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Comment by zapdrive | Hacker News Reader

> Petroleum for transportation currently accounts for 27% of US energy usage

> 25% * 27% = 7% more electricity

There is no relation between amount of petroleum used and amount of electricity generated in the data provided by you. All you can say is we need the equivalent amount of 7% extra of total energy used today. You did not provide any data about how much of total energy used is electricity . If electricity is 7% of total energy usage, then we need 100% extra to charge all the cars.

TLDR: your math is wrong.

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> There is no relation between amount of petroleum used and amount of electricity generated in the data provided by you.

There is.

> All you can say is we need the equivalent amount of 7% extra of total energy used today.

No.

We know how many BTU equivalent are used for electricity generation vs gasoline for transportation. And how much BTU equivalent is needed to power electric cars.

> TLDR: your math is wrong.

It probably is. Looks like transportation is 36% not 27% - that comes out to ~9% instead of ~7%.

The point still stands.

> We know how many BTU equivalent are used for electricity generation vs gasoline for transportation. And how much BTU equivalent is needed to power electric cars.

Show us the data.

> There is.

There is literally no relation.

"Cars use 27% of total energy in US. And 25% of 27% is equal to 7% of electricity generated." HOW??

I already did.

Unless you show us data on how much %age of total energy usage is electricity, there is no relation between the two!

According to some sources, electricity accounts for about 20% of total energy usage. So with your numbers, we would need extra 6.75% of total energy used. 6.75% of 20% is an extra 33.5% of electricity.

It's literally right here: https://www.eia.gov/energyexplained/us-energy-facts/

100.4q BTU total US energy usage.

37.8q BTU electricity (~37% or ~18% depending on how you count loss).

27.5q BTU transportation (~27% OR ~36% depending on how you count loss).

You're assuming that ~60% of NEW electric generation will come from fossil fuels. We won't have a ~60% loss in electric generation from solar & wind - which is currently ~90% of NEW generation. In 5 years, coal & natural gas will likely drop to ~0% of NEW generation.

So you admit your original conclusion of "we only need 25% * 27% = 7% more electricity." is wrong?

If you take energy use used for transport (27.47), multiply it by 25% (because it's more efficient), you get 6.87. That's 18% of how much we generate in electricity today (37.75), not 7%.

Ok, 25% of 27.5q BTU = ~ 7q BTU

So we need extra 7q BTU of electricity, right? Which is about 18% of 37.8!

So, not 7, not 9, we would need at least 18% extra electricity.

TLDR: Your math was wrong!

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