Butanol fuel

Butanol fuel

Butanol may be used as a fuel in an internal combustion engine. Because its longer hydrocarbon chain causes it to be fairly non-polar, it is more similar to gasoline than is ethanol. Butanol has been demonstrated to work in some vehicles designed for use with gasoline without any modification.cite web
url= http://www.butanol.com
title= ButylFuel, LLC
date= |year= |month= |format= |work= |publisher=
accessdate= 2008-01-29
] It can be produced from biomass (as "biobutanol") as well as fossil fuels (as "petrobutanol"); both biobutanol and petrobutanol have the same chemical properties.

Production of biobutanol

Butanol from biomass is called biobutanol [ [http://www.eere.energy.gov/afdc/fuels/emerging_biobutanol.html Alternative Fuels and Advanced Vehicles Data Center: Biobutanol ] ] .


It can be produced by fermentation of biomass by the A.B.E. process. The process uses the bacterium "Clostridium acetobutylicum", also known as the "Weizmann organism". It was Chaim Weizmann who first used this bacteria for the production of acetone from starch (with the main use of acetone being the making of Cordite) in 1916. The butanol was a by-product of this fermentation (twice as much butanol was produced). The process also creates a recoverable amount of H2 and a number of other by-products: acetic, lactic and propionic acids, acetone, isopropanol and ethanol.

The difference from ethanol production is primarily in the fermentation of the feedstock and minor changes in distillation. The feedstocks are the same as for ethanol: energy crops such as sugar beets, sugar cane, corn grain, wheat and cassava as well as agricultural byproducts such as straw and corn stalks.Fact|date=October 2008 According to DuPont, existing bioethanol plants can cost-effectively be retrofitted to biobutanol production. [http://www.dupont.com/ag/news/releases/BP_DuPont_Fact_Sheet_Biobutanol.pdf DuPont Fact Sheet on Biobutanol] (PDF).]

Algae butanol

Biobutanol can be made entirely with solar energy, from algae (called Solalgal Fuel) or diatoms. [ [http://www.fossilfreedom.com Fossil Freedom - Home Page] ]

Centia process

Centia is based on a three-step thermal, catalytic, and reforming process that has the potential to turn virtually any lipidic compound—e.g., vegetable oils, oils from animal fat and oils from algae—into 1-for-1 replacements for petroleum jet fuel, diesel, and gasoline. The three steps are: [cite web
url= http://www.greencarcongress.com/2008/01/centia-biofuels.html
title= Centia Biofuels Process Produces Bio-gasoline Similar to Conventional Unleaded Gasoline
author= |last= |first= |authorlink= |coauthors=
date= 9 January 2008 |work= |publisher= Green Car Congress
pages= |language= |doi= |archiveurl= |archivedate= |quote=
accessdate= 2008-01-29

* Hydrolytic conversion.
* Decarboxylation.
* Reforming long-chain alkanes.


ButylFuel, LLC used a U.S. Department of Energy Small Business Technology Transfer [ [http://www.er.doe.gov/sbir/ Small Business Innovation Research ] ] grant to develop a process aimed at making biobutanol production economically competitive with petrochemical production processes. ButylFuel is planning to market its biobutanol as a solvent first, and then market it as a fuel in the future.

DuPont and BP are making biobutanol the first product of their joint effort to develop, produce, and market next-generation biofuels. In Europe the Swiss company Butalco [http://www.butalco.com] is developing genetically modified yeasts for the production of biobutanol from cellulosic materials.


Butanol better tolerates water contamination and is less corrosive than ethanol and more suitable for distribution through existing pipelines for gasoline. In blends with diesel or gasoline, butanol is less likely to separate from this fuel than ethanol if the fuel is contaminated with water. There is also a vapor pressure co-blend synergy with butanol and gasoline containing ethanol, which facilitates ethanol blending. This facilitates storage and distribution of blended fuels.cite web
url= http://www.ext.colostate.edu/PUBS/FARMMGT/05010.html
title= Alcohol for Motor Fuels
author= J.L. Smith | coauthors= J.P. Workman
date= December 20, 2007 |work= |publisher= Colorado State University
accessdate= 2008-01-29
] cite web
url= http://www.usatoday.com/money/industries/energy/2006-06-20-butanol_x.htm?csp=34
title= "DuPont, BP join to make butanol; they say it outperforms ethanol as a fuel additive"
author= Randall Chase | date= 2006-06-23 | publisher= Associated Press
accessdate= 2008-01-29

Properties of common fuels

Energy content and effects on fuel economy

Switching a gasoline engine over to butanol would in theory result in a fuel consumption penalty of about 10% [Calculated from the difference in energy densities listed above] but butanol's effect on mileage is yet to be determined by a scientific study. While the energy density for any mixture of gasoline and butanol can be calculated, tests with other alcohol fuels have demonstrated that the effect on fuel economy is not proportional to the change in energy density. [ [http://www.ethanol.org/pdf/contentmgmt/ACEFuelEconomyStudy_001.pdf ACE Fuel Economy Study] (PDF).]

Octane rating

The octane rating of n-butanol is similar to that of gasoline but lower than that of ethanol and methanol. n-Butanol has a RON (Research Octane number) of 96 and a MON (Motor octane number) of 78 while t-butanol has octane ratings of 105 RON and 89 MON. [ [http://www.unep.org/PCFV/Documents/PubGraboskiReport.pdf UNEP.org-Properties of oxygenates] (PDF).] t-Butanol is used as an additive in gasoline but cannot be used as a fuel in its pure form because its relatively high melting point of 25.5 °C causes it to gel and freeze near room temperature.

A fuel with a higher octane rating is less prone to knocking (extremely rapid and spontaneous combustion by compression) and the control system of any modern car engine can take advantage of this by adjusting the ignition timing. This will improve energy efficiency, leading to a better fuel economy than the comparisons of energy content different fuels indicate. By increasing the compression ratio, further gains in fuel economy, power and torque can be achieved. Conversely, a fuel with lower octane rating is more prone to knocking and will lower efficiency. Knocking can also cause engine damage. [{cite web |url = http://www.motorera.com/dictionary/EN.HTM |title = DICTIONARY OF AUTOMOTIVE TERMS - "En" (scroll way down to "engine knock")~~~~ |accessdate=2008-03-21]

Air-fuel ratio

Alcohol fuels, including butanol and ethanol, are partially oxidized and therefore need to run at richer mixtures than gasoline. Standard gasoline engines in cars can adjust the air-fuel ratio to accommodate variations in the fuel, but only within certain limits depending on model. If the limit is exceeded by running the engine on pure butanol or a gasoline blend with a high percentage of butanol, the engine will run lean, something which can critically damage components. Compared to ethanol, butanol can be mixed in higher ratios with gasoline for use in existing cars without the need for retrofit as the air-fuel ratio and energy content are closer to that of gasoline.

pecific energy

Alcohol fuels have less energy per unit weight and unit volume than gasoline. To make it possible to compare the net energy released per cycle a measure called the fuels specific energy is sometimes used. It is defined as the energy released per air fuel ratio. The net energy released per cycle is higher for butanol than ethanol or methanol and about 10% higher than for gasoline.Fact|date=January 2008


The viscosity of alcohols increase with longer carbon chains. For this reason, butanol is used as an alternative to shorter alcohols when a more viscous solvent is desired. The kinematic viscosity of butanol is several times higher than that of gasoline and about as viscous as high quality diesel fuel. [ [http://www.engineeringtoolbox.com/kinematic-viscosity-d_397.html Engineering Toolbox] ]

Heat of vaporization

The fuel in an engine has to be vaporized before it will burn. Insufficient vaporization is a known problem with alcohol fuels during cold starts in cold weather. As the latent heat of vaporization of butanol is less than half of that of ethanol, an engine running on butanol should be easier to start in cold weather than one running on ethanol or methanol.

Potential problems with the use of butanol fuel

The potential problems with the use of butanol are similar to those of ethanol:Fact|date=January 2008
*To match the combustion characteristics of gasoline, the utilization of butanol fuel as a substitute for gasoline requires fuel-flow increases (though butanol has only slightly less energy than gasoline, so the fuel-flow increase required is only minimal, maybe 10%, compared to 40% for ethanol.)
*Alcohol-based fuels are not compatible with some fuel system components.
*Alcohol fuels may cause erroneous gas gauge readings in vehicles with capacitance fuel level gauging.
*While ethanol and methanol have lower energy densities than butanol, their higher octane number allows for greater compression ratio and efficiency. Higher combustion engine efficiency allows for lesser greenhouse gas emissions per unit motive energy extracted.

As an advantage, butanol production from biomass could be more efficient (i.e. unit engine motive power delivered per unit solar energy consumed) than ethanol or methanol routes. Also, some bacteria that produce butanol are able to digest cellulose, not just starch and sugars.Fact|date=January 2008

Possible butanol fuel mixtures

Standards for the blending of ethanol and methanol in gasoline exist in many countries, including the EU, the US and Brazil. Approximate equivalent butanol blends can be calculated from the relations between the stochiometric fuel-air ratio of butanol, ethanol and gasoline. Common ethanol fuel mixtures for fuel sold as gasoline currently range from 5% to 10%. The share of butanol can be 60% greater than the equivalent ethanol share, which gives a range from 8% to 16%. "Equivalent" in this case refers only to the vehicle's ability to adjust to the fuel. Other properties such as energy density, viscosity and heat of vaporisation will vary and may further limit the percentage of butanol that can be blended with gasoline.Fact|date=January 2008Consumer acceptance may be limited due to the offensive smell of butanol.

Current use of butanol in vehicles

Currently no production vehicle is known to be approved by the manufacturer for use with 100% butanol, though any model that is able to run 10% ethanol blends should be able to use butanol without any problems.Or|date=January 2008

David Ramey drove from Blacklick, Ohio to San Diego, California using butanol in an unmodified 1992 Buick Park Avenue. [cite web
url= http://www.greencarcongress.com/2005/07/boosting_biomas.html
title= Boosting Biomass-to...Butanol?
author= |last= |first= |authorlink= |coauthors=
date= 20 July 2005 |work= | publisher= Green Car Congress
accessdate= 2008-01-29
] Although further long term testing must be done, it is highly likely that most late model cars can run on 100% butanol safely with no modifications. Justification for this conclusion is based on data for RON in comparison of n-Butanol with Gasoline. Also, modern ECU-injected motorcar piston engines are designed to be flexible enough to deliver good performance with 91-RON fuels, which n-Butanol exceeds in RON rating.

Research challenges

The key research challenge that must be resolved is that butanol production inhibits microbial growth even at low concentrations. The result is that the product of the fermentation is less than 2% butanol. The overwhelming majority of the fermentation broth is water, so an energy-intensive distillation step is required for purification. This may be acceptable if the goal is to produce butanol for use as a solvent, but if butanol is to gain traction as a motor fuel, energy inputs into the process need to be minimized. [ [http://i-r-squared.blogspot.com/2007/06/problem-with-biobutanol.html R-Squared Energy Blog] .]

The Swiss company Butalco GmbH uses a special technology to modify yeasts in order to produce butanol instead of ethanol. Yeasts as production organisms for butanol have decisive advantages compared to bacteria. [cite web
url= http://www.butalco.com
title= BUTALCO: Bio-based Innovations
date= | year= 2007 |month= |format= |work= |publisher= Butalco GmbH
pages= |language= |doi= |archiveurl= |archivedate= |quote=
accessdate= 2008-01-29

ee also

* Agricultural byproduct
* Air-fuel ratio
* Bioalcohol
* Biofuel
* Biodiesel
* Biohydrogen
* Bioconversion of biomass to mixed alcohol fuels
* Butanol
* Catalyst
* Distillation
* Emission standards
* Energy crop
* Ethanol fuel
* Gevo
* Fermentation facility
* List of vegetable oils section on oils used as biofuel

External links

* [http://www.eere.energy.gov/afdc/fuels/emerging_biobutanol.html Biobutanol] (EERE).
* http://www.greencarcongress.com/biobutanol/index.html
* [http://i-r-squared.blogspot.com/2006/05/bio-butanol.html Bio-Butanol]
* [http://i-r-squared.blogspot.com/2007/06/problem-with-biobutanol.html The Problem With Biobutanol]
* [http://www.welsch.com/e/index.php?ch
* [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=373084&tools=bot Acetone-butanol fermentation revisited] .
* [http://www.enn.com/energy/article/30121 ENN: New Techniques Create Butanol, A Superior Biofuel]
* [http://www.physorg.com/news140099908.html Argonne's "omnivorous engine," an automobile engine tailored to efficiently run on blends of gasoline, ethanol and butanol] .


* [http://www.butanol.com/ ButylFuel]
* [http://www.bpdupontbiofuels.com/ BP DuPont Biofuels]
* [http://www.dupont.com/ag/news/releases/BP_DuPont_Fact_Sheet_Biobutanol.pdf Biobutanol Fact Sheet] (PDF)
* [http://www.greencarcongress.com/2008/02/dupont-and-bp-p.html DuPont and BP Partnership Targeting Multiple Butanol Molecules; Testing 16% Blends]
* [http://www.butalco.com/ Butalco Biofuels]
* [http://www.butanol.com/ Environmental Energy Inc's Butanol Webpage: butanol.com]
* [http://www.greencarcongress.com/2008/01/centia-biofuels.html Centia Biofuels Process Produces Bio-gasoline Similar to Conventional Unleaded Gasoline] by North Carolina State University and Diversified Energy Corporation (DEC).



* Continuous two-stage ABE fermentation using "Clostridium beijerinckii" NRLL B592 operating with a growth rate in the first stage vessel close to its maximal value, J Mol Microbiol Biotechnol. 2000 Jan;2(1):101-5.
* [http://www.aces.uiuc.edu/news/stories/news3615.html As Gas Prices Climb, Butanol Research Reaches Exciting Stage]
* The Economics of Acetone-Butanol Fermentation: Theoretical and Market Considerations, J.R. Gapes, J Mol Microbiol Biotechnol. 2000 Jan;2(1):27-32.

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