NPV Economic Analysis Between EV and ICE Automobile??

[thollandpe]

If you are saying a saving of 45% (compared to ICE, and this conveniently omits the much higher up-front cost of EVs) is worthwhile, then much more worthwhile would be to get people to do most of their chores on bikes/ electric assist bikes.

Abso-fucking-lutely. You get an amen from this congregation. Our current over-reliance, over-acceptance, and over-enabling of using the single-occupant automobile for too many, too short trips is at the heart of the problem.

I rode my bike to work today but I should do it all the time. The population of my town will more than double this weekend, and while not all of those students bring cars with them, a whole lot of them do. But the biggest change in traffic will come from parents dropping kids off at the three schools between my house and work. I'm hoping that more of those folks see the theme-park-style grins plastered on my friend's and his two kids' faces as he ferries them back and forth to school in their battery-assisted bakfiets.

[darkmother]

Source-site ratio* = 1.01
Gas car energy efficiency = 1.01 * 1.51 = 1.67 kWh/mile

Thanks for doing the analysis. I'm confused by the 1.01 number. I would have expected 3, or perhaps 4.

I'm not sure what the overall thermal efficiency is for a car throughout it's use, but I *think* the peak efficiency of a gas powered ICE is less than 40%-as in to make 1kW of drive power, you produce 1.5kW of waste heat. Am I missing something?

[32x20]

I went through this recently, but like you, had pretty disparate vehicles as options. Essentially our 2018 ~100k mi F150 needed a good amount of $$ in repairs, we had a Lightning on order, and as the third option we could fix the existing gas truck and get a (cheap) Bolt. Pretty basic calculations fed the graphs below, assuming ROM maintenance costs for each vehicle option. I did a few permutations. What you see below assumes that if you keep the existing truck and drive only it, you'd get ~4 more trustworthy years, putting it at ~200k mi and requiring a replacement EV truck that's essentially a current Lightning but cheaper as competition heats up (watch me be wrong). The third vehicle would allow the gas truck to last longer, and cuts yearly maintenance costs. Maybe also worth mentioning: we have a electric cargo bike that we use a lot in the warmer seasons, but becomes pretty useless when the snow starts. We put maybe 800mi/yr on it, but for trips longer than 5ish miles one-way it's seldom used due to time crunch.

What I realized while doing this is that there are so many predictions about future costs that it's total data manipulation. How you predict maintenance costs, gas and electric price hikes, insurance costs totally change the cost data. Similarly, you could add a curve for 'greening' of the grid power sources that'd make the EVs look even better. Gas GHG emissions can be made pretty linear. I did see a few trends that really didn't change based on reasonable inputs:

1) If your existing car will be relatively reliable for awhile, it will be the cheaper option unless there are some WILD maintenance and fuel costs
2) Even factoring in manufacturing emissions for EVs (based on ROMs from a few sources) the EV breaks even after ~3-4years (for my area, not counting contributions from our solar installation). It'd happen even earlier if you did a true replacement for small, efficient EV (as opposed to a truck).
3) Total costs for operating motor vehicles is really high.

We ultimately went with fixing the gas truck and buying a Bolt. There are so many cost guesses that it comes down to what you value and want as well. The costs seemed to balance GHG emissions with capability of the vehicles and peace of mind of having an 'extra' car when/if one needs work. I also didn't want to drive a gas truck around to cart kids to school/daycare, which weighed heavily on the decision. An EV truck also seemed sort of stupid for the daily activity rounds.

Somewhat meaningless charts:

[32x20]

Thanks for doing the analysis. I'm confused by the 1.01 number. I would have expected 3, or perhaps 4.

If we're talking upstream emissions, the EPA says the factor is 1.25. https://www.epa.gov/greenvehicles/co...ectric-vehicle

They also have a calculator that'll figure total (including upstream) emissions for an EV.

[thollandpe]

Thanks for doing the analysis. I'm confused by the 1.01 number. I would have expected 3, or perhaps 4.

I'm not sure what the overall thermal efficiency is for a car throughout it's use, but I *think* the peak efficiency of a gas powered ICE is less than 40%-as in to make 1kW of drive power, you produce 1.5kW of waste heat. Am I missing something?

You're correct, the efficiency of the internal combustion engine is probably in the mid 20's, and that's reflected in the high kWh/mile number. So yeah, you have to reject a lot more energy (as heat) than what makes it to the wheels. See the chart below, the transportation sector is by far our least energy efficient, only 21%. There's certainly an opportunity there.



The 1.01 number was a swag at the source-to-site energy ratio I pulled from a building-specific guide for distillate fuel (No. 2 oil). Adding 1% for production and transport sounded low to me, and @32x20 cited a source (EPA instead of DOE) that puts it at 25%.

If we're talking upstream emissions, the EPA says the factor is 1.25. https://www.epa.gov/greenvehicles/co...ectric-vehicle

They also have a calculator that'll figure total (including upstream) emissions for an EV.

[sailor]

I’m pretty sure tco is lower on our leaf than my cargo bike. Leaf was $7000 used and is basically not depreciating, insurance is a few hundred per year and we put new tires on it. E cargo bike was $5000+ accessories, eats a chain every 1000 miles and has needed 2 tires, a pair of new wheels and a replacement frame in 8000 miles/5years. It is also probably only worth $2500 now.
I can afford to have both but the leaf is cheaper and more useful and my wife can use it but not my bike so that is an easy choice if I had to make it.

[jclay]

Who knows...hurricane Idalia might make make new transpo mandatory and the economic analysis moot! I wouldn't cry about it. Insurance? Doesn't everybody park their car underneath a dozen 100' pines during a Cat 3 hurricane?? Gosh Mr/Ms insurance adjuster, who knew there might be a problem with that?

It's in the carport....but that's no guarantee. Tomorrow will be an interesting day. Long time since we had a serious blow in Tallahassee but I'm glad to see my FSU sister Steph Abrams on the job; she and Big Jim will bring us all home safely (as Jim leans into the wind at a 45...and.... kids don't do this at home)!! The TV weather drama is fun, and a lot more fun from a distance; it is a serious storm; surfboards are in the house, not on the car! Time to hunker down. Got the beer, chips, mac'n cheese, fuel for the little generator...if the big sticks will stay vertical we're good.

Cheers!