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Study concludes US will not meet Renewable Fuel targets with ethanol as primary biofuel

If ethanol is the US’ primary biofuel, it will be “essentially impossible” to achieve the federal Renewable Fuel Standard volume mandates because of the ethanol blending limit (the “blend wall”), regardless of whether it is the current 10% or raised to 15%, according to a study by researchers at Purdue University.

The constraint, the authors say, is not economic but infrastructural, and “it is highly unlikely that adequate infrastructure [i.e., flex-fuel vehicles and E85 fuel dispensers] can be put into place in time to achieve the RFS goals.” However, they concluded, the RFS could be met with a combination of ethanol from corn and sugarcane and renewable hydrocarbons from biomass.

The study was presented as an invited paper at the 2010 annual meeting of the Agricultural and Applied Economics Association in Denver, CO and published in the American Journal of Agricultural Economics.

Wally Tyner, the James and Lois Ackerman Professor of Agricultural Economics, and co-authors Frank Dooley, a Purdue professor of agricultural economics, and Daniela Viteri, a former Purdue graduate student, used US Department of Energy (DOE) and Environmental Protection Agency (EPA) data to conclude that the United States is at the saturation point for ethanol use.

The federal Renewable Fuel Standard requires an increase of renewable fuel production to 36 billion gallons per year by 2022. About 13 billion gallons of renewable fuel was required for 2010, the same amount Tyner predicts is the threshold for US infrastructure and consumption ability.

Total national consumption of gasoline in the United States has been about 140 billion gallons in 2010 and is expected to fall over time due to increasing fuel economy standards (Tyner and Viteri 2010). Thus, at present, if every drop of gasoline were blended as E10, the maximum ethanol that could be absorbed would be 14 billion gallons. In reality, 10% cannot be blended in all regions and seasons. Most experts consider an average blend of 9% to be the effective maximum, which amounts to about 12.6 billion gallons (Tyner et al. 2008). US ethanol production capacity already exceeds this level. Thus, our ability to consume ethanol has reached a limit called the blend wall.

This physical constraint is the biggest issue facing the US ethanol industry today. If the current blending limit of 10% is maintained, the ethanol industry cannot grow; indeed, it cannot even operate its existing productive capacity of over 13 billion gallons. That partially explains why about 2 billion gallons of capacity was shut down during much of 2009, and over 1 billion gallons of capacity remains inoperative. It also explains why ethanol prices during much of 2009 were driven mainly by corn instead of gasoline, as it had been previously.

...At present we face two opposing realities: first, the RFS requirements for production of more biofuels each year to 2022; and second, a physical blend wall that does not permit ethanol consumption to grow at all beyond present levels. An ethanol industry support and lobby group called Growth Energy petitioned the EPA to increase the blending limit from 10% to 15%.The EPA has indicated it will rule during the fall of 2010 whether this limit can be increased to 15% after additional vehicle tests are completed. But even increasing the blending limit to 15% will only buy some time (about four years) so long as ethanol remains the primary biofuel.

—Tyner et al.

The team examined the consequences of six alternative pathways to reaching the RFS targets:

  1. The blend limit remains at 10% (E10), and all biofuel is ethanol.
  2. The blend limit is increased to 15% (E15), and all biofuel is ethanol.
  3. The blend limit is 10% (E10), and all cellulosic biofuel is thermochemically produced biogasoline or equivalent. The physical properties of thermochemical biofuel are identical with gasoline, and thus it can be similar to gasoline at any percentage.
  4. The blend limit is 15% (E15), and all cellulosic biofuel is thermochemically produced biogasoline or equivalent.
  5. The blend limit is 10% (E10), and cellulosic technology is so expensive that EPA waives the cellulosic part of the RFS.
  6. The blend limit is 15% (E15), and cellulosic technology is so expensive that EPA waives the cellulosic part of the RFS.

Tyner said there simply aren’t enough E85 flex-fuel vehicles or E85 stations to distribute more ethanol. According to EPA estimates, flex-fuel vehicles make up 7.3 million of the 240 million vehicles on the nation’s roads. Of those, about 3 million of flex-fuel vehicle owners aren’t even aware they can use E85 fuel.

Also, there are only about 2,000 E85 fuel pumps in the United States, and it took more than 20 years to install them.

Even if you could produce a whole bunch of E85, there is no way to distribute it. We would need to install about 2,000 pumps per year through 2022 to do it. You’re not going to go from 100 per year to 2,000 per year overnight. It’s just not going to happen.

—Wally Tyner

Even if the fuel could be distributed, E85 would have to be substantially cheaper than gasoline to entice consumers to use it because E85 gets lower mileage, Tyner said. If gasoline were $3 per gallon, E85 would have to be $2.34 per gallon to break even on mileage.

In short, ethanol cannot be the only biofuel in the US market, given current and possible future blend levels and the low level of penetration of FFVs and E85 stations. The blend wall becomes an impenetrable barrier to meeting the RFS.

—Tyner et al.


  • Wallace E. Tyner, Frank J. Dooley, and Daniela Viteri Alternative Pathways for Fulfilling the RFS Mandate (2010) Alternative Pathways for Fulfilling the RFS Mandate Amer. J. Agr. Econ. 1–8; doi: 10.1093/ajae/aaq117



The irony is that EVs and PHEVs make the target even less attainable, while being better at the primary goal (reducing US oil demand).

The thermochemical route is probably the one most worth pursuing. Not because it eliminates the blend wall, but because it would produce non-petroleum feedstocks for chemical synthesis of other products. This allows a relatively seamless changeover of e.g. plastic production.

Long-term sequestration of bio-carbon as durable plastic products is a potential bonus.


More corn/grain/sugar cane based ethanol is not the proper solution. Escalating food prices have already started hostilities with bloodshed in Tunisia, Algeria and other places. Sugar price is up 57% in the last 12 months and it will keep going up as long as sugar canes are used to produce ethanol. Animal feed (and meat) will follow the same spiral if more corn is used for ethanol.

We cannot and should not starve the world to feed our gas guzzlers and reduce crude oil imports. Too many people will rightfully hate us for doing so.

There are many other better ways to reduce crude imports.

We should find and implement ways to reduce our (vehicle fleet) liquid fuel consumption. One of the more effective way would be to revise CAFE to 40 mph by 2015/16 and increase it by at least 2 mpg per year to reach 50 mpg by 2020 and 60 mpg by 2025 etc. It can be done. Hyundai already said that they will do even better. If Hyundai can do it so can all other vehicle manufacturers.

Dynamically test all vehicles regularly for fuel consumption and adjust registration fees accordingly. Let the liquid fuel users pay for their high consumption.

Progressively increase (all) liquid fuel tax by $0.02 to $0.05 per month until average price reaches $6.00 to $7.00 per gallon.

Use part of the extra tax revenues:

1. to advance electrified vehicles market penetration and to develop and produce batter lower cost batteries.

2. to help cities to upgrade there buses/vehicles to electrified units.

3. to buy electrified vehicles for government offices and agencies.

4. to increase production of clean electricity.

5. to move USA into the new electrification age.


Clearly this ethanol fever was a terrible idea to start with. Ethanol is not the right choice as a biofuel. Biofuel has to be blended with gazoline with no limit, period. So Butanol or Grassoline but ethanol is a distraction at the best.Biofuel can play a role in offsetting oil dependency but we need something smarter than ethanol.


If you can make synthetic gasoline from natural gas and biomass then the problem would seem to be solved. The goal should be to reduce oil imports, whether EV/PHEV, E85, methanol, fuel cells or whatever, reduce oil imports.


If a plug in vehicle allowed you to do most of your miles on electric, you will only need a small amount of liquid fuel. This will make your limited bio-fuel go further if you will pardon the poor pun!


Using food stock to produce liquid fuels for our gas guzzlers is a near sighted subterfuge concocted by large corn and sugar cane growers and gas guzzler makers to:

1. raise to price of all food products and increase farming conglomerates profits.

2. justify making more high profit gas guzzlers.

3. shift $$$$B, from crude oil producers, to USA and other food exporters.

The plan will misfire because people will rise against higher food prices. A few countries, with large productive land mass, cannot elect to feed their gas guzzlers by starving a high percentage of the world human population for an extended period of time. It is unfair, wrongful and will drive many to anarchy and into the arms of terrorist organisations.

We cannot fix our energy problems on the backs of others. If we do, it will come back to haunt us.


The food/fuel discussion has been done over and over, use cellulose instead of grain, that is obvious. 100 million true FFVs on the road opens a whole new alternative fuels industry.

Pointing to the fact that E85 pumps have lagged deployment just outlines the problem. If I have a franchised gasoline station I need permission to install an alternative fuel pump from the oil company. It is highly unlikely that I will get that permission from a company that does not make alternative fuels.


SJC the time has come to seriously consider ways to use less liquid fuels not to find ways to extend the status quo for another century.

Since the total switch may take 30 to 40 years it is not too early to start moving. The goals should not be to replace fossil fuels with bio-fuels but to do away with most liquid fuel uses except where it is very difficult to do so, like for heavy commercial airplanes.


Harvey and long range with heavy load like trucking that consumes almost half of the oil consumed in US. In is not tomorrow that you are going to power a 30 Tons truck over 500miles with batteries.


The answer is butanol produced from non food biomass, no blending problem, almost the same heating value as gasoline, no pipelines rotting out problem, and no food shortage.

We don't need more studies and reports telling us what we already know.


Mannstein and Harvey have it right imho.
Butanol, biodeisel, and biogassoline from non-food sources including farm waste, bioGTL, dry-land energy crops, and algae.
...and EVs/PHEVs with increase solar, wind, geothermal, tidal, and nuclear.
...and may the best technologies come to dominate.

Treehugger said: "long range with heavy load like trucking that consumes almost half of the oil consumed in US."
That is FALSE. Light trucks and cars account for 50% (actually it might be closer to 60%), heavy trucks and airliners account for something like 20%, and industrial use (plastics, fertilizers, etc) account for the remainder. Look it up or provide a source.
He also said: "In is not tomorrow that you are going to power a 30 Tons truck over 500miles with batteries."
Now that I can agree with. So! This doesn't take away from getting light trucks and cars off oil! Again, Treehugger shows he's a naysayer in disguise. Want us to go back to a pastural existance? Not me. Lower population, sure. Farming the land by hand? No thanks.


"The irony is that EVs and PHEVs make the target even less attainable"
I don't agree. What makes you say this?



ok 20% not 50%, my point was not about the numbers though I also doubt that light truck can make it to electric, i was just pointing out that electric is not the answer to everything and research is still required in alternative liquid fuels, I don't think there is any nay saying in disguise behind this. As for farming the land by the hand, please keep it for yourself I never supported such an absurdity.

I don't agree. What makes you say this?
Electric vehicles make the ethanol target harder to hit because you can't blend alcohol with electricity. More EVs means less liquid fuel consumed which means less alcohol blended unless the concentration goes over 10%; perhaps well over 10%. The only "solution" is probably E85, and nobody wants to buy it (without big subsidies) because it's a poor deal.
If a plug in vehicle allowed you to do most of your miles on electric, you will only need a small amount of liquid fuel.
3PeaceSweet has it exactly right.

The goal should be just what is happening now. The steady transition to electrification via EV and PHEVs that CAN use E85 or blends. We put this into application when the Volt incorporates a FF ICE in the next gen model.

What will this do practically? Allow the 2+ million green car owners to begin to use a MORE GREEN FUEL. Obviously at the 15% level - blends will not meet the RFS. But it is MOVING IN THE RIGHT DIRECTION. Since it is economically and politically (security-wise) positive to lower payments for foreign oil and spend the saved $$ domestically.

The food/fuel claim is largely bogus and Harvey mistakenly supports the oilcos with this position. IF more corn goes to make fuel and cattle feed goes up - people MIGHT JUST EAT LESS BIG MACS. A friggin health benefit!!!

Now, for the butanolites amidst us check out Butazyme Inc:

And Coskata, and Range Fuels continue down the road of cellulosic-based fuels with a new goal of $60-70 barrel, making scale-up realistic. To the Obama Administration's credit, the USDA continues to support rapid commercialization in this area.

Here is a plausible scenario: GM Volt and Prius dealers install one E85 fuel pump in their dealership. GM/Toyota then subsidize the fuel at $2.00/gallon for Volt/Prii owners who have purchased next gen FFVs and want to be as GREEN as possible. "You only need a small amount of liquid fuel."

Biofuels will play an expanding role in the development of sustainable energy and there's little point fighting it. Emphasis on waste2fuel should be the focus. And looking at corn ethanol as a human health benefit during its short transitional life - demonstrates sustainable vision.


The Open Fuel Standard will have all new cars be true FFV, that means HEV/PHEV/EREVs as well. I have advocated for a long time that all the electrified vehicles be true FFV.

This either/or discussion makes no sense, it is an AND deal. Saying that everyone should drive an EV and if they don't it is their fault makes no sense.

People will buy and drive EVs if it makes sense to them. The OFS is a national security issue and as such every new car sold will be a true FFV at very low cost.


There is nothing wrong with HEVs and PHEVs for cars and light trucks but they are useful and necessary transitional technologies. We all know that by 2020 or so, EVs with 100+ Kwh quick charge batteries will not need on-board genset. A possible exception may be long range heavy vehicles where an on-board genset or FC may be required until such time as those heavies can pick up energy on the way. However, future FCs could do the job for a long time. Main highways could have hydrogen stations every 100+ miles or so or they could be transported by e-trains.

The real problem will be with heavy commercial airplanes. Too many FCs and batteries would be required. A new technology is required.


I agree with about everything posted since my initial comment.

I apologize for coming on so strong. We agree. Continued research and development support is needed for liquid fuels. Electric transport cannot do it all.

Thanks for the response. I agree 3PeaceSweet has it right. That's why I think ethanol needs to be phased out in favor of 100% blendable or alternative fuels. Butanal, biogasoline, biodiesel, bioGTL, etc.

Reel$$ and SJC,
I agree that:
"The goal should be just what is happening now. The steady transition to electrification via EV and PHEVs that CAN use E85 or blends."
"This either/or discussion makes no sense, it is an AND deal."
Although, I do think Harvey has a point about the food for fuel problem. The increased cost of corn has already been a problem in Mexico and we should be supporting a food export market. We don't have enough exports. Cellulosic and algae will help solve this problem as this technology marches on.

I agree but am not as optimistic as you. I believe EVs and PHEVs will be cost effective and will be taking off in sales volumes by 2020. I don't think there will be enough EVs or charging stations by then to transition to all EVs. I think battery prices will drop by then, but I'm not sure they'll drop enough to make 300 mile EVs economical. I'd love to be wrong on that.
I also doubt hydrogen will have any role to play in transport, especially by 2020. Several tough problems there. Nocera's electrolysis may make hydrogen useful as low cost long-term storage for solar and wind by then. I think fuels, hopefully more biofuels, will continue to play a role for heavy trucking, planes, plastics, and fertilizers for some time into the future. Some of these, plastics and fertilizers, may always require a source of carbon based fuels. (Although I don't like to say "always". You can see trends, but that only lets you make educated guesses about the relatively short term future. When will fusion come to pass?))


mds. Even if electrified vehicles go main stream by 2020+, it does mean that ICE vehicles will disappear over night. The phasing out of the 2B ICE vehicles will probably take 30 to 40 years and progressively decreasing volume of liquid fuels will be required during that phase.

By the time that most or 90+% of ICE vehicles have been replaced (by 2050/2060?), the remaining 10% (heavy long range vehicles?) may stick around for a while. By that time, jet engines may have been replaced by new propulsion technologies. Here too, Jet Engines will no be phased out over night, it may take 3 to 4 decades to replace them.

ICE vehicles can be improved but they will be phased out by the middle of the current century.


So, the liquid fuel phase of transportation is going to eventually contract. But remember the emerging nations' reluctance to mandate EVs or even PHEVs. This is making a catastrophe in India and China where they have no infrastructure to handle the millions of new cars. Nor do they have the political will to limit the type of liquid fuels made available.

Thus as the developed world ends its oil addiction - it appears the developing world is repeating our mistakes. With the failure of China's BEV industry this bodes badly for the future of green energy in those nations.


Phase in a mandate for E85 and M85 fuels for all cars and light trucks over a reasonably short time. Re-direct some of the ethanol subsidy to subsidize E85 pump retrofits and mandate E85 pumps for all new construction and remodels. Phase out, over time, corn ethanol and continue the subsidy for cellulosic ethanol. Note: these simple options were not even considered in this study --just rejected as "not going to happen".

GM and Ford are increasing the percentages of FFV in their fleets, others not so much. At 11.5 million 100% FFV produced per year, the E85 capable fleet numbers would increase dramatically with these mandates in a short time.

Compared to the current mandate of dramatically higher CAFE which will greatly increase vehicle costs (and I support), these small and relatively cheap steps could be easily done.


Chops....higher CAFE which will greatly increase vehicle cost........... This is not true. The new Sonata 2011 uses 25% less fuel and cost less. Al current ICE vehicles can be made 25+% more efficient at the same or lower cost. A more aerodynamic vehicle does not necessarily cost more. A more efficient lighter power plant can cost even less than older heavier units etc. The idea that more efficient units cost more has been well orchestrated Big-3 propaganda for too long.

Going from gasoline to ethanol does not cost less but often cost more.

Eventually, alternative liquid fuels made from coal and NG/SG may be better solutions for special uses such as airplanes and heavy vehicles.

Ground cargo could be handled by e-trains with e-truck at each ends for final delivery.


"ICE vehicles can be improved but they will be phased out by the middle of the current century."
I agree for light trucks and cars, with the caveat that E-REVs (Series PHEVs) may still be in used. We will cut out half our oil use but we still need alternative sources or solutions for long-haul trucking, airlines, and industrial uses.

The developing world is a problem, but this is already changing. China and India are already adopting wind and solar. This will accelerate. They will not be the early adopters of EVs and PHEVs because of the new-tech price premium. This will change with increasing economies of scale and then they will adopt faster than the USA.


The OFS will buy us some time. We can install many more E85 and blender pumps every day as soon as we get over the permission and finance road blocks. It does not make any sense having less than 1% E85 pumps and almost 10% E85 capable vehicles.

I would like to see us use 1% LESS imported oil each year and NOT 1% more each year. We will not reach those goals with EVs because there will not be that many sold. I can convert my car to run on E85, but the nearest pump is 30 miles away. That will not do.



I agree both nations are pursuing alternative energy for their grids. They are doing little to mitigate problems inherent to ICEs. We are told daily that China's low cost manufacturing can build anything at a fraction of the cost in the West. How about a simple EV???? For domestic consumption?

Fact is the best selling car in China is the Buick Excelle - a big luxury-type sedan. If the Chinese government really cared about their air quality (worst in the world), 10 day-long traffic jams, or oil addiction - they would mandate an EV production program. Clearly they do not.

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