Plug-in Hybrid vs. Carbon Offsets

Factual Questions
1

I’m looking for a new car and was thinking about getting a plug-in hybrid. They’re basically unavailable these days, at least in my area, and the ones on for example, Carvana, are tremendously overpriced.

At some point, I’m better off getting a regular car and giving the excess cash I would have spent to offset my carbon usage. For example, if a hybrid costs $100 million and the non-hybrid version cost $35k, I would be better off getting the normal car and spending $99,965,000 buying a big chunk of the Amazon rain forest and setting it aside or something.

In reality, I saw a used Toyota Rav-4 Prime (plug in hybrid) for $65k, which is probably around $30k more than a regular one. How much of that $30k difference would I have to spend in order to offset the extra damage from a non-plug-in car? And, how should I spend it?

More information: I live in NJ, so my power generation isn’t especially clean (probably coal or gas).

I’m happy to make simplifying assumptions, since I’m only looking for rough estimates:

Drive 12k miles per year, half of which would be all electric
Assume regular mileage is 35 mpg, electric equivalent in terms of carbon usage is 100 mpg
Keep the car for 10 years
Difference between plug in and regular is $30k, $65k vs. $35k

Leave aside carbon used in creating the two cars, environmental damage from the batteries, gas savings. I’m just interested in offsetting my excess carbon used by getting the regular vs. the plug-in.

How much do I need to set aside? And, what’s the most efficient way to spend $10k-$30k to offset my carbon usage?

2

The main theoretical benefit is that a ICE runs at varying speeds, idles putting out exhaust, etc. At very least, in stop-and-go traffic you are wasting energy turning the motor over idling. An electric car charges from a power plant running at its most efficient with minimal incomplete combustion or wasted energy.

There’s also the consideration, most of those power plants today are using natural gas. gasoline etc. are long-chain carbons (think, “octane”) so a bit more than 2 hydrogens per carbon. Natural gas is mostly methane, 4 hydrogens per carbon. So for the same amount of energy, burning natural gas produces less carbon dioxide.

Other questions - what’s the range of the vehicle on battery? Can you add some charge at work too?

My experience with a non-plugin 2008 Camry hybrid was that it micromanaged fuel consumption, used the battery to recapture braking energy, and with a smaller engine used less gas. The Camry had 1600cc, same as my 1990 Honda Civic and used the battery to aid acceleration. It turned off when it did not need to idle. Generally, I would say it got highway mileage even in stop-and-go traffic.

3

This analysis can get crazy complicated, but let’s keep it simple.

Like I said, assume I’ll drive 12k miles/year, half all-electric, the other half ICE

To simplify, let’s assume 100 mpg equivalent when driving all electric, in terms of carbon usage.

4

Substantially every new pure ICE car does this too. So not an advantage of hybrids. Or at least not much anymore.

I don’t have time now to address the rest of the OP’s question. But it is a fascinating one and I expect we’ll have some good answers in the next day or so.

5

I did some math and I think I would end up emitting an extra 9,903 kg of CO2, using my assumptions above driving the regular car vs the hybrid. Does anyone else get that?

If that’s right, how much does it cost and how would I remediate the damage caused by that amount of CO2?

6

I can do the calcs and give you numbers, but need clarifications. So :

Case 1 : Rav-4 Hybrid driven 12k miles every year over 10 years. Assume average mileage is 35 mpg.

Case 2: Rav-4 Plug in Hybrid driven 12k miles every year over 10 years. Assume 6000 miles per year driven on gas and 6000 miles per year driven on electricity. Assume Electricity comes from Coal power plant.

Calculate total CO2 emissions for Case 1 and Case 2. Also calculate how much will one spend if they were to buy CO2 credits for (Case 1 - Case 2) ?

Is the above essentially your question ?

7

Yes, but I’m happy to make the simplifying assumption that the electric miles get the equivalent of 100 mpg, in terms of carbon release (seems like a good ballpark guess - if that’s way off, LMK).

8

9,903 kg of CO2 ~ 10,000 kg of CO2 ~ 22,000 lb of CO2

1000 lb CO2 offset costs about $8. So 22,000 will cost 22*8 = $176 and over 10 years it will $1,760

9

I did not do the calc, since you provided the final CO2 numbers. But I did convert them to $ figures. Hope that helped

10

I think you’re double counting the 10 years – my calculation was meant to be over the whole ten years.

I would love for someone else to do the math, and if I’m way off in any other assumptions, I’m interested.

If it’s really something like $176, or even ten times that amount, then these hybrid cars are a boondoggle. I must have done something wrong.

11

I repeated the calcs for you:
A typical passenger vehicle emits about 4.6 metric tons of carbon dioxide per year. This assumes the average gasoline vehicle on the road today has a fuel economy of about 22.0 miles per gallon and drives around 11,500 miles per year. Greenhouse Gas Emissions from a Typical Passenger Vehicle | US EPA.

4.6 Metric tons @ 22 MPG and 11,500 miles per year

or

4.8 Metric tons @ 22 MPG and 12,000 miles per year

Case 1

3 Metric tons @ 35 MPG and 12,000 miles per year

Case 2
1.5 Metric tons @ 35 MPG and 6,000 miles
0.53 Metric tons @ 100 MPG and 6,000 miles

Total
2 Metric tons

Difference in Case 1 and Case 2
3 - 2 = 1 Metric tons = 2200 lbs
1000 lbs of CO2 offsets costs $8,
2200 lbs of CO2 offsets costs ~ $18
Over 10 years, it costs $180

The assumption here is that the CO2 offsets are scalable and the cost will remain the same when the demand goes up which is not true.

12

This is stunning to me. Are there predictions for how the cost will increase with scale? If they were 100x the cost, I’d still be ahead if I bought the gas car and sent $18k to buy offsets.

So, do you know of the offsets will be 5x,10x, something else, in the future?

The other part of my question is, what’s the best way to pay offset my additional carbon usage?

13

One problem is that carbon offsets are, frankly, bullshit. I’m skeptical of the idea that you can plant a thousand tiny little saplings to offset some amount of carbon thrown into the atmosphere. For one thing, very few of those saplings are going to ever become substantial trees. John Oliver covered this subject in his show about a month ago; see here for the video.

14

Apparently, you can pay to have carbon removed from the atmosphere and buried, and that’s like $1,200/ton. I could still buy a regular car and send $12k to have carbon buried and come out ahead.

15

Only if you drive very, very little; Googling, “A typical passenger vehicle emits about 4.6 metric tons of carbon dioxide per year.” So your $12,000 covers only two years of typical passenger car driving.

16

I did the math up top, but I certainly could have it wrong. And, I’m comparing a plug-in hybrid with a non-hybrid.

Using my assumptions, I think I would emit about 9,900 more kilograms of CO2 using a regular car than using a plug-in, over 10 years.

17

But isn’t the “100mpg” rating assuming a mix of gas operation and battery? Pure battery would use no gas, so a 50-50 use would be 6,000 miles electric only, 6,000 miles battery. And anywhere where there is nuclear power or hydroelectric (i.e. not NJ?), the calculations are even more different.

but this:

Renewables, mostly solar energy, at both utility- and small-scale facilities accounted for about 8% of New Jersey’s total in-state electricity generation in 2020, about double the 2015 share. Coal generated less than 1.5% of the state’s utility-scale net generation from coal, about half its share from 2015. There are two coal-fired power plants left in the state, one of which is scheduled to shut down in 2024.50,51

Yes, my BMW does this - but when the AC or the heat is needed while stopped, it turns back on and idles for a while. Unless it’s moderate out, it will only last about half a red light cycle before starting. My Tesla just uses battery for either.

18

No, I’m saying that using the car in all-electric mode emits carbon, unless the electricity is generated all by renewables (which it isn’t in NJ, as you show).

I think I’ve read that electric vehicles get about 100 mpg equivalent in energy usage, so I used that as a round number.

19

New Jersey’s electrical sources emit 0.537 lbs/kWh:

A reasonable ballpark number for EVs is 4 mi/kWh, so the EV would be emitting ~0.13 lbs CO2/mi.

In comparison, a gallon of gas emits 20 lbs CO2 when burned. That’s 0.57 lbs CO2/mi, so >4x worse.

However, it’s worse than that. The gallon of gas took about 7 kWh just to refine. Including that, it’s more like 0.68 lbs CO2/mi, or >5x worse.

Assuming 120k miles over the lifetime, that’s 66k lbs extra CO2 for the non-PHEV. If capture costs $1200/ton, that’s $39.6k in extra lifetime costs.

The number goes down the less you depend on the plug-in miles. But it’s pretty much linear. If half your miles are electric, then it’s still around $20k in capture costs.