The Walden Effect: Farming, simple living, permaculture, and invention.

Ethanol: enhanced destruction?

right fuel for the right weed eater

A few years back I got some advice from multiple sources strongly urging me not to use ethanol enhanced fuel on our chainsaw or weedeater.

Today I was reading the new weedeater manual and the section on fuel removed any doubts for me as to if the ethanol issue is a myth or not.

"Gasoline with an ethanol content of more than 10% can cause running problems and major damage in engines with a manually adjustable carburetor and should not be used in such engines."

I should probably read instruction manuals more often.

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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People in Brazil have been driving on E100 (pure ethanol, no gasoline) for years.

It it necessary to adapt the engine, especially the carburator or injection; the energy content by volume for ethanol is 34% lower than that of gasoline, so in a carburator, you'll need a bigger jet. (And yes, your mileage will go down because of the lower energy content, but that is offset IMO because it is much more renewable than petrol. Burns cleaner too.) Also some components of the fuel system might not be resistant against ethanol. However, the octane rating is higher so you can build engines with a much higher compression.

In two-stroke engines standard petroleum-based two-stroke oils won't mix with ethanol, but some synthecic oils do.

Comment by Roland_Smith Mon Jul 25 17:15:21 2011

Well, I don't think I'd call it a myth if it does so much damage to the un-adapted engine. After all, since they're putting adding part ethanol to the gas at the pumps now, most people assume it can be used the same and just put it in their car, chainsaw, lawn mower, etc.

That's a useful tip about some synthetic oils helping, and explaining why it's especially bad in two-stroke engines.

However, I can't really agree with you about ethanol being better for the environment than petrol. (You said "more renewable", which is technically true, but I think that is what you're getting at.) When you start looking into it, at the moment the ethanol used as fuel (at least in the U.S.) is primarily created from corn. That's extremely problematic because many folks report that it actually takes more petrol to drive the big equipment to grow that monoculture corn than you get out of the ethanol! Meanwhile, people who depend on cheap grain to stay alive are getting priced out of their dinners since that corn is being sidetracked to rich people driving SUVs. If we ever get our act together and make ethanol out of really renewable resources, it might be better for the earth, but right now it actually seems worse.

Comment by anna Tue Jul 26 08:11:21 2011

The E85 doesn't harm engines that were actually built with it in mind, i.e. reasonably recent passenger cars. Fuels in general are not interchangeable (e.g. petrol, diesel, hevy fuel oil).

IMO, pre-mix two strokes are generally environmentally unfriendly due to their simple construction and lubrication. They should really be changed to designs with seperate air pumps so we can get rid of the total-loss lubrication, and direct gasoline injection to prevent scavenging losses (where unburnt fuel/air mixture is lost because both the inlet and exhaust ports are open at the same time).

Regarding the renewable thing, I indeed choose my words carefully. :-) But as I understand it, the growing of corn is heavily subsidized in the US, which includes a price floor. With those in play, I don't think a solid argument about ethanol robbing corn for human consumption can be made.

I agree that therre are better feedstocks for ethanol production than corn for the current state of the art of ethanol productions from sugar; like the sugarcane used in Brazil. It will be even better when the bio techniques for making ethanol from cellulose mature, because then we can use material that certainly doesn't compete with foods.

Comment by Roland_Smith Tue Jul 26 10:56:45 2011

While I'm sure you're right that different engines would work fine with ethanol, you have to consider the environmental costs of constructing new vehicles. I'm a firm believer in running cars (and other pieces of machinery) into the ground (we finally gave up on the Festiva when it hit 21), and I think that any realistic fuel model should allow us to do that. I think it's easy for the average consumer to ignore the environmental problems caused by building new things because it happens over somewhere far away, then laud themselves for being able to use better fuel, but in many (most?) cases, I suspect that using the old vehicles is better for the world.

The argument I've read about using corn for ethanol isn't that we're taking food away from poor people in the U.S., but that we end up starving people in Mexico. I can't remember the exact chain of reactions that led to that (too complex to keep in my head), but the source seemed reliable (even though I can't remember it... :-) ) Whether or not my shoddy memory of that is right, you can't argue with the environmental point of using more petrol to grow the corn than you get ethanol back from it. It's a prime example of greenwashing (and of the political power of our corn industry.)

Comment by anna Tue Jul 26 14:26:42 2011

You don't have to build new vehicles. To the best of my knowledge there is nothing fundamental that would prevent four stroke petrol engines from being adapted to ethanol. For engines with a carburator it mostly depends on larger jets. For (electronicly) fuel injected engines it would mean new "mapping" (programming). For both kinds of engines the components of the fuel circuit would need to be tested if they can withstand ethanol and maybe some components would need to be replaced.

W.r.t. the corn situation in Mexico, you should read the Wikipedia article on ethanol fuel in the United States. The situation is complex and it does not seem clear if and what the effects on food prices are. The fact that corn production in the US is heavily subsidized makes is difficult to discern market effects.

It seems clear and undisputed that making ethanol from sugarcane has a much better energy balance than using corn. But cellulosic alcohol would potentially be even better.

Comment by Roland_Smith Tue Jul 26 15:09:02 2011
When used in relatively small percentages (up to 15%) its main purposes are as an oxygenator to reduce carbon monoxide emissions and to boost the octane number.
Comment by Roland_Smith Wed Jul 27 06:11:46 2011

I wonder how much the retrofitting would cost? That could really add up, monetarily and environmentally, if everyone's car had to be retrofitted.

Ethanol is generally added up to 10% in gas stations around here. But I think that would still cause some of the same problems, especially in two-stroke engines, right?

Comment by anna Wed Jul 27 08:28:23 2011

The 10% mix was chosen for its limited effect on things like mileage, performance and carburator settings while still acting as an oxygenator and octane rating booster. But this was probably chosen with only cars and motorcycles in mind.

I'm not sure how a 10% ethanol level would influence e.g. the lubrication of a two-stroke engine that uses pre-mix. It would probably depend on the oil. If the oil dissolves in the E10 and doesn't separate it should be OK, I think. You can easily check that by pouring some E10 into a glas jar, mixing it with the correct amount of two-stroke oil and leaving it standing for a day or so.

I've read hypotheses on the 'net that ethanol in a two-stroke would prevent the two stroke oil from adhering to the insides of the engines. But I find that hard to believe, since those insides would be much hotter than the boiling point of ethanol, even at higher pressures.

W.r.t retrofitting, I found conversion kits from $367. That is a lot less than a new car. :-)

Comment by Roland_Smith Wed Jul 27 18:20:35 2011

The conversion kit is a lot less than a new car, but a lot more than I think is fair to make people have to pay if they're driving old clunkers. I've bought four vehicles in my lifetime and they cost me $800, $500, $1,500, and $2,500. Figuring it's going to cost at least $100 extra to have the kit installed if you're not mechanically inclined, the conversion kit would cost nearly as much as my cheapest vehicle and 19% of my most expensive. I suspect that most people would choose to send their cars to the junkyard and find a way to buy newer ones rather than paying such a high price, which means a lot more cars being constructed and more people in debt --- doesn't sound good for the environment to me...

Interesting idea about the oil-mix test --- we may have to try that!

Comment by anna Wed Jul 27 19:04:48 2011

You might have a point about the cost if there was some mandatory move beyond E10 to say E85. I don't think that is likely. As for the environment, at least in Europe cars are almost totally recycled these days.

And there are other disadvantages to old clunkers. First they tend to be less fuel efficient to start with. People who buy old cars will probably skimp on maintenance as well (1). A badly maintained car is likely to be less efficient and pollute more and is possibly unsafe as well. (1): In Europe cars older than three years have to undergo a yearly inspection for safety reasons. Before that was mandated there were a lot of four-wheeled death-traps around causing accidents (failing brakes, structural members corroded away completely, et cetera). Now it is virtually unheard of.

And ethanol from cane sugar or cellulose has a excellent positive energy balance, more so than corn derived ethanol. But even that is considered to have a positive energy balance.

Comment by Roland_Smith Thu Jul 28 02:29:33 2011

Actually, in the U.S., old cars can often be more fuel efficient. In Europe (with your more realistic gas prices), car manufacturers are sane and have been trying to make more efficient cars over time. Here, I'm ashamed to say, we've instead been building monstrosities.

My old Festiva (that was the $800 car we retired at age 21) got 40+ miles to the gallon, which is comparable to what the highly expensive new hybrids get nowadays. The average new car in 2010 got 33.7 miles to the gallon, which sounds okay until you realize that our government gave the ever-more-popular SUV category a break by turning them into "light trucks", which had an average mpg of 25.1 in 2010. I'll keep my old cars....

Most states in the U.S. also have annual safety inspections.

Comment by anna Thu Jul 28 07:28:28 2011

I think your example of the Ford Festiva is not a very good one. Since it is actually not an american car. :-) It was designed my Mazda and built by Mazda in Japan, Kia in Korea and Ford in Venezuala. Its mileage will probably be superior to contemporary US designs.

Comment by Roland_Smith Thu Jul 28 17:10:27 2011
My other numbers weren't looking just at American cars either --- just the cars on the road in America. Foreign cars are definitely a major component of the market here (although we don't seem to get the most gas efficient versions, it seems like...)
Comment by anna Thu Jul 28 17:29:25 2011

About 1/3rd of the US corn crop is turned into EtOH each year. If the entire crop went into ethoanol, it would offset about 2% of the world's demand for automotive fuel. Keep in mind that just keeping your tires properly inflated can improve your mileage by about 10%. Isn't turning food into fuel pretty stupid?

Studies suggest the US EtOH mandate adds from 25-40 cents to the price of a bushel of corn. With corn now selling around 7 bucks/bu, that's not that much and can't be blamed for any "starvation."

Comment by doc Wed Aug 3 13:18:33 2011

I'm glad to hear from someone with real data. I didn't realize that it would take so much corn to replace gasoline! Put that way, ethanol production does sound like a drop in the bucket.

A 6% increase in the price of a staple food, though, sounds like more of an impact than you give it credit for. People in the poorest countries spend about 55% of their income on food (according to, so if corn was their primary food, that would require them to come up with 3% more money per year or go hungry. That's a pretty significant percentage --- if you make $40,000 per year, you'd have to come up with another $1,200. (I know that you don't spend that much of your income on food and that eating only corn would be seriously bad for your health, but I'm just trying to put it in perspective.)

Comment by anna Wed Aug 3 16:54:33 2011

What is the logic between comparing US corn production with global gasoline usage?

According to this source, gasoline accounts for 58% of all fuels used for transportation, while biofuels (which are predominantly ethanol {15 billion gallons in 2010 in the US (a)} and biodiesel {0,32 billion gallons in the US in 2009 (b)}) amount to 4%.

It seems to me that algae have a much higher potential for fuel production ((c), (d)) than plants though, because of their significantly higher yields per acre and fast growing cycle, and the fact that they can be grown in non-potable water.

Comment by Roland_Smith Thu Aug 4 18:15:29 2011

Roland, let me restate the comparison this way: the US produces over 1/2 of all the corn (maize) produced in the world-- so, if over 1/2 of all world corn were turned into automoticve fuel, only 2% of world demand would be satisfied- as opposed to a 10% by keeping our tires properly inflated. Bio-fuel from food is not very efficient.

You're right about oilgae: it can be grown in 3-D, saving land and harvested continuosly.

Liquid fuel is very convenient for transportation/shipping purposes, as opposed to battery power. Our economy depends on cheap transportation costs and oilgae may be our salvation after oil is depleted.

I always laugh when the TreeHugger types (people who are advocates for conservation, but haven't got a clue about the science) want us to switch to electric autos. We have blackouts now at peak utilization periods because they've blocked nuclear development. How are we gunna supply twice our current juice capability to power cars too?

Comment by doc Fri Aug 5 07:39:25 2011

Roland --- I'm glad you said that, because that's precisely what Mark said when I ran doc's data by him at the dinner table.

Doc --- Thanks for the clarification!

Comment by anna Fri Aug 5 08:46:26 2011

The problem with two-stroke engines is that they're very susceptible to washdown from ethanol. By using an ester-based oil, washdown can be eliminated.

For those arguing about corn ethanol's effect on food prices, you should first know why the corn ethanol program started. U.S. farmers flooded the market with too much cheap grain, which meant that prices dropped and foreign farmers couldn't make a living. By creating a new market for ethanol, the market balanced out. Food prices are driven primarily by oil prices. The corn in a box of corn flakes costs about eight cents, but the energy that goes into transportation, processing and packaging add a few dollars.

Corn has a pretty low EROEI (about 1.4:1) because it needs to be cooked to expose the starch, then it needs to be converted with enzymes before fermentation. Sugarcane is 8:1 because it's already a sugar crop and has a high yield. Small farms are actually more efficient for ethanol production because crops don't have to be transported up to 45 miles away, along with transporting fuel to stations. It's possible to obtain 28+:1 using crops like energy beets or Jerusalem artichokes on a small farm.

Oil companies and OPEC seem to have brainwashed people into thinking that corn is destroyed when it's turned into ethanol. It's turned into dried distiller's grains with solubles, or DDGS. About 28% of the starch is used up in the conversion to ethanol. Before I go continue, another important thing to know is that 70% of U.S. corn is used to feed livestock, either in the U.S. or other wealthy countries. Now... when cattle eat DDGS, they actually gain more meat or milk than straight corn because they don't have to pass that extra 28% starch. Cows can't digest starch so it ends up going out the back door. Humans can also make nutritious foods from DDGS, like breads, muffins and crackers.

When people say that it's inefficient to make energy from crops, I have to ask, "Compared to what?" Oil was about 100:1 and now it's about 10:1. Solar panel efficiency is about 15%. David Pimentel cited the low solar efficiency of plants which is between 3-6%. However, plants are incredibly cheap compared to solar. In the case of perennials, they just keep growing back.

Comment by Cobalt Fri Aug 3 01:37:59 2012
Cobalt- Thanks for the additional numbers and how they relate to corn. Sounds like you are in favor of the Big Corn industry as it functions today. Do you do that type of farming?
Comment by mark Fri Aug 3 09:12:36 2012

I'm not a farmer or anything. There are a lot of problems with modern farming. Some of the biggest are GMOs, monocropping, reliance on petrochemicals and runoff.

I don't support industrial-scale ethanol from corn. I support small-scale, locally-produced ethanol production with sugar crops using organic farming techniques.

Comment by Cobalt Fri Aug 3 13:16:00 2012

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