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Toyota Tests: E10 vs. MTBE for Tailpipe and Evaporative Emissions

Toyota_mtbe
Summary of Toyota’s emissions findings.

Tests done by Toyota in 2000, and just published by the California Air Resources Board, show that compared to using MTBE as an oxygentate, using about a 10% blend of ethanol as an oxygenate in gasoline increases NOx tailpipe emissions and evaporative emissions in vehicles.

Toyota tested the different blends in a number of vehicles—the LS 400, Sequoia, GS 300, ES 300, 4Runner, Camry, Corolla and Echo—and found that on average the use of E10 increased NOx emissions 5.5% over MTBE, while reducing emissions of NMHC by 0.3% and CO by 6%.

MTBE (methyl tertiary-butyl ether) is a chemical compound that is manufactured by the chemical reaction of methanol and isobutylene and is used almost exclusively as a fuel additive in motor gasoline.

California banned the use of MTBE in 1999 due to the threat it posed to groundwater when underground fuel tanks leak, and switched to ethanol as an oxygenate instead. MTBE is more difficult to remove from water than other components and, in small amounts, renders drinking water unusable. Fifteen other states have also banned the additive, with others considering such measures as well.

Toyota_mtbe2

The E10 blend, in addition to producing more NOx out, proved more volatile and with higher permeation than the MTBE blend. While that makes achieving near-zero emissions “challenging”, according to Toyota, it makes achieving zero-emissions “very difficult.”

These characteristics of ethanol blends, highlighted in this assessment of lower E10 blends, add to the challenge for automakers who are seeking to develop flexible-fuel (E85) hybrids and still achieve the PZEV status—Ford being the case in point with its work on the E85 Escape Hybrid. (Earlier post.)

Comments

Mark A

Hmmm, it would appear that some of these "godsend" solutions, such as growing our fuel in place of growing our food, arent as all encompasing of a solution as first thought. Do you think GM knows about these higher NOx emissions now with its "yellow" campaign, and have a solution for them?

Electric cars, with better batteries and capacitors, and DME fuel for over the road diesels truck and locomotives should be one of the directions for the future.

Brett

This data has a serious spread. You're going to need some serious statistics to get any useful and realistic conclusions out of that spread. And why did it take 5 years to publish? The volatility of ethanol is an issue. However it boils down to: Can you seal your fuel in a tank without any getting out? I find it hard to believe that this in unachievable. Gasoline has a significant volatility, and they figured out the problem, so it should be doable with minimal additional cost.

tom deplume

The comparison was E10 vs MTBE. Anybody have the emission figures of E10 vs gasoline? What are the figures for E85?

Angelo

I'm not an engineer, but wasn't this testing performed on current vehicles using their existing emission control systems & catalysts, that may not have necessarily been optimized for E10 in the first place? This might make it more challenging than if MTBE was used, but if we are close to getting diesel's to meet emissions standards, I'm sure this could be done....

If MTBE can poison our water, should our biggest concern be the 5% increase in NOX emissions?

Tripp Bisop

Also, NOx emissions is one part of the problem but CO is also a powerful ozone producer. Ethanol cut CO emissions by a larger margin than the increase in NOx. Stangely the importance of that wasn't discussed.

An Engineer

Ethanol is not a very good fuel. Period. It takes a ton of energy to separate it from water (if produced by fermentation), it has a high vapor pressure and it is hygroscopic. As currently sold to US voters it is just another farm subsidy in disguise.

I know, cellulosic ethanol would be better than corn ethanol. But at the end of the day, ethanol just is not the right solution.

Gasification/F-T yields fuels that are virtually indistinguisable from today's fuels. So, not only can you blend these into the existing fuel supply at any ratio convenient, they also share all the advantages to today's liquid fuels.

Unfortunately, ethanol has the farm state politicians behind it, which means in today's spineless political scene, there will be no serious questions about the serious amount of your tax dollars going to waste, or more precisely, to enrich a few well-connected political donors...

A Better Engineer

"Gasification/F-T yields fuels that are virtually indistinguisable from today's fuels."

I'll say, you got all the same pollution and CO2 emmission problems.

You'd be better of using the hydrogen from the gasification process directly. You can run it through a pressure swing absorption unit for purification and then use it in a fuel cell vehicle.

Justin

So how about testing E10 vs straight gasoline. California is forced by the federal gov to import ethanol from the midwest as a form of farm subsidy. At the same time the federal GOV prohibits ethanol imports from abroad namely Brasil which is much much cheaper. YAY for farm subsidies.

Angelo

"Ethanol is not a very good fuel. Period. It takes a ton of energy to separate it from water (if produced by fermentation), it has a high vapor pressure and it is hygroscopic."

Not a good fuel as compared to what? F-T fuels would still come mostly from fossil fuels (I would agree that those derived from waste do have a huge potential though). Yes, hydrogen can even be turned into F-T, but the only way that is really a benefit is if hydrogen can be derived using solor or hydro power.....doesn't seem to be happening anytime soon.

I think one could say that it takes a TON of energy to separate GAS from the GROUND! It takes a TON of energy to just COMPRESS hydrogen.

This high vapor pressure is more difficult to manage than say.....the constant bleed-off required for liquid hydrogen?

Assuming most ethanol would be stored in a sealed container, is the fact that it is hydroscopic really that much of a hurdle to overcome?

I don't know....ethanol is cleaner than gasoline, renewable, domestically produced, and can be used within our current infrastructure with limited modifications. What are your criteria for a "good fuel"?

Brett

Back to the topic, whether there really is a difference between the emissions performance for these two fuels. The vehicles in the study were all Toyotas. Who knows how the emissions systems from other car companies react to the difference in fuels. I'd be willing to bet that they perform differently.

Justin

I still want to see E10 tested against regular 100% gasoline. They are forcing this ethanol into my car without any evidence that it does anything for in a modern car other than reduce fuel economy by 3-10%.

An Engineer

I would think that "A Better Engineer" would get the underlying assumption right. To spell it out: using biomass as a feedstock to produce a liquid fuel. G/F-C would produce a superior fuel that is chemically alsmost identical to existing fuel supplies and can therefore be blended into the existing supply at any required ratio. No engine adjustment required. No change in all the beneficial properties of the existing supply. Lower in sulfur, so not the same pollution problems. Carbon neutral, so no GHG concern. Capable of processing most carbon containg waste, unlike ethanol which requires the feedstock to be converted to fermantable sugar.

No good engineer could get excited about hydrogen, as a simple review of the difference between pumping (and storing) liquids and gases would show (Oh, you have a car under that hydrogen tank?). Add to that hydrogen's tendency to go WOOF! and the conclusion is elementary, my dear Watson.

David

I would totaly suport farm subities if they make all the corn into E85 and stop the production of High frutose corn syrup which is being proven to be very unhealty for us and has been a factor in the fating of america as well as the record rise in type 2 diabeties

Guest

All you need to know about MTBE: http://www.mtbelitigationinfo.com/

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