Oxygenated Gasoline: Still Needed or Useful with Modern Engines?

[MRC01]

Back when oxygenated fuel was mandated, many of the car engines on the road were carbureted or early generation fuel injection "dumb" engines. Oxygenated fuel made them run leaner, they could not detect it and compensate. In that sense, the oxygenates could have achieved the intended effect of reducing emissions.
Fast forward a few decades, most of the engines on the road are "smart". They detect the A/F ratio and compensate. Oxygenated fuel won't make them run leaner, it will just make them ring up more fuel to richen the mixture to compensate.
So, do oxygenated gasoline mandates still have any use or benefit? If so, what is it? If not, is it time to retire these mandates?

 

[tmorris1]

I think the only use is to support local farmers more than anything. Maybe a little less emissions since ethanol is supposed to burn cleaner?

 

[brianl703]

Oxygenates are also used as an octane booster. So even if not mandated, you'll still find it being sold.

 

[JohnnyG]

The first go-around with Ethanol was exactly as you say, so it was discontinued, FOR A FEW, MAYBE 10 YEARS. ( I was there to see it) Then as an octane booster, it came back into vogue. Now it has become such a political football, that you would be hard pressed for any official to say that it's not necessary.
The worldwide food crisis, with Ukraine production off the market might change that, but it will take years to accomplish.
It's a proven fact that Ethanol production creates more greenhouse gasses than it saves.

 

[BMWTurboDzl]

Still needed.

They reduce soot and CO which is separate from the performance gains of higher octane.

 

[y_p_w]

Some sort of oxygenate is still mandated in certain areas because it reduces certain emissions. But the whole thing about high blending octane for ethanol (and that MTBE is too much of a hot potato) means that ethanol is here to stay. I assume that all the fuel I get is at or near the maximum ethanol. It is a bit tricky because most fuel isn't. "Fuel ethanol" is denatured with up to 5% (I think a minimum of 2%?) gasoline to make it unsafe to consume in beverages. So some will actually use more than 10% fuel ethanol where the end result is closer to 10% actual ethanol.

 

[MRC01]

Oxygenate and Octane are 2 different things. We can boost octane with Xylene or Toluene, which have benefits over ethanol as an octane booster:
1. They have lower sensitivity (tighter MON-RON spread)
2. They have higher energy density - which means better fuel economy
3. They are relatively non-toxic

Put differently, ethanol is not the best octane booster since it has high sensitivity and low energy density. The only real purpose it serves is as an oxygenate, and I'm wondering if modern engines obviate the need for this.

 

[Rmay635703]

Octane yes oxygenate nope, does absolutely nothing for a modern car

 

[brianl703]

Oxygenate and Octane are 2 different things. We can boost octane with Xylene or Toluene, which have benefits over ethanol as an octane booster:
1. They have lower sensitivity (tighter MON-RON spread)
2. They have higher energy density - which means better fuel economy
3. They are relatively non-toxic

Put differently, ethanol is not the best octane booster since it has high sensitivity and low energy density. The only real purpose it serves is as an oxygenate, and I'm wondering if modern engines obviate the need for this.

The EPA limits the amount of aromatics in fuel (that's benzene, toluene, xylene--aka BTX) because they are believed to contribute to air pollution. Specifically ultra-fine particulates (UFPs) and polycyclic aromatic hydrocarbons (PAHs).

 

[garageman402]

Back when most stations sold gas with MTBE as an oxygenate, you could tell the difference in performance if you happened to get gas with ethanol in it. Beacon stations were the only ones that had ethanol at that time, IIRC. But MTBE is water soluble and polluted lakes especially when used in 2-stroke boat/jet-ski engines.

The only stations that sell non-ethanol gas to my knowledge is Buc-ee's in Texas. Price is considerably higher, tho. Lol

 

[jhellwig]

Still needed.

They reduce soot and CO which is separate from the performance gains of higher octane.

This.

I think it effects NOx emissions also.

Kinda like EGR, air injection and catalyst. They don't decrease emissions. They trade more harmful ones for less harmful ones.

 

[Luftmasse]

This.

I think it effects NOx emissions also.

Kinda like EGR, air injection and catalyst. They don't decrease emissions. They trade more harmful ones for less harmful ones.

Can you elaborate why these 3 emission control devices does not decrease emission? What is the purpose of having them?

 

[Rmay635703]

Can you elaborate why these 3 emission control devices does not decrease emission? What is the purpose of having them?

Which emissions?

The supply side of fuel makes emissions that dwarf what your car emits in pollution on a per gallon delivered basis if we include VOC from spoilage and spills and heavy metal pollution from extraction.

This isn’t mentioning random stationary industrial pollution sources are nearly unlimited in certain cases and usually don’t have to follow as stringent of requirements as a vehicle.

So US Centric is nearly 100% focused on one specific emission with a distant second on sulphur/particulate and this focus is mostly on road going vehicles and power plants, distant 3rd being homes.
Further we measure emissions not by weight per mile but by percentage.

The issue is not whether those devices decrease emissions percentage in the exhaust, they certainly do and in an inversion layer are needed.

But outside that inversion layer is it worth burning 20% more fuel alongside the resources and pollution created to maintain the devices in question including the fact that the supply side “creating” your gallon of fuel delivered dwarfs your car’s emissions?

AKA to reduce primarily NOX and some VOC (in the summer at least) we burn 20% more fuel which creates 20% more co2 and a token amount of carbon monoxide.

Open up Nox limits, outside inversion layers and using the existing Pollution controls but tuned differently can save 20% fuel, despite claims to the contrary Nox does go up in lean but with any cat the amount it goes up is far less than the 40’s era chart everyone posts suggests.

Holistically the only way to reduce overall pollution is to use less fuel and less energy but nobody likes that answer.

That is even true of Bev, we need to use less energy to make less pollution whether the pollution is in the air, water ground or in my neighbors backyard instead of mine doesn’t matter.

All energy conversion devices cause some form of pollution whether it’s during use or during assembly in the air, in the ground or in the water, still makes a form of pollution.

 

[Luftmasse]

Which emissions?

The supply side of fuel makes emissions that dwarf what your car emits in pollution on a per gallon delivered basis if we include VOC from spoilage and spills and heavy metal pollution from extraction.

This isn’t mentioning random stationary industrial pollution sources are nearly unlimited in certain cases and usually don’t have to follow as stringent of requirements as a vehicle.

So US Centric is nearly 100% focused on one specific emission with a distant second on sulphur/particulate and this focus is mostly on road going vehicles and power plants, distant 3rd being homes.
Further we measure emissions not by weight per mile but by percentage.

The issue is not whether those devices decrease emissions percentage in the exhaust, they certainly do and in an inversion layer are needed.

But outside that inversion layer is it worth burning 20% more fuel alongside the resources and pollution created to maintain the devices in question including the fact that the supply side “creating” your gallon of fuel delivered dwarfs your car’s emissions?

AKA to reduce primarily NOX and some VOC (in the summer at least) we burn 20% more fuel which creates 20% more co2 and a token amount of carbon monoxide.

Open up Nox limits, outside inversion layers and using the existing Pollution controls but tuned differently can save 20% fuel, despite claims to the contrary Nox does go up in lean but with any cat the amount it goes up is far less than the 40’s era chart everyone posts suggests.

Holistically the only way to reduce overall pollution is to use less fuel and less energy but nobody likes that answer.

That is even true of Bev, we need to use less energy to make less pollution whether the pollution is in the air, water ground or in my neighbors backyard instead of mine doesn’t matter.

All energy conversion devices cause some form of pollution whether it’s during use or during assembly in the air, in the ground or in the water, still makes a form of pollution.

He listed EGR, Air injection and Catalyst.

 

[Rmay635703]

He listed EGR, Air injection and Catalyst.

Which are primarily in this country used to reduce nox and due to how the cars are tuned that means increased “Carbon” emissions yearound and increased VOC in the winter as your car burns twice as much fuel attempting to light the cat.

Those extensively driving short winter trips would benefit greatly from have the lengthy warmup phase tuned out given it just spits raw gas and ruins the cat prematurely, also kills your pocketbook

 

[Luftmasse]

Which are primarily in this country used to reduce nox and due to how the cars are tuned that means increased “Carbon” emissions yearound and increased VOC in the winter as your car burns twice as much fuel attempting to light the cat.

Those extensively driving short winter trips would benefit greatly from have the lengthy warmup phase tuned out given it just spits raw gas and ruins the cat prematurely, also kills your pocketbook

Well, a healthy engine will produce high amount of CO2%. This would be an arduous mission to lower down Carbon Emissions.

 

[Rmay635703]

Well, a healthy engine will produce high numbers of CO2%. This would be an arduous mission to lower down Carbon Emissions.

But that is what we are tasked with,

Pollution is pollution, NG fuel efficiently makes more exotic pollution but less CO2

There have been several vehicles that minimize energy use and I own one of them

There is even a 16mpg streamlined 80,000lb bullet semi w/ load that came about the last fuel crisis .

If we are serious efficiency and simply not using energy is how we have to go.

 

[jhellwig]

Well, a healthy engine will produce high amount of CO2%. This would be an arduous mission to lower down Carbon Emissions.

Research smog and acid rain. Those were the big drivers behind emissions controls on vehicles that started in the late 60s and 70s. It is a short term problem with severe consequences to health. Oxygenated fuel, computer controls, better equipment and a better understanding of how things work have led to a different way of controlling these emissions but control is still necessary because the technology isn't perfect.

Everyone complains about how energy production creates massive emissions which it does but they being controlled in some ways like the emissions on your car are. Trading more harmful ones for less and spreading what ones cannot be controlled over a wide area till the concentration is not immediately harmful to life. The later part is not something easily done with a bunch of cars bunched up in one area with buildings keeping air stagnant.

Carbon emissions have only recently come into focus as being an issue in the long run which is why the push for reducing it has come up but it is not the reason vehicle emission controls are needed. As said the only way to reduce CO2 emission is to use less energy but trading more harmful emissions for CO2 is better in the short term.

 

[redbone3]

Alcohol reduces NOX be reducing the combustion termperature. EGR does the same.

 

[Skippy722]

Further we measure emissions not by weight per mile but by percentage.

EPA standards for vehicles is measured in grams per mile.

For Tier 3 (phase in started in 2017, full effect by 2025) a manufacturers fleet average for NOx+NMOG is 0.03g/mi with Bin limits starting at 0 and going up to Bin 160 with 0.16g/mi. CO, PM, and HCHO do not have fleet average mandates.

Tier 2 (2004-2016) was a big higher, NOx across the fleet must be 0.07g/mi, with the bins ranging from 0 to .20g/mi, NMOG was separate at 0 to 0.125g/mi with no fleet average for it or the rest.