5 ms·

it's not the hydrocarbons or the fact that ethanol provides higher octane that I'm disagreeing with, it's this: > and so less efficient engines, and fewer mpg

it's not the hydrocarbons or the fact that ethanol provides higher octane that I'm disagreeing with, it's this: > and so less efficient engines, and fewer mpg ethanol, while providing a higher octane rating (which if you drive a car that requires a higher octane rating for its immediate power might matter), actually lowers the mean mpg quite a bit, since it has much lower energy density. that, and the fact that we're literally burning food, are some of my issues with ethanol. I drive a car that knocks if I put less than 91 octane in, but if that octane is obtained from ethanol, it reduces the mpg by 25% (for 10% ethanol, higher if the ethanol percentage is raised). that's a problem. sure, I too want to get off of hydrocarbons that produce co2 for energy, but making that energy less efficient is not the way to do it, especially when we're burning our food and destroying the soil to achieve that.

credit_guy 3y ago
No, ethanol has a lower energy density, but not that much lower as to make a huge difference. Wikipedia has a handy table with the energy density of various fuels used in tranportation [1]. The net energy density per liter of regular gasoline is 32.2 MJ (megajoules). For gasoline with alcohol (which they call gasohol) it is 31.3 MJ. So gasohol has an energy density about 2.7% lower than regular gasoline, not 25% lower. [1] https://en.wikipedia.org/wiki/Gasoline#Comparison_with_other_fuels https://en.wikipedia.org/wiki/Gasoline#Comparison_with_other...
- windexh8er 3y ago
  > No, ethanol has a lower energy density, but not that much lower as to make a huge difference. This isn't correct. It does make a huge difference in 4-stroke and an even larger difference in 2-stroke. Any engines that are being used for capacity / load will showcase the differential in a very significant way. Even according to the US Department of Energy they state that: "Denatured ethanol (98% ethanol) contains about 30% less energy than gasoline per gallon." [0] If you've never towed in a vehicle that can use E-10 or E-15 and compared, I'd suggest you give it a shot. Be prepared for upwards of over 25% difference in gas mileage alone, not to mention reduction of power. [0] https://afdc.energy.gov/fuels/ethanol_fuel_basics.html https://afdc.energy.gov/fuels/ethanol_fuel_basics.html
  - credit_guy 3y ago
    Well, as someone else replied in the thread, if pure ethanol (98% is basically pure) has 30% less energy density than gasoline, then a mix of 90% gasoline and 10% ethanol has 3% less energy density. I'm not sure what you mean by E-10. Basically all gasoline that is sold in the US is E-10. You have to look hard to not get E-10. I doubt you have performed the experiment you described, for the simple reason that it's hard to find gasoline that's not mixed with ethanol. I just googled, and apparently gasoline without ethanol is called "recreational gasoline", or REC-90 [1]. [1] https://en.wikipedia.org/wiki/REC-90 https://en.wikipedia.org/wiki/REC-90
    - windexh8er 3y ago
      > I'm not sure what you mean by E-10. Basically all gasoline that is sold in the US is E-10. You have to look hard to not get E-10. I doubt you have performed the experiment you described, for the simple reason that it's hard to find gasoline that's not mixed with ethanol. It's not really productive to make assumptions. Where I live I can buy non-oxygenated gas at almost every station. And, yes, I actually do this experiment all the time given I'll drive to places with a trailer where I'm forced to run an ethanol blend. I realize my comment conflated two things: the reduction of performance and the difference in power per straight gallon. My point is that even with a minimal blend you can lose significant mileage / power. The easiest layman's way to measure that is in MPG. And, yes, there is a significant drop in both power available and MPG. And for reference [0]: "Due to ethanol's lower energy content, FFVs operating on E85 get roughly 15% to 27% fewer miles per gallon than when operating on regular gasoline, depending on the ethanol content. Regular gasoline typically contains about 10% ethanol." The above is in normal driving. So, no, I'm not making my statement up. [0] https://www.fueleconomy.gov/feg/ethanol.shtml https://www.fueleconomy.gov/feg/ethanol.shtml
    - jerrysievert 3y ago
      it's called "clear" gas around here. there's a website that tracks places to buy it in all 50 states: https://www.pure-gas.org https://www.pure-gas.org - but I've noticed that it doesn't track every location and is often wrong about prices, at least in my area. I've never seen "REC-90" and had never heard of it before your posting. clear gas in my area is 92 octane, with up to 110 available in select locations. most everyone I know who drives a performance vehicle, or a motorcycle can tell you where their closest gas station that sells clear gas is. > I doubt you have performed the experiment you described, for the simple reason that it's hard to find gasoline that's not mixed with ethanol. I've performed it many times over the last 17 years I've owned my current car. the results are always the same: 25% better gas mileage with the clear gas. I keep track of my mpg, and am able to quickly see any difference between gasoline grades. I typically drive in my car's "power band", staying between 5000 and 6700 RPM.
arthur2e5 3y ago
> lowers the mean mpg… energy density And that's why we don't quantify energy efficiency using just MPG. You adjust for the density to get some sort of mile per gallon-energy-equivalent. > Making that energy less efficient I have no idea at all how this could happen, except to say that your very rough numbers do suggest a reduction in energy efficiency. EtOH is supposed to have 34% less energy per volume, so for E10 the reduction should be around 3.4% (IGNORING VOLUME CHANGES WHEN MIXING). This matches well with the "up to 2.8%" claim of Wikipedia citing[1], but certainly not what your engine is doing. [1]: https://web.archive.org/web/20070609142818/http://www.raa.net/page.asp?TerID=146 https://web.archive.org/web/20070609142818/http://www.raa.ne... > the fact that we're literally burning food We are all minions of corn. The hope has for a long time been on grass and other stalks full of waste cellulose digestible only by microbes in ruminants and fermentation plants, but these just keep on not delivering. Isobutanol was supposed to be a more gasoline-like biofuel too. Nobody figured out how to make it cheaply enough to burn either.

credit_guy 3y ago

No, ethanol has a lower energy density, but not that much lower as to make a huge difference. Wikipedia has a handy table with the energy density of various fuels used in tranportation [1]. The net energy density per liter of regular gasoline is 32.2 MJ (megajoules). For gasoline with alcohol (which they call gasohol) it is 31.3 MJ. So gasohol has an energy density about 2.7% lower than regular gasoline, not 25% lower. [1] https://en.wikipedia.org/wiki/Gasoline#Comparison_with_other_fuels https://en.wikipedia.org/wiki/Gasoline#Comparison_with_other...

windexh8er 3y ago
> No, ethanol has a lower energy density, but not that much lower as to make a huge difference. This isn't correct. It does make a huge difference in 4-stroke and an even larger difference in 2-stroke. Any engines that are being used for capacity / load will showcase the differential in a very significant way. Even according to the US Department of Energy they state that: "Denatured ethanol (98% ethanol) contains about 30% less energy than gasoline per gallon." [0] If you've never towed in a vehicle that can use E-10 or E-15 and compared, I'd suggest you give it a shot. Be prepared for upwards of over 25% difference in gas mileage alone, not to mention reduction of power. [0] https://afdc.energy.gov/fuels/ethanol_fuel_basics.html https://afdc.energy.gov/fuels/ethanol_fuel_basics.html
- credit_guy 3y ago
  Well, as someone else replied in the thread, if pure ethanol (98% is basically pure) has 30% less energy density than gasoline, then a mix of 90% gasoline and 10% ethanol has 3% less energy density. I'm not sure what you mean by E-10. Basically all gasoline that is sold in the US is E-10. You have to look hard to not get E-10. I doubt you have performed the experiment you described, for the simple reason that it's hard to find gasoline that's not mixed with ethanol. I just googled, and apparently gasoline without ethanol is called "recreational gasoline", or REC-90 [1]. [1] https://en.wikipedia.org/wiki/REC-90 https://en.wikipedia.org/wiki/REC-90
  - windexh8er 3y ago
    > I'm not sure what you mean by E-10. Basically all gasoline that is sold in the US is E-10. You have to look hard to not get E-10. I doubt you have performed the experiment you described, for the simple reason that it's hard to find gasoline that's not mixed with ethanol. It's not really productive to make assumptions. Where I live I can buy non-oxygenated gas at almost every station. And, yes, I actually do this experiment all the time given I'll drive to places with a trailer where I'm forced to run an ethanol blend. I realize my comment conflated two things: the reduction of performance and the difference in power per straight gallon. My point is that even with a minimal blend you can lose significant mileage / power. The easiest layman's way to measure that is in MPG. And, yes, there is a significant drop in both power available and MPG. And for reference [0]: "Due to ethanol's lower energy content, FFVs operating on E85 get roughly 15% to 27% fewer miles per gallon than when operating on regular gasoline, depending on the ethanol content. Regular gasoline typically contains about 10% ethanol." The above is in normal driving. So, no, I'm not making my statement up. [0] https://www.fueleconomy.gov/feg/ethanol.shtml https://www.fueleconomy.gov/feg/ethanol.shtml
  - jerrysievert 3y ago
    it's called "clear" gas around here. there's a website that tracks places to buy it in all 50 states: https://www.pure-gas.org https://www.pure-gas.org - but I've noticed that it doesn't track every location and is often wrong about prices, at least in my area. I've never seen "REC-90" and had never heard of it before your posting. clear gas in my area is 92 octane, with up to 110 available in select locations. most everyone I know who drives a performance vehicle, or a motorcycle can tell you where their closest gas station that sells clear gas is. > I doubt you have performed the experiment you described, for the simple reason that it's hard to find gasoline that's not mixed with ethanol. I've performed it many times over the last 17 years I've owned my current car. the results are always the same: 25% better gas mileage with the clear gas. I keep track of my mpg, and am able to quickly see any difference between gasoline grades. I typically drive in my car's "power band", staying between 5000 and 6700 RPM.

arthur2e5 3y ago

> lowers the mean mpg… energy density And that's why we don't quantify energy efficiency using just MPG. You adjust for the density to get some sort of mile per gallon-energy-equivalent. > Making that energy less efficient I have no idea at all how this could happen, except to say that your very rough numbers do suggest a reduction in energy efficiency. EtOH is supposed to have 34% less energy per volume, so for E10 the reduction should be around 3.4% (IGNORING VOLUME CHANGES WHEN MIXING). This matches well with the "up to 2.8%" claim of Wikipedia citing[1], but certainly not what your engine is doing. [1]: https://web.archive.org/web/20070609142818/http://www.raa.net/page.asp?TerID=146 https://web.archive.org/web/20070609142818/http://www.raa.ne... > the fact that we're literally burning food We are all minions of corn. The hope has for a long time been on grass and other stalks full of waste cellulose digestible only by microbes in ruminants and fermentation plants, but these just keep on not delivering. Isobutanol was supposed to be a more gasoline-like biofuel too. Nobody figured out how to make it cheaply enough to burn either.