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Just saying (thelemmy.club)
submitted 6 months ago by to c/memes@lemmy.world
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[–] 6 points 6 months ago* (last edited 6 months ago) (1 child)

Okay, so I've double-checked all the most important numbers you've used. One thing I've noticed is that Alec compared the land-use of ethanol and solar power, but our fuel is only 10% ethanol. Even then though that doesn't explain the whole number you got to.

By that math, the current total land for existing plants should be ~400,000 acres but the equivalent if we switched to 100% solar power would be 270-675 million acres of land.

With 270 million acres, and 1mW for every 10 acres, that's 27 million mW (648 trillion Wh a day). Far more than what you say is needed for all cars to be electric. At some point you must have swapped to the goal of meeting America's entire electricity demand with solar. Even then though ...

America consumes 25,000tWh of energy per year (about 7Twh per day, or 3Tw). 27 million mW is 27tW. Even with 10 acres per mW, we'd only require about 30 million acres to meet the entire country's energy with solar (which happens to be exactly the same as the amount of land we spend on ethanol).

You should really double-check your math.

EDIT: 30-35 million acres is still correct, but my working is wrong. I made two mistakes that cancel each-other out. See https://aussie.zone/post/29798627/21519669

EDIT: I basically skipped over your 3rd and 4th paragraph, but what is that nonsense math your doing? I didn't even bother trying to comprehend it because it was so nonsensical, but what in the actual hell were you trying to do there.

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  • [–] 1 point 6 months ago* (1 child)

    Okay, so I’ve double-checked all the most important numbers you’ve used. One thing I’ve noticed is that Alec compared the land-use of ethanol and solar power, but our fuel is only 10% ethanol. Even then though that doesn’t explain the whole number you got to.

    As I said in my post, this guy is talking about fuel for cars, not the entire power usage

    With 270 million acres, and 1mW for every 10 acres, that’s 27 million mW (648 trillion Wh a day). Far more than what you say is needed for all cars to be electric

    I basically skipped over your 3rd and 4th paragraph

    That is literally what I said in paragraph 3 "The US currently has ~12.5k utility scale electric power plants, to replace those with solar and switch all cars to electric you would need ~2-2.5 million solar farms the size represented in the video."

    America consumes 25,000tWh of energy per year (about 7Twh per day)

    My research said the US produces 11 trillion Wh per day and said that if all US vehicles were electric it would require 2.2-5.5 trillion Wh more per day. Looking at consumption is important, but looking at production is more accurate. Some electricity is sold or wasted, but that's to ensure demand is met when the grid sees a spike in usage.

    27 million mW (648 trillion Wh a day)

    You must have skipped paragraph 2 as well. A 27 MW solar plant is rated as such because that is the maximum instantaneous power outout, but most places only have ~16 hours of sunlight and won't be running at 27 MW for all 16 hours. As such a 27 MW solar farm will only make ~130-150 MWh/day.

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  • [–] 2 points 6 months ago* (last edited 6 months ago) (1 child)

    Okay, lets redo the math with your new numbers.

    • 11TWh (+6TWh) per day production.
    • Average of 1/5 of maximum output (27MW * 24 = 648 MWh per day. 648 / 130 = factor of 5).
    • 1 MW per 10 acres of solar power (It's 27MW on 120 acres at the DePue site)
    • 270-675 million acres.

    Now lets get all the units into average MW

    • 700,000MW needed (17TWh per day = 0.7 TW average)
    • 0.02MW per acre. (1MW / 10 / 5 = 0.02MW average)

    That means 35 million acres. Now I'm going to post this immediately before double-checking my math previous maths, because this number should be about 10 times higher than my previous answer based on the numbers you've given me. Did I overestimate the land required in my first reply?

    EDIT: Found my problem.

    America consumes 25,000tWh of energy per year (about 7TWh per day, or 3TW)

    7TWh per day is not 3TW, it's 0.3TW.

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  • [–] 1 point 6 months ago* (2 children)

    I worked the problem a different way, first of all I evaluated both ends of both spectrum (2.2-5.2 trillion for adding cars to get the number of solar farms needed and 5-10 acres per MW rating, this is how I built my range). I believe I have an error in the number of solar farms needed (2-2.5 million farms in my original post), but I have not been able to replicate my math that got me the error. I made this post in sections and at some point realized that 27 MW doesn't make 648 MWh, but I might have missed switching it out somewhere to get the math I got.

    Rerunning the math I took the amount produced and needed (~17 trillion Wh) and divided it by the production for one 27 MW site (150 MWh) to get the number of plants and then multiplied that by 27x10.

    17x10^12 / 150x10^6 x 27 x 10 = 30,600,000 or 30.6 million acres.

    All that aside we are still talking about 75x more land usage before we talk about time zones, day night cycles, distribution of the panels, etc. The big counterpoint that people seem to have is batteries, but we already use batteries and the amount more we would need to provide 24 hour coverage with just solar would be astonishing.

    Market forces push business decisions, the only way solar power would be cheaper for the consumer is if it was also cheaper for the business. If solar was realistically cheaper then power production facilities then corporations would be switching to it and probably not drop our end costs because that would just be extra profit. Whether it's a lack of battery capability, unattainable capital costs, lack of reliability, or something else at play, solar power would not be cheaper for the end user or else corporations would be switching to it.

    EDIT: Good work on your math.

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  • [–] 2 points 6 months ago (1 child)

    As per the video, 30 million acres of land is used to grow ethanol that is mixed into petrol. We could replace every car in the country with electric, and power our entire electricity grid with solar power, with that land. Solar farms are less destructive to the land than corn farming so even if replacing all that farmland with solar panels only provided enough power for electric cars, it would still be a positive in terms of land use.

    75x land use is as compared only to power-plants. If I go swimming tomorrow I've 999999x'd my shark attack risk. And as a share of America it's only 1-2% of the total area of the United States (to power the entire country) and can replace all the corn ethanol crops to a net environmental benefit.

    As for batteries, they are recyclable (as the video goes into). They do add to the cost of renewables but not so much that they cancel out having to constantly mine coal and set it on fire to never be used again. There are wind turbines which even out the duck curve, but in this thought experiment the entire country is going solar powered only.

    As for why business leaders aren't investing in renewables, I need to make an important distinction. Renewables aren't the "cheapest form of power generation", they are the "cheapest form of new power generation". It is cheaper to keep running existing gas-fired and nuclear power stations until they reach EOL than it is to tear them down prematurely and replace them with solar. A large number of power stations are rapidly reaching EOL and it's very important that we don't build any more coal-fired power plants right now (due to an explicit government policy of burning more coal, perhaps). Each one we build will last 50-100 years and be cheaper to keep running than replace with renewables.

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  • [–] 1 point 6 months ago (1 child)

    30 million acres of land is used to grow ethanol that is mixed into petrol

    The majority of ethanol based crop production comes from growing corn in the Midwest, specifically Kansas, Nebraska, Iowa, Illinois, Missouri, and Indiana. Ranked by population density that's:

    • Nebraska #43
    • Kansas #41
    • Iowa #36
    • Missouri #28
    • Indiana #17
    • Illinois # 12

    By percentage of the US population that's

    • Nebraska @ 0.5%
    • Kansas @ 0.8%
    • Iowa @ 0.9%
    • Missouri @ 1.8%
    • Indiana @ 2%
    • Illinois @ 3.7%

    There are practical reasons why we typically try to generate power close to where it will be used. Yes, theoretically you can realistically supply power up to 3000 miles away, but most power plants only provide power to around 500 miles away. Yes we could cover the Corn Belt with solar panels and then wire it to the coasts, but doing so has it's own risks and drawbacks. Ethanol agriculture makes sense where it is because the population density is so low and both corn and ethanol can be shipped with relatively low loss.

    As for batteries, they are recyclable (as the video goes into). They do add to the cost of renewables but not so much that they cancel out having to constantly mine coal and set it on fire to never be used again

    I'm not arguing that they aren't recyclable but rather they aren't accessible at the volume needed. A quick google search said that current utility scale battery storage exceeds 26 GW (10^9), but only represents 2% of total generating capacity. To provide power for approximately half the day, based on our previous math, we would need need ~7x10^11 W.

    Just so my math is clear from the beginning, 17x10^12 W / 2 (half the day) / 12 (hours per half day) = 7x10^11 W of battery which is 27 times more than we currently have.

    Renewables aren’t the “cheapest form of power generation”, they are the “cheapest form of new power generation”. It is cheaper to keep running existing gas-fired and nuclear power stations until they reach EOL than it is to tear them down prematurely and replace them with solar. A large number of power stations are rapidly reaching EOL and it’s very important that we don’t build any more coal-fired power plants right now

    I think this is a fair and nuanced point. In my opinion the solution is not one singular option, such as 100% solar, but a mix of options which might include some percentage of non-renewable energy. I think reduction of non-renewable should be the goal, but switching 100% to renewable does not seem feasible to me.

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  • [–] 2 points 6 months ago (1 child)

    The majority of ethanol based crop production comes from growing corn in the Midwest, specifically Kansas, Nebraska, Iowa, Illinois, Missouri, and Indiana.

    My argument was never that we "should" replace all our ethanol corn crops with solar panels. Just that we could. And we could still theoretically make it work with enough money and gumption (and moving energy intensive industries inland to reduce the need for transmission).

    I’m not arguing that they aren’t recyclable but rather they aren’t accessible at the volume needed.

    Lithium supply is a concern. We don't have enough in the world to support the green transition and there's no clear solution. A few that come to mind are:

    • New battery technologies that have been in the pipeline for a while.
    • Overbuilding renewable electricity to account for a lack of batteries.
    • Building a diverse range of renewable power sources.
    • Peak pricing, and load shedding when there's not enough supply.
    • Interstate power connections to share surplus and deficits.

    I think this is a fair and nuanced point. In my opinion the solution is not one singular option, such as 100% solar, but a mix of options which might include some percentage of non-renewable energy. I think reduction of non-renewable should be the goal, but switching 100% to renewable does not seem feasible to me.

    I think we should use a small amount of methane to supply power in the event of an emergency, instead of building enough batteries to supply us for an entire year of cloudy weather and stagnant air. In the first place the thought experiment was about 35 million acres of solar, not about a 100% renewable grid. That's a separate discussion to be had among engineers.

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  • [–] 2 points 6 months ago* (last edited 6 months ago) (1 child)

    Guys, Gals...hear me out: I can easily half all the numbers in your calculations: do something about the energy efficiency and get to the same per capita consumption as e.g. France and Germany.

    Boom, instant less area consumption.

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