Are we all ready to go to electric cars (Fermi problem)
I myself am trying to be somewhere in the middle between the "global conspirators" and our "fighters for the environment", because I believe that the truth is somewhere there ...
Recently there was Earth Day and, after reading a little on Wikipedia about the Earth Hour and, especially, the Critic section, I got to an interesting article by Konstantin Ranks, How the struggle against global warming harms the environment . It states that the modern capacity of cars is 37 times the power of all the power plants in the world. It’s not said where the data for these calculations come from. Wanting to check yourself, but how? Googling for raw data? It is possible, but long, unreliable and boring. There is another way, no less interesting!
Somehow at school in “Quantum” I read an article about Fermi's problems and its classic example about the number of rubber molecules erased in one revolution of the wheel. So I wanted to try to apply the same method and “estimate” the numbers in our case.
Most likely, I did not take into account many facts that you would later indicate in the comments, but, as I wrote above, we will find the truth somewhere in the middle ...
As usual in these tasks, only the question is given in the condition, but we are looking for the initial data ourselves. Input data:
Imagine that we can and want to transfer ALL the cars of the earth to electricity. We need to evaluate this possibility by comparing the current power consumption of all vehicles with the current provided power of all power plants .
')
So how many cars do we have? As in the example above, I converged on the value of 1 billion, because we only need order, and we can safely say that there are fewer machines than 10 billion, but more than 100 million.
N a = 10 9
And what is the power of one car? Here I am even less strong ... But I understand that it is somewhere in the range of 50 hp. (subcompacts) up to 500 hp (sports cars), with a mathematical expectation somewhere around 100:
w a = 100 hp ≈ 73 kW ≈ 100 kW (again round up to order).
Thus, the total power consumption of all cars at the same time:
W a = N a × w a = 10 9 × 100 kW = 10 11 kW.
But this is the “peak” load, but what is the effective power, namely how many cars drive per day? I suggested that 1/10 of the day (~ 2.5 hours). As before, I was guided by the reasoning that 1 day is too much, and 1/100 days (15 minutes) is too little!
Hence, the total effective power consumption of all cars:
W eff = W a / 10 = 10 10 kW
The article by Konstantin Ranks gives the number of 2 billion kilowatts. Let's try to estimate.
We come out of the fact that we produce exactly as much energy as we consume, because we do not accumulate it anywhere and do not “drain it” (at least, again, within the limits of “orders”).
The biggest difficulty in this calculation - I can not estimate how much the industry consumes. In various articles they write that the population consumes not something more than industry, or less. Where is the truth here - I do not know. Common sense dictates that industry consumes more. First, let's estimate how much the population consumes.
The population of the land is N l = 7 ∙ 10 9 . As in the case of cars, we estimate the effective population of the earth, i.e. one that consumes energy. Having thrown out half of India, half of China, almost all of Africa, I decided 30% of Latin America that ~ 3-5 billion people use electricity “efficiently” (so far I don’t round up the mantissa, it will be clear why).
Now how they use. Take a simple example: my family of 4 people (2 children) consumes ~ 100 kW h per month (in short: 10 are few, 1000 are many). It does not even matter 2 or 4 people in the family - the order does not change! Therefore, we assume that for every 3 people on earth there are 100 kWh per month. So in a month we all consume / produce:
E month = 100 kW ∙ h / 3 × 3 ∙ 10 9 = 10 11 kW ∙ h / month (this is why I left the mantissa in the population).
In the month of 720 hours. From here we find the total capacity of power plants:
W es = 10 11/720 ≈ 10 8 kW
So, that all moved to electric cars:
we need - 10 10 kW
now we can - 10 8 kW
lack of power - ~ 100 times !
Thus, the method of solving Fermi problems clearly shows us that, despite all the ecologists' cries, we are still clearly not ready to absolutely transplant everyone at once to electric cars. Where do you get the missing 2 power orders? At what speed do we now need to burn fuel oil / coal / gas, split atoms, how many rivers do we need to block with dikes to ensure our environmentally friendly machines? And let's not forget that we now need to increase by several times the cross-sectional area of the main transmission lines, and which transformers should now be at substations, I can’t even imagine. How much more aluminum / copper should be smelted? For the time being, I haven’t even tried to give an answer to these questions, but I already doubt very much that global electrification will improve the ecological situation!
Next time we will try to estimate how much land you need to cover with solar panels or wind turbines to satisfy, again, our electricity needs.
Recently there was Earth Day and, after reading a little on Wikipedia about the Earth Hour and, especially, the Critic section, I got to an interesting article by Konstantin Ranks, How the struggle against global warming harms the environment . It states that the modern capacity of cars is 37 times the power of all the power plants in the world. It’s not said where the data for these calculations come from. Wanting to check yourself, but how? Googling for raw data? It is possible, but long, unreliable and boring. There is another way, no less interesting!
Somehow at school in “Quantum” I read an article about Fermi's problems and its classic example about the number of rubber molecules erased in one revolution of the wheel. So I wanted to try to apply the same method and “estimate” the numbers in our case.
Most likely, I did not take into account many facts that you would later indicate in the comments, but, as I wrote above, we will find the truth somewhere in the middle ...
Formulation of the condition and solution of the problem
As usual in these tasks, only the question is given in the condition, but we are looking for the initial data ourselves. Input data:
Imagine that we can and want to transfer ALL the cars of the earth to electricity. We need to evaluate this possibility by comparing the current power consumption of all vehicles with the current provided power of all power plants .
')
Search for source data
How much do we need
So how many cars do we have? As in the example above, I converged on the value of 1 billion, because we only need order, and we can safely say that there are fewer machines than 10 billion, but more than 100 million.
N a = 10 9
And what is the power of one car? Here I am even less strong ... But I understand that it is somewhere in the range of 50 hp. (subcompacts) up to 500 hp (sports cars), with a mathematical expectation somewhere around 100:
w a = 100 hp ≈ 73 kW ≈ 100 kW (again round up to order).
Thus, the total power consumption of all cars at the same time:
W a = N a × w a = 10 9 × 100 kW = 10 11 kW.
But this is the “peak” load, but what is the effective power, namely how many cars drive per day? I suggested that 1/10 of the day (~ 2.5 hours). As before, I was guided by the reasoning that 1 day is too much, and 1/100 days (15 minutes) is too little!
Hence, the total effective power consumption of all cars:
W eff = W a / 10 = 10 10 kW
How much can we give now
The article by Konstantin Ranks gives the number of 2 billion kilowatts. Let's try to estimate.
We come out of the fact that we produce exactly as much energy as we consume, because we do not accumulate it anywhere and do not “drain it” (at least, again, within the limits of “orders”).
The biggest difficulty in this calculation - I can not estimate how much the industry consumes. In various articles they write that the population consumes not something more than industry, or less. Where is the truth here - I do not know. Common sense dictates that industry consumes more. First, let's estimate how much the population consumes.
The population of the land is N l = 7 ∙ 10 9 . As in the case of cars, we estimate the effective population of the earth, i.e. one that consumes energy. Having thrown out half of India, half of China, almost all of Africa, I decided 30% of Latin America that ~ 3-5 billion people use electricity “efficiently” (so far I don’t round up the mantissa, it will be clear why).
Now how they use. Take a simple example: my family of 4 people (2 children) consumes ~ 100 kW h per month (in short: 10 are few, 1000 are many). It does not even matter 2 or 4 people in the family - the order does not change! Therefore, we assume that for every 3 people on earth there are 100 kWh per month. So in a month we all consume / produce:
E month = 100 kW ∙ h / 3 × 3 ∙ 10 9 = 10 11 kW ∙ h / month (this is why I left the mantissa in the population).
In the month of 720 hours. From here we find the total capacity of power plants:
W es = 10 11/720 ≈ 10 8 kW
Result
So, that all moved to electric cars:
we need - 10 10 kW
now we can - 10 8 kW
lack of power - ~ 100 times !
What was not taken into account:
- all industrial and military transport equipment (and it is unlikely that they will be so quickly transferred to electrical supply with their capacity). Honestly, I do not even venture to judge whether they are changing the order, but it can definitely be stated that they only “aggravate” the situation.
- industrial energy consumption. I do not know how to take it into account and is it worth it? The calculation was taken cars of the population and the amount of electricity produced for the population. Even if we take into account that the actual capacity of power plants is more than 10 times, we still will not be able to "take" this power from industry in favor of the population.
- Engine efficiency. Almost no effect (uniquely more than 0.1 and less than 1)
findings
Thus, the method of solving Fermi problems clearly shows us that, despite all the ecologists' cries, we are still clearly not ready to absolutely transplant everyone at once to electric cars. Where do you get the missing 2 power orders? At what speed do we now need to burn fuel oil / coal / gas, split atoms, how many rivers do we need to block with dikes to ensure our environmentally friendly machines? And let's not forget that we now need to increase by several times the cross-sectional area of the main transmission lines, and which transformers should now be at substations, I can’t even imagine. How much more aluminum / copper should be smelted? For the time being, I haven’t even tried to give an answer to these questions, but I already doubt very much that global electrification will improve the ecological situation!
Next time we will try to estimate how much land you need to cover with solar panels or wind turbines to satisfy, again, our electricity needs.
What I did NOT try to reveal in this article:
- elements of a global conspiracy. Let's skip this in the comments;
- neither refute nor confirm the calculations of Konstantin Ranks. Although the answers are close;
- neither prove nor disprove the extreme necessity / harmfulness of environmental energy technologies. I think the truth is somewhere in the middle ...
Source: https://habr.com/ru/post/177621/
All Articles