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Comment by ars | Hacker News Reader

Honestly there isn't much you can do. Most pollution is industrial, and most industrial pollution is not in the US.

Recycling just causes more pollution, so that doesn't help. You can turn lights off and install CFL's, but the difference is tiny.

Riding a bike vs driving actually causes more pollution (because farms make lots of pollution) [unless you replace exercise you anyway do with bike riding].

Coal burning in China is so bad that anything you can do is so utterly dwarfed by it as to almost be pointless.

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"Riding a bike vs driving actually causes more pollution (because farms make lots of pollution) [unless you replace exercise you anyway do with bike riding]."

That is totally nonsense. You simply invented that nonsense.

Let's put some numbers in : My bike weights 15kg, my body 85. So I move around 100kg with my bike. My small Toyota weights naked 1500kg, so I am moving 1700kg around(including my weight and gas or fuel as we call it).

1700/100 = 17 times more weight.

I move around at 30km/h max speed with my bike, normally around 15 or so. With my car it is over 80km/h.

The resistance f the air is proportional to the square of the velocity so we are using over 28 times more energy per kg(as velocity resistance surpasses rolling resistance by far).

So that's it :28x17 = 476 times more energy

So let's consider half of that because velocity resistance is going to be similar to rolling resistance somewhere in the middle, that's over 200 times more energy, but then you have to add the car shape that exposes way more than 5 times my surface on the bike to wind.

Farms don't make lots of pollution, and their pollution is natural, My grandpas had a farm. Dung is not the same kind of pollution than mercury or exotic organic compounds in the car's paint, or in the car's polymers, or in diesel exhaust.

Lots of numbers and you ignored the only two important ones because it doesn't fit with your preconceived notion.

1: The efficiency of converting that energy into motion. A car is MUCH MUCH more efficient than a person.

2: The amount of energy from diesel needed to grow those food calories in the first place. Again, a car comes out way way ahead.

> Farms don't make lots of pollution, and their pollution is natural, My grandpas had a farm .... not the same kind of pollution .... in diesel exhaust.

A farm with no tractor. Interesting. Maybe in your grandpas day, but certainly not today. Farms use a TON of diesel to grow that food.

If both of those were correct, it would cost more to cycle 10 miles every day than it would cost to drive 10 miles every day. It doesn't, therefore your points are wrong.

Except it does actually cost more to cycle. You just don't notice because when you buy food it doesn't have a label saying where you used those calories.

It does depend on what you choose to eat though. If you eat beans vs burgers. The cheap food comes close enough to driving to not matter, but most people eat nicer food and then it's more expensive to bicycle.

No it doesn't I used to cycle over 16 miles day and I did not eat any more food - I just lost weight which made me healthier.

I'm sorry, but this is crazy science.

Looking at kilojoules and efficiency of energy, a bicycle is much more efficient on the order of hundreds, just looking at mechanical resistance and the energy needed to get the vehicle moving.

Also, while competitive/fast cycling requires large amounts of food to sustain, the extra fuel needed to commute by bike doesn't require much more than an extra handful of almonds or in my case, an extra beer in the evening.

The human body gets more efficient at a given exercise over time –– that's why calories-in/calories-out is never an equal proposition in a trained athlete (and regular bike commuting is in some ways "training.")

If you break it down into prices, bike commuting might cost an extra $1-$2 in food per day. OK, fine. However, that mitigates the $3-4 in fuel cost for mileage over a 20 mile commute. Maintenance costs on a bike are negligible compared to a car: $100 in chains, cassettes and brake pads annually vs. the $1,000-2,000 in usual car maintenance costs per year (PLUS, repairs).

As for environmental costs: yes a bike requires carbon to build and transport across the Pacific. But the heavy huffing-and-puffing C02 contributions of a cyclist is negligible to that of a car.

> Except it does actually cost more to cycle.

No, this is plainly wrong.

Don't take my word for it, work out the cost per mile for yourself. You'll quickly see that you have to choose ridiculously low car costs vs expensive, low calorie foods to get it remotely close. With average car prices vs cheap food...it isn't even a contest.

Lets look at a model. You are making the claim, so you provide the cited numbers to fill it in.

To begin with - lets assume all joules are equally polluting. This isn't true, but we'll get to that.

Jp = the number of joules needed to move a person a distance.

Je = the number of joules needed to deliver Jp to the point of use.

Jt = the total number of joules for a mode of transport

Simply:

Jt = Jp + Je

Therefore a first approximation is to compare Jt(bike) with Jt(car)

However there are other factors that must be accounted for in this equation:

Jm - the total number of joules needed to manufacture the transport (full supply chain), and deliver it to first point of use.

Jl - the number of joules needed by a person anyway - farming can't just be eliminated, people require food to remain people. (Jl stands for joule's life)

Jl' - the number of joules needed to transport the minimal "keep people living" joules to point of use.

It should be noted, that Je and Jl' are related in the bike case, so Je in the bike case will only be the extra energy required to deliver additional food, not the energy required if the Je for a bike were delivered in an entirely separate manner. With Je for a car - the energy source, energy delivery etc are an entirely different infrastructure.

So factoring those in we get:

Jt = Jp + Je + Jm + Jl + Jl'

Of course - at the beginning I mentioned not all joules are created equal. So we need some sort of pollution index. I don't know a simple polution index formula, but assuming it exists, we will call it P. The output will be a normalized value that can be simply added to understand total polution. So:

P(Jt)= P(Jp) + P(Je) + P(Jm) + P(Jl) + P(Jl')

I want to note about the pollution function - the pollution of P(Jp) is essentially 0 in the bike case, because it is just metabolism. P(Jl) will most always be close 0, because it is metabolism again. The polution from delivery is captured in other variables.

This model could be further refined into pollution per travelled km, rather than the pollution per joule used. It could be better refined by including the Jm costs as an amortization of efficiency over the total number of travelled km. Etc. But for now, the model as stands is a good way of determining the claims first order validity.

What kind of silly propaganda made you read where biking causes more pollution than driving?! btw, if you look at CO2 emission and greenhouse gas emission, you'll find that USA and CHINA are pretty much tete a tete: http://en.wikipedia.org/wiki/List_of_countries_by_carbon_dio... http://en.wikipedia.org/wiki/List_of_countries_by_greenhouse...

Obviously, emission pro-capita is quite different. So, yes, the low hanging fruit it in your living room pretty much.

> What kind of silly propaganda made you read where biking causes more pollution than driving?

Do the math. It's quite clear. You don't realize just how much fuel (diesel) farms use to grow that food, and then your body is not as efficient at converting the food into motion. It's a double whammy and you end up with cars being more efficient than bicycles.

> Obviously, emission pro-capita is quite different.

Yes. Obviously. And since this article is talking about pollution why would you even look at CO2 numbers?

I commute 30km a day, consuming around 600 kcalories (it's about (0.1 calories per kg per minute for a 70kg adult going 25kmh). Driving would cost me about 21000 kcal (0.7 gallons a day, that is 0.7 * 31000 kcal in a gallon of diesel). So my car is about 36 times less efficient than me.

Do yourself a favour and stop watching fox news.

@ars: You're not doing the math. You're just repeating the same claim, which seems wrong, and probably is wrong. You should certainly not be surprised that you're not convincing anyone. And saying "It's quite clear" is really rich, because, of course, it is not clear at all.

I think the best rebuttal has to do with the cost. The cost of buying, fueling, and maintaining a car is much greater than that of a bicycle plus the incremental food cost for the rider.

Additionally, @wes-exp has pointed to figures (just concerning MPG equivalent, not counting buying and maintaining) that have bicycles much more efficient than cars.

According to this calculator http://bicycleuniverse.info/transpo/energy.html

A 155 lb. cyclist gets about 75mpg equivalent, factoring in a typical diet. The vegan gets 145mpg. The site also claims that even with an all-beef diet, cycling is more efficient than driving.

A physics professor (http://physics.ucsd.edu/do-the-math/2011/11/mpg-of-a-human/) gets similar results: factoring in the carbon footprint of extra food consumed, biking comes in at roughly 70–130 MPG.

Even these analyses don't seem to include the embodied energy it takes to manufacture a car, which is huge and should be considered a tax on every mile driven. Bicycle manufacturing is obviously much less energy-intensive.

> Riding a bike vs driving actually causes more pollution (because farms make lots of pollution) [unless you replace exercise you anyway do with bike riding].

Can you explain or provide a reference? Are you suggesting that because you consume more calories if you exercise, and your food comes from farms, the extra farm pollution is worse than what your car would have produced?

Yes, and because your body is much less efficient at converting that energy into motion than a car is.

This assumes that you will eat more from the exercise--many Americans eat more than they need to, and doing something for your health makes you more conscious of that.

I know. I said that explicitly in my original message - if you are bicycling as your form of exercise then this doesn't apply.

It's only if you are bicycling extra - then you end up eating more.

Emissions per capita in China are well under half of those in the US so something doesn't add up about your post.

Emissions of pollution or emissions of CO2?

Plus China has a LOT of people, and a TON of them are rural and very poor - it's not exactly the preferred way to reduce emissions (of any kind).

I think the point is, China isn't the one that needs to reduce, it is the US.

Nope. China.

The only reason China has reasonably good numbers is that most of their population lives in miserable poverty.

Regardless, it should be measured on per capita, and China are WAY a head. So you are arguing to measure different countries in different ways. This seems inherently unfair.

C02 per capita, China: 5.77 tons

CO2 per capita, US: 17.28 tons

Population, China: 1,334 million

Population, US: 313 million

Total CO2 emissions, China: 7.754 million tons

Total CO2 emissions, US: 5.408 million tons

(Source: Google queries).

Note that this is CO2 emissions, where the article is discussion particulates. Given emissions controls (or lack thereof), China's going to be emitting far more particulate matter than the US. Factor in prevailing westerly winds and the lack of coal-burning facilities in California, and most particulate matter will come from elsewhere. Note too that long-range particulates are more likely to be small, which is to say, more harmful to health.

China's coal consumption has been growing dramatically (it's roughly paralleled, and I'd argue, fed, its industrial and GDP growth), so that China has surpassed the US within recent years on total (though not per-capita) emissions. It's on track for the latter. You can also argue that China uses much of its coal (about 40%) for industrial uses, and exports much of that manufacture, so that the US and other importers of Chinese products have essentially outsourced not only jobs but carbon emissions and pollution.

As for personal action to reduce CO2 emissions: lighting is actually pretty good low-hanging fruit. Dittos reducing your transportation usage (or sharing rides). And especially air travel. Huge contributor there.

Who cares about CO2? (There is a serious obsession with CO2 in the world right now.)

Pollution is the problem here. And it's a real bad problem.

> And especially air travel. Huge contributor there.

Sigh. OK, lets talk about CO2: http://www.travelmatters.org/calculator/individual/methodolo...

Airplanes produce less CO2 per passenger mile than buses. And far less than cars.

And if you do want to talk about CO2, how about CO2 per GDP? After all we can't keep the entire world in poverty in order to reduce CO2. In that measure the US is much better than China.

As I've said elsewhere, the only reason China has low numbers is because of the human misery of their poor population.

Who cares about CO2?

I do. Among other things.

Airplanes produce less CO2 per passenger mile than buses.

Airplanes are used to travel much further distances than buses. And by reducing the marginal cost of that travel, greatly increase the total amount traveled. So while a typical daily motor vehicle trip is on the order of 35 miles (based on average annual miles driven in the US), air flights are typically 10-100 times that (300-3000) or more. And with take-off and altitude gain, short-haul flights are relatively less efficient than long-haul. The per-trip CO2 emissions are thus vastly higher -- you're dividing by 2-4, but multiplying by 10-100.

Additionally, many of the modes listed on your reference can substitute electricity (which can be generated from non-fossil sources). Heavier-than-air travel pretty much doesn't exist without fossil fuels: liquid hydrocarbons are simply too dense, cheap, and versatile a fuel and energy carrier. The maths on biofuels simply don't work out, except at very low fractions of existing fossil fuel use. Substituting 10% of present oil consumption biofuels might be possible), but with an effective cost of $600/barrel or more, and that 10% would have to supply portable, emergency, and defense, as well as commercial aviation needs. I see lighter-than-air craft as more viable in a not too distant future.

And if you do want to talk about CO2, how about CO2 per GDP?

That works out roughly to the amount of fossil fuels used per unit GDP, though it varies based on fuel source (which I don't factor in). I used Wolfram-Alpha to look up GDP per quadrillion BTUs a couple months back:

For China & India, it's about $60b/quad.

http://www.wolframalpha.com/input/?i=china+GDP+%2F+%28total+...

http://www.wolframalpha.com/input/?i=india+GDP+%2F+%28total+...

And for comparison, the United States -- we use far more energy, but use it far more efficiently as well at $150b/quad: http://www.wolframalpha.com/input/?i=United+States++GDP+%2F+... But nothing like the Swiss at just a hair under $400b/quad: http://www.wolframalpha.com/input/?i=Switzerland+GDP+%2F+%28...

Italy shows in at ~$275b, Germany ~200 (plot's a bit wonky), UK ~$250b/quad, Spain ~$240b/quad, Japan ~$250b/quad, Russia ~$40b/quad.

Incidentally, growth in GDP and energy use for China & India:

http://www.wolframalpha.com/input/?i=china+total+primary+ene...

http://www.wolframalpha.com/input/?i=india+total+primary+ene...

After all we can't keep the entire world in poverty in order to reduce CO2.

I see no real choice in the matter. GDP's going to get tanked one way or othe other (climate change, peak oil, peak everything). We're on an unsustainable path. Not cutting carbon emissions is going to be rather markedly worse than cutting them, in the long run (though next quarter's profits will take a hit in the latter case but not former). And we're going to have to learn to get by on vastly fewer fossil fuels as well.

As I've said elsewhere, the only reason China has low numbers is because of the human misery of their poor population.

Given their present energy mix, yes. However if they were to pursue renewables to a maximum extent, you might be proven wrong (I've got some doubts on the feasibility of this as well, but given other alternatives, it's really the only option we've got).

"Riding a bike vs driving actually causes more pollution (because farms make lots of pollution) [unless you replace exercise you anyway do with bike riding]."

This is a very interesting point, do you have some numbers to back that claim? Food production costs, car production, oil production etc.?

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