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Toyota did some pretty substantial-sounding testing in 2000, and CARB published it recently. They found the running E10 instead of MTBE as the oxygenate produced 5.5% higher levels of NOx out the tailpipe.

Although its well-known that evaporative emissions increase noticeably with ethanol, I was not aware of any studies showing an increase in NOx (smog precursors). I didn't guess this at first, but I suppose the extra oxygen present in an already almost-stoichiometric burn has to go somewhere...so it oxidizes the nitrogen hanging around.

I wonder if the noticeably lower combustion temp with E85 are cool enough to inhibit 'burning' the nitrogen?

They mention that CO (also a smog precursor) output dropped 6%. So on balance using ethanol still lowers (barely) the total smog-making emissions. But that is not pointed out. And NOx primarily assists in ozone producton only in the presence of CO, so less CO still means less ozone.

http://www.greencarcongress.com/2006/03/toyota_tests_e1.html#more

source doc: http://www.arb.ca.gov/fuels/gasoline/carfg3/toyota_prstn.pdf

Hi GoNavy:

___Excellent post as usual.

___Because of the Ground Water contamination, MTBE had to go … Whether Ethanol is worse or better then MTBE should not have been the question. What is important is Ethanol laced RFG by comparison to straight up gasoline that most of the rest of the country receives. Notice Toyota’s last sentence in the pdf: More study is needed to determine the emissions effects of RFG3 with ethanol. Well, here is a 2005 ARB study doing just that:

THE EFFECT OF ETHANOL IN CALIFORNIA GASOLINE ON EMISSIONS (http://www.arb.ca.gov/fuels/gasoline/meeting/2005/030105etohrpt.pdf)

___ I believe wholeheartedly in requiring E10 for reducing our dependence on foreign oil although it is making such a small dent as to be almost worthless. What I do not believe in is using Winter/Summer E10 based RFG. There just isn’t any benefit other then some lobbyist and his perspective employer (Big oil with their tens of boutique fuels hampering supply) getting his/her/their pockets lined in some form or fashion. Lots of wheeling and dealing to force the Federal mandates and the states are suffering because of it imho. I am glad I am not one of those smart guys making these decisions …

___Good Luck

___Wayne

I'm fairly certain the testing was done vs MTBE because 1) back in '00 few foresaw the tide against MTBE and coincidence of forces promoting ETOH- oxygenation was here to stay, so it really was apples to apples, and 2) carmakers wanted to prove to CARB that meeting Cali. emissions regs (PZEV, et al) with even just 10% mixed in is a nontrivial challenge. They still tremble at the thought of trying to make a FFV meet PZEV regs- what's Ford's ship date on the FFV FEH...? It will be done- I have no doubts in the engineering prowess- but it will take appreciable effort. Ethanol is a wonderful, yet slippery, little sucker of a molecule.

I can't find the links now, but doesn't the EPA's site have tons of data on gas vs ethanol? The missing piece was comparing the different oxygenates.

However, as you said and has been pointed out, its all OBE now anyway. RIP, MTBE.

question how long did we use MTBE for until banning it today? Is it just the US that just banned it or is it nationwide?

since the advent of unleaded fuel in the 70s to maintain octane, and more so since RFG and oxygenation came to be required in the mid 90s.

It is not banned nationally- a few states and localities have banend it. The producers are running away from it because they see the lawsuit writing on the wall, and do not want to be on the wrong side of that table. Market forces at work all by themselves, in a sort of fashion.

If E10 in your fuel bothers you at all, there are a few companies that meet oxygenate requirements without E10. Shell is one of them. I usually fill up there because it's on the Top Tier Gas list which is endorsed by Honda as well as a few other automakers.

what about chevron, do they still use MTBE?

Chevron is a toptier member, so they use ethanol.

The pipeline owners control the ability to ship MTBE-laden fuel. They all stopped because the energy act of 2005 removed liability coverage for any MTBE litigation, in addition to the Feds requiring xyz amount of ethanol to start being used (7.5billion gal/year, I think?)