Anyone have effective energy numbers for gasoline and ethanol in units of horsepower-hours?
Likewise equivalent pounds of CO2 and H2O output?
Thanks!
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |
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| 1962 | America: Land of the Free, Because of the Brave
I just realized that I, myself, have been succumbing to the greenie bullshit... ethanol IS a hydrocarbon ;-)
My bet is, when normalized to unit energy, they're equivalent greenhouse gas polluters.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
How many gallons of fossil fuel does it take to grow and process that slightly more than 1 gallon of ethanol (that contains the same energy as a gallon of fossil fuel)?
Right now, it is considerably more than 1. Of course, you could use ethanol instead, for those steps, but that only increases the fossil need more.
It is like losing money on each item sold, but making up the loss with high volume.
Everyone kids "W" about his references to prairie grass, but I think that's where it'll be.
Ever struck a match to tumbleweed ?:-)
You'd think you just threw gasoline on a fire.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
Yeah, I guess. It's just that oil comes out of the ground and generates "new" CO2 while planted stuff consumes CO2 during growth and then releases it again. Of course that doesn't take into account other nasties such as fertilizer usage.
It's like our wood stove versus other people's gas heaters. Wood burning is CO2 neutral while gas isn't.
The octane rating is not meant to measure the energy content of fuel. It is a measure of the knock (pre-ignition) resistance of the fuel. If you don't have a pre-ignition problem to solve, higher octane fuel is all cost (including higher exhaust pollution and worse engine grime) and no benefit for you.
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
One of my rants has been with the Bureau of Weights and Measures that seals all the scales and gas pumps to ensure accurate delivery. There is an Octane rating but that does not really equate to the energy content in a gallon of fuel. I care less about the quantity of the fuel than the BTU per gallon. With lots of distributors now adding alcohol to gasoline, the miles per gallon is decreasing and cost keeps increasing.
You can find out this information easily enough on the web, or in a decent technical library
My pocket scientific data books lists enthalpies of combustion for ethanol - 1371 kilojoule per mole - and for n-octane - 5512 kilojoule per mole. You need to know the molecular weight of ethanol - 46.07 - and of n-octane -114.23 - before you can do anything useful with these numbers, as a mole of ethanol is 46.07 grams of ethanol, and a mole of n-octane is 114.23 grams.
If you really do want to convert joules in to horse-power hours, you will also need to know that one horsepower is 745.7 watts (or joules per second) and that an hour contains 3600 seconds.
The molecular weight of CO2 is 44.01 and of H2O is 18.016, and there are 454 grams to the pound. Jim either didn't do high school chemistry or has forgotten all he was taught.
Ethanol is C2H6O - two carbon, six hydrogen and one oxygen. That single oxygen molecule means that it isn't a hydrocarbon, but an alcohol.
As has been pointed out by Joerg, ethanol is produced from green plants, which absorb their carbon from atmospheric CO2, making ethanol carbon-neutral.
Furthermore, it contains a lttle more hydrogen than regular hydrocarbons fuels - octane is C8H18 - so a bit more of the energy you get from burning ethanol comes from turning hydrogen into water, which isn't a greenhouse gas.
I wouldn't bet on the "accurate delivery". I've been keeping a spreadsheet on the new car and discovered that mileage was low about
5% from a certain store... could be junk gas of course, but I suspect more likely a "tweaked" pump.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
The internal combustion I am looking forward to operating is a variable displacement, variable compression ratio design that has no carburetors or throttle body, but just intake ports with fuel injectors. It adjusts its displacement and stroke to compress the fuel air mixture to just below that which causes pre-ignition while producing only the horse power required, from idle to full, high speed acceleration. It can also adjust to run on any vaporizable fuel of any octane rating, from hydrogen to ethanol to 98 octane jet fuel, obtaining the maximum practical mechanical energy from it.
Experimental (and impractically heavy) hydraulically adjusted versions are being tested in dynamometer, and the test results, so far, indicate that a typical vehicle with a given peak horsepower capability would use about half the fuel, on average, compared to a fixed displacement and compression ratio engine in use, today.
How would you like to have a vehicle that goes something like 50 miles on a gallon of low grade gasoline with 200 HP available, or 55 on premium with 220 HP available?
A more reasonable unit of measurement is the watthour per liter.
Ethanol, of course, is utterly worthless in that it is simply diesel fuel in disguise when grown as corn under US farm conditions.
You have basically a big funnel. You pour lots of diesel fuel in the top, and a little ethanol dribbles out the bottom.
Ethanol is pretty much an outrgeous twelve billion dollar federal vote buying scam.
Ethanol from switchgrass or bagasse MAY EVENTUALLY have some net energy potential.
--
Many thanks,
Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
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Please visit my GURU\'s LAIR web site at http://www.tinaja.com
Not necessarily so. Some cars adjust the ignition timing, mixture and other things to keep the process efficient but just shy of knocking/pinging. That can yield a few percent on higher octane fuels. But probably not more than the cost difference.
But having both variable displacement (over a big range from fractional horsepower to a hundred or so horsepower) with constant (over that displacement range) compression ratio, is hard.
I have a similar fantasy for a valveless engine based on a pair of scroll compressors, one to compress the air (with fuel continuously injected at its output) and one operating in reverse to extract mechanical energy from the decompression of the hot exhaust.
The scroll is easier to build to efficiently compress a variable volume (compressible gas).
I don't accept it's greenie bullshit, seems more like the powerful farmer's lobby to me. As for me, I'm for nuclear and electric or hybrid off-line-chargeable cars. I wish my new Prius had an electric-outlet jack. Time for a retrofit.
OK, Bill, thanks for the chemist's perspective. What about the hydrocarbons burned in making the fertilizer and planting, maintaining, harvesting and processing the corn crops into ethanol? How does that sum play out?
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