Hacker News Reader

Comment by perl4ever | Hacker News Reader

But maybe 50 kWh a day is embodied in the manufacturing/depreciation of the car, I'd estimate.

Where does your estimate of 50 kWh per day come from? According to [1], Tesla's 2017 manufacturing and delivery released 186000 metric tons of CO2, most of that "indirect" (as in at their suppliers). (146000 for "Facilities" and 39000 for Sales, Service, and Delivery.) According to [2], they delivered 101312 vehicles in the same period. That is 1.8 metric tons of CO2 per delivered car. Your rate of conversion between kWh and metric ton of CO2 may vary, but the US average is about .99 lbs/kWh [3] or 3640 kWh per car. If we assume a car lasts 10 years, that is about 1 kWh/day. Also these numbers are from back when the made almost entirely Model S and X, so it is probably with a 3-filled fleet.

[1] https://www.tesla.com/ns_videos/tesla-impact-report-2019.pdf , page 16

[2] https://ir.tesla.com/news-releases/news-release-details/tesl...

[3] https://www.eia.gov/tools/faqs/faq.php?id=74&t=11

I was assuming a car that cost $30K and lasted 15 years.

The parent seemed to be talking about cars in general, so I wasn't referring to Teslas in particular.

I can try this again using some different sources and methods.

- GDP of $1000 equates to about 1540 pounds CO2.[1]

- Each pound of CO2 implies about a kWh based on average power generation intensity.[2]

- Therefore, a $30K car implies 30 x 1540 or about 46,200 kWh.

- Divided by 15 years and by 365 days gives about 8.5 kWh per day.

So, I was probably off by a lot, and may still be off, but I feel like my point is intact, because 8.5 kWh still almost doubles the energy requirement originally stated. It's not negligible.

[1]https://en.wikipedia.org/wiki/Emission_intensity

[2]https://www.eia.gov/tools/faqs/faq.php?id=74&t=11

I see. For a regular gas car, the 4 miles per kWh is wildly optimistic -- 134 miles per gallon. The kWh per mile (just from tank to wheels) would be something like 4 times higher than that. (1 kWh per mile = 33 miles per gallon). So that 8.5 kWh per day from manufacturing would be on top of something like 41 kWh per day of driving, not the 10.3 from the post up there.

Sure, I get kind of lost trying to figure out what you are saying when you're addressing me about someone else's comments that neither of us may fully understand the thinking behind.

However you look at it, Tesla or not, 10 kWh leaves out a lot which was my original point.

Cars last far longer than 15 years on average. For the average car in the US to be almost 12 years old means they must last on average about 25 years as the rate of car production has been increasing.

Secondly, GDP to CO2 figures are a poor fit. Agriculture for example is directly 10% of US CO2 emissions but only 5.4% of GDP.

I think 15 years is a good estimate.

First thing that comes up when I Google:

"While an average lifespan of vehicles is not given in the IHS report, a 2014 Automotive News article stated that, at that time, the peak lifespan or “scrapping age” of a vehicle was 13 to 17 years old"

Scrapping age relates to when the car is no longer worth repairing after an accident. In the US many cars also get exported when their not worth keeping in used car lots. Still a huge number of older cars are on the road and many of them are far older than 25 years.

From 2014: https://www.nbcnews.com/business/autos/old-clunkers-rule-roa...

How many of these "pre-'99" models are still around? 53.3 million.

76000kwh at 50kwh/day is about 1500 days, or 4+ years.

https://blogs.nicholas.duke.edu/citizenscientist/embodied-en...

The average car is a smidge under 12 years old, which is about 17kWh/day.

I was assuming 15 years, but I was also assuming too high an energy intensity; please see my other follow-up.

Reply on news.ycombinator.com