Living Car Free - Hydrogen and Pollutions Questions

I have a friend who thinks that cars produce only .5% of the pollution in this world. I tried searching the net, but then remembered there are a lot of smart people on this board! Can anyone help me with this? I think .5% is absurd... its got to be more than this...


Also, I was wondering what your thoughts on Hydrogen Fuel is? I have a co-worker who is always talking about it. He gave me links to read about it, but I would rather hear any thoughts on the subject by you guys.

The thing is, I'd love everyone to screw the automobile and just walk and bike places. But it just seems like a HUGE goal.... and one that probably will never happen. I personally like living close to stores/work/etc. I don't even want to be in a place where I have to drive far... now that I realize how much I love non-car related forms of transportation.

But for the rest of the population that doesn't do this.... who are contributing to Global Warming... who are ****ing all of US car-free people over...for their own selfish benefit (sorry it makes me mad)....

Maybe we just need to focus on car-free living...designing cities and living places differently...and encouraging people to not drive.... but not just this... but also focusing considerably on developing alternative fuels, like possibly hydrogen.... because I really don't think everyone is going to ditch the car.... and our ****ing planet is depending on us.

When you said "hydrogen and pollutions," I thought you might be quoting that guy (http://www.whitehouse.gov/president/) who was talking about the internets that time... :p

Take a look at this (http://www.nrdc.org/air/pollution/benchmarking/default.asp), there's a spreadsheet that tabulates all emissions from power generation across the States. Making the (probably inaccurate) assumption that the average EPA pollution for an automobile in the US is 5, considering the average driver goes 10,000 miles per year, and we have ~130 million cars, you can tabulate how much of each pollutant cars contribute, going off of these (http://www.epa.gov/autoemissions/rating.htm) figures.

Hydrogen isn't a fuel in the conventional sense. We don't mine, or collect it, we produce it. It's an energy carrier, like a chemical battery, or mechanical flywheel. We have to use some process to create energy, and use hydrogen to transport it. So, we must get the hydrogen from some sort of power generation, be it solar electric, wind, nuclear, coal, NG, hydro electric, gerbils running in a wheel, etc...
The efficiency of hydrogen then depends on the efficiency of the energy we're using, the efficiency of the conversion process, and the efficiency of the system that uses the hydrogen. Imho it reminds me of refining crude, versus burning straight VO. It can be done, but it just adds complications and makes the whole process outside the reach of the average person. Which is why I think it's done. A business that can easily be done by everyone won't be in business for very long. The same goes for electric cars, which can be charged at home with the use of a solar or wind based electric setup and some storage capacity (batteries). Why use electricity directly and efficiently when we can convert the energy to other forms, encouraging consumption, increasing profit, and locking the consumer out of the production market?

The tricky thing about bikes is that while they may get infinite mpg, as is observed on some shirts, humans don't. Our food supply needs a lot of fossil fuel use, something like 10 calories of fossil fuels for every one calorie of food produced (not shipped or stocked) in the average diet. Meats are the most inefficient, and bagged unprocessed vegetation like potatoes or wheat are the most efficient. Taking this into context, the most efficient passenger vehicles available today gets ~80mpg in the EPA combined cycle, and close to 100mpg cruising at 55mph. An approximation of how efficient a cyclist is can be found here (http://auto.howstuffworks.com/question527.htm). The 912mpg figure is impressive, but since every calorie of food requires ~10 of fossil fuels, it's the equivalent of ~90mpg assuming an average diet. Not to mention, the car is traveling at ~55mph, while the cyclist is moving at ~15mph, so the energy efficiency of the car is much, much better than that of the cyclist.

Otoh, potatoes use .5 calories of fossil fuels per calorie of potatoe. They are second only to oats in energy efficiency (.4 calories). Of course this only refers to *growing the food, not collecting, processing, shipping, and disributing it. Which all require fossil fuel inputs. The 10 to 1 ratio I included earlier does not seem to include the energy required to transport and stock the items on store shelves, so it is likely higher. In the case of potatoes, one pound contains 288 calories according to the USDA, and a bag I have contains 10lbs of potatoes. A reasonable guestimate has ~50 bags of potatoes per wooden shipping container, and 20-32 containers per semi truck, depending on whether the trailer is a pup or longbox. These potatoes came from Winemucca Nevada, which is 800 miles away, or 1600 miles round trip. A semi gets ~6mpg of diesel fuel, which contains ~35,000 calories per gallon. So to get the ~4.5 million calories of potatoes requires ~9 million calories of fuel. We just went from more calories of food produced per fossil fuel 2.25million ff to 4.5million potatoe, to 11.25million ff to 4.5million potatoe. Otoh, LTLs have become very good at minimizing empty runs since it drops profits, but I'm not sure how growers get their supply to the market, so the minimum would be 800 miles, which would be more than breakevensville. Tack on the required energy to stock the food, and the energy expended by the consumer to come get it, even by bicycle, and we're using more than a calorie of fossil fuel to get a calorie of food. And this is for one of the most efficient foods we have.

Odds are, if you toss an appropriately powerful two stroke engine on the back of your bicycle, and keep your speed at **15mph, you'll use the same amount of fossil fuels you would use if you had biked at 15mph and eaten the additional calories needed to travel, even if those calories were the most efficient foods we have, because even these require more in the way of fossil fuels then they give back. If you use a small electric bicycle, which has enough battery for your range, you'll probably have half the fossil fuel impact (depending on where you get your electricity from) that riding it and eating strict vegetarian does.

You should also consider the impact of the electricity you use, where it comes from, etc... The goods you purchase, the money your purchase goes to, and it goes on and on. I try to buy used at all times because it's cheaper, generally more reliable, and doesn't encourage increased production of stuff that's already there. If you take one idea away from this long ass post, take this. If you do it yourself, DIY, you know what your inputs are, and how much you are contributing to various processes. So DIY mother****er. ;)

*I think it's likely that someone who puts in the effort to quantify the calories of FF's used in producing a calorie of potatoe would similarly indentify growth as what it is, uniquely. That is to say, their language is likely explicit. Otoh, maybe it's not, and approach this assumption with that possibility in mind. Take it as you will.
**I say 15mph because if you toss an engine on and go 35mph, you're increasing your energy, aka fuel, consumption by a factor of ~five. So all those reports of people getting ~150mpg are probably with them going ~25-35mph, when they could be using a smaller, more efficient engines to move at the same speed as they would if they biked, and get ~400-800mpg@15mph.

Here are some stats to throw at the guy.
They are on the Living Car Free website at:
http://www.bikesatwork.com/carfree/automobiles-and-environment.html

The thing is, I'd love everyone to screw the automobile and just walk and bike places.

What do you mean by everyone? Everyone in America or everyone in the world?

75% of British households have 1 or more cars. 95% of American households. When I was in Tanzania last month, it seemed about 5% had cars.

well, re: hydrogen, lyeinyoureye just said everything I was gonna (You rock lye!) hydrogen is a sort of red herring, and there's even a possibility of it contributing to global warming through increased water-vapour in the air (if its hydrogen produced from fossil fuels/non water sources, and even water-produced hydrogen probably isn't vapour-neutral, that is to say that more vapour could hang in the air than falls back out from hydrogen produced vapour) but most importantly, as he said, its an energy transport medium, not an energy source...there's only one of those around these parts, the big yellow thing that hangs in the sky half the day, and even then in the grand cosmic scheme of things, its just redistributing energy stored in matter via the big bang.

regarding carfree...just do it. my biggest impediments right now are a lack of cash for a rack and some better locks, so I have to go out with my S.O. to buy anything.

so far, successfully being car-lite has more to do with thinking things out in advance. (pooling trips, etc)

just remember the 6p principle: proper planning prevents piss poor performance. and alliteration makes me sound like an idiot, but there, I said it.

its an energy transport medium, not an energy source...there's only one of those around these parts, the big yellow thing that hangs in the sky half the day, and even then in the grand cosmic scheme of things, its just redistributing energy stored in matter via the big bang.

regarding carfree...just do it. my biggest impediments right now are a lack of cash for a rack and some better locks, so I have to go out with my S.O. to buy anything.

I'm obviously not as knowledgeable about science as you are, but I think this is an error. You say (and not for the first time, IIRC) that the sun is the only source of energy on earth. Correct me if I'm wrong, but I think this is not true. It will take billions more years for it to cool completely.

Nuclear energy was not produced by the sun, although I think it was produced by other stars billions of years ago, when they basically blew up and deposited the various elements into the solar system, and this material then became part of the planets including earth. Geothermal energy also was not produced by the sun. It's residual heat from the time eons ago when the planet was a ball of molten metal. It's still a ball of hot liquid metal, in fact, with a thin skin of cooler, hardened metal on the surface.

Roody, the energy of the sun is generated by the fusion of hydrogen. This hydrogen is a product of the big bang. The non-solar source energy of the Earth is mainly in the form of long lasting radioisotopes, such as U-238 (1/2 life on the order of billions of years), which would have been created as a byproduct of stellar evolution seeding the primordial solar nebula with "metals" (astrophysics views all elements above helium metals). The other sources of energy is tidal forces, which result from the incomplete condensation of the earth-moon system, and residual heat from the condensation of the earth.

Of non-solar energy sources, that leaves us with nuclear, geothermal (half residual, half from radioactive decay), and tidal forces.

Roody, the energy of the sun is generated by the fusion of hydrogen. This hydrogen is a product of the big bang. The non-solar source energy of the Earth is mainly in the form of long lasting radioisotopes, such as U-238 (1/2 life on the order of billions of years), which would have been created as a byproduct of stellar evolution seeding the primordial solar nebula with "metals" (astrophysics views all elements above helium metals). The other sources of energy is tidal forces, which result from the incomplete condensation of the earth-moon system, and residual heat from the condensation of the earth.

Of non-solar energy sources, that leaves us with nuclear, geothermal (half residual, half from radioactive decay), and tidal forces.
Thanks rajman. I left out tidal forces, because I thought they mainly were from the sun, albeit from the sun's mass rather than its energy.

Also, I was wondering what your thoughts on Hydrogen Fuel is? I have a co-worker who is always talking about it. He gave me links to read about it, but I would rather hear any thoughts on the subject by you guys.


The change to Hydrogen fuel vehicle was to get around the possible success of an electric car. The electric car in California is the technology we've been waiting for but GM pulled the plug because it didn't make enough profit. They wanted you to keep buying gasoline cars until the last drop of oil is sucked from the earth. Then we'll go back to electric cars again.

The price of a hydrogen fuel vehicle is so out of reach, it will take 25-50 years before it becomes affordable. The high cost of producing and transporting hydrogen fuel is yet another reason why we won't be using this fuel anytime soon and this technology is even further down the road.

The push for hydrogen car only makes it seem like the auto manufacturers are doing something when they're not! They just don't want to go back to electric cars if there's millions of gallons of gas in the earth to extract at high prices. The hydrogen car is a dead end and they know it. Eventually the electric car will show up again but that's in another 50 years or more when all the oil is just about gone.

H2 is an energy carrier like lye wrote.
Its use in a car generally displaces emissions (from local to the car to the source of H2 generation). However, it allows for fuel substitution: oil to any of nuclear, wind, solar, coal, natural gas, etc. This may have a positive or negative effect depending on what mix is used, but making H2 as a car fuel practical opens up new possibilities.
In addition to possibly using a more renewable mix of fuel, it relocates emissions. This can be good for cities, where local car emisisons (heavy metal, nox, sox, etc.) can have ecotoxicity, human health, and smog effects.
As for the general value of car emissions. In the U.S., it is much higher than 0.5%. I can't say off the top of my head, but I would guess that it is more like 20% (for global warming potential that is). If they are talking only about nox and sox, maybe they can get the figure much lower.

Cager,

I think you're friend might have misread something, and misplaced the decimal. About a year ago I read that private autos are responsible for about 55% of all air pollution. So I suspect he might have just misread the stat.

As for H cars... From what I've read, I tend to agree that it's a red herring. The technology is still at the very least a decade from being viable for most drivers, plus there's no infrastructure for it (ie H fueling stations will need to be built).

There's something I don't get with the "bikes are less efficient than cars" argument. The figure I have seen is that about 43% of petroleum usage in the us is due to cars and light trucks (I'm assuming the majority of this is personal transportation).

The figure for food (according to lye and others) is that it takes 10 cal of petroleum to make 1 cal of food. One question arises here - nutritionists say cal but mean kcal. So does it take 10 kcal of petroleum to make 1 kcal of food or is it 10 cal of petroleum for 1 kcal of food? Judging from the howstuffworks site, the value of 515 cal per hour ridden is really 515 kcal (otherwise you could ride for an hour with just one tic tac!).

Ok, so lets say that everyone rides one hour a day. If we have an average diet of 2000 kcal a day, then we would add an additional 515 to that total. Food energy per person is now 2515 kcal. Now what we have is a petroleum consumption due to food production of some 25 150 cal (i'm unsure of this, but if you look at the howstuff works this is how they figure it). That adds up to less than one gallon a day in total and only one sixth of a gallon of petroleum used to make food energy for our cyclist. If everyone in america traded in their cars and rode their bicycles for six hours a day, they would only be using one gallon of gas extra a day in petroleum. It seems highly unlikely to me that US gas consumption is as low as a gallon of gas a day per person, but in any case few people would be riding six hours a day. As a car - lite person (I borrow/rent sometimes) I might ride anywhere from 1-2 h a day (1/3 gal of gas in food fuel).

If on the other hand, the amount of petroleum required for producing 1 cal (not 1 kcal) of food is 10 cal then to produce a diet of 2000 kcal of food a day, then it would require 20 000 kcal of petroleum per day to feed the average person. That is 645 gallons of gas for food eaten daily per person. Since about half of petroleum consumption is due to cars and light trucks, even assuming that all petroleum not used for transportation is used in agriculture, we get an average daily consumption per person of gasoline of something on the order of 500 gallons a day, or 10 000 miles a day in a car that gets 20 mpg.

It seems to me if that 10 cal petroleum:1 kcal food figure is right, then just about all of the petroleum not used for personal transportation in america is used in food production, just to feed joe six pack, not to mention us food guzzling cyclists. What about plastics, manufacturing, diesel (remember that 43% is for cars and light trucks), airlines, shipping, and all of the other uses of petroleum in the US????

P.S. I was thinking of lunar tidal forces, but yes solar tidal forces are greater. When I think of solar energy, I was just thinking of radiation, but you're absolutely right.

@rajman
I thought about that too and figured it's all in kcal, or Cal. The howstuffworks site uses ~31,000 calories per gallon fuel, and if you go to the onlineconversion.com site, and convert a gallon of US gasoline to kcal, you get ~31,000 kcal/calories per the howstuffworks site. They aren't using calories, they're using the USDA calorie, which is actually a kilocalorie. So yeah, for everything they did, and I did, calorie=kilocalorie and not 10 cal petroleum:1 kcal food.

Like you stated, if you ride from an hour at 15mph and go 15 miles, you use an extra 515 calories of food. This equates to 5,150 calories of fossil fuel assuming the average diet, or ~.17 gallons of gas, implying you're getting ~1/.17gal(15miles)=~90mpg. But, you're only going 15mph. For any object with a relatively consistent CdA, the energy lost due to fluid friction increases by a factor of ~13 when going from 15mph to 55mph, but the speed only increases by a factor of ~4. From this we can say that the 90mpg car is about three times more efficient than the average bicyclist on the average diet.

Assuming that I only eat energy dense grains, vegetables, and fruits with an average fossil fuel penalty of *two calories of fossil fuel per one of food, then as a bicyclist my fuel efficiency is ~1,000 calories per 15 miles, or ~1/.03gal(15miles)=~500mpg. Given that this is only using ~150wh over the one hour ride, and most small DI diesel engines use **~37grams of fuel per 150wh, this means a diesel engine would use .01 gallon to do the same amount of work, i.e. it uses ~350 calories to do the same thing you did with 515 calories, meaning it is more energy efficient at moving you than you are and would get ~700mpg at the same speed. Unless you manage to get that food to your mouth with ~.68 calories of fossil fuel used per calorie of food, you can't even break even in fossil fuel use compared to an efficient engine on the same vehicle at the same speed.

*I say two even though the only estimate I'v seen states .5 calorie of fossil fuel per calorie of food grown. If we add transportation we break even, if we count packaging, stocking, and you expending energy going to and from the store, I figure it's safe to say we're a two calories of fossil fuel per one of food.
**~250grams/kwh

Nutritionists deciding to call a kilocalorie a "calorie" is the dumbest thing I've ever seen. It's like calling a gallon an ounce.

I've been checking things out, if you look at statscan's petroleum usage survey here:http://www40.statcan.ca/l01/cst01/prim72.htm, they say that only about 4% of petroleum, about 3% of natural gas and liquids and about 3.5% of electricity are used for agriculture. They also state that more than 50% of petroleum use is for transportation. There is something fishy in the argument...

@Platy
I think they do it because there's only so much room on the side of a small box. ;)

@rajman
The US supposedly uses ~20x10^6 barrels of oil per day, and each barrel of crude contains ~5.6x10^6 btu. So we use ~112x10^12btu per day of oil, four percent of that goes to agriculture and is ~4.48x10^12btu, or ~1.2x10^12 kilocalories. If the average American eats ~2000 kilocalories per day, like you mentioned, and there are ~300x10^6 of us, then we eat ~6x10^12 kilocalories. So just for agriculture, which may be fed to livestock, or processed, packaged and shipped, we use 1 calorie of petroleum for every 5 of agriculture. Then we have to add natural gas energy required, the electricity required and where that comes from, the energy required over the lifetime of the equipment used, etc...
When all is said and done, 1 calorie of fossil fuel for every 2 calories of food in terms of agriculture seems about right. Then there's possibly processing, definitely packaging, transportation, stocking, you getting it, and you preparing it assuming it wasn't processed.

Otoh, cars are designed to be inefficient. They are large, have powerful gasoline engines that are inefficient for the majority of use, and can seat 4-8 people when 95% of the time they seat one, and an additional 4% of the time two. They are essentially designed to waste energy. The 90mpg@55mph vehicle I was refering to is sadly the most efficient passenger vehicle available on the market. Although ~300mpg@55mph is entirely doable by any major manufacturer. Once we split the atom, we had an energy source that was larger, safer, cleaner, and cheaper than fossil fuels will ever be. Along these lines, it's wise for fossil fuel companies to maximize profits by encouraging the minimization of efficiency. They want to sell as much as they can, while they can. I actually think that nuclear energy was the second nail in the fossil fuel coffin, Mr. Diesel and his engine that could run on plant oil was the first, but the fossil fuel industry dodged that bullet, and they're tryin' to dodge the nuclear one as well.

on a side note, I think I saw some food packaged for both US/CAN complete with french. I sear I think the "energy" measurement on the french side gave the value in either kilojoules or actually spelled out kilocalories.

the use of Calorie for kilocalorie is the precise reason I try to stick to joules for all my energy calculations...something about cals just makes me feel icky.

@roody. all that heat stored in the earth was the result of the gravitational accretion which produced the planet, which probably wouldn't have happened were it not for the mass involved in the nebula that formed the sun. in some roundabout way, stars (through fusion or gravitation) or the big bang can usually be considered the source of most other energy sources.

nuclear is star (ok, maybe not necessarily our star, but a star) or big-bang derived in a decompositional sense: fission and fusion are the opposite sides of a parabola drawn on an energy-vs-mass curve. fusion relies on heavier nuclei being more stable than the lighter (first 50 or so) elements while fission relies on a comparatively lighter nucleus being more stable than a heavier (everything above lead) nucleus. (there's some stuff about neutron number in there too) so that more or less brings geothermal back to having stellar roots.

I guess a better claim would be that all energy is the result of intense gravitation,fission or fusion, and that everything else is a method of redistributing energy produced via those methods. on the grandest scale...its all energy and every force, piece of matter and "energy source" out there is a means of redistributing that energy into states of successively lower potential.

but since stars are the biggest sources of gravitation and fusion, and fission is the result of stellar byproducts, I just usually argue that it's all stellar/solar energy.

@lye: a large powerful engine isn't always grounds for inefficiency. I've seen a lot of cars underpowered to the point that a larger engine would give better gas mileage over the life of the car. (sure, a dodge stratus with a 4 cylinder gets its stickered mileage when you buy it...just wait six months...meanwhile an 8-year old v6 taurus will probably still get better mileage than the same, (mostly) equal weight class stratus)

@rajman
I thought about that too and figured it's all in kcal, or Cal. The howstuffworks site uses ~31,000 calories per gallon fuel, and if you go to the onlineconversion.com site, and convert a gallon of US gasoline to kcal, you get ~31,000 kcal/calories per the howstuffworks site. They aren't using calories, they're using the USDA calorie, which is actually a kilocalorie. So yeah, for everything they did, and I did, calorie=kilocalorie and not 10 cal petroleum:1 kcal food.

Like you stated, if you ride from an hour at 15mph and go 15 miles, you use an extra 515 calories of food. This equates to 5,150 calories of fossil fuel assuming the average diet, or ~.17 gallons of gas, implying you're getting ~1/.17gal(15miles)=~90mpg. But, you're only going 15mph. For any object with a relatively consistent CdA, the energy lost due to fluid friction increases by a factor of ~13 when going from 15mph to 55mph, but the speed only increases by a factor of ~4. From this we can say that the 90mpg car is about three times more efficient than the average bicyclist on the average diet.

Assuming that I only eat energy dense grains, vegetables, and fruits with an average fossil fuel penalty of *two calories of fossil fuel per one of food, then as a bicyclist my fuel efficiency is ~1,000 calories per 15 miles, or ~1/.03gal(15miles)=~500mpg. Given that this is only using ~150wh over the one hour ride, and most small DI diesel engines use **~37grams of fuel per 150wh, this means a diesel engine would use .01 gallon to do the same amount of work, i.e. it uses ~350 calories to do the same thing you did with 515 calories, meaning it is more energy efficient at moving you than you are and would get ~700mpg at the same speed. Unless you manage to get that food to your mouth with ~.68 calories of fossil fuel used per calorie of food, you can't even break even in fossil fuel use compared to an efficient engine on the same vehicle at the same speed.

*I say two even though the only estimate I'v seen states .5 calorie of fossil fuel per calorie of food grown. If we add transportation we break even, if we count packaging, stocking, and you expending energy going to and from the store, I figure it's safe to say we're a two calories of fossil fuel per one of food.
**~250grams/kwh


If your going to attempt to twist numbers around to suit your views, at least do it properly. For example, if your going to include the cals needed to produce food so you can make the calories used by a cyclist look worse in comparison to a car, you better add all the calories and energy used to produce that car and the fuel it burns. Numbers are great, but without perspective they are worthless.

If your going to attempt to twist numbers around to suit your views, at least do it properly. For example, if your going to include the cals needed to produce food so you can make the calories used by a cyclist look worse in comparison to a car, you better add all the calories and energy used to produce that car and the fuel it burns. Numbers are great, but without perspective they are worthless.

I'm comparing fuel used, to fuel used, that's the perspective. Addressing the supposed infinite mpg that bicycles get. The mpg rating of a car doesn't include production, and when I buy a bicycle I have no idea how much it cost in energy, but since I'm talking about fuel consumption, I don't include those numbers, which I can't find in the first place. In the case of bicycling, since our engine is human, and our food/fuel requires fossil fuels, I'm comparing the use of fossil fuels in food production, to their direct use in an efficient car. I never stated I was doing a lifecycle analysis, but if you have the pertinent information, we could do that as well! :D

Even in an energy to energy basis, assuming an individual expends no additional calories, and their food magically appears on their table, no calorie overhead of any kind, a small diesel engine is still more efficient. If a person burns 515calories going 15mph they're probably using ~150wh, or ~370g/kwh of diesel. You can buy a 4hp diesel engine off of ebay for less than the cost of a new road bike that has specific fuel consumption of ~250g/kwh, strap it on the back of an old schwinn, and have a tank that's more energy efficient, and definitely more fossil fuel efficient, than the average cyclists using their legs. Engines can be more efficient than humans at doing work, and aerodynamic vehicles need less energy than vehicles that aren't to move at some speed. Bicycles are both inefficient in terms of design, and motive power, compared to alternatives. Riding a bicycle because you like it, because you want to get in shape, or because the stars have aligned is great. But riding a bicycle because it's more efficient than a anything else is, well, it's great too, do what you want to do, but it's not accurate. I can just as well state that 5>24551885, and by the way, have I got a bridge for you! It's in NY! :roflmao:

Here's another spanner in the works to keep things going.

Is it cheaper to burn fuel in a car or buy food to run the human engine on a bicycle?

Assume a 20 mpg car (about avg) vs a 515 kcal/hr cyclist on a 20 mile rt commute.

1 gallon of gas: $2.75

686 kcal food. Most endurance atheletes stock up on the carbs to keep going (that's what I do), and I would therefore eat pasta with tomato sauce to make up the energy I need. 1 serving of blue menu high protein high fiber pasta has 330 kcal per 1/5 box so lets eat 1/4 box =412 kcal (0.65 $cdn at real canadian superstore in CGY) 1/2 bottle of classico portobello mushroom sauce (about $1.50) and a sprinkling of parmesan (say 0.35 $). Adds up to $2.50 canadian or $2.25 US$.

So it seems to be marginally cheaper to ride your bike. Of course with different diet choices - say bulk rice - you could reduce the cost of the food calories to probably about $0.25.

Here's another spanner in the works to keep things going.

Is it cheaper to burn fuel in a car or buy food to run the human engine on a bicycle?

Definitely cheaper! From personal experience, if you're looking at it from cost, the best used cars on the market get ~50-70mpg, and assuming you geta reliable hooptie for $500 that get's 50-70mpg it'll cost you ~$1.00 a day to drive. Otoh, I've picked up a hooptie schwinn traveler and refurbed it for $5.38. If you eat an extra potatoe (160 calories), and a tuna salad sandwich (500 calories?) it only costs you, at most, like 40 cents per day. This is, of course, ignoring the fact that the large majority of Americans overeat, and can probably bike short distances with no change in caloric consumption, just a change in diet, unhealthy to healthy, so you'll probably end up saving cash since healthy foods are cheaper.

Otoh, I can't bike 250 miles in a few hours, so it's limiting in terms of time contraints. The best, imho, comprimise is a faired trike with a 10hp diesel engine, a press, filtration, and some sort of plant making oil. All you have is initial costs, practically no operating costs, especially since some plants with decent oil production are very hardy and can use grey water for irrigation/nutrients. The faired trike should be superior to a bicycle for human powered use, with speeds of ~25mph@150watts, and FE with the diesel engine should be in excess of 1000mpg@55mph, on free fuel. Unbolt and jack out the engine for short commutes, and drop it in there for visiting the family 300 miles away.

:beer:

The analysis of humans vs machines is far from complete. Although humans are initially assembled at no cost with voluntary unskilled labor, a full life cycle analysis would probably show that the maintenance and repair costs of humans far exceeds that of cars. Since the purpose of life is to drive, it follows as the night follows the day that all humans should be replaced by robotic cars as soon as possible.

I see you believe in the singularity (http://www.singinst.org/). We will become car. :lol:

O.k. no more bikeforums, time to go cut up bikes! :o

erm, with regards to calculating humans vs. engines, an equal-speed comparison is considerably unrealistic. part of why cars exist is the fact that they run more comfortably at higher speeds. further, to start comparing the current situation of cars vs bikes, one would have to consider average speeds.

just taking the power to fuel ratios, albeit an elegant means of answering the question, fails to address the reality of how much of a car's time is spent idling (where it consumes a ridiculous volume of fuel) and how much of its drive time is spent above speeds any cyclist could hope to do.

also, since diesels are the minority of passenger car engines, their efficiency isn't very representative.

I'm sure that at the far extremes of engineering a fossil-fuel burner can be devised that uses less energy than a human on a bike. but proving that doesn't have much to do with the price of gas, tea or rice in china.

Sure it's realistic. Just take the sum of rolling, fluid, and *sliding friction for autos and plot it over a range of speeds. This should provide you with a decent approximation of energy required and allow you to measure changes you make compared to FE, in an A-B-A manner. Granted, Crr and Cd may change, but they will vary within some small range, and you can always run coast down tests with different tire pressures to account for the decrease in Crr wrt speed, and use fuel consumption to figure out how much Cd changes wrt speed. Of course, this does depend on your drivetrain, NA diesels are usually the best to quantify changes in FE wrt to changes in Crr, Cd, and drivetrain efficiency because NA diesel efficiency is pretty consistent, especially through the lower rev range. With gasoline engines, we can ballpark how much power we need to move at some average speed, and figure out how much power each cylinder firing at whatever rpm makes and compare this to the delta pressure between the cylinder, depending on the A/F ratio, and crankcase to figure out the approximate pumping losses at low engine speed, since this is where they are >> than friction losses. Ideally, if we can find out where the engine stalls, we can accurately determine pumping losses, since this is the point where they equal power. This also allows us to observe the approximate increase in friction losses wrt rpm as well. EV's powered by lead acid deep cycle batteries suffer from Peukert's effect with increased current draw, but this is still easier to account for than pumping/friction losses in a gasoline engine, especially if using NiCD batteries that don't suffer from decreased capacity with increased current draw. In any event, comparing different vehicles at different speeds, with different drivetrains is realistic, and doable.

Essentially, you have a glider (bike, car, shopping cart) that requires a certain amount of energy to move under certain conditions, and a drivetrain that provides that energy, with some efficiency. As per your idling comment, diesels expend little energy idling, EVs none, and gasoline cars, a lot, about as much as they do cruising at 30,40, or 50mph depending on design. Personally, I was able to increase city FE in my gas pickup by ~30% just by altering my driving so that I can coast with the engine off for ~3-4 out of a 10 mile trip. As for representative efficiency, while diesels are a minority in the US, they are the majority in Europe iirc, and are a significant portion of ICE powered transportation. In fact, contrary to popular belief, even gasoline engine can attain FE in excess of 100mpg (http://www.cleanmpg.com/forums/showthread.php?t=1793), with an average speed of ~25mph, which is within a cyclist's reach imle. While the hybrid drive does make the pulse and glide technique easier on the engine, there is nothing new about using pulse and glide to get **good FE (http://www.cleanmpg.com/forums/showthread.php?t=1207) out of gasoline powered vehicles... It's just that gas has been cheap enough that most people haven't given a rat's ass about it. After reading about these Shell mpg contests, it occured to me that all those rumors about 100mpg carbs and the like probably stemmed from these competitions, or some back yard mechanic who knew a thing or two about gasoline engines. If the car's small enough, and the carb's designed to run it at a maximum of ~25mph with a superlean mixture, then that might be where those rumors came from. If you want a 100mpg gasoline hybrid/short range EV, it may even be doable (http://www.cleanmpg.com/forums/showpost.php?p=10233&postcount=10) for a few thousand.

*I've only seen this done with semis via polynomial interpolation because rolling/sliding friction is much closer to fluid friction.
**Hybrids don't actually increase FE by any great leap foward in technological innovation, it's just that the use of an electric motor eliminates iding, and the majority of low speed, inefficient, gasoline engine operation. The electric motor also allows for the engine to be started with much less wear in tear, which makes hybrids well suited for P&G. A car with exactly the same engine/body as the Prius would get about the same mpg using P&G, but the engine would take more abuse from starting without the electric motor spinning it up.

The reason that 10kcal / kcal seems high is that it is not correct.

Take corn for instance, which is a starting point for many foods, and is probably similar to other grains.
The cradle to finished corn energy requirement is 900kJ/kg (including fertilizer production). This equates to about 0.25 kcal/kcal in the corn kernels. In addition to the low energy requirement required, additional CO2 is converted to O2 by the corn. The reason that you get more energy out than you put in, is that the corn is utilizing energy from the sun. The reason that converting corn to ethanol becomes about equivalent to just using gasoline, is that the corn must be converted to ethanol by microbes. It is then in a dilute beer, which must be distilled to remove the water. The distillation takes up the balance of energy, so that 1kcal is used to produce 1 kcal of ethanol.

The biker who displaces driving, say by riding 10,000 miles/yr, will increase his/her diet mostly by increasing carbs. For instance by eating more corn, wheat, and soy. This person most likely doesn't just eat a ton more meat, which would be terrible for their diet, and hard to keep down. It would take a lot of meat.

I think you are a bunch of showoffs forgetting some very simple facts. Cars need gas to move and the people driving them need food. Bikes you need food only, and very little additional. My basal metabolism is about 2400 Cals/day. 20 % more food lasts me a long time on the bike--as long as anybody needs to ride in the real world. Cars are a ton of garbage, bikes are 25 pounds of garbage. Cars and food are both transported by rail. Three times a week I wait for a train full of shiny new Cadillacs and SUVs to pass by my little bike and me. You think there is some kind of realistic comparison between the two--bike and and 240 cars filled with cars? The real danger of modern life is global warming. Cars emit 5 pounds of carbon per mile.

Get real.....

^Roody, the problem ocurs when you start riding 10,000 miles / yr. That leads to about a 50% increase in calorie intake to maintain weight. If you drop 20 lbs, it is different of course.

There's something I don't get with the "bikes are less efficient than cars" argument. The figure I have seen is that about 43% of petroleum usage in the us is due to cars and light trucks (I'm assuming the majority of this is personal transportation).

Most of the arguments eliminate one small fact from their calculation, and that is, they factor that all calories are obtained through the eating of beef. Beef, is in fact a very ineffiicient provider of calories, it also provides way more protein and fat, then is needed. Muscle burns glucose and the fastest conversion from food to glucose, is from carbohydrates, and the best sources are starch rich foods like potatoes, not far down the list are carrots, breads and other grains. The amount of petroleum needed to produce 1,000 calories from potatoes and carrots, is considerably less then the amount of petroleum needed to produce 1,000 calories from beef. I am not saying that you should not eat any meat, but North Americans typically eat a lot more of it, then they need to.

^Roody, the problem ocurs when you start riding 10,000 miles / yr. That leads to about a 50% increase in calorie intake to maintain weight. If you drop 20 lbs, it is different of course.

The typical North American could afford to lose 20lbs, in fact a good number could afford to lose a lot more, I have seen scales for calories per mile, but they are usually for someone who is under 150lbs, what we really need are burn rates for someone who is 200lbs, 250lbs or 300lbs? I would assume the burn rate per mile for a person who weighs 300lbs (mostly fat) is considerably higher then for someone at 150lbs, under the same conditions. As for me, I should be around 170, currently 210, so I have a ways to go.....

Well, lots of interesting things to read. Um... I'll just wait till you guys can hash out this whole debate becuase its got me thinking!

^Roody, the problem ocurs when you start riding 10,000 miles / yr. That leads to about a 50% increase in calorie intake to maintain weight. If you drop 20 lbs, it is different of course.
First, who rides more than 10,000 miles? Maybe .001% of cyclists, and most of those are professionals--messengers, road racers or randonneurs.

Second, who eats beef any more? In the US, per capita consumption is less than half of what it was 25 years ago.

Third, and most important, food is a renewable resource, especially when it is produced organically and locally. Even the water that is used in agriculture is renewed, provided it isn't poisoned with pesticides and excessive fertilizer. We do need to switch over to eating more locally grown food, as much of the oils used is for transporting food. But this is starting to happen in many areas. Burlington. VT grows 7 % of its food on 100 acres reclaimed from the former city dump. Organic farms are sprouting up around every city.

If environmentalism is important to you, it is not beneicial to criticize those who are making positive efforts. Instead: Ride your bike--guilt-free--and seek out locally grown food!

@CagerTools

The debate really depends on your situation. If you can grow/raise all of your own food with no fossil fuel inputs, then ride your bike to your hearts content. If you can't, and depend on store bought food, then even buying the cheapest and most energy efficient foods, like potatoes, corn, oats, etc.. may not be any better than tossing a small gas engine on the back of your bike. Just growing corn for *example, had a ratio of 1:2.5 back in 1983 (http://oregonstate.edu/~muirp/fossfuel.htm), and given the trends in industrial agriculture, this probably hasn't gotten better. This does not include transportation to the store's distribution center, transportation to the store, the storage of the corn at the store, the energy needed for the consumer to go down to the store, and the energy needed to prepare the corn. When all is said and done, we're probably near 1:1, or maybe even greater like 2:1, etc...

Looking at small gasoline engine efficiency on bicycles, we can usually get ~200mpg (http://lee.org/blog/archives/2005/08/10/motorized-bicycle/) with speeds of ~25mph. Since going from 15mph to 25mph requires about three times the energy, we would probably get ~300mpg on bicycle at these speeds.

The people riding in a race like the Tour de France are riding more like 25 mph. Because air resistance rises very quickly with speed, they are burning about three times more calories -- something like 100 calories per mile.
We can get ~300mpg@25mph when pedaling, or ~200+mpg@25mph with a small engine give or take. If our diet has a 1.5:1 ratio, then there's no difference in fossil fuel use when riding or using a small engine. If our diet requires more fossil fuels, then cycling requires more fossil fuels than a small engine would in the exact same conditions. A 100lb 4hp diesel on the back of an old schwinn will probably get ~700mpg at 15mph, and an electric bike with appropriate range owns (http://groups.yahoo.com/group/power-assist/message/52934) almost everything else in terms of efficiency if you have your own wind or solar electricity, because that's essentially free fuel. The same goes for growing your own plant oil with a diesel powered bicycle. I have seen one interesting bit that states the equivalent mileage of a cyclist on bread is ~300mpg according to the NRDC (3.5:1), which seems appropriate considering that it's not very dense (more fuel for transport) and has to be prepared. This seems to imply that using a gas or electric stove adds quite a bit to the fossil fuel cost of food, probably enough to put the most efficient crops into the 2:1 range.

Buying from organic producers can be environmentally friendly, but it depends on who is selling it to you and what they do with your money. What are they going to do with the profit they made from the sale? Even if they don't dump it into the tank of an SUV, they may go buy a new plasma tv, and the money is distributed through the economy from there, etc... The point being, the large majority of power production is based off of fossil fuels, so any money going back into the economy will just encourage this. The most environmentally sound life involves changing what you can, and minimizing what you can't change. Never ever buy new is generally a sound rule, use what other's won't, be a cheapskate, and build/fix your own stuff. Ideally, the less you depend on others, the more environmentally sound your life probably is. Here's a nice bit of info on fossul fuel use and food. (http://www.ehponline.org/members/2002/110p445-456horrigan/EHP110p445PDF.PDF)

*1:4 for corn was mentioned, but I can't find this.

Hey, Thanks alot for this post. Its really making me think more broadly about energy... and the efficiency of a bike.

Maybe the solution is to find good ways of producing energy, then just funneling that into Hydrogen... like the fuel cell. That way we can have pollution away from human beings, at the very least.

This stuff is way more complicated than I could imagine. Well, I knew it was complicated...but still.

Kind of like the biodiesel and veggie oil arguments, one good thing about fuel for cycling is that you have a choice in the matter. Car -> gas-> gas station. Simple. Deadly.
For cycling fuel, you can choose to grow your own, buy a 50lb bag of rice, go to taco bell, pluck apples from the trees on the side of the road (oh such a great time to be here in Sonoma county right now), shoot a deer, and so-on.

Another good argument for cycling: less medical costs down the road, which means less time hooked up to life support, which has GOT to be energy intensive! I think there is plenty of evidence out there supporting an active lifestyle as great preventative maintenence for the human body compared to a sedentary one. Add to this the savings from the massive USA health tab associated with obesity and overweight (diabetes, heart disease, bad knees, etc) and you have a winning formula. Fact is, the average American probably already eats enough to fuel a very adequate cycling regimen with no added caloric intake.

Even in an energy to energy basis, assuming an individual expends no additional calories, and their food magically appears on their table, no calorie overhead of any kind, a small diesel engine is still more efficient. If a person burns 515calories going 15mph they're probably using ~150wh, or ~370g/kwh of diesel. You can buy a 4hp diesel engine off of ebay for less than the cost of a new road bike that has specific fuel consumption of ~250g/kwh, strap it on the back of an old schwinn, and have a tank that's more energy efficient, and definitely more fossil fuel efficient, than the average cyclists using their legs. Engines can be more efficient than humans at doing work, and aerodynamic vehicles need less energy than vehicles that aren't to move at some speed. Bicycles are both inefficient in terms of design, and motive power, compared to alternatives. Riding a bicycle because you like it, because you want to get in shape, or because the stars have aligned is great. But riding a bicycle because it's more efficient than a anything else is, well, it's great too, do what you want to do, but it's not accurate. I can just as well state that 5>24551885, and by the way, have I got a bridge for you! It's in NY!

1- just don't ignore the fact that fossil fuel transport and production actually use fossil fuels

Humans are the only machine that becomes more efficient, the more you use it. The real "waste" in a human engine is that it's running all the time, it can't be shut down, even when it isn't producing any useful work. In other words, for even the most active human, more calories go into basal metabolism (basically, just stayin' alive), than go into actual work, like cycling. Basal metabolism, like other human energy use, is highly dependant on body weight. When I weighed 250, my basal energy requirements were about 3000 Cal/day. At my ideal weight of 176, that drops to about 2000. So when cycling leads to weight loss, as in my case, there is a drastic reduction in daily energy repuired for "stayin' alive." Even a lot of cycling will not erase this defecit.

1- just don't ignore the fact that fossil fuel transport and production actually use fossil fuels

Well, I'm ignoring the fossil fuels used to get that food to the human's mouth, so I figure it's appropriate to ignore the fossil fuels used to get that diesel to the engine. It's energy to energy efficiency. But, if you insist, you'll only find that the human "engine" suffers a larger efficiency overhead...

The EPA goes with efficiency of ~84% for crude refining/transport iirc. So we're at something like ~300g/kwh equivalent for a small diesel on an old schwinn. But, since we're talking about the energy to energy efficiency when comparing a human to a diesel, adding in refining/production and transport hurts human efficiency more than diesel efficiency, which needs at least ~700-800g/kwh if we look at the fossil fuels needed to get that food to their mouth, assuming a 2:1 fossil fuel calorie to food calorie ratio, and given that bread is supposedly ~3.5:1, this is a reasonable assumption for even the most stringent production diets. Something else... it's probably easier to grown our own plant oil than it is to grow our own food due to the hardiness of some species used for plant oil, but it really depends on where we live, so YMMV.

But aren't we already at a certain point of desperation where it's necessary to start making ethanol car fuel from human food, i.e. corn or sugar?

Fossil fuel was an incredible energy bonanza. Maybe fossil fuel had such a terrific energy density that it was cheaper than food as an energy source. But that's beside the point and in the past. Is it not true that we're already burning comparatively expensive food crops in cars now?

Eh? Political desperation? If anything, fossil fuels -> corn -> ethanol seems to be pretty energy neutral from what I've gathered, meaning the energy we put in, in terms of fossil fuels, is about the same as the energy we get out in terms of ethanol. The largest difference I suppose is in terms of constituents, it takes a certain amount of coal, natural gas, petroleum to make ethanol, while gasoline is just petroleum, so we are changing the inputs? The thing is EROI calcs are very uh... wishy washy imho, so I wouldn't take them at face value.

Another example may be the use of nuclear power to heat oil shale/sands. It'd be much more efficient to add a 5th wheel electric system (a small wheel, electric motor, and battery pack good enough for ~10-30 miles all electric city driving) to every car on the road and a nuclear power plant to charge all those cars, but nuclear power may be used, and natural gas is definitely used to extract oil from shale/sand, not because we're desperate for energy, but because certain people are desperate for oil. It's price has been driven up by speculation, so you could say we're desperate for profit, but not energy. We have so much energy (fossil fuels), we waste so much energy (transportation, housing, even lighting wastes a lot of energy, these things are designed to be wasteful because it encourages consumption, and increases profit), and we could utilize so much more energy (fission, maybe fusion down the line)... If we have want for anything, it's not energy. Maybe fresh water, maybe a stable climate, maybe democracy, but we have plenty of energy.

Lets put it this way, a human being is only capable of maybe 300Wh maximum for an hour plus. However, this is enough to move a very spartan, minimal HPV streamliner at 50mph. It uses ~6wh/mile. A car that gets ~36.6mpg@50mph uses ~1000wh/mile, so we're using ~167 times the energy we actually need move ourselves. Assuming we create a vehicle that's not cramped and hot, we may need a whopping ~50wh/mile@50mph in something that's ~8 times roomier. By now we're at something that looks like vw's 1L prototype, is capable of getting ~300mpg on diesel, or ~600-700mpg electric equivalent. We'll need something like 500kwh to go 10,000 miles, which is ~13 gallons of diesel with a diesel engine, ~26 gallons of gasoline with a gasoline engine, or ~500kwh electric. We could probably switch (http://blogs.vertigosoftware.com/jatwood/archive/2006/07/26/3150.aspx) all of our incandescant bulbs to cfls and "save" enough energy to drive the 10,000 miles in a vw 1L prototype EV.

I'm really getting off track, but imho our energy use is designed to insure we don't switch to alternatives. Our houses and cars are built so solar/wind electricity, and electricity/biofuels for aren't an alternative for most people if they want to keep living "like they do". Another advantage of inefficient contructs is they require less to make, so profit is increased in the production arena as well. Sure, we could use a well designed house with evaporative cooling/good insulation/efficient lighting/solar hot water, but why would we when we can have the consumer pay more for crap that's inefficient. So they pay more up front, and during use... Win, win!