1 US gallon of gasoline contains 104,000 BTUs of energy.
1hp = 2,540 BTU/hour of energy consumption.

A typical car requires about 9hp to cruise at 60mph, given aero loads and rolling resistance from tires.

So, if engines were 100% efficient at extracting energy from gasoline, you'd get 273 mpg at 60mph in a typical car. Since most cars actually get less than 30mpg, most engines are extracting roughly 10% of the energy in the gas and applying those to actually propelling the car. Most of the energy is being thrown out as waste heat directly out of the exhaust, or in heating up the coolant, the engine itself, the gearbox, and the tires.

btw, hydrogen has 180,000 BTU/US gal, so if a liquid H2 fuelled engine were produced that only had the same efficiency as a 27mpg gasoline engine, you'll see 45mpg typically.

Pure ethanol has only 70,000 BTU/US gal, for only 18mpg. E85 would bring this up to 20mpg. Britt noted E85 where he lived was $2.10/gal v. $2.58/gal for gasoline, meaning E85 costs 81% as much, but only takes you 74% as far...

Now, as for the efficiency of a Mr. Fusion powered car...

Its like-

THERMODYNAMICS!

Aaaaaaarrrrrrrggghhhhhh

my head and stomach hurt.

and that's a Flux Capacitor...3 beer can & a bananna peel gets you 35 years

gaaaaahhhhh!!!

it gets into that conveying engergy thing..... heat... to friction .... to light..... to motion....all at the same time. little leeches sucking efficiency all throughout the process..... can't have 100% use of fuel to propulsion..... all reactions have an exothermic component and motion results in frictions of atmosphere and mechanics further reducing efficiency.......all working with/against each other.... convection/friction/evaporation/reduction...... all very complicated....

internal combustion is not all that efficient..... but awfully fun!

Jives with numbers I've seen before. Good stuff James!


Then you get to add in the cost (in energy or dollars if you wish) of getting oil out of the ground, refining it, and transporting it via tankers and trucks (that get oh-so-great gas millage!)

Last time I heard this same thing it was 15% to move the car, 25% for friction, and 60% lost to heat.

Not very efficent except that gas is sooooooooo darn cheap considering, even at today's prices.
Anyone want to guess at what a gallon of liquid H2 costs? Hint, you doan wanna know.

And to the cost of the Hydrogen, add the cost of making the fuel, in terms of energy consumed, which is substantially higher, I've read, than the energy it provides. Can you say "net loss"? The Cap'n

Cost is an interesting issue, actually. There are 42 US gallons in one barrel of oil, and the recent peak price has been $66/barrel, so each gallon of oil costs $1.57. Now, each barrel of oil actually only produces 19.5 gallons of gas (plus 4 gallons of fuel oil, plus kerosene, yada, yada). Let's say 60% of the money produced by a barrel of oil comes from gasoline, so $40 per "barrel" of gasoline, or $2.05 per gallon of refined gasoline, just in the price of the raw materials. Throw in transport and refining costs, and taxes, and it's a wonder gas prices in the US are still only $2.60/gallon (more or less, depending on where you are). 8M barrels of oil are produced per day, or 156M gallons, or $320M worth of oil, sold for $406M, for 22% gross margins (before transport and refining costs, as well as lining the pockets of the oil execs). EVERY DAY.

But, I also like internal combustion, and would vastly prefer it to, say, an all-electric. I'd much rather have a hydrogen powered V12 than an equally powerful electric, simply because the V12 sounds so much nicer. Gasoline-electric hybrids are unsatisfying as they generally add a lot of weight to the car, and aren't as efficient as a "proper" gasoline-electric hybrid would be (i.e. a 30-40hp tiny gas engine only there to charge batteries, with electric motors doing all the driving). If you're going to go for efficient, might as well go all the way.

For the powerheads, since typical efficiencies for IC engines are 10-20%, there's a LOT of power available in the fuel that's being lost. Turbos exploit some of the heat lost to the exhaust stream, but a full gas turbine with some regeneration (again capturing lost exhaust heat) can approach 60% efficiency. Same amount of fuel, but 3x the power. Or same amount of power, and 3x the mileage. Problem with gas turbines is they make terrible direct drive engines (major lag, very inefficient at light loads), so they're better suited for being the fossil fuel side of a hybrid.

QUOTE (Cap'n Krusty @ Aug 23 2005, 06:22 PM)

And to the cost of the Hydrogen, add the cost of making the fuel, in terms of energy consumed, which is substantially higher, I've read, than the energy it provides. Can you say "net loss"? The Cap'n

I agree, but that's not what H2 is or should be about. I have no idea what it costs (in energy terms) to refine and deliver gas, either, but I'll bet it's pretty remarkable. Hydrogen and gasoline aren't "energy sources" but "energy storage mechanisms". You can oxidize either one to release energy in a mobile application, like a car, relatively easily. In terms of energy density per unit mass, they have it all over electricity using any electric storage technology we have now, and electricity is also a "net loss" form of energy storage.

The only *real* forms of energy available are solar, nuclear, and geothermal. Geothermal's not going to work in a car for obvious reasons. Nuclear's not going to work until someone devises a Mr. Fusion. Solar on the car doesn't work for sheer energy delivery v. area issues. So, you have to tap one of these sources, store the energy in some medium, and use it to power the car. Oil is solar power that's been stored over millions of years. Hydrogen is all around us (the most abundant element in the universe by far), but not in a convenient form, and it's that conversion that costs. The big difference is that the oil cycle takes millions of years, whereas the hydrogen cycle takes no time at all. Emissions from a hydrogen IC engine are water and nitrogen oxides. With a catalyst, they're water, N2, and O2. H2 is currently made in bulk from natural gas, but CAN be made from water and enough electricity (which can be generated by one of the "real" power sources). Once we got going using hydrogen directly as a fuel, we'd never run out of it, for all practical purposes, no matter how much we used (again, up to practical limits).

Hydrogen could be "refined" from seawater using shoreline wave-power electricity generation stations, making delivery to much of the California population rather simple. Cutting out the drilling and oil tanker steps would reduce the costs (both in dollars and energy spent) quite dramatically.

There are lots of other problems with using hydrogen as a fuel (storage on the car, for one), but if this really is the way things are going, I'm optimistic. The IC-powered car could remain a fixture in daily life. Without this, I'm sure that within my lifetime, the only place you'd hear a V12 would be at at the Monterey Historics or similar events.

uh.....

it's like


oh wait. I already did this...

Really James, all that is damn fascinating. I'm assuming there is some basis for the numbers you come up with. Shows why it is easier for the oil industry to cavort with people who don't actually like 'em instead of developing other sources, I guess.

So we gotta develop a better way to capture turbine energy and convert to appropriate rotational forces. Sounds like it could be pretty inefficient and still be an improvement....
turbines can be hydrogen powered i would think.

QUOTE (SGB @ Aug 23 2005, 07:12 PM)

uh..... it's like oh wait. I already did this... Really James, all that is damn fascinating. I'm assuming there is some basis for the numbers you come up with. Shows why it is easier for the oil industry to cavort with people who don't actually like 'em instead of developing other sources, I guess. So we gotta develop a better way to capture turbine energy and convert to appropriate rotational forces. Sounds like it could be pretty inefficient and still be an improvement....

The numbers I quoted in the first post were primarily from a Wikipedia article (BTUs/gallon), and from coast-down figures Car & Driver used to put in their road tests (9hp for an Accord-class car). btw, motorcycles are much worse, at 12hp for 60mph, due to terrible aerodynamics (from Cycle magazine). The rest is just straight, simple math. I'd read years ago that an IC engine was about 30% efficient at the crank, at best. Given known figures for gearbox and final drive losses, 8-15% sounds about right.

The oil figures I got off the web, just googling. They could be very wrong, but sound about right.
The prices/barrel or gallon are, of course, right out of the news.

The gas turbine figures are also out of Wikipedia, and the problems as a direct drive powerplant are from a fascinating story relating to the history of BRM (British Racing Motors), which built a car around a gas turbine engine made by Rover in the mid-1960s, driven at Le Mans by Graham Hill. This story has been related by Doug Nye, in his history of BRM.

QUOTE (lapuwali @ Aug 23 2005, 07:09 PM)

electricity is also a "net loss" form of energy storage.

Please please please I'm not trying to start an argument...

I'm just curious as to what you mean by this statement. Aren't ALL forms of energy transfer in the universe "net loss"? Some more than others.

entropy!

QUOTE (lapuwali @ Aug 23 2005, 07:09 PM)

Hydrogen and gasoline aren't "energy sources" but "energy storage mechanisms".  You can oxidize either one to release energy in a mobile application, like a car, relatively easily.

"Good old gasoline" is the hands down winner for "energy density" combined with ease of "handling", ie; no pressurization, no cryogenic storage, etc.

Although "handling" of hydrogen is generally safer as one just can't "spill" it.

entropy is my copilot.

QUOTE (sgomes @ Aug 23 2005, 07:30 PM)

QUOTE (lapuwali @ Aug 23 2005, 07:09 PM) electricity is also a "net loss" form of energy storage. Please please please I'm not trying to start an argument... I'm just curious as to what you mean by this statement. Aren't ALL forms of energy transfer in the universe "net loss"? Some more than others.

Hey, I don't mind a good argument, and I can keep it civil.

That statement is roughly as true as saying "hydrogen is a net loss", though one has to do a lot of hand-waving to get there...

Since, as said, entropy is the ultimate process here, and we're ALL using power that somehow came into being through a process we don't understand, and is winding down all the time (no matter what we do), then everything is a net loss. All we can do is convert things from one form into another. We can take solar power and convert it into electricity and store it chemically in a battery. How much power does that take? Do we count all of the wattage coming off the sun? How efficient is THAT process? Where exactly do we measure the losses? Do we NOT count all of the Sun's energy that's not even falling on the Earth?

In other words, my reaction to "that's a net loss" is "so what?". And if I bend and twist terminology enough, I can say (and defend) the idea that hydrogen is "renewable", since it isn't destroyed in the process of being used, and can readily be converted back into a useful form in a timescale that's reasonable, using a level of power that's reasonable.

If none of that made any sense, well, it's late...

I dont much about the energy held in various fuels. Just know my Toyota Echo gets 45 mpg highway on regular unleaded and will get close to 50 MPG if I drive it like I'm on my way to the retirement home.

Let's enter diesel.

I can get as good as 16 mpg in my 7000# F350 turbo.
Towing the car.

I would like to learn more about bio-D.
Spent fryer oil is everywhere. People pay to get rid of it.

Guys are making it work.
Smells like burnt fish-n-chips though


KT

I get 22 mpg out of my F250 when unladen, when Im towing I get about 14 mpg

Home brew biodiesel is something to consider, though you have to use some nasty chemicals to make the diesel, and are left with glycerin as a byproduct that you have to dispose of

in a nutshell you take Lye, and Methanol, and mix that, which become methoxide... some nasty schtuff

mix that with veggie oil.. swirl wait... pour off the diesel, dispose of the glycerin, wash the diesel.

Ive read of people brewing their own BioD for about sixty cents/gallon. Im not sure if these people factor there own time into the equation though.

87 went down 3 cents at the corner this morning....

QUOTE (trekkor @ Aug 23 2005, 09:27 PM)

Let's enter diesel. I can get as good as 16 mpg in my 7000# F350 turbo. Towing the car. I would like to learn more about bio-D. Spent fryer oil is everywhere. People pay to get rid of it. Guys are making it work. Smells like burnt fish-n-chips though KT

And when substantial numbers of drivers switch to biodiesel, does that mean we all need to begin eating a LOT more fried foods so they'll have fuel? There are several locals here that are actively advocating the change over, and the newspaper (well, what passes for one) loves to print stoies about them. What's gonna happen when their numbers grow? BTW, they're pretty picky about where they get their cooking oil. The Cap'n