

[–] wolframhydroxide@sh.itjust.works 2 points 16 hours ago* (last edited 11 hours ago) (1 children)

And hey, you know what, that's almost got a point. Firstly, I'm in the US, and I'll freely admit that my comment was highly US-normative. However, I believe my comment on government corruption stands for the US case, where there is an insane amount of space that is already partly-developed in random bits of desert.

Now, let's get into your claims against the Netherlands case. Let's do some "basic maths":

  1. Unless the IEA is very, VERY wrong, your claim that the Netherlands consumes "2600 petajoule per day" is INSANELY high. Every statistic I can find shows electricity consumption being between 113 [2] and 121 [1] Terawatt-hours per annum. Let's divide that larger value by 365 (assuming uniform seasonal demand), then convert that into joules, and we get 1.19 Petajoules per day. more than a THOUSAND times smaller than your number.
  2. Secondly, this "just 1 small country" bit is spurious, since your "small country" is the 33rd-greatest electricity consumer in the world for the 77th highest population [2]
  3. The assumption that you must store an entire day's worth of energy demand is ludicrous. Let's be generous and assume that you have to store 50% of the day's energy demand, despite the fact that the off-hours are during the night, when electricity demands fall off.
  4. Next, let us point out that we don't need to abandon literally every other method of energy generation. From wind energy to, yes, nuclear, the Netherlands is doing quite well for itself outside of solar. Let's assume that we need to cover all of the electricity that is currently produced using coal, oil and natural gas. All other sources already have infrastructure supporting them, including the pre-existing solar. This amount comes to about 48% [1], so let's assume 50%.
  5. Now, we need to cover 50% of 50% of 1.9 petajoules at any one time, or 475 gigajoules, at any one time.
  6. Because I neither want nor need your supposedly-charitable assumptions, let's use the actual numbers from ARES in Nevada:
  • Their facility's mass cars total 75000 tons in freedom units, or about 68040000 kg. [3]
  • They claim 90+% efficiency round-trip [4], but let's assume that your condescending tone has made the train cars sad, so they're having a bad day, and only run at 80% efficiency, despite the fact that we've known how to convert to and from GPE with insane efficiency ever since Huygens invented the fucking pendulum clock.
  1. Now, is this perfect for everywhere? Of course not. Not everywhere has the open space necessary. The ARES site requires a straight shot about 5 miles long, but they managed to find one that, in that distance, drops 2000 feet (~610 m) [5]
  2. Now, let's do the math together: 475000000000J / 10m/s^2 / 68040000kg / 80% Efficiency = 880m total elevation needed
  3. Thus, unless my math is quite off, we would only need 2 of the little proof-of-concept ARES stations running at 80% efficiency to more than cover the energy storage needs required for your country to completely divest from fossil fuels and go all-in on solar for the remainder of your needs.

Quod Erat Demonstrandum.

[1] https://www.iea.org/countries/the-netherlands [2] https://en.wikipedia.org/wiki/List_of_countries_by_electricity_consumption [3] https://aresnorthamerica.com/nevada-project/ [4] https://aresnorthamerica.com/gravityline/ [5] https://energy.nv.gov/uploadedFiles/energynvgov/content/Programs/4%20-%20ARES.pdf

ETA: rectify a quote ("just 1 small country"), and make it more civil in response to the prior commenter removing some of their more condescending language.

[–] Tar_alcaran@sh.itjust.works 1 points 8 hours ago* (last edited 8 hours ago)

You're right in that I used yearly numbers and wrongly used them as daily numbers. The stats are from the central statistics bureau, and unfortunately it auto translates poorly https://www.cbs.nl/nl-nl/cijfers/detail/83989NED

The numbers include use of gas and coal for heating and industry, which often get ignored by people (mostly because it makes us look fucking terrible in renewable power stats).

  1. The assumption that you must store an entire day's worth of energy demand is ludicrous.

It is, in fact extremely generous, if you're using the solar+storage method. But let's go with this and I'll demonstrate what it means in practice.

Let's assume that we need to cover all of the electricity that is currently produced using coal, oil and natural gas. All other sources already have infrastructure supporting them, including the pre-existing solar. This amount comes to about 48% [1], so let's assume 50%.

You just made the switch from "energy used" to "electricity generated". For a country that still does most of its heating with imported gas, that's a big difference. The real amount of non-fossil energy is about 18%, call it 80% fossil.

  1. Now, we need to cover 50% of 50% of 1.9 petajoules at any one time, or 475 gigajoules, at any one time.

So it's 50% of 80% of 2600/365, or 2.8 petajoules. So that's only 10 of those facilities. Not great, not terrible. But that's not the point. Nor is it important that their demo facility has a height difference twice that of the whole country.

Let's stick with the "one night of power store is plenty".

That's true, but only if you can use solar to power your whole day. In other words, to make do with only 1 night of storage, you need to generate all your power for 24 hours in December during December daylight hours. Assuming it doesn't snow, one solar panel produces about .15kwh on a december day (working off of 2% of yearly production happening in december, and 300Wattpeak panels), or 540kj.

So you're right, we only need to build 10 facilities twice the height difference of the entire country, to save one night of energy use. Unfortunately in order for that to be true, we would also need to cover about 960.000 hectares in solar panels, which is roughly twice the total built up area in the country, including roads.

And that's assuming you keep a perfectly level energy use throughout the year, and a perfectly level production during December. Neither of which is true, and generally the worst days for solar production are the worst ones for use as well.

On the bright side, if we can put down two extra cities worth of solar panels for every city, we'll probably have no issues building 600m tall hills by hand as well.