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Comment by cogman10 | Hacker News Reader

Bike > walk == public transit > used EV > new EV > used ICE > new ICE

That's pretty much the order of "greenness" in personal transport.

New EVs will pay off their added carbon footprint in roughly 1 or 2 years in most locations. The ultimate determining factor of how fast that is the energy mix of your local power generation.

The only time it'd probably be better to continue using an ICE is if that ICE is a moped or you live in West Virginia and drive a hybrid. For pretty much all other vehicle choices, switching to an EV will be greener.

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How is biking better than walking?

New EV vs used ICE will depend on how much you drive and in what conditions. I would guess what I do (in the UK) is uncommon in the US but it must be possible but working from home plus living in a town rather than a city means I only do low single digit thousands of miles a year and that almost entirely on clear roads.

People in much of the UK commute by public transport and use their cars lightly (e.g. for shopping on the weekend, trips, etc).

Bike is the most efficient form of transportation, even walking doesn’t compare.

I want to get more exercise. Therefore I should walk rather than bike.

This is about transportation. Walking doesn't get you far. A bike uses similear energy but you get farther.

Walking covers most of my journeys for which a bike would work. I am not going to bike a hundred mile, or even 15 and back. Nor is it practical to bike to the supermarket. On the other hand its easy to walk a few minutes to the local shops and pubs.

Transportation and exercise are linked. Walking kills two birds with one stone.

> How is biking better than walking?

Glad you asked.

Biking has an energy efficiency of around 99%. Very little of the effort you put into biking ends up as waste heat. Walking, on the other hand, has a much lower energy efficiency. You are putting much more effort overcoming and generating friction as you move your legs. You are also doing it for a longer period of time since you are going slower.

It's one of my favorite counterintuitive facts.

> I would guess what I do (in the UK) is uncommon in the US

And that's for sure. In almost every US city if you want to do anything, you are driving. Where I'm at, everything is at least 10mi from my home. That racks up the miles pretty quickly.

This type of thinking is flawed. Me buying a new EV does not take my old ICE out of circulation, it just puts it in the hands of someone else. Buying less, whether that's cars or anything else, is the baseline to aim for.

My small car does 3,000 miles a year, or 300 litres of petrol a year, or about 1 ton of co2 a year.

How many co2 tons are generated in making a new Nissan leaf?

From an old forum post in 2013, the best I can find is about 15 tons.

I suspect it's much lower than that number now-a-days. Primarily because the energy going into batteries production will both use less power and likely comes from greener power sources.

If nissan is to be believed, since then they've cut the CO2 emissions from production by 40%. So maybe in the range of 9T?

Buy a used Nissan Leaf, then?

The sunk cost fallacy applies not only to dollars, but also to any quantitative phenomenon. The important thing to evaluate is the cost going forward. When you look at the cost of that new Nissan Leaf, you need to amortize the initial carbon cost over the rest of its lifetime, not just the few years you have it!

I kept my last car for almost 20 years for that reason, but parts were rusting off - the fuel tank fell off was what made me give up. At this point that car is scrap and I am in a newer car that is made no matter what, so that co2 is a given.

How on earth is Bike > Walk? Walk is > Bike.

Bike is the most efficient form of transportation, period.

Shoes have a lower environmental impact and cost than than steel, plastic, rubber tyres (which AFAIK use at least some synthetic rubber made from oil), etc. Walking does not use fuel so efficiency is not really relevant. It requires less physical extortion so is more efficient that way, but another way to phrase that is that it is less exercise.

Bikes require very little steel and the rubber tires end up lasting longer (typically) than the shoes you do.

> Walking does not use fuel so efficiency is not really relevant.

Ah, it is. You eat food, that's fuel. It's the major source of CO2 for both activities. Now, it can be insignificant. If the only food you eat is like oatmeal and beans that you grow yourself, then yeah it's going to have a non-existent impact.

However, if you have any sort of meat or imported foods, that CO2 budget can go up pretty quickly.

The actual energy for making the steel for a bike, which will outlast your children, isn't significant.

> Ah, it is. You eat food, that's fuel. It's the major source of CO2 for both activities.

That implies all exercise is a bad thing. i think you will find very few people are sufficiently keen to reduce CO2 that they will deliberately get less exercise and damage their health. I am certainly not doing that. At the moment I am trying to get more exercise.

> Bikes require very little steel

Compared to a car, certainly. Compared to shoes, an awful lot.

> a bike, which will outlast your children

The typical life span of a bike seems to be about five and ten year years. I really hope my kids last a reasonable multiple of the top end! The level of sales of cycles in the UK (well over 1 million a year) vs the number of people who cycle at least once a week (less seven million) implies a life of about five years. About half of that is leisure cyclists so not really comparable to people using transport to get somewhere.

Leisure cyclists want to get more exercise so by your argument about that being a bad thing they (and therefore half of all UK cyclists) are actively harmful.

https://road.cc/content/news/uk-cycle-sales-plummet-early-19...

https://assets.publishing.service.gov.uk/media/64e71a4f20ae8...

> another way to phrase that is that it is less exercise

Biking is less demanding on some parts of the body that only can take so much stress. So you can push other parts more if that makes sense: top cyclists can do 400-600 W sustained or 1-2 kW in short sprints. That's not less exercise, that's several times more than a walker or runner can do. So in the same time as walking you can either be faster at your destination and save time and/or energy, or go further while spending the same or less energy, or output more energy. The choice is yours.

Anyway, from the CO2 perspective, biking vs walking is splitting hairs really.

> So you can push other parts more if that makes sense: top cyclists can do 400-600 W sustained or 1-2 kW in short sprints.

Very few people are top cyclists, or top anything else. Top cyclists are doing it as a sport, not as a means of transport.

> Anyway, from the CO2 perspective, biking vs walking is splitting hairs really

I agree. I am responding to people who are claiming it is better than walking to a significant extent.

> Top cyclists are doing it as a sport, not as a means of transport.

Well you were mentioning exercise, so I reacted to that. The point is everyone biking as exercise can push more watts than when walking, if they want to.

What about the extra set of Lycra clothing you need? The extra shower you take? The razors and electricity to shave your legs? Your helmets?

Those must be US estimates involving huge mileage, because - taking your existing ICE car's production emissions as an already sunk cost - replacing an existing ICE with a new EV would over a decade of driving the average EU mileage (~10k km) before reaching emissions parity.

It takes 2-4 years of that mileage alone for a new EV to reach lifetime emissions parity with a new ICE in the EU (which I know is longer than the US due to the vast differences in average emissions per vehicle between the two continents).

For most of the world, the GP is correct. Driving whatever car you have will always be more environmentally friendly than buying a new EV. Reduce and reuse are environmental cornerstones for a reason.

People keep their cars for longer than 2 to 4 years and an EV sold in 2 to 4 years will likely be driven by someone else.

Which is why I put a used EV as being better for the environment vs a new one.

But both will be better for the environment in their lifetime than keeping a used ICE on the road.

It's more economical to keep your current car until it starts seeing major mechanical issues. However, environmentally an EV will (almost) always beat an ICE, the sooner you get one the better. Especially in a place like the EU where you can get even more environmentally friendly EVs due to the lower amounts of driving. You can, for example, grab the BYD seagull which has a 30kWh battery pack. That alone significantly reduces the new EV environmental impact beyond what some of the older numbers would have shown.

> However, environmentally an EV will (almost) always beat an ICE, the sooner you get one the better. Especially in a place like the EU where you can get even more environmentally friendly EVs due to the lower amounts of driving.

This is simply not true. A new EV will not reach emissions parity with a used ICE car in its average useful lifetime (12.5 years).

This isn't close or controversial, so I wonder what the basis for your mistaken belief otherwise is? Not even EV companies make this claim.

The payoff period for an EV is anywhere from 15,000 to 25,000mi. The moment any EV crosses that threshold, it becomes better for the environment than the ICE vehicle that you'd otherwise buy.

If your used ICE vehicle has 15 to 25,000mi in it, then yeah, replacing it with an EV today is the better choice. It's more a matter of when it will be the better choice.

This is only not true if you have very low yearly milages or a particularly efficient ICE. Which, maybe you do.

[1] https://www.politifact.com/article/2022/dec/06/carbon-dioxid...

> The payoff period for an EV is anywhere from 15,000 to 25,000mi. The moment any EV crosses that threshold, it becomes better for the environment than the ICE vehicle that you'd otherwise buy.

That's the payoff period for the carbon differential between a new EV and a new ICE, not a new EV and your existing ICE, where the carbon cost of production is already sunk. Hence why the GP commented that keeping your ICE is environmentally better than buying a new EV.

Also note that 15-25k miles is 24-40k km, or 2.4-4 years of the average annual mileage in the EU. That's to break even with a new ICE. To break even with a second hand ICE, it's on the order or 15-20 years, or effectively longer than the useful life of the EV.

> If your used ICE vehicle has 15 to 25,000mi in it, then yeah, replacing it with an EV today is the better choice. It's more a matter of when it will be the better choice.

This claim is simply false. There is no point in the lifetime of a used ICE where replacing it with a new EV will result in reduce overall emissions.

> That's to break even with a new ICE.

No, that's to break even with a new EV per the article I posted.

I'd love to see a source that says otherwise. I think you have a bad source for the CO2 emissions of new EV production.

From the ICCT, ironically under the subtitle "Addressing misuse of data in the EV debate":

> One common claim is that electric vehicles have higher emissions associated with battery manufacturing. While manufacturing emissions for battery electric cars are roughly 40% higher than for gasoline cars, the ICCT’s research shows that this initial “emissions debt” is typically offset after around 17,000 kilometers of driving, usually within the first one to two years of use in Europe.

The emissions debt is relative to a new ICE.

In cradle-to-grave emissions, electric cars are much lower than ICE cars in lifetime carbon footprint, often 50% lower.

That doesn't change the fact the replacing a used ICE with a new EV will result in increased overall emissions and increase the net carbon footprint.

> I'd love to see a source that says otherwise. I think you have a bad source for the CO2 emissions of new EV production.

This is a completely uncontroversial fact and no environmental or governmental bodies make the claim which you are putting forward, so I'd rather like to see your sources.

Source: https://theicct.org/pr-electric-cars-getting-cleaner-faster/...

So I'm looking at the given graphs in your linked article and I just don't see how you are coming up with the 12 and 20 year timeframes for payback of EVs.

Just fuzzy eyeballing (I don't see the actual numbers for the manufacturing estimated CO2, just the graph), it looks like ~10% of the lifetime emissions for a new ICE come from manufacturing. That would put the the new EV payback vs used ICE at 4 or 5 years.

At that point, it just sort of depends on how long you hold onto your ICE for.

Surely the composition of one’s local power grid factors in? There are areas where the share of renewables is much higher than the average.

It does, but single digit percentages.

I've now heard three different carbon payback estimates for an EV in the last week, and one year is by far the most optimistic of the lot.

My wife might be able to do it with the amount she commutes, but for me, working from home, it's utterly laughable.

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