5 ms·

that doesn't make sense. there is clear gas with 110 octane, and most clear gas is 92 octane. clear gas does not have ethanol nor lead. there are other octan

that doesn't make sense. there is clear gas with 110 octane, and most clear gas is 92 octane. clear gas does not have ethanol nor lead. there are other octane boosters that don't raise the price of food. editing to add that other octane boosters don't drop mpg efficiency nearly as much as ethanol does. ethanol also has a much lower energy content, meaning a much lower mpg.

credit_guy 3y ago
Petroleum contains many hydrocarbons, with chains of different lengths. Octane (C8H18) is one. Refineries separate various hydrocarbons. In principle a refinery can separate pure octane. If sold at the pump, that would be by definition gasoline with 100 octane rating. The majority of the hydrocarbons are worse than octane, but some are slightly better. So you could have gasoline without any additives that has an octane rating slightly higher than 100. The problem is that most chains have octane rating significantly lower than 100. What do you do with them? You throw them? Of course not. People create different blends, and add some additives so they can sell as much of the original petroleum as gasoline with a decent octane rating. Yes, there are some other octane boosters. The main ones today are 3: ethanol, MTBE and ETBE. MTBE and ETBE are derived from methanol and ethanol respectively [1]. I don't know if there is anything wrong with MTBE or ETBE, but the ethanol lobby managed to push the idea that ethanol is good, so it is widely mixed in gasoline in the US. According to the DOE [2]: Lower-octane gasoline is blended with 10% ethanol to attain the standard 87 octane. [1] https://en.wikipedia.org/wiki/Methyl_tert-butyl_ether#Alternatives_to_MTBE_as_an_anti-knock_agent https://en.wikipedia.org/wiki/Methyl_tert-butyl_ether#Altern... [2] https://afdc.energy.gov/fuels/ethanol_fuel_basics.html https://afdc.energy.gov/fuels/ethanol_fuel_basics.html
- jabl 3y ago
  MTBE/ETBE is banned in many places due to groundwater contamination. But ethanol-less gasoline wouldn't be a disaster either, it would mean the refiners would have to do more processing (alkylation, reformation etc.) to increase the octane of the gasoline, which would increase costs. But OTOH without an ethanol mandate there might be less cost via agricultural subsidies etc., so it wouldn't surprise me if the total cost to society would be less. There are also some other octane boosters that could be used (which aren't environmental disasters like lead, or arguably corn ethanol), like aromatic amines.
- jerrysievert 3y ago
  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
- maxerickson 3y ago
  MBTE is a persistent ground water contaminant. Ethanol is definitely a better oxygenate.
- deleted 3y ago
  [deleted]
- Retric 3y ago
  You’re missing the chemistry involved, refineries don’t just separate out the constituents of oil as their name suggests. They manufacture the specific hydrocarbon blends using heat, catalysts, steam, and solvents that maximize the value of that oil. EX: https://en.wikipedia.org/wiki/Cracking_(chemistry) https://en.wikipedia.org/wiki/Cracking_(chemistry)
thsksbd 3y ago
But how much octane 110 fuel can you squeeze from a barrel of oil?

credit_guy 3y ago

Petroleum contains many hydrocarbons, with chains of different lengths. Octane (C8H18) is one. Refineries separate various hydrocarbons. In principle a refinery can separate pure octane. If sold at the pump, that would be by definition gasoline with 100 octane rating. The majority of the hydrocarbons are worse than octane, but some are slightly better. So you could have gasoline without any additives that has an octane rating slightly higher than 100. The problem is that most chains have octane rating significantly lower than 100. What do you do with them? You throw them? Of course not. People create different blends, and add some additives so they can sell as much of the original petroleum as gasoline with a decent octane rating. Yes, there are some other octane boosters. The main ones today are 3: ethanol, MTBE and ETBE. MTBE and ETBE are derived from methanol and ethanol respectively [1]. I don't know if there is anything wrong with MTBE or ETBE, but the ethanol lobby managed to push the idea that ethanol is good, so it is widely mixed in gasoline in the US. According to the DOE [2]: Lower-octane gasoline is blended with 10% ethanol to attain the standard 87 octane. [1] https://en.wikipedia.org/wiki/Methyl_tert-butyl_ether#Alternatives_to_MTBE_as_an_anti-knock_agent https://en.wikipedia.org/wiki/Methyl_tert-butyl_ether#Altern... [2] https://afdc.energy.gov/fuels/ethanol_fuel_basics.html https://afdc.energy.gov/fuels/ethanol_fuel_basics.html

jabl 3y ago
MTBE/ETBE is banned in many places due to groundwater contamination. But ethanol-less gasoline wouldn't be a disaster either, it would mean the refiners would have to do more processing (alkylation, reformation etc.) to increase the octane of the gasoline, which would increase costs. But OTOH without an ethanol mandate there might be less cost via agricultural subsidies etc., so it wouldn't surprise me if the total cost to society would be less. There are also some other octane boosters that could be used (which aren't environmental disasters like lead, or arguably corn ethanol), like aromatic amines.
jerrysievert 3y ago
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
maxerickson 3y ago
MBTE is a persistent ground water contaminant. Ethanol is definitely a better oxygenate.
deleted 3y ago
[deleted]
Retric 3y ago
You’re missing the chemistry involved, refineries don’t just separate out the constituents of oil as their name suggests. They manufacture the specific hydrocarbon blends using heat, catalysts, steam, and solvents that maximize the value of that oil. EX: https://en.wikipedia.org/wiki/Cracking_(chemistry) https://en.wikipedia.org/wiki/Cracking_(chemistry)

thsksbd 3y ago

But how much octane 110 fuel can you squeeze from a barrel of oil?