350htrr

Wouldn't the Prius need 1,250 gallons to travel the same miles as the bike? a ratio of 5 to1 in distance...?

cooker

Ignoring the fact that those 2,000,000 calories of food are generated using 20,000,000 calories of industrial energy. That's the amount the Prius would have access to in this comparison, and if it carries two passengers, it beats the bike on fuel efficiency.

cooker

I was responding to your suggested comparison of 20 years of riding the bike VS 1 year of driving the Prius.If you want to do a per mile comparison using the same assumption, the bike comes out ahead if there is one person in the Prius, but a Prius with two occupants is slightly more fuel efficient than two cyclists.

350htrr

OK, I couldn't go as far as I thought, I could only go 23,232 Miles on the same amount of "gas" as the Prius, that's still almost 2X farther... No?

spare_wheel

especially if you do not bother to read the link:

so once again its the word of an anonymous internet poster versus the word of a research-focused nonprofit who first reported the negative impact of generation source on e-vehicle CO2e.

with all due respect your posts here stink of cognitive dissonance.

the assumptions and false premises in that response made me smile.
i personally have zero need to drive. my preference is always to walk or bike and i have walked more miles than i have driven. my main goal in purchasing this used vehicle was to reduce the miles my partner puts on her prius.

thanks for playing.

metro2005

That was my point also.

And also dont forget that is takes roughly 260 gallons of fuel to produce a car (in the case of a prius 320 gallons) to begin with and 6 to 35 tons of CO2 depending on the car:

Manufacturing a car creates as much carbon as driving it | Environment | The Guardian

Put that against roughyl 238 kg CO2 for a bike

I see its already mentioned but if you have to compare driving a car vs riding a bike you cant ignore the fact that simply building one car has the equivalent carbon footprint of producing 25 to 147 bikes (again, depening on the car) and the amount of fuel used is the equivalent of riding your bike for 40.000km to 50.000km when you're on a high CO2 emission american diet (which is the highest in the world) :

Daily calorie intake of countries across the world revealed | Daily Mail Online

So again: its just a really strange way of calculating things when you only look at the amount of kcal burned per mile and forget that a car driver also has to eat, breathe and that the car has to be produced, scrapped and that fossil fuels also dont just come from the tap.

Another thing i also failed to see in the calculations is the amount of road that is needed for a car and a bike and also the damage cars do to roads vs damage bikes do to roads. Roads must be maintained and built which also costs a lot of CO2 emissions. as mentioned here:

https://www.slate.com/articles/health...s_vs_four.html


Same as the hummer vs prius discussion which was also ridicoulus to say the least.

cooker

Yes, using the assumptions in these messages, a bike is almost twice as fuel efficient as a Prius with one person in it.

cooker

The cyclist has to eat and breathe more when cycling than when inactive. It is that extra energy that is being estimated.

Roody

For the 7th time, the energy from the potato itself adds nothing, zero, zip, to the net carbon in the atmosphere. If the cyclist did not eat the potato, and it rotted in the field, it would emit exactly the same amount of carbon--through the process of decomposition--as if it had been eaten by the cyclist. If the cager ate the potato instead of the cyclist, again, same amount of carbon is later re-emitted into the atmosphere. If the potato burned up in a wildfire, also same carbon back into the atmosphere.

The only way to effect long-term removal of the potato's carbon is to bury it in such a way that it will turn into petroleum or coal. If this happens, the plant's carbon will be safely sequestered for incredibly long periods of time. That is, until somebody digs it up and uses it as liquid fuel to power a conventional car or as coal or natural gas to produce electricity for an electric car.

Good point. But the take-away should not be that it's better to drive an electric car than to bike. The real lesson is that the way we produce and transport food is wasteful, unsustainable, and just plain stupid. We're using a lot more carbon, and especially a lot more water, than we have any business doing. We need to take a lesson from the potato plant: use solar power, grow up not out (vertical agriculture), and grow food in places where it needs less energy and water inputs.

Roody

Read this:

https://physics.ucsd.edu/do-the-math/...pg-of-a-human/

cooker

Agreed.
Agreed.From that link:

Fly in the Ointment

Our walking or biking economies look pretty decent stacked up against cars—especially if we considered consuming foodstuff as potent as gasoline. This is all well and good until one appreciates that because of the way Americans grow, harvest, distribute, and prepare their food, every one kilocalorie of food eaten has consumed about 10 kcal of fossil fuel energy (dominated by oil).

My point is this: when advocates of cars, and especially advocates of very efficient cars, make statements about how biking uses [more/similar amounts/almost as much] fossil fuel as driving (per mile), they're actually right! However we both agree, the solution is not to drive more. Instead, we need to optimize the fuel efficiency of the bike.

Plus, energy used per mile is only one comparator, and it doesn't take into account the myriad other factors that favour the bike.

Roody

Yes.

But the article accounts for the fossil energy needed to produce and transport the food used by the cyclist. But it doesn't figure in the energy used to produce and transport the fossil fuel used by the cager. If it takes energy to grow wheat in North America and ship it to Asia, it also takes energy to mine oil in Asia, refine it, and ship it to North America. You have to count both or neither.

cooker

Those energy delivery/distribution costs are counted. It's probably not much different to deliver fuel to a private car than to a harvester or food transport truck. A lot of the energy costs were already paid when the oil or whatever was extracted, refined, shipped and so on. There might be a slight economy of scale favoring the big machines.

Roody

He says in another article that the cost of refining crude oil to gasoline is about 25%. But I don't see where he is including this cost of operating a car in his comparison. But he is including it in his estimate of the cost of food.

McBTC

True and given that a cyclist spends about 34 calories /mile -- essentially getting the equivalent of 31,000 / 34 or 911 mpg -- you'd have to turn a Prius into a clown car to match a cyclists mpg/person.

cooker

I don't know why I'm bothering, since at this point I can only conclude you are trolling, but for the benefit of anyone newly reading your post, that only works if the cyclist can eat gasoline. If he eats food, then his gasoline mileage is 1/10th of what you claim, because it takes 10 units of gasoline to produce 1 unit of food.

If the cost of refining fuel for cars is the same as refining it for tractors and transport trucks, then it washes out - if you have 31,000 kcal of refined fuel (a gallon), you can put it in your Prius and drive 50 miles, or you can give it to food industry to produce 3100 kcal of food, and use that to bike maybe 90 miles.

McBTC

2 units of ad hominem attack...? Why is anyone bothering? 34 calories /mile is essentially getting the equivalent of 31,000 / 34 or 911 mpg. Simple fact! Not to mention the fact that no Prius can run on peanut butter and jelly. "Is climate change making us stupid? I fear that the answer is yes." (Judith Curry)

wphamilton

The Devil is in the details. Trying to calculate energy costs or carbon costs is fun and I've tried my hand at it several times, but you always get to some point where the next detail is "not enough data", or else too complex with inter-related variables, or dependent on external factors.

This is where it occurs to me that energy costs, and all other production costs, are already factored in to the final consumer price. Granted there is no guarantee of a proportional factor of energy cost in the market price of a product, but if you're ultimately approximating anyway, it may be as good or better an approximation to simply use price. After all, energy cost is intrinsic in just about every product that we consume. I mean, literally, that the cost of the biscuit powering my commute, vs the cost of gas to drive, may be a better approximation of the energy cost than are these calculations.

The only way we'll truly know the answer is by imposing an energy tax or carbon tax on literally everything, every step of the way, and price that into the final product. The free market will efficiently optimize for the cheapest method of transportation, dependent on the weight given to external costs of energy used.

cooker

I agree - proper costing of non-renewable energy usage and other polluting activities, incorporating currently externalized costs, would go a long way towards eliminating abuse of the environment. The only problem is that it won't happen because nobody actually wants a free market - they all want it tilted in their direction.

McBTC

True, the energy cost of a bicycle tour down the Pacific coast from Astoria to San Francisco can be measured in Biscuits and gravy, pizzas and fried chicken livers.

cooker

Not one single ad hominem attack.

cooker

Food waste can be converted to biodiesel or ethanol, or incinerated to produce electricity.

McBTC

True and, people can drink vegetable oil, which contains nearly the same number of calories per gallon (if you look at How Fats Work you can see that fat contains long hydrogen/carbon chains just like gasoline does). ~ Is there a way to compare a human being to an engine in terms of efficiency? - HowStuffWorks

Roody

The only sane answer is--

eat more locally grown food, preferably grown without synthetic fertilizer,
eat a little less meat,
and keep on riding your bike whenever possible.

At least we didn't burn many extra calories trying to do the math!

cooker

What is the production and distribution cost of vegetable oil compared to gasoline?